WO2026013112A1 - Improved method for recovering and purifying phosphoric acid from ash - Google Patents

Abstract

The invention relates to a method for recovering phosphoric acid from phosphate-containing ash from waste incinerators, in particular from sewage sludge ash from sewage sludge incinerators. In said method, pure phosphoric acid, in particular purified phosphoric acid, is recovered in multiple steps. Further products produced are calcium sulphate, which is used as a construction material, for example, and acidic metal salt solutions, which can be reused for precipitation in sewage treatment plants. In the improved method according to the invention, turbidity or precipitation occurring in the filtrates, supernatants and eluates is reduced or removed in at least one turbidity separation step.

Description

Improved process for the extraction and purification of phosphoric acid from ash

The invention relates to an improved process for obtaining phosphoric acid from phosphate-containing ash from waste incineration plants, in particular from sewage sludge ash from sewage sludge incineration plants. Pure phosphoric acid, especially purified phosphoric acid, is obtained in several steps. Calcium sulfate, which is used, for example, as a building material, and acidic metal salt solutions, which can be used again for precipitation in wastewater treatment plants, are also produced. In the improved process according to the invention, turbidity or precipitation occurring in the filtrates, supernatants, and eluates is reduced or removed in at least one turbidity separation step.

Phosphoric acid is a highly sought-after raw material used, for example, in the production of fertilizers. To replace finite phosphate rocks, it is well known that European industrialized countries are striving to recover phosphorus and phosphates from waste and wastewater. This is also advisable because phosphate rocks are increasingly contaminated with heavy metals such as cadmium, copper, arsenic, and uranium (some of which is radioactive), and this contamination is found in fertilizers and groundwater. In the coalition agreement of December 2013, the German Federal Government stipulated: "The protection of water bodies from nutrient inputs and pollutants will be strengthened and legally structured in such a way as to correct negative developments. We will end the application of sewage sludge for fertilization purposes and recover phosphorus and other nutrients."

A significant phosphate resource in Europe is wastewater from municipal and industrial sewage treatment plants. Over 50,000 metric tons of phosphorus enter wastewater in Germany each year and are almost entirely precipitated as metal salts using precipitating agents such as iron or aluminum salts and removed with the sewage sludge. Today, phosphate-containing sewage sludge is mostly incinerated, and the resulting ash is either landfilled or otherwise misused (e.g., in road construction or mine backfilling), as the phosphorus it contains is not recovered—with a few exceptions in pilot plants. Similar to other industrial recycling processes, such as the recovery of iron from scrap, the recovery of paper from waste paper, and the recovery of copper and other metals from electrical appliances, the industrial recovery of phosphorus from waste is also possible. A key requirement for this is that the phosphorus-containing residues have a sufficiently high phosphorus concentration and low levels of impurities.

Therefore, there is a need for new, simpler and more economical methods for obtaining phosphoric acid from ash.

Such processes offer a cost-effective way to obtain/produce phosphates or pure phosphoric acid.

The German patents DE102013018650B3 (WO 2015/067328 A1) and DE102014006278B3 (WO 2015/165481 A1) and the German patent application DE102013018652A1, which were filed and granted by Remondis Aqua GmbH % Co. KG, have already described corresponding processes.

The problem is solved very cost-effectively and efficiently with the process described here, which is a further development of the methods mentioned above. Phosphoric acid is extracted from the ash of waste incineration plants by adding diluted phosphoric acid and purifying it. Ash from waste incineration plants—for example, when sewage sludge or animal meal is burned—contains over 10 wt% phosphorus (P), which can be converted to H3PO4. Based on the molar ratios (molecular weight phosphorus/P = 30.98; molar weight phosphoric acid/ _H3PO4 = 98), 10 g of phosphorus yields 31.6 g of phosphoric acid; that is, 31.6 g of H3PO4 can be obtained from 100 g of ash with 10% P.

The invention is based on a process for obtaining phosphoric acid (H3PO4) and calcium sulfate (CaSO4) (including the hydrates CaSO4 x 2 _H2O and CaSO4 x 0.5 _H2O ) from phosphate-containing ash from a waste incineration plant, in which a) in one step the ash is reacted with phosphoric acid, b) in one step the acid-insoluble part of the ash is separated and a first filtrate is formed, and c) in a further step by adding sulfuric acid to the first filtrate calcium sulfate precipitate is obtained and separated, so that a second filtrate is formed.

If ash is dissolved in a dilute phosphoric acid solution according to the invention _, for example in a ratio of 1 part ash to >1 part acid, the _H₃PO₄ concentration in the eluate increases enormously. The resulting phosphoric acid-ash suspension is separated, for example, by a filter (e.g., a belt filter). The filtrate obtained in this way, or the phosphoric acid eluate, which contains mainly calcium in dissolved form in addition to small amounts of metal ions, can be further processed according to the invention.

Calcium sulfate (gypsum) is first precipitated from the phosphoric acid ash eluate by adding sulfuric acid (setting a pH value <1) and phosphoric acid is obtained by protolysis.

HPO ₄ ² ' + Ca ²⁺ + H2SO4 = CaSO ₄ + H ₃ PO ₄ i

The calcium sulfate precipitate (gypsum; _CaSO₄ including the hydrates _CaSO₄ x 2 _H₂O and CaSO₄ x 0.5 H₂O) is filtered off in a known manner. It can be used, for example, as a building material.

The crude acid/phosphoric acid obtained in this way still contains dissolved metals, primarily iron and aluminum, which crystallize out as salts with increasing standing time and concentration. For this reason, the crude acid/phosphoric acid must be freed from interfering metal ions. In principle, all separation processes that can "decompose" acidic metal salt solutions into purified (low-metal) acid and concentrated metal salt solutions using membranes, electrodialysis, osmosis, or ion exchange resins are suitable for this purpose.

According to the invention, however, an ion exchanger is preferably used for phosphoric acid purification. Therefore, following the underlying process described above, the second filtrate is subjected to purification in an ion exchanger in a further process step, so that an eluate is formed. The resins loaded with metal ions can be regenerated using hydrochloric, sulfuric, or nitric acid, especially hydrochloric acid. If these acids are subsequently regenerated—for example, by nanofiltration—acidic metal salt solutions are produced, such as those containing iron or aluminum salts like chlorides, which can then be used for precipitation in wastewater treatment plants.

The filtrates/supernatants and eluates obtained in the entire process (such as the metal-poor eluate from the ion exchanger) are always forms of aqueous phosphoric acid. For process engineering and economic reasons, according to the invention, in a further process step of the underlying process, the filtrate, the supernatant, the eluate and/or the collected phosphoric acid are at least partially recycled for use as phosphoric acid in the reaction with the ash in the first step.

The low-metal crude acid/phosphoric acid of the eluate from the ion exchanger can subsequently be concentrated to a concentration of over 70% H3PO4 by, for example, vacuum evaporation, without crystallization occurring. It can then be sold commercially.

However, an unforeseen problem arose during the execution of the underlying process described above. Turbidity or precipitation occurred in the filtrates, supernatants, and eluates. This turbidity (or turbidity compounds) and precipitation hinders the process, particularly the solid/liquid separation, and also impairs the quality of the phosphoric acid as the final product.

The inventors suspect that the turbidity and precipitation are due to the formation of silicon compounds present in the ash, particularly in sewage sludge ash, which dissolve from it and/or subsequently form. Presumably, silicon compounds originating from sources such as tire abrasion, cosmetics, silanes, and silanols are responsible. These compounds would then partially polymerize in the resulting liquid phases (filtrate, eluate, supernatant), causing the turbidity, precipitates, and other deposits. According to the inventors' observations, the formation of these turbidities/precipitates is dependent on time, temperature, and pH value and is influenced by changes in the ionic composition during purification and concentration in the underlying process. This unforeseen problem of turbidity/precipitation, by limiting the solid/liquid separation, hindered the entire process by which phosphoric acid was recovered from ash from waste incineration plants, in particular from sewage sludge ash from sewage sludge incineration plants, and the inventors have found a solution to these problems, as described below.

OVERVIEW:

In its main aspect (aspect I), the invention comprises a process for obtaining phosphoric acid from phosphate-containing ash from waste incineration plants, in particular from sewage sludge ash from sewage sludge incineration plants. Pure phosphoric acid, especially purified phosphoric acid, is obtained in several steps. Calcium sulfate, which is used, for example, as a building material, and acidic metal salt solutions, which can be used again for precipitation in wastewater treatment plants, are also produced as further products.

In this main aspect (aspect I), the invention comprises a process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid, so that an ash-phosphoric acid suspension is formed, and the ash reacts with the phosphoric acid; b) following step a), in step b), the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension, and a filtrate 1 or a supernatant 1 is obtained; c) following step b), in step c), calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1, and a filtrate 2 or supernatant 2 is obtained; d) following step c), in step d) the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger, yielding an eluate 3; e) following step d), in step e) the eluate 3 eluted from the ion exchanger is recovered as collected phosphoric acid, which is optionally subsequently subjected, at least partially, to volume reduction for concentration in step f); g) following step g), in step b), step c), step d), step e) and/or step f), the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d), e) and/or f) and/or before recycling for use in step a), at least one turbidity precipitation reagent is added to the filtrate, the supernatant, the eluate and/or the collected phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitation reagent and/or turbidity compounds bound to the turbidity precipitation reagent are separated again from the filtrate, the supernatant, the eluate and/or the collected phosphoric acid.

The method according to the invention, in its respective specific embodiments, is characterized as follows:

In embodiment A): that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer.

In embodiment B): that the precipitating reagent added in at least one turbidity separation step, step h), is a non-ionic (synthetic) polymer. In embodiment C): that a turbidity separation step, step h), is carried out in the process when the concentration of the phosphoric acid recovered from the phosphate-containing ash increases. In embodiment D): that in the process a turbidity separation step, step h), is then carried out when the concentration of metal ions in the filtrate(s)/eluate(s) and/or the collected phosphoric acid changes.

In embodiment E): that in the process a turbidity separation step, step h), is carried out when the concentration of the phosphoric acid obtained from the phosphate-containing ash increases, and that in the process a turbidity separation step, step h), is carried out when the concentration of the metal ions in the filtrate(s)/eluate(s) and/or the collected phosphoric acid changes.

In embodiment F): that in the process a turbidity separation step, step h), is carried out when the concentration of the phosphoric acid obtained from the phosphate-containing ash increases, and that in the process a turbidity separation step, step h), is carried out when the concentration of the metal ions in the filtrate(s)/eluate(s) and/or the collected phosphoric acid changes, and that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer.

In a particularly preferred embodiment of this main aspect (aspect I), the invention comprises a process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid, so that an ash-phosphoric acid suspension is formed, and the ash reacts with the phosphoric acid; b) following step a), in step b), the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension, and a filtrate 1 or a supernatant 1 is obtained; c) following step b), in step c), calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1, and a filtrate 2 or supernatant 2 is obtained; d) following step c), in step d) the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger, yielding an eluate 3; e) following step d), in step e) the eluate 3 eluted from the ion exchanger is recovered as collected phosphoric acid; f) following step e), in step f) the collected phosphoric acid (and/or the eluate 3) is at least partially subjected to volume reduction to concentrate the collected phosphoric acid, resulting in concentrated phosphoric acid; g) in step g) following step b), step c), step d), step e) and/or step f) the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d), e) and/or f) and/or before recycling to step g) for use in step a), at least one turbidity precipitating reagent is added to the filtrate, the supernatant, the eluate and/or the collected phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitating reagent and/or turbidity compounds bound to the turbidity precipitating reagent are separated again from the filtrate, the supernatant, the eluate and/or the collected phosphoric acid, and characterized in that the precipitating reagent added in at least one of the turbidity separation steps, step h), is a cationic polymer or a non-ionic polymer.

In a further particularly preferred embodiment of this main aspect (aspect I), the invention comprises a process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid, so that an ash-phosphoric acid suspension is formed, and the ash reacts with the phosphoric acid; b) following step a), in step b) the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension, and a filtrate 1 or a supernatant 1 is formed; c) following step b), in step c) calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1, and a filtrate 2 or supernatant 2 is formed; d) following step c), in step d) the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger, and an eluate 3 is formed; e) following step d), in step e) the eluate 3 eluted from the ion exchanger is recovered as collected phosphoric acid; f) following step e), in step f) the collected phosphoric acid (and/or the eluate 3) is at least partially subjected to volume reduction to concentrate the collected phosphoric acid, so that concentrated phosphoric acid is obtained; g) in step g) following step b), step c), step d), step e) and/or step f) the filtrate, the supernatant, the eluate and/or the collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d), e) and/or f) and/or before recycling in step g) for use in step a), at least one turbidity precipitation reagent is added to the filtrate, the supernatant, the eluate and/or the collected phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitation reagent and/or to the turbidity- The turbidity compounds bound by the precipitating reagent are separated from the filtrate, the supernatant, the eluate and/or the collected phosphoric acid and are characterized in that the precipitating reagent added in at least one of the turbidity separation steps, step h), is a synthetic polyelectrolytic cationic polymer.

A further aspect II) concerns a process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash from a waste incineration plant, in which a) in one step the ash is reacted with phosphoric acid, b) in one step the acid-insoluble part of the ash is separated and a first filtrate is formed, and in at least one turbidity separation step, step h), following step b), at least one turbidity precipitation reagent is added to the filtrate and/or the collected phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitation reagent and/or the turbidity compound(s) bound to the turbidity precipitation reagent are separated again from the filtrate and/or the collected phosphoric acid.

This further aspect II) is characterized in that in at least one of the turbidity separation steps, step h), the added turbidity precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer; or that in at least one turbidity separation step, step h), the added turbidity precipitation reagent is a non-ionic (synthetic) polymer (a preferred example of a non-ionic (synthetic) polymer is Prästol2500®); in particular, characterized in that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a synthetic, polyelectrolytic cationic polymer. A preferred example of a (synthetic and polyelectrolytic) cationic polymer within the meaning of the invention is SK-140®. Another aspect III) concerns a process for obtaining phosphoric acid (H3PO4) and calcium sulfate (CaSC) (including the hydrates CaSC x 2 _H2O and CaSC x 0.5 _H2O ) from phosphate-containing ash from a waste incineration plant, in which a) in one step the ash is reacted with phosphoric acid

5 b) in one step the acid-insoluble part of the ash is separated and a first filtrate is formed, and c) in a further step calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the first filtrate, so that a second filtrate is formed; and in at least one turbidity separation step, step h), following step c) at least one turbidity precipitation reagent is added to the filtrate and/or the collected phosphoric acid or a part thereof and subsequently the at least one turbidity precipitation reagent and/or the turbidity compound(s) bound to the turbidity precipitation reagent are separated again from the filtrate and/or the collected phosphoric acid,

This further aspect III) is characterized in that in at least one of the turbidity separation steps, step h), the added turbidity precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer; or that in at least one turbidity separation step, step h), the added turbidity precipitation reagent is a non-ionic (synthetic) polymer (a preferred example of a non-ionic (synthetic) polymer is Prästol2500®); in particular, characterized in that in at least one of the turbidity separation steps, step h), the added turbidity precipitation reagent is a synthetic, polyelectrolytic cationic polymer. A preferred example of a (synthetic and polyelectrolytic) cationic polymer within the meaning of the invention is SK-140®. Another aspect IV) concerns a process for removing turbidity (or turbidity compounds) and precipitates from phosphoric acid in which, in at least one turbidity separation step, step h), at least one turbidity precipitation reagent is added to the phosphoric acid and subsequently the at least one turbidity precipitation reagent and/or the turbidity compounds bound to the turbidity precipitation reagent are separated from the phosphoric acid.

This further aspect IV) is characterized in that, in at least one of the turbidity separation steps, step h), the added turbidity precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer; or that, in at least one turbidity separation step, step h), the added turbidity precipitation reagent is a non-ionic (synthetic) polymer (a preferred example of a non-ionic (synthetic) polymer is Prästol2500®); in particular, characterized in that, in at least one of the turbidity separation steps, step h), the added turbidity precipitation reagent is a synthetic, polyelectrolytic cationic polymer. A preferred example of a (synthetic and polyelectrolytic) cationic polymer within the meaning of the invention is SK-140®.

Another aspect V) concerns the use of a turbidity precipitation reagent to eliminate turbidity (or turbidity compounds) and precipitates from phosphoric acid.

This further aspect V) is characterized by the fact that the turbidity precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer; or that the turbidity precipitation reagent is a non-ionic (synthetic) polymer (A preferred example of a non-ionic (synthetic) polymer is Prästol2500®.); characterized in particular in that the precipitation reagent is a synthetic, polyelectrolytic cationic polymer. A preferred example of a (synthetic and polyelectrolytic) cationic polymer within the meaning of the invention is SK-140®.

In this use of this further aspect V), preferably in at least one turbidity separation step, step h), the at least one turbidity precipitation reagent is added to the phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitation reagent and/or the turbidity compound(s) bound to the turbidity precipitation reagent are separated from the phosphoric acid.

DETAILED INVENTION DESCRIPTION:

In this main aspect (aspect I), the invention comprises a process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid, so that an ash-phosphoric acid suspension is formed, and the ash reacts with the phosphoric acid; b) following step a), in step b), the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension, and a filtrate 1 or a supernatant 1 is obtained; c) following step b), in step c), calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1, and a filtrate 2 or supernatant 2 is obtained; d) following step c), in step d) the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger and an eluate 3 is formed; e) following step d), in step e) the eluate 3 eluted from the ion exchanger is recovered as collected phosphoric acid, wherein this optionally, in step f) the filtrate is at least partially subjected to volume reduction for concentration; g) in step g) following step b), step c), step d), step e) and/or step f), the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d), e) and/or f) and/or before recycling for use in step a), at least one turbidity precipitating reagent is added to the filtrate, supernatant, eluate and/or collected phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitating reagent and/or turbidity compounds bound to the turbidity precipitating reagent are separated from the filtrate, supernatant, eluate and/or collected phosphoric acid.

The method according to the invention, in its respective specific embodiments, is characterized as follows:

In embodiment A): that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer.

In embodiment B): that the precipitating reagent added in at least one turbidity separation step, step h), is a non-ionic (synthetic) polymer. In embodiment C): that a turbidity separation step, step h), is carried out in the process when the concentration of the phosphoric acid recovered from the phosphate-containing ash increases.

In embodiment D): that in the process a turbidity separation step, step h), is then carried out when the concentration of metal ions in the filtrate(s)/eluate(s) and/or the collected phosphoric acid changes.

In embodiment E): that in the process a turbidity separation step, step h), is carried out when the concentration of the phosphoric acid obtained from the phosphate-containing ash increases, and that in the process a turbidity separation step, step h), is carried out when the Concentration of metal ions in the filtrate(s)/eluate(s) and/or the collected phosphoric acid changed.

In embodiment F): that in the process a turbidity separation step, step h), is carried out when the concentration of the phosphoric acid obtained from the phosphate-containing ash increases, and that in the process a turbidity separation step, step h), is carried out when the concentration of the metal ions in the filtrate(s)/eluate(s) and/or the collected phosphoric acid changes, and that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer.

In a particularly preferred aspect of this main aspect, the invention comprises a process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid, so that an ash-phosphoric acid suspension is formed, and the ash reacts with the phosphoric acid; b) following step a), in step b) the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension, and a filtrate 1 or a supernatant 1 is obtained; c) following step b), in step c) calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1, and a filtrate 2 or supernatant 2 is obtained; d) following step c), in step d) the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger, yielding an eluate 3; e) following step d), in step e) the eluate 3 eluted from the ion exchanger is recovered as collected phosphoric acid; f) following step e), in step f) the collected phosphoric acid (and/or the eluate 3) is at least partially subjected to a volume reduction for The collected phosphoric acid is subjected to concentration so that concentrated phosphoric acid is obtained; g) in a step g) following step b), step c), step d), step e) and/or step f) the filtrate, supernatant, eluate and/or the collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d), e) and/or f) and/or before recycling (step g)) for use in step a), at least one turbidity precipitation reagent is added to the filtrate, the supernatant, the eluate and/or the collected phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitation reagent and/or turbidity compounds bound to the turbidity precipitation reagent are separated again from the filtrate, the supernatant, the eluate and/or the collected phosphoric acid, and characterized in that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer.

It is particularly preferred if, in the inventive method, no turbidity separation step, step h), is carried out during or directly following step b) or before step c).

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), the cationic polymer is a synthetic cationic polymer.

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), the cationic polymer is a polyelectrolytic cationic polymer.

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), the cationic polymer is a synthetic, polyelectrolytic cationic polymer. In preferred embodiments of this method according to the invention (and the aforementioned embodiments), in at least one turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density; preferably, in at least one turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter.

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), in each turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density; preferably, in each turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter.

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), the turbidity compounds are silicon compounds.

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), at least one of these turbidity separation steps, step h), is carried out following step f); or, at least one of these turbidity separation steps, step h), is carried out before step g).

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), at least one of these turbidity separation steps, step h), is carried out following step f) and before step g; or is carried out.

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), at least one of these turbidity separation steps, step h), is carried out following step e) and before step g).

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), at least one of these turbidity- Separation steps, step h), following step c) or at least one of these turbidity separation steps, step h), following step c) and before step d).

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), at least one of these turbidity separation steps, step h), is carried out following step d); or at least one of these turbidity separation steps, step h), is carried out following step d) and before step f).

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), at least one of these turbidity separation steps, step h), is carried out following step c) and at least one of these turbidity separation steps, step h), is carried out following step d); or at least one of these turbidity separation steps, step h), is carried out following step c) and before step d) and at least one of these turbidity separation steps, step h), is carried out following step d) and before step f).

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), at least one of these turbidity separation steps, step h), is carried out following step c) and before step d), or at least one of these turbidity separation steps, step h), is carried out following step d) and before step f); and at least one of these turbidity separation steps, step h), is carried out following step f); and/or (or) at least one of these turbidity separation steps, step h), is carried out before step g); or at least one of these turbidity separation steps, step h), is carried out following step f) and before step g).

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), at least one of these turbidity separation steps, step h), is carried out following step c), and at least one of these turbidity separation steps, step h), is carried out following step d); and at least one of these turbidity separation steps, step h), is carried out following

step f); andZor.(or) at least one of these turbidity separation steps, step h), before step g) or at least one of these turbidity separation steps, step h), is carried out following step f) and before step g).

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), at least one of these turbidity separation steps, step h), is performed following step c) and before step d), and at least one of these turbidity separation steps, step h), is performed following step d) and before step f); and at least one of these turbidity separation steps, step h), is performed following step f) and/or at least one of these turbidity separation steps, step h), is performed before step g), or at least one of these turbidity separation steps, step h), is performed following step f) and before step g).

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), the precipitation reagent added in one of these respective turbidity separation steps, step h), is a cationic polymer, a cationic synthetic polymer or a synthetic polyelectrolytic cationic polymer;

In preferred embodiments of this method according to the invention (and the aforementioned embodiments), the precipitation reagent added in each of these respective turbidity separation steps, step h), is a cationic polymer, a cationic synthetic polymer or a synthetic polyelectrolytic cationic polymer.

In preferred embodiments of this process according to the invention, the phosphate-containing ash is obtained by burning phosphate-containing sewage sludge, biodegradable waste, biowaste and/or animal waste in a waste incineration plant or sewage sludge incineration plant, in particular by obtaining the phosphate-containing ash by burning phosphate-containing sewage sludge and/or animal waste in a waste incineration plant or sewage sludge incineration plant, preferably by obtaining the phosphate-containing ash by This is obtained by burning phosphate-containing sewage sludge in a sewage sludge incineration plant.

In preferred embodiments of the process according to the invention, in step a) the reaction between the ash and the phosphoric acid lasts 2 to 300 minutes, preferably 10 to 60 minutes, or less than 10 minutes, preferably in step a) the reaction between the ash and the phosphoric acid lasts less than 5 minutes, or particularly preferably in step a) the reaction between the ash and the phosphoric acid lasts less than 2 minutes, wherein the reaction between the ash and the phosphoric acid preferably lasts between 1 and 2 minutes, less than 1.75 minutes, less than 1.5 minutes, less than 1 minute, or less than 30 seconds; and/or in step a) the reaction between the ash and the phosphoric acid takes place at room temperature or at between 20°C and 30°C or at 15°C to 70°C, or at 25°C to 50°C; and/or in step a) the reaction between the ash and the phosphoric acid is carried out with dilute phosphoric acid, preferably in aqueous dilution, preferably in step a) the reaction between the ash and the phosphoric acid is carried out with a dilute phosphoric acid in a concentration of 5 wt.% to 50 wt.%, preferably 10 wt.% to 30 wt.%, preferably in aqueous dilution, particularly preferably with a dilute phosphoric acid with a concentration between 25 wt.% to 35 wt.%, preferably in aqueous dilution; and/or in step a) in the reaction between the ash and the phosphoric acid, the proportion of ash is 5 wt.% to 50 wt.%, preferably 20 wt.% to 30 wt.% or 25 wt.% to 35 wt.% or 20 wt.% to 35 wt.% or 25 wt.% based on the ash-phosphoric acid suspension; and/or in step a) the reaction between the ash and the phosphoric acid takes place in a reactor. In preferred embodiments of the method according to the invention

- in step b), the separation of the acid-insoluble part of the ash is carried out using dewatering units; preferably, in step b), the separation of the acid-insoluble part of the ash is carried out using a vacuum belt filter, chamber filter press, membrane filter press, belt screen press, or centrifuge; particularly preferably, in step b), the separation of the acid-insoluble part of the ash is carried out using a vacuum belt filter; and/or

- in step b) after separation of the acid-insoluble part of the ash, the residue (from the (retentate 1 or precipitate 1 ) is washed with water, preferably in step b) after separation of the acid-insoluble part of the ash, the residue is washed with water in the dewatering units, optionally the wash water is recycled for use in step a) or the wash water is combined with the filtrate 1 or supernatant 1 before step c).

In preferred embodiments of the method according to the invention

- in step c) a pH value <1 is adjusted by adding sulfuric acid to filtrate 1 or supernatant 1; and/or in step c) sulfuric acid is added in a dilution of 10 to 98 wt.%, preferably 40 to 80 wt.%; and/or

- in step c) the sulfuric acid is added in a molar ratio corresponding to the dissolved calcium concentration of 0.5 Ca to 1.5 SO4 (sulfate), preferably 1.0 Ca to 1.0 SO4 (sulfate); and/or in step c) the sulfuric acid is added in a stirred reactor; and/or the precipitation in step c) takes place over a period of 1 to 7 or 1 to 12 hours, preferably 2 to 6 or 2 to 12 hours, in particular 3 to 5 or 3 to 10 hours or approximately 4 hours;

- and/or the precipitation in step c) is carried out by stoichiometric addition of sulfuric acid in a 1:1 ratio of sulfate to calcium ions; and/or - in step c) the reaction temperature during the precipitation of calcium sulfate after the addition of sulfuric acid in the stirred reactor is 20° to 90°C, preferably 60° to 90°C; and/or

- in step c) the calcium sulfate precipitate is separated by mechanical filtration and/or dehydration processes; and/or

- in step c) the calcium sulfate precipitate is separated using dewatering units; preferably in step c) the calcium sulfate precipitate is separated using a vacuum belt filter, a chamber filter press, a membrane filter press, a belt screen press, or a centrifuge; particularly preferably in step c) the calcium sulfate precipitate is separated using a vacuum belt filter; and/or

- in step c) after separation of the calcium sulfate precipitate, the residue is washed with water, preferably in step c) after separation of the calcium sulfate precipitate, the residue is washed with water in the dewatering units, optionally the wash water is recycled for use in step a) or the wash water is combined with the filtrate 2 or supernatant 2 before step d).

In preferred embodiments of the inventive method, in step d) the ion exchanger is subjected to at least one washing step, preferably with water, after the purification of the filtrate 2 or the supernatant 2, so that a further eluate 4 is formed.

In preferred embodiments of the process according to the invention, in step e) in addition to the eluate 3, the eluate 4 eluted from the ion exchanger after at least one washing step, preferably with water, is also obtained as collected phosphoric acid.

In preferred embodiments of the method according to the invention

- Following step e), the eluate 3 and optionally the eluate 4, or the collected phosphoric acid, are subjected in step f) at least partially to a volume reduction to concentrate the collected phosphoric acid, so that concentrated phosphoric acid is obtained; preferably Following step e), the eluate 3 and the eluate 4 eluted from the ion exchanger after at least one washing step, preferably with water, or the collected phosphoric acid, are subjected in step f) to a volume reduction to concentrate the collected phosphoric acid, so that concentrated phosphoric acid is obtained; and/or

- the phosphoric acid collected following step e) or the phosphoric acid concentrated in step f) is concentrated to 65 - 85 wt.% by volume reduction; or the phosphoric acid collected following step e) or the phosphoric acid concentrated in step f) is divided into part A and part B, and part A of the phosphoric acid is recycled for use in step a), wherein preferably this part A of the collected or concentrated phosphoric acid has a concentration of 25–35 wt.% or is concentrated to 25–35 wt.% by volume reduction, and preferably part B of the collected or concentrated phosphoric acid is concentrated to 65–85 wt.%, wherein part A preferably constitutes at least 20%, more preferably 20% to 80%, and even more preferably 40% to 66% or 80% to 85%, based on the total volume of the collected or concentrated phosphoric acid from part A and part B, wherein the volume reduction is preferably achieved by evaporation, in particular vacuum evaporation.

In preferred embodiments of the method according to the invention

- In step g), at least 10% of the filtrate, supernatant, eluate and/or collected phosphoric acid is recycled for use in step a), preferably at least 20%, more preferably 20% to 80%, and even more preferably 40% to 66% or 80% to 85%, based on the total amount of filtrate, supernatant, eluate and/or collected phosphoric acid obtained. Step g) is carried out following step d), step e) and/or step f), preferably following step d), step e) or step f), particularly preferably following step f).

In preferred embodiments of the method according to the invention, in at least one turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably, in at least one turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter.

In a particularly preferred embodiment of the main aspect (aspect I), the invention comprises a process (the process according to the invention) for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid, so that an ash-phosphoric acid suspension is formed, and the ash reacts with the phosphoric acid, b) following step a), in step b) the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension, and a filtrate 1 or a supernatant 1 is obtained; c) following step b), in step c) calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1, and a filtrate 2 or supernatant 2 is obtained; d) following step c), in step d) the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger and an eluate 3 is formed; e) following step d), in step e) the eluate 3 eluted from the ion exchanger is obtained as collected phosphoric acid, f) following step e), in step f) the collected phosphoric acid (and/or the eluate 3) is at least partially subjected to a volume reduction to concentrate the collected phosphoric acid, so that concentrated phosphoric acid is obtained; g) in step g) following step b), step c), step d), step e) and/or step f) the filtrate, supernatant, eluate and/or the collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d), e) and/or f) and/or before recycling to step g) for use in step a), at least one turbidity precipitating reagent is added to the filtrate, the supernatant, the eluate and/or the collected phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitating reagent and/or turbidity compounds bound to the turbidity precipitating reagent are separated again from the filtrate, the supernatant, the eluate and/or the collected phosphoric acid, and characterized in that the precipitating reagent added in at least one of the turbidity separation steps, step h), is a cationic polymer or a non-ionic polymer.

In a further particularly preferred embodiment of the main aspect (aspect I), the invention comprises a process (the process according to the invention) for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in a step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid, so that an ash-phosphoric acid suspension is formed, and the ash reacts with the phosphoric acid, b) following step a), in a step b) the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension and a filtrate 1 or a supernatant 1 is formed; c) following step b), in step c), calcium sulfate precipitate is obtained and separated by adding sulfuric acid to filtrate 1 or supernatant 1, and filtrate 2 or supernatant 2 is formed; d) following step c), in step d), the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger, and eluate 3 is formed; e) following step d), in step e), the eluate 3 eluted from the ion exchanger is obtained as collected phosphoric acid; f) following step e), in step f), the collected phosphoric acid (and/or eluate 3) is at least partially subjected to volume reduction to concentrate the collected phosphoric acid, so that concentrated phosphoric acid is formed; g) in a step g) following step b), step c), step d), step e) and/or step f) the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d), e) and/or f) and/or before recycling in step g) for use in step a), at least one turbidity precipitation reagent is added to the filtrate, the supernatant, the eluate and/or the collected phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitation reagent and/or turbidity compounds bound to the turbidity precipitation reagent are separated again from the filtrate, the supernatant, the eluate and/or the collected phosphoric acid, and characterized in that the precipitation reagent added in at least one of the turbidity separation steps, step h), is a synthetic polyelectrolytic cationic polymer. A further aspect II) concerns a process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash from a waste incineration plant, in which a) in one step the ash is reacted with phosphoric acid, b) in one step the acid-insoluble part of the ash is separated and a first filtrate is formed, and in at least one turbidity separation step, step h), following step b) at least one turbidity precipitation reagent is added to the filtrate and/or the collected phosphoric acid or a part thereof and subsequently the at least one turbidity precipitation reagent and/or the turbidity compound(s) bound to the turbidity precipitation reagent are separated again from the filtrate and/or the collected phosphoric acid.

This further aspect II) is characterized in that in at least one of the turbidity separation steps, step h), the added turbidity precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer; or that in at least one turbidity separation step, step h), the added turbidity precipitation reagent is a non-ionic (synthetic) polymer (a preferred example of a non-ionic (synthetic) polymer is Prästol2500®); in particular, characterized in that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a synthetic, polyelectrolytic cationic polymer. A preferred example of a (synthetic and polyelectrolytic) cationic polymer within the meaning of the invention is SK-140®.

Another aspect III) concerns a process for obtaining phosphoric acid (H3PO4) and calcium sulfate (CaSO4) (including the hydrates CaSO4 x 2 _H2O and CaSO4 x 0.5 _H2O ) from phosphate-containing ash from a waste incineration plant, in which a) in one step the ash is reacted with phosphoric acid b) in one step the acid-insoluble part of the ash is separated and a first filtrate is formed, and c) in a further step calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the first filtrate, so that a second filtrate is formed; and in at least one turbidity separation step, step h), following step c), at least one turbidity precipitation reagent is added to the filtrate and/or the collected phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitation reagent and/or the turbidity compound(s) bound to the turbidity precipitation reagent are separated again from the filtrate and/or the collected phosphoric acid.

This further aspect III) is characterized in that in at least one of the turbidity separation steps, step h), the added turbidity precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer; or that in at least one turbidity separation step, step h), the added turbidity precipitation reagent is a non-ionic (synthetic) polymer (a preferred example of a non-ionic (synthetic) polymer is Prästol2500®); in particular, characterized in that in at least one of the turbidity separation steps, step h), the added turbidity precipitation reagent is a synthetic, polyelectrolytic cationic polymer. A preferred example of a (synthetic and polyelectrolytic) cationic polymer within the meaning of the invention is SK-140®.

Another aspect IV) concerns a process for removing turbidity (or turbidity compounds) and precipitates from phosphoric acid in which, in at least one turbidity separation step, step h), at least one turbidity precipitation reagent is added to the phosphoric acid and subsequently the at least one turbidity precipitation reagent and/or the turbidity compounds bound to the turbidity precipitation reagent are separated from the phosphoric acid. This further aspect IV) is characterized in that, in at least one of the turbidity separation steps, step h), the added turbidity precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer; or that, in at least one turbidity separation step, step h), the added turbidity precipitation reagent is a non-ionic (synthetic) polymer (a preferred example of a non-ionic (synthetic) polymer is Prästol2500®); in particular, characterized in that, in at least one of the turbidity separation steps, step h), the added turbidity precipitation reagent is a synthetic, polyelectrolytic cationic polymer. A preferred example of a (synthetic and polyelectrolytic) cationic polymer within the meaning of the invention is SK-140®.

Another aspect V) concerns the use of a turbidity precipitation reagent to eliminate turbidity (or turbidity compounds) and precipitates from phosphoric acid.

This further aspect V) is characterized in that the turbidity-precipitating reagent is a (synthetic and/or polyelectrolytic) cationic polymer; or that the turbidity-precipitating reagent is a non-ionic (synthetic) polymer (a preferred example of a non-ionic (synthetic) polymer is Prästol2500®); in particular, characterized in that the precipitation reagent is a synthetic, polyelectrolytic cationic polymer. A preferred example of a (synthetic and polyelectrolytic) cationic polymer within the meaning of the invention is SK-140®.

In this application of this further aspect V), preferably in at least one turbidity separation step, step h), the at least one turbidity precipitation reagent is added to the phosphoric acid or a part thereof, and then the at least one turbidity precipitation reagent and/or the turbidity compound(s) bound to the turbidity precipitation reagent are separated from the phosphoric acid.

DEFINITIONS

The term "precipitate" as used in the invention refers to the precipitation of a dissolved substance as a solid from a solution, usually triggered by the addition of suitable substances (precipitating agents). In particular, the term includes any completely or partially insoluble precipitate in the form of flakes or crystalline material, in any microcrystalline, crystalline, or amorphous form. The term "precipitate" expressly includes any further processing, modification, refining, etc., of the precipitates obtained in the process according to the invention into powders, dusts, bulk materials, granular materials, grits, etc.

The term "ash" as used in this invention refers to any solid residue from the combustion of organic material, for example, sewage sludge, biodegradable waste, organic waste and/or animal waste, slaughterhouse waste, e.g., animal meal. Ash consists primarily of oxides and silicates of various metals, e.g., Al₂O₃, Fe₂O₃, MgO, MnO, P₂O₅, P₄O₁₀, K₂O, SiO₂, Na₂SiO₃, CaSiO₃, etc.

The term “phosphate-containing ash” as used in the invention refers to ashes, as defined herein, which contain at least one phosphate, as defined herein.

The term “phosphates” as used in the invention refers, firstly, to P2Os and P4O10. Furthermore, the term “phosphates” refers to the salts and esters of orthophosphoric acid (H3PO4), and expressly includes the condensates (polymers) of orthophosphoric acid and their esters. In particular, the term “phosphates” refers to metallic salts of phosphoric acid with the general formula X(Y)m(P04)n, where X and optionally Y are metals selected from the group consisting of aluminum, beryllium, bismuth, lead, calcium (whitlockite), cadmium, chromium, iron, gallium, indium, potassium, cobalt, copper, magnesium, manganese, molybdenum, sodium, nickel, osmium, palladium, rhodium, ruthenium, strontium, titanium, vanadium, tungsten, zinc, and tin. The term “waste incineration plants” as used in the invention refers to all plants, facilities and the like that are suitable for burning the atmospherically combustible components of any type of waste.

The term “sewage sludge” as used in the invention refers to any suspension of finely dispersed particles of a solid substance in a liquid, preferably a liquid originating from a wastewater treatment plant (sewage treatment plant).

In a preferred embodiment, the liquid in which the particles are suspended is a wastewater as defined herein.

The term "wastewater" as used in this invention refers to all liquids of an aqueous and/or organic nature, or mixtures thereof, that do not meet the drinking water quality standards defined by the German Drinking Water Ordinance (TrinkwV) and/or national and/or international drinking water standards (e.g., DIN 2000 in Germany). The term "wastewater" also includes all wastewater as defined in Section 54 Paragraph 1 of the German Water Resources Act (WHG).

In a preferred embodiment, the wastewater referred to in the invention is water that has been contaminated through use or whose properties or composition have been altered. Furthermore, the term "wastewater" as used in the invention includes water whose properties have been altered through domestic, commercial, agricultural, or other use, and the water that flows off with it during dry weather (sewage), as well as water that runs off from precipitation collected from built-up or paved areas (stormwater). Liquids escaping from and collected in facilities for treating, storing, and disposing of waste are also considered wastewater. Sewage includes domestic wastewater from toilets (fecal or blackwater), sanitary facilities, kitchens, and washing machines (wash or greywater), as well as wastewater from businesses that discharge into the public sewer system (commercial or industrial wastewater). Heated water from cooling systems is also considered wastewater. Wastewater generated during the various cleaning and treatment processes of water treatment plants is also considered wastewater as defined in the invention. In a particularly preferred embodiment, the sewage sludge is present as primary sludge, raw sludge, excess sludge, as treated and/or stabilized sewage sludge (aerobic/anaerobic).

The term "biowaste" as used in this invention refers to all organic waste of animal or plant origin that arises in a household or business and can be broken down by microorganisms, soil organisms, or enzymes. This includes, for example, food scraps and grass clippings. Biowaste is generally collected separately via the so-called organic waste bin and treated separately through composting and fermentation. The resulting compost and digestate are often returned to the environment, for example, in horticulture and agriculture. The term "biowaste" encompasses waste as defined in the EU Waste Framework Directive, including garden and park waste as well as food and kitchen waste (from households, restaurants, catering businesses, retail outlets, and food processing companies).

The term "biodegradable waste" as used in the invention includes, in addition to biowaste as defined herein, all organic waste of animal or plant origin from agriculture and forestry that can be degraded by microorganisms, soil organisms, or enzymes. In particular, this term includes all organic waste of animal or plant origin from agriculture and forestry that also contains at least one of the following biodegradable materials selected from the list consisting of wood, paper, and cardboard.

The term "animal waste" as used in the invention includes carcasses of deceased, dead or stillborn large or domestic animals - or parts thereof - as well as slaughter waste, spoiled food of animal origin, and animal by-products such as milk, eggs, confiscated items, but also intestinal contents and manure, as well as all other products and products.

In particular, the term "animal waste" as used in the invention includes meat and animal by-products from domestic animals, wild animals, or farm animals that were killed or died due to illness, especially BSE-infected animal carcasses, as well as animals contaminated with chemicals or prohibited substances and laboratory animals. It also includes meat and by-products that carry the risk of other, non-communicable diseases. The term "animal waste" as used in the invention also includes killed (i.e., not slaughtered) animals, animal by-products (e.g., milk), and any animal products containing drug residues. It also expressly includes all waste and by-products from slaughterhouses, kitchen and food waste, food of animal origin no longer suitable for human consumption, raw milk, fresh fish, or fresh fish by-products. In particular, the following are included:

• Kitchen and food waste of any kind,

• Fish or other marine animals, as well as fish waste of any kind,

• Former animal-based food products that are no longer intended for human consumption due to other, non-harmful consequences, e.g., packaging defects,

• Carcass parts,

• Raw milk,

• Shells, incubator by-products and cracked egg by-products,

• Hair, fur, horns, etc.,

• Animal waste from the food industry,

• Hides, hooves and horns, pig bristles and feathers of animals,

• overripe meat,

• inferior meat,

• Meat from animals under significant stress,

• Blood from animals (not ruminants) that were slaughtered after an examination in a slaughterhouse,

• Animal carcass parts and by-products obtained in the manufacture of products intended for human consumption, defatted bones and greaves, and animal meal.

The term "turbidity-precipitating reagent" as used in this invention refers to a flocculant in the form of a natural or synthetic polymer. Synthetic polymers include, in particular, non-ionic polymers, anionic polymers, and cationic polymers, and natural polymers include, in particular, gelatin.

The term “natural polymer” as used in this invention refers to a flocculant in the form of a natural polymer. This is, in particular, gelatin. The term “synthetic polymer” as used in this invention includes in particular non-ionic polymers, anionic polymers and cationic polymers.

The term “cationic polymer” as used in this invention refers to a preferably polyelectrolytic (carrying multiple charges) polymer that is a flocculant and carries a cationic charge. Preferably, as used in this invention, a synthetic cationic polymer or a polyelectrolytic synthetic cationic polymer is used. A preferred example of a (synthetic and polyelectrolytic) cationic polymer as used in this invention is SK-140®.

The term "non-ionic polymer" as used in this invention refers to a high-molecular-weight polymer that is a flocculant and is non-ionic/non-ionogenic. Preferably, a synthetic non-ionic polymer is used in the invention. A preferred example of a non-ionic (synthetic) polymer is Prästol2500®.

For the purposes of this invention, the term "separation by applying artificial gravity" refers to the separation in the turbidity separation step (step h), in which the separation is carried out by applying artificial gravity. This would be precipitation by gravity separation (centrifugation), for example, also by utilizing the specific density. Equipment such as a centrifuge or a decanter can be used for this purpose.

For the purposes of this invention, the term "turbidity compounds" refers to the turbidity or precipitates in the filtrates, supernatants, and eluates. These turbidity compounds and precipitates impede the process, particularly the solid/liquid separation, and also impair the quality of the phosphoric acid as the final product. In a turbidity separation step (step h), a turbidity precipitation reagent is used to which the turbidity compounds bind and can thus be separated from the filtrate, supernatant, eluate, and/or the collected phosphoric acid. Within the scope of this invention and the processes according to the invention for the production of phosphoric acid (H3PO4) from phosphate-containing ash, the turbidity compounds are silicon compounds. EXECUTION FORMS:

Design A)

Turbidity separation step, step h), with (synthetic and/or polyelectrolytic) cationic polymer

AD Process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid to form an ash-phosphoric acid suspension, and the ash reacts with the phosphoric acid; b) following step a), in step b) the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension to form a filtrate 1 or a supernatant 1; c) following step b), in step c) calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1 to form a filtrate 2 or supernatant 2; d) following step c), in step d) the filtrate 2 or supernatant 2 obtained from step c) is purified in an ion exchanger to form an eluate 3; e) following step d) in step e) the eluate 3 eluted from the ion exchanger is recovered as collected phosphoric acid; g) in step g) following step b), step c), step d) and/or step e) the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d) and/or e) and/or before recycling for use in step a), at least one turbidity precipitation reagent is added to the filtrate, the supernatant, the eluate and/or the collected phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitation reagent and/or turbidity compounds bound to the turbidity precipitation reagent are separated again from the filtrate, the supernatant, the eluate and/or the collected phosphoric acid, and characterized in that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer.

The inventors noticed that the precipitation/separation of the turbidity with (synthetic and/or polyelectrolytic) cationic polymers was particularly successful in the phosphoric acids obtained from sewage sludge ash under investigation.

A2) Method according to embodiment AI), characterized in that the precipitation reagent added in the turbidity separation step, step h), in particular in each turbidity separation step, step h), is a synthetic and/or polyelectrolytic cationic polymer, in particular a synthetic polyelectrolytic cationic polymer.

A3) Method according to one of the embodiments AI) or A2), characterized in that the cationic polymer is SK-140.

A4) Method according to one of the embodiments AI) - A3), characterized in that in at least one turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably in at least one turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter.

A5) Method according to embodiment A4), characterized in that in each

Turbidity separation step, step h), the separation by applying a Artificial gravity, for example by utilizing the specific density, is used to perform gravity separation; preferably in each turbidity separation step, step h), the separation is carried out by an aggregate such as a centrifuge or a decanter.

A6) Method according to one of the embodiments AI) - A5), characterized in that the turbidity compounds are silicon compounds.

A7) Method according to one of the embodiments AI) - A6), characterized in that following step e) the collected phosphoric acid (and/or the eluate 3 and optionally the eluate 4) is subjected in a step f) at least partially to a volume reduction to concentrate the collected phosphoric acid, so that concentrated phosphoric acid is produced.

A8) Method according to embodiment A7), characterized in that at least one of these turbidity separation steps, step h), is carried out following step f).

A9) Method according to embodiment A7), characterized in that at least one of these turbidity separation steps, step h), takes place before step g).

A10) Method according to embodiment A7), characterized in that at least one of these turbidity separation steps, step h), is carried out following step f) and before step g).

A11) Method according to one of the embodiments AI) - A10), characterized in that at least one of these turbidity separation steps, step h ) , is carried out following step c); or at least one of these turbidity separation steps, step h ) , is carried out following step c) and before step d).

A12) Method according to one of the embodiments AI) - A11), characterized in that at least one of these turbidity separation steps, step h ) , is carried out following step d); or at least one of these turbidity separation steps, step h ) , is carried out following step d) and before step f). A13) Method according to one of the embodiments AI) - A12), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c) and at least one of these turbidity separation steps, step h), is carried out following step d); or at least one of these turbidity separation steps, step h), is carried out following step c) and before step d) and at least one of these turbidity separation steps, step h), is carried out following step d) and before step f).

A14) Method according to embodiment A7), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c), at least one of these turbidity separation steps, step h), is carried out following step d), and at least one of these turbidity separation steps, step h), is carried out following step f).

A15) Method according to one of the embodiments A7) - A14), characterized in that a turbidity separation step is carried out after each step h) after step c), after step d) and after step f).

A16) Method according to one of the embodiments A7) - A13), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c) and before step d) or at least one of these turbidity separation steps, step h), is carried out following step d) and before step f); and that at least one of these turbidity separation steps, step h), is carried out following step f); or at least one of these turbidity separation steps, step h), is carried out before step g); or at least one of these turbidity separation steps, step h), is carried out following step f) and before step g).

A17) Method according to one of the embodiments A7) - A13), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c) and at least one of these turbidity separation steps, step h), is carried out following step d); and that at least one of these turbidity separation steps, step h), is performed following step f); or at least one of these turbidity separation steps, step h), is performed before step g); or at least one of these turbidity separation steps, step h), is performed following step f) and before step g).

A18) Method according to one of the embodiments A7) - A13), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c) and before step d) and at least one of these turbidity separation steps, step h), is carried out following step d) and before step f); and that at least one of these turbidity separation steps, step h), is carried out following step f); or at least one of these turbidity separation steps, step h), is carried out before step g); or at least one of these turbidity separation steps, step h), is carried out following step f) and before step g).

A19) Method according to one of the embodiments A8) - A18), characterized in that the precipitation reagent added in one of these respective turbidity separation steps, step h), is a cationic polymer, a cationic synthetic polymer or a synthetic polyelectrolytic cationic polymer; or that the precipitation reagent added in each of these respective turbidity separation steps, step h), is a cationic polymer, a cationic synthetic polymer or a synthetic polyelectrolytic cationic polymer.

Design B)

Turbidity separation step, step h), with non-ionic (synthetic) polymer

BI) Process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in one step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid, so that an ash-phosphoric acid suspension is formed, and the ash reacts with the phosphoric acid, b) following step a), in step b), the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension, yielding a filtrate 1 or a supernatant 1; c) following step b), in step c), calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1, yielding a filtrate 2 or supernatant 2; d) following step c), in step d), the filtrate 2 or supernatant 2 obtained from step c) is purified in an ion exchanger, yielding an eluate 3; e) following step d), in step e), the eluate 3 eluted from the ion exchanger is obtained as collected phosphoric acid; g) in a step g) following step b), step c), step d) and/or step e) the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d) and/or e) and/or before recycling for use in step a), at least one turbidity precipitation reagent is added to the filtrate, the supernatant, the eluate and/or the collected phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitation reagent and/or turbidity compounds bound to the turbidity precipitation reagent are separated again from the filtrate, the supernatant, the eluate and/or the collected phosphoric acid, and characterized in that the precipitation reagent added in at least one turbidity separation step, step h), is a non-ionic (synthetic) polymer.

The inventors noticed that the precipitation/separation of the turbidity using non-ionic synthetic polymers was successful in the phosphoric acid from sewage sludge ash under investigation. B2) Method according to embodiment B1 , characterized in that the non-ionic synthetic polymer is Prästol2500®.

B3) Method according to one of the embodiments BI) or B2), characterized in that in at least one turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably in at least one turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter.

B4) Method according to embodiment B3), characterized in that in each turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably in each turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter.

B5) Method according to one of the embodiments BI) - B4), characterized in that the turbidity compounds are silicon compounds.

B6) Method according to one of the embodiments BI) - B5), characterized in that following step e) the collected phosphoric acid (and/or the eluate 3 and optionally the eluate 4) is subjected in a step f) at least partially to a volume reduction to concentrate the collected phosphoric acid, so that concentrated phosphoric acid is produced.

B7) Method according to embodiment B6), characterized in that at least one of these turbidity separation steps, step h), is carried out following step f).

B8) Method according to one of the embodiments BI) - B7), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c). B9) Method according to one of the embodiments BI) - B7), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c).

BIO) Method according to one of the embodiments BI) - B7), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c) and at least one of these turbidity separation steps, step h), is carried out following step d).

B1 Method according to embodiment B6), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c), at least one of these turbidity separation steps, step h), is carried out following step d), and at least one of these turbidity separation steps, step h), is carried out following step f).

B12) Method according to one embodiment B6), characterized in that a turbidity separation step is carried out after each step h) after step c), after step d) and after step f).

Design C)

Turbidity separation step, step h), if the concentration of phosphoric acid changes, preferably increases (after each concentration step).

CD process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in a step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid, so that an ash-phosphoric acid suspension is formed, and the ash reacts with the phosphoric acid, b) following step a) in a step b) the acid-insoluble part of the ash (retentate 1 or precipitate 1 ) is separated from the ash-phosphoric acid suspension and a filtrate 1 or a supernatant 1 is formed; c) following step b), in step c), calcium sulfate precipitate is obtained and separated by adding sulfuric acid to filtrate 1 or supernatant 1, resulting in filtrate 2 or supernatant 2; d) following step c), in step d), the filtrate 2 or supernatant 2 resulting from step c) is purified in an ion exchanger, resulting in eluate 3; e) following step d), in step e), the eluate 3 eluted from the ion exchanger is obtained as collected phosphoric acid; f) following step e), in step f), the collected phosphoric acid (and/or the eluate 3) is at least partially subjected to volume reduction to concentrate the collected phosphoric acid, resulting in concentrated phosphoric acid; g) in a step g) following step b), step c), step d) and/or step e), the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d), e) and/or f) and/or prior to step g), the recycling for use in step a), at least one turbidity precipitating reagent is added to the filtrate, supernatant, eluate and/or collected phosphoric acid or a portion thereof, and subsequently the at least one turbidity precipitating reagent and/or turbidity compounds bound to the turbidity precipitating reagent are separated from the filtrate, supernatant, eluate and/or collected phosphoric acid; wherein the precipitating reagent added in step h) is a natural or synthetic polymer; and characterized in that a turbidity separation step, step h), is carried out in the process when the concentration of the phosphoric acid obtained from the phosphate-containing ash increases. It is noticeable that the precipitation/separation of the turbidity is particularly successful when it is carried out after steps in which the recovered phosphoric acid is concentrated. This applies, for example, and especially to step f), so that it is particularly preferred if a turbidity separation step h) is carried out after step f).

C2) Method according to embodiment CI), characterized in that at least one of these turbidity separation steps, step h), is carried out following step f).

C3) Process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid to form an ash-phosphoric acid suspension, and the ash reacts with the phosphoric acid; b) following step a), in step b) the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension to form a filtrate 1 or a supernatant 1; c) following step b), in step c) calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1 to form a filtrate 2 or supernatant 2; d) following step c), in step d) the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger, yielding an eluate 3; e) following step d), in step e) the eluate 3 eluted from the ion exchanger is obtained as collected phosphoric acid; f) following step e), in step f) the collected phosphoric acid (and/or the eluate 3) is at least partially subjected to volume reduction to concentrate the collected phosphoric acid, resulting in concentrated phosphoric acid; g) in a step g) following step b), step c), step d) and/or step e), the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d), e) and/or f) and/or prior to step g), the recycling for use in step a), at least one turbidity precipitating reagent is added to the filtrate, supernatant, eluate and/or collected phosphoric acid or a portion thereof, and subsequently the at least one turbidity precipitating reagent and/or turbidity compounds bound to the turbidity precipitating reagent are separated from the filtrate, supernatant, eluate and/or collected phosphoric acid; wherein the precipitating reagent added in step h) is a natural or synthetic polymer; and characterized in that at least one of these turbidity separation steps, step h), is carried out following step f).

C5) Method according to one of the embodiments CD - C4) characterized in that no turbidity separation step, step h), is carried out after step b).

C6) Method according to one of the embodiments CD - C5) characterized in that no turbidity separation step, step h), is carried out directly after step e).

C7) Method according to one of the embodiments CD - C3) characterized in that in at least one of the following cases no turbidity separation step, step h), is carried out: before a recycling step g) for use in step a),

- after step b) or

- after step e).

C8) Method according to one of the embodiments CD - C3) characterized in that in at least two of the following cases no turbidity separation step, step h), is carried out: before a regression step g) for use in step a), after step b) or after step e).

C9) Method according to one of the embodiments CD - C3) characterized in that in the method according to the invention no turbidity separation step, step h), is carried out during or directly following step b) or before step c).

CIO) Method according to one of the embodiments C1)- C9), characterized in that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer.

C1 process according to one of the embodiments CD - CIO), characterized in that the precipitation reagent added in the turbidity separation step, step h) following step f), is a synthetic and/or polyelectrolytic cationic polymer.

C12) Method according to one of the embodiments CD - C1D, characterized in that in the turbidity separation step, step h), in particular in each turbidity separation step, step h), the added precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer.

C14) Method according to one of the embodiments CIO) - C13), characterized in that the cationic polymer is SK-140.

C15) Method according to one of the embodiments C1)- C9), characterized in that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a non-ionic (synthetic) polymer.

C16) Method according to one of the embodiments CD - C9) and C15), characterized in that the precipitation reagent added in the turbidity separation step, step h) following step f), is a non-ionic synthetic polymer. C17) Method according to one of the embodiments CD - C9), C15) and C16), characterized in that in the turbidity separation step, step h), in particular in each turbidity separation step, step h), the added precipitation reagent is a non-ionic synthetic polymer.

C18) Method according to one of the embodiments C15) - C17), characterized in that the non-ionic synthetic polymer is Prästol2500®.

C19) Method according to one of the embodiments CD - C18), characterized in that in at least one turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably in at least one turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter.

C20) Method according to embodiment C19), characterized in that in each turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably in each turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter.

C2D process according to one of the embodiments CD - C20), characterized in that the turbidity compounds are silicon compounds.

Design D):

Perform the turbidity separation step (step h) when the concentration of metal ions changes, preferably decreases (after each purification step).

DD process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid, so that an ash-phosphoric acid suspension is formed, and the ash reacts with the phosphoric acid; b) following step a), in step b) the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension, and a filtrate 1 or a supernatant 1 is formed; c) following step b), in step c) calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1, and a filtrate 2 or supernatant 2 is formed; d) following step c), in step d) the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger, and an eluate 3 is formed; e) following step d) in step e) the eluate 3 eluted from the ion exchanger is recovered as collected phosphoric acid; g) in step g) following step b), step c), step d) and/or step e) the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that, in at least one turbidity separation step, step h), during or following steps b), c), d) and/or e) and/or prior to step g), the recycling for use in step a), at least one turbidity precipitating reagent is added to the filtrate, the supernatant, the eluate and/or the collected phosphoric acid or a portion thereof, and subsequently the at least one turbidity precipitating reagent and/or turbidity compounds bound to the turbidity precipitating reagent are separated again from the filtrate, the supernatant, the eluate and/or the collected phosphoric acid; wherein the precipitating reagent added in step h) is a natural or synthetic polymer; and characterized in that a turbidity separation step, step h), is carried out in the process when the concentration of metal ions in the filtrate(s)/eluate(s) and/or the collected phosphoric acid changes.

D2) Method according to embodiment DI), characterized in that the concentration of metal ions in the filtrate(s)/eluate(s) or the collected phosphoric acid decreases.

D3) Method according to embodiment DI), characterized in that the concentration of metal ions in the filtrate(s)/eluate(s) or the collected phosphoric acid increases.

It is noticeable that the precipitation/separation of the turbidity was particularly successful when carried out after steps in which the concentration of metal ions in the filtrate(s)/eluate(s) and/or the collected phosphoric acid changes, for example, after a purification step such as gypsum precipitation or purification by the ion exchanger. This applies, for example, and especially, to step d) or step c). Therefore, it is particularly preferred if a turbidity separation step h) is carried out after step c). It is also particularly preferred if a turbidity separation step h) is carried out after step d). It is most particularly preferred if a turbidity separation step h) is carried out after step c) and after step d).

D4) Method according to one of the embodiments DI) - D3), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c).

D5) Method according to one of the embodiments DI) - D3), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c).

D6) Method according to one of the embodiments DI) - D3), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c) and at least one of these turbidity separation steps, step h), is carried out following step d). D7) Method according to one of the embodiments DI) - D6), characterized in that following step e) the collected phosphoric acid (and/or the eluate 3 and optionally the eluate 4) is subjected in a step f) at least partially to a volume reduction to concentrate the collected phosphoric acid, so that concentrated phosphoric acid is produced.

Accordingly, the following D8) is a highly preferred embodiment:

D8) Process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid to form an ash-phosphoric acid suspension, and the ash reacts with the phosphoric acid; b) following step a), in step b) the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension to form a filtrate 1 or a supernatant 1; c) following step b), in step c) calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1, and a filtrate 2 or supernatant 2 is formed; d) following step c), in step d) the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger, yielding an eluate 3; e) following step d), in step e) the eluate 3 eluted from the ion exchanger is obtained as collected phosphoric acid; f) following step e), in step f) the collected phosphoric acid (and/or the eluate 3) is at least partially subjected to volume reduction to concentrate the collected phosphoric acid, resulting in concentrated phosphoric acid; g) in a step g) following step b), step c), step d) and/or step e), the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d), e) and/or f) and/or prior to step g), the recycling for use in step a), at least one turbidity precipitating reagent is added to the filtrate, supernatant, eluate and/or collected phosphoric acid or a portion thereof, and subsequently the at least one turbidity precipitating reagent and/or turbidity compounds bound to the turbidity precipitating reagent are separated from the filtrate, supernatant, eluate and/or collected phosphoric acid; wherein the precipitating reagent added in step h) is a natural or synthetic polymer; and characterized in that at least one of these turbidity separation steps, step h), is carried out following step c) and at least one of these turbidity separation steps, step h), is carried out following step d).

D9) Method according to one of the embodiments DI) - D8) characterized in that no turbidity separation step, step h), is carried out before a recycling step g) for use in step a).

DIO) Method according to one of the embodiments DI) - D8) characterized in that after step b) no turbidity separation step, step h), is carried out.

D11) Method according to one of the embodiments DI) - D8) characterized in that no turbidity separation step, step h), is carried out after step e).

D12) Method according to one of the embodiments DI) - D8) characterized in that in at least one of the following cases no turbidity separation step, step h), is carried out: before a recycling step g) for use in step a),

- after step b) or after step e).

D13) Method according to one of the embodiments DI) - D8) characterized in that in at least two of the following cases no turbidity separation step, step h), is carried out: before a recycling step g) for use in step a),

- after step b) or

- after step e).

D14) Method according to one of the embodiments DI) - D8) characterized in that

D14) Method according to one of the embodiments DI) - C58 characterized in that in the method according to the invention no turbidity separation step, step h), is carried out during or directly following step b) or before step c).

D15) Method according to one of the embodiments DI) - D14), characterized in that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer.

D16) Method according to one of the embodiments DI) - D15), characterized in that the precipitation reagent added in the turbidity separation step, step h) following step f), is a synthetic and/or polyelectrolytic cationic polymer.

D17) Method according to one of the embodiments DI) - D16), characterized in that in the turbidity separation step, step h), in particular in each turbidity separation step, step h), the added precipitation reagent is a synthetic and/or polyelectrolytic cationic polymer.

D19) Method according to one of the embodiments D15) - D18), characterized in that the cationic polymer is SK-140. D20) Method according to one of the embodiments DI) - D14), characterized in that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a non-ionic (synthetic) polymer.

D21 ) Method according to one of the embodiments DI) - D14) and D20), characterized in that the precipitation reagent added in the turbidity separation step, step h) following step f), is a non-ionic synthetic polymer.

D22) Method according to one of the embodiments DI) - D14), D20) and D21 ), characterized in that in the turbidity separation step, step h), in particular in each turbidity separation step, step h), the added precipitation reagent is a non-ionic synthetic polymer.

D23) Method according to one of the embodiments D20) - D22), characterized in that the non-ionic synthetic polymer is Prästol2500®.

D24) Method according to one of the embodiments D1 ) - D23), characterized in that in at least one turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably in at least one turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter.

D25) Method according to embodiment D24), characterized in that in each turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably in each turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter.

D26) Method according to one of the embodiments DI) - D25), characterized in that the turbidity compounds are silicon compounds. Design E)

Turbidity separation step, step h), when the concentration of the phosphoric acid changes, preferably increases (after each concentration step) and turbidity separation step, step h), whenever the concentration of the metal ions in the filtrate(s)/eluate(s) or the collected phosphoric acid changes.

(after each cleaning step)

E1) Process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid to form an ash-phosphoric acid suspension, and the ash reacts with the phosphoric acid; b) following step a), in step b) the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension to form a filtrate 1 or a supernatant 1; c) following step b), in step c) calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1, and a filtrate 2 or supernatant 2 is formed; d) following step c), in step d) the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger, yielding an eluate 3; e) following step d), in step e) the eluate 3 eluted from the ion exchanger is obtained as collected phosphoric acid; f) following step e), in step f) the collected phosphoric acid (and/or the eluate 3) is at least partially subjected to volume reduction to concentrate the collected phosphoric acid, resulting in concentrated phosphoric acid; g) in a step g) following step b), step c), step d) and/or step e), the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d), e) and/or f) and/or prior to step g), the recycling for use in step a), at least one turbidity precipitating reagent is added to the filtrate, supernatant, eluate and/or collected phosphoric acid or a portion thereof, and subsequently the at least one turbidity precipitating reagent and/or turbidity compounds bound to the turbidity precipitating reagent are separated from the filtrate, supernatant, eluate and/or collected phosphoric acid; wherein the precipitating reagent added in step h) is a natural or synthetic polymer; and characterized in that a turbidity separation step, step h), is carried out in the process when the concentration of the phosphoric acid obtained from the phosphate-containing ash increases; and characterized in that a turbidity separation step, step h), is carried out in the process when the concentration of the metal ions in the phosphoric acid obtained from the phosphate-containing ash changes.

E2) Method according to embodiment El), characterized in that the concentration of metal ions in the filtrate(s)/eluate(s) or the collected phosphoric acid decreases.

E3) Method according to embodiment El), characterized in that the concentration of metal ions in the filtrate(s)/eluate(s) or the collected phosphoric acid increases.

It is noticeable that the precipitation/separation of the turbidity is particularly successful when it is carried out after steps in which the recovered phosphoric acid is concentrated. This applies, for example, and in particular, to step f), so it is especially preferred if a turbidity separation step h) is carried out after step f). Furthermore, it is noticeable that the precipitation/separation of the turbidity was also particularly successful when it was carried out after steps in which the concentration of metal ions in the filtrate(s)/eluate(s) and/or the collected phosphoric acid changes, for example, after a purification step such as gypsum precipitation or purification by the ion exchanger. This applies, for example, and in particular, to step d) or also step c). Therefore, it is then particularly preferred if a turbidity separation step h) is carried out after step c). It is also particularly preferred if a turbidity separation step h) is carried out after step d). It is then most particularly preferred if a turbidity separation step h) is carried out after step c) and after step d).

E4) Method according to one of the embodiments El) - E3), characterized in that at least one of these turbidity separation steps, step h), is carried out following step f).

E5) Method according to one of the embodiments El) - E4), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c).

E6) Method according to one of the embodiments El) - E4), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c).

E7) Method according to one of the embodiments El) - E4), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c) and at least one of these turbidity separation steps, step h), is carried out following step d).

E8) Method according to one of the embodiments El) - E3), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c), at least one of these turbidity separation steps, step h), is carried out following step d), and at least one of these turbidity separation steps, step h), is carried out following step f).

Or: E9) Method according to one of the embodiments El) to E3), characterized in that a turbidity separation step is carried out after each step h) after step c), after step d) and after step f).

Accordingly, the following E10) is a highly preferred embodiment:

E10) Process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid to form an ash-phosphoric acid suspension, and the ash reacts with the phosphoric acid; b) following step a), in step b) the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension to form a filtrate 1 or a supernatant 1; c) following step b), in step c) calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1, and a filtrate 2 or supernatant 2 is formed; d) following step c), in step d) the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger, yielding an eluate 3; e) following step d), in step e) the eluate 3 eluted from the ion exchanger is recovered as collected phosphoric acid; f) following step e), in step f) the collected phosphoric acid (and/or the eluate 3) is at least partially subjected to volume reduction to concentrate the collected phosphoric acid, resulting in concentrated phosphoric acid; g) in step g) following step b), step c), step d) and/or step e) the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following steps b), c), d), e) and/or f) and/or before step g), the recycling for use in step a), at least one turbidity precipitating reagent is added to the filtrate, the supernatant, the eluate and/or the collected phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitating reagent and/or turbidity compounds bound to the turbidity precipitating reagent are separated again from the filtrate, the supernatant, the eluate and/or the collected phosphoric acid; wherein the precipitating reagent added in step h) is a natural or synthetic polymer; and characterized in that at least one of these turbidity separation steps, step h), is carried out following step c), at least one of these turbidity separation steps, step h), is carried out following step d), and at least one of these turbidity separation steps, step h), is carried out following step f).

E11) Method according to one of the embodiments E1) - E10) characterized in that no turbidity separation step, step h), is carried out before a recycling step g) for use in step a).

E12) Method according to one of the embodiments E1) - E10) characterized in that no turbidity separation step, step h), is carried out after step b).

E13) Method according to one of the embodiments E1) - E10) characterized in that no turbidity separation step, step h), is carried out after step e).

E14) Method according to one of the embodiments E1) - E10) characterized in that in at least one of the following cases no turbidity separation step, step h), is carried out: before a recycling step g) for use in step a),

- after step b) or

- after step e). E15) Method according to one of embodiments E - E10) characterized in that in at least two of the following cases no turbidity separation step, step h), is carried out: before a recycling step g) for use in step a),

- after step b) or

- after step e).

E16) Method according to one of the embodiments El) - E10) characterized in that in the method according to the invention no turbidity separation step, step h), is carried out during or directly following step b) or before step c).

E17) Method according to one of the embodiments El) to E10), characterized in that only after step c), after step d) and after step f) a turbidity separation step, step h), is carried out.

E18) Method according to one of the embodiments El) to E10), characterized in that a turbidity separation step, step h), is carried out after step c), after step d) and after step f), and no turbidity separation step, step h), is carried out after step b).

E19) Method according to one of the embodiments El) to E10), characterized in that a turbidity separation step, step h), is carried out after step c), after step d), and after step f), and in at least one of the following cases no turbidity separation step, step h), is carried out: before a recycling step g) for use in step a),

- after step b) or

- after step e).

E20) Method according to one of the embodiments ED- E19), characterized in that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer. E2D process according to one of the embodiments ED- E19), characterized in that the precipitation reagent added in the turbidity separation step, step h) following step c) and/or following step d) and/or following step f) is a synthetic and/or polyelectrolytic cationic polymer.

E22) Method according to one of the embodiments E1 ) - E21 ), characterized in that in the turbidity separation step, step h), in particular in each turbidity separation step, step h), the added precipitation reagent is a synthetic and/or polyelectrolytic cationic polymer.

E24) Method according to one of the embodiments E20) - E23), characterized in that the cationic polymer is SK-140.

E25) Method according to one of the embodiments ED- E19), characterized in that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a non-ionic (synthetic) polymer.

E26) Method according to one of the embodiments ED - E19) and E25), characterized in that the precipitation reagent added in the turbidity separation step, step h) following step f), is a non-ionic synthetic polymer.

E27) Method according to one of the embodiments ED - E19), E25) and E26), characterized in that in the turbidity separation step, step h), in particular in each turbidity separation step, step h), the added precipitation reagent is a non-ionic synthetic polymer.

E28) Method according to one of the embodiments E25) - E27), characterized in that the non-ionic synthetic polymer is Prästol2500®.

E29) Method according to one of the embodiments ED - E28), characterized in that in at least one turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably in at least one turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter. E30) Method according to embodiment E29), characterized in that in each turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably in each turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter.

E3D method according to one of the embodiments E1 ) - E30), characterized in that the turbidity compounds are silicon compounds.

Design F)

Turbidity separation step, step h), when the concentration of the phosphoric acid changes, preferably increases (after each concentration step) and when the concentration of the metal ions in the phosphoric acid obtained from the phosphate-containing ash changes (after each purification step) and turbidity separation step, step h), with (synthetic and/or polyelectrolytic) cationic polymer,

FD process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid to form an ash-phosphoric acid suspension, and the ash reacts with the phosphoric acid; b) following step a), in step b), the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension to form a filtrate 1 or a supernatant 1; c) following step b), in step c), calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1, and a filtrate 2 or supernatant 2 is formed; d) following step c), in step d) the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger, yielding an eluate 3; e) following step d), in step e) the eluate 3 eluted from the ion exchanger is recovered as collected phosphoric acid; f) following step e), in step f) the collected phosphoric acid (and/or the eluate 3) is at least partially subjected to volume reduction to concentrate the collected phosphoric acid, resulting in concentrated phosphoric acid; g) in step g) following step b), step c), step d) and/or step e) the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following steps b), c), d), e) and/or f) and/or before step g), the recycling for use in step a), at least one turbidity precipitating reagent is added to the filtrate, the supernatant, the eluate and/or the collected phosphoric acid or a portion thereof, and subsequently the at least one turbidity precipitating reagent and/or turbidity compounds bound to the turbidity precipitating reagent are separated again from the filtrate, the supernatant, the eluate and/or the collected phosphoric acid; wherein the precipitating reagent added in step h) is a natural or synthetic polymer; and characterized in that a turbidity separation step, step h), is carried out in the process when the concentration of the phosphoric acid obtained from the phosphate-containing ash increases; and characterized in that a turbidity-

The separation step (step h) is carried out when the concentration of Metal ions in the phosphoric acid obtained from the phosphate-containing ash are modified; and characterized in that the precipitation reagent added in the at least one turbidity separation step, step h), is a (synthetic and/or polyelectrolytic) cationic polymer.

F2) Method according to embodiment Fl), characterized in that the concentration of metal ions in the filtrate(s)/eluate(s) or the collected phosphoric acid decreases.

F3) Method according to embodiment Fl), characterized in that the concentration of metal ions in the filtrate(s)/eluate(s) or the collected phosphoric acid increases.

It is noticeable that the precipitation/separation of the turbidity is particularly successful when carried out after steps in which the recovered phosphoric acid is concentrated. This applies, for example, and especially to step f), so it is particularly preferred if a turbidity separation step h) is carried out after step f). It is also noticeable that the precipitation/separation of the turbidity is particularly successful when carried out after steps in which the concentration of metal ions in the filtrate(s)/eluate(s) and/or the collected phosphoric acid changes, for example, after a purification step such as gypsum precipitation or purification by the ion exchanger. This applies, for example, and especially to step d) or also step c). Therefore, it is particularly preferred if a turbidity separation step h) is carried out after step c). It is also particularly preferred if a turbidity separation step h) is carried out after step d). It is particularly advantageous if a turbidity separation step h) is performed after step c) and another after step d). Furthermore, the inventors noticed that the precipitation/separation of the turbidity with (synthetic and/or polyelectrolytic) cationic polymers was particularly successful with the phosphoric acids obtained from sewage sludge ash under investigation.

F4) Method according to one of the embodiments Fl) - F3), characterized in that at least one of these turbidity separation steps, step h), is carried out following step f). F5) Method according to one of the embodiments F1) - F4), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c).

F6) Method according to one of the embodiments F1) - F4), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c).

F7) Method according to one of the embodiments F1) - F4), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c) and at least one of these turbidity separation steps, step h), is carried out following step d).

F8) Method according to one of the embodiments F1) - F3), characterized in that at least one of these turbidity separation steps, step h), is carried out following step c), at least one of these turbidity separation steps, step h), is carried out following step d), and at least one of these turbidity separation steps, step h), is carried out following step f).

Or:

F9) Method according to one of the embodiments F1) to F3), characterized in that a turbidity separation step is carried out after each step h) after step c), after step d) and after step f).

Accordingly, the following F10) is a highly preferred embodiment:

F10) Process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein g) in a step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid so that an ash-phosphoric acid suspension is formed, and the ash reacts with the phosphoric acid, h) following step a) in a step b) the acid-insoluble part of the ash (retentate 1 or precipitate 1 ) is separated from the ash-phosphoric acid suspension and a filtrate 1 or a supernatant 1 is obtained; i) following step b), in step c), calcium sulfate precipitate is obtained and separated by adding sulfuric acid to filtrate 1 or supernatant 1, and filtrate 2 or supernatant 2 is formed; j) following step c), in step d), the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger, and eluate 3 is formed; k) following step d), in step e), the eluate 3 eluted from the ion exchanger is obtained as collected phosphoric acid; l) following step e), in step f), the collected phosphoric acid (and/or eluate 3) is at least partially subjected to volume reduction to concentrate the collected phosphoric acid, so that concentrated phosphoric acid is formed; g) in a step g) following step b), step c), step d) and/or step e), the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d), e) and/or f) and/or prior to step g), the recycling for use in step a), at least one turbidity precipitating reagent is added to the filtrate, supernatant, eluate and/or collected phosphoric acid or a portion thereof, and subsequently the at least one turbidity precipitating reagent and/or turbidity compounds bound to the turbidity precipitating reagent are separated from the filtrate, supernatant, eluate and/or collected phosphoric acid; wherein the precipitating reagent added in step h) is a natural or synthetic polymer; and characterized in that at least one of these turbidity separation steps, step h), following step c), at least one of these turbidity- separation steps, step h), are carried out following step d) and at least one of these turbidity separation steps, step h), is carried out following step f) and is characterized in that in at least one of the turbidity separation steps, step h), the added precipitation reagent is a (synthetic and/or polyelectrolytic) cationic polymer.

F11) Method according to one of the embodiments F1) - F10) characterized in that no turbidity separation step, step h), is carried out before a recycling step g) for use in step a).

F12) Method according to one of the embodiments F1) - F10) characterized in that after step b) no turbidity separation step, step h), is carried out.

F13) Method according to one of the embodiments F1) - F10) characterized in that no turbidity separation step, step h), is carried out after step e).

F14) Method according to one of the embodiments F1) - F10) characterized in that in at least one of the following cases no turbidity separation step, step h), is carried out: before a recycling step g) for use in step a),

- after step b) or

- after step e).

F15) Method according to one of the embodiments F1) - F10) characterized in that in at least two of the following cases no turbidity separation step, step h), is carried out: before a recycling step g) for use in step a),

- after step b) or

- after step e).

F16) Method according to one of the embodiments F1) - F10) characterized in that in the method according to the invention no turbidity separation step, step h), is carried out during or directly following step b) or before step c). F17) Method according to one of the embodiments F1) to F10), characterized in that only after step c), after step d) and after step f) is a turbidity separation step, step h), carried out.

F18) Method according to one of the embodiments F1) to F10), characterized in that a turbidity separation step, step h), is carried out after step c), after step d) and after step f), and no turbidity separation step, step h), is carried out after step b).

F19) Method according to one of the embodiments F1) to F10), characterized in that a turbidity separation step, step h), is carried out after step c), after step d), and after step f), and in at least one of the following cases no turbidity separation step, step h), is carried out: before a recycling step g) for use in step a),

- after step b) or

- after step e).

F20) Method according to one of the embodiments F1) - F20), characterized in that the precipitation reagent added in the turbidity separation step, step h) following step c) and/or following step d) and/or following step f) is a synthetic and/or polyelectrolytic cationic polymer.

F21) Method according to one of the embodiments F1) - F20), characterized in that in each turbidity separation step, step h), the added precipitation reagent is a synthetic and/or polyelectrolytic cationic polymer.

F22) Method according to one of the embodiments E20) - F21), characterized in that the cationic polymer is SK-140.

F23) Method according to one of the embodiments F1) - F22), characterized in that in at least one turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably in at least one turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter. F24) Method according to embodiment F23), characterized in that in each turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably in each turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter.

F24) Method according to one of the embodiments Fl) - F24), characterized in that the turbidity compounds are silicon compounds.

General embodiments X) for all embodiments A), B), C), D), E) and F)

X1) Method according to one of the embodiments A), B), C), D), E) and F), characterized in that the phosphate-containing ash is obtained by combustion of phosphate-containing sewage sludge, biodegradable waste, biowaste and/or animal waste in a waste incineration plant or sewage sludge incineration plant, in particular characterized in that the phosphate-containing ash is obtained by combustion of phosphate-containing sewage sludge and/or animal waste in a waste incineration plant or sewage sludge incineration plant, preferably characterized in that the phosphate-containing ash is obtained by combustion of phosphate-containing sewage sludge in a sewage sludge incineration plant.

X2) Method according to one of the embodiments A), B), C), D), E) and F), as well as XI), characterized in that in step a) the reaction between the ash and the phosphoric acid lasts 2 to 300 minutes, preferably 10 to 60 minutes, or less than 10 minutes, preferably in step a) the reaction between the ash and the phosphoric acid lasts less than 5 minutes or particularly preferably in step a) the reaction between the ash and the phosphoric acid lasts less than 2 minutes, wherein the reaction between the ash and the phosphoric acid preferably lasts between 1 and 2 minutes, less than 1.75 minutes, less than 1.5 minutes, less than 1 minute or less than 30 seconds. X3) Method according to one of embodiments A), B), C), D), E) and F), as well as X1 ) and

X2), characterized in that in step a) the reaction between the ash and the phosphoric acid takes place at room temperature or between 20°C and 30°C or between 15°C and 70°C, or between 25°C and 50°C.

X4) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1 ) - X3), characterized in that in step a) the reaction between the ash and the phosphoric acid is carried out with dilute phosphoric acid, preferably in aqueous dilution, preferably in step a) the reaction between the ash and the phosphoric acid with a dilute phosphoric acid in a concentration of 5 wt.% to 50 wt.%, preferably 10 wt.% to 30 wt.% preferably in aqueous dilution, particularly preferably with a dilute phosphoric acid with a concentration between 25 wt.% to 35 wt.%, preferably in aqueous dilution.

X5) Method according to one of embodiments A), B), C), D), E) and F), as well as XI) -

X4), characterized in that in step a) in the reaction between the ash and the phosphoric acid the proportion of ash is 5 wt.% to 50 wt.%, preferably 20 wt.% to 30 wt.% or 25 wt.% to 35 wt.% or 20 wt.% to 35 wt.% or 25 wt.% based on the ash-phosphoric acid suspension;

X6) Method according to one of embodiments A), B), C), D), E) and F), as well as XI) -

X5), characterized in that in step a) the reaction between the ash and the phosphoric acid takes place in a reactor.

X7) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1 ) - X6), characterized in that in step b) the separation of the acid-insoluble part of the ash is carried out with dewatering units, preferably in step b) the separation of the acid-insoluble part of the ash is carried out with a vacuum belt filter, chamber filter press, membrane filter press, sieve belt press or centrifuge, particularly preferably in step b) the separation of the acid-insoluble part of the ash is carried out with a vacuum belt filter.

X8) Method according to one of embodiments A), B), C), D), E) and F), as well as X1 ) -

X7), characterized in that in step b) after deposition of the acid-insoluble part of the ash the residue (from which (retentate 1 or precipitate 1 ) is washed with water, preferably in step b) after separation of the acid-insoluble part of the ash the residue in the dewatering units is washed with water, optionally the wash water being recycled for use in step a) or the wash water being combined with the filtrate 1 or supernatant 1 before step c).

X9) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1) - X8), characterized in that in step c) a pH value <1 is set by adding the sulfuric acid to the filtrate 1 or supernatant 1.

X10) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1) - X9), characterized in that in step c) the addition of sulfuric acid takes place in a dilution of 10 to 98 wt.%, preferably 40 to 80 wt.%.

X11) V Method according to one of the embodiments A), B), C), D), E) and F), as well as XI) - X10), characterized in that in step c) the sulfuric acid is added in a molar ratio corresponding to the dissolved calcium concentration of 0.5 Ca to 1.5 SO4 (sulfate), preferably 1.0 Ca to 1.0 SO4 (sulfate).

X12) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1) - X11), characterized in that in step c) the addition of sulfuric acid takes place in a stirred reactor.

X13) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1) - X12), characterized in that the precipitation in step c) takes place over a period of 1 to 7 or 1 to 12 or 12 to 24 hours, preferably 2 to 6 or 2 to 12 hours, in particular 3 to 5 or 3 to 10 hours or approximately 4 hours.

X14) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1) - X13), characterized in that the precipitation in step c) is carried out by stoichiometric addition of sulfuric acid in the ratio 1 :1 sulfate to calcium ions.

X15) Method according to one of embodiments A), B), C), D), E) and F), as well as X1) -

X14), characterized in that in step c) the reaction temperature at the Precipitation of calcium sulfate after addition of sulfuric acid in a stirred reactor at a temperature of 20° to 90°C, preferably 60° to 90°C.

X16) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1) - X15), characterized in that in step c) the calcium sulfate precipitate is separated by mechanical filtration and/or dehydration processes;

X17) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1) - X16), characterized in that in step c) the separation of the calcium sulfate precipitate is carried out with dewatering units, preferably characterized in that in step c) the separation of the calcium sulfate precipitate is carried out with a vacuum belt filter, a chamber filter press, a membrane filter press, a belt screen press or a centrifuge, particularly preferably characterized in that in step c) the separation of the calcium sulfate precipitate is carried out with a vacuum belt filter;

X18) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1) - X17), characterized in that in step c) after separation of the calcium sulfate precipitate the residue is washed with water, preferably in step c) after separation of the calcium sulfate precipitate the residue is washed with water in the dewatering units, wherein optionally the wash water is recycled for use in step a) or the wash water is combined with the filtrate 2 or supernatant 2 before step d).

X19) Method according to one of embodiments A), B), C), D), E) and F), as well as X1) -

X18), characterized in that in step d) the ion exchanger is subjected to at least one washing step, preferably with water, after the purification of the filtrate 2 or the supernatant 2, so that a further eluate 4 is formed.

X20) Method according to embodiment X19), characterized in that in step e) in addition to the eluate 3, the eluate 4 eluted from the ion exchanger after at least one washing step, preferably with water, is also obtained as collected phosphoric acid. X21) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1) - X20), characterized in that following step e) the eluate 3 and optionally the eluate 4, or the collected phosphoric acid, is subjected in step f) at least partially to a volume reduction to concentrate the collected phosphoric acid, so that concentrated phosphoric acid is obtained; preferably following step e) the eluate 3 and the eluate 4 eluted from the ion exchanger after at least one washing step, preferably with water, or the collected phosphoric acid, is subjected in step f) to a volume reduction to concentrate the collected phosphoric acid, so that concentrated phosphoric acid is obtained.

X22) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1) - X21), characterized in that the phosphoric acid collected following step e) or the phosphoric acid concentrated in step f) is concentrated to 65 - 85 wt.% by volume reduction, wherein the volume reduction is preferably achieved by evaporation, in particular vacuum evaporation.

X23) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1) - X22), characterized in that the phosphoric acid collected following step e) or the phosphoric acid concentrated in step f) is divided into part A and part B, and part A of the phosphoric acid is recycled for use in step a), wherein preferably this part A of the collected or concentrated phosphoric acid has a concentration of 20 to 40%, 25 to 35 wt.%, or is concentrated to 25 to 35 wt.% by volume reduction, and preferably part B of the collected or concentrated phosphoric acid is concentrated to 65 to 85 wt.%, wherein part A preferably comprises at least 20%, more preferably 20% to 80%, and even more preferably 40% to 66% or 80% to 85%, based on the total volume of the total quantity of the collected or concentrated phosphoric acid from part A and part B. B is, wherein the volume reduction is preferably achieved by evaporation, in particular vacuum evaporation.

X24) Method according to one of embodiments A), B), C), D), E) and F), as well as X1) -

X23), characterized in that in step f) the collected phosphoric acid at least partially subjected to a volume reduction to concentrate the collected phosphoric acid, so that concentrated phosphoric acid is produced, preferably the collected phosphoric acid subjected to step f) is concentrated to 25 - 35 wt.% or 65 wt.% to 85 wt.%.

X25) Method according to one of the embodiments A), B), C), D), E) and F), as well as X1) - X24), characterized in that in step g) at least 10% of the filtrate, supernatant, eluate and/or collected phosphoric acid is recycled for use in step a), preferably at least 20%, more preferably 20% to 80%, and even more preferably 40% to 66% or 80% to 85%, based on the total amount of filtrate, supernatant, eluate and/or collected phosphoric acid obtained;

X26) Method according to one of the embodiments A), B), C), D), E) and F), as well as XI) - X25), characterized in that step g) is carried out following step d), step e) and/or step f), preferably following step d) or step e) or step f), particularly preferably following step f).

X27) A process according to any one of embodiments A), B), C), D), E) and F) for obtaining phosphoric acid (H3PO4) from phosphate-containing ash from the combustion of phosphate-containing sewage sludge and/or animal waste in a waste incineration plant or sewage sludge incineration plant, wherein a) in a step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid to form an ash-phosphoric acid suspension, and the ash reacts with the phosphoric acid, wherein the reaction between the ash and the phosphoric acid takes less than 5 minutes or less than 2 minutes, is carried out at 25°C to 50°C and with a dilute phosphoric acid in aqueous dilution with a concentration between 25 wt.% and 35 wt.% and the proportion of ash is 20 wt.% to 35 wt.% based on the ash-phosphoric acid suspension, b) following step a) in a step b) from the ash-phosphoric acid suspension the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated and a filtrate 1 or a supernatant 1 is formed, whereby the Separation of the acid-insoluble part of the ash is carried out using a vacuum belt filter, and the residue is subsequently washed with water, and the wash water is recycled for use in step a), or the wash water is combined with filtrate 1 or supernatant 1 before step c); c) following step b), in step c), calcium sulfate precipitate is obtained and separated by adding sulfuric acid to filtrate 1 or supernatant 1, and a filtrate 2 or supernatant 2 is formed, wherein a pH value <1 is adjusted by adding sulfuric acid to filtrate 1 or supernatant 1, and after separation of the calcium sulfate precipitate, the residue is washed with water and the wash water is recycled for use in step a), or the wash water is combined with filtrate 2 or supernatant 2 before step d); d) following step c), in step d) the filtrate 2 or supernatant 2 obtained from step c) is subjected to purification in an ion exchanger, yielding an eluate 3, wherein the ion exchanger is subjected to at least one washing step with water after purification of the filtrate 2 or supernatant 2, yielding a further eluate 4; e) following step d), in step e) the eluate 3 eluted from the ion exchanger and the eluate 4 are recovered as collected phosphoric acid; f) following step e), in step f) the collected phosphoric acid is subjected, at least partially, to volume reduction to concentrate the collected phosphoric acid; g) in step g) following step c), step e) and/or step f) the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a).

X28) Method according to embodiment X27), either characterized in that in step g) 40% to 66% of the filtrate, supernatant, eluate and/or collected phosphoric acid is used in Step a) is recycled, based on the total amount of filtrate, supernatant, eluate and/or collected phosphoric acid obtained, wherein step g) is carried out following step c) and/or step e); and characterized in that following step e) the collected phosphoric acid is subjected to a volume reduction in step f) so that concentrated phosphoric acid with a concentration of 65 wt.% - 85 wt.% is obtained, wherein the volume reduction is preferably achieved by vacuum evaporation; or characterized in that, following step e), the collected phosphoric acid is subjected to a volume reduction in step f) so that concentrated phosphoric acid with a concentration of 25 wt.% - 35 wt.% is obtained and the concentrated phosphoric acid is divided into part A and part B and part A of the concentrated phosphoric acid - within the scope of step g) - is recycled for use in step a), wherein part A comprises 40% to 66% of the total volume of the concentrated phosphoric acid (part A and part B), and subsequently part B of the concentrated phosphoric acid is further concentrated to 65 - 85 wt.%, the volume reduction preferably being achieved by vacuum evaporation.

Claims

Patent claims 1. A process for obtaining phosphoric acid (H3PO4) from phosphate-containing ash, wherein a) in step a) the phosphate-containing ash from a waste incineration plant is mixed with phosphoric acid to form an ash-phosphoric acid suspension, and the ash reacts with the phosphoric acid; b) following step a), in step b), the acid-insoluble part of the ash (retentate 1 or precipitate 1) is separated from the ash-phosphoric acid suspension to form a filtrate 1 or a supernatant 1; c) following step b), in step c), calcium sulfate precipitate is obtained and separated by adding sulfuric acid to the filtrate 1 or supernatant 1, and a filtrate 2 or supernatant 2 is formed; d) following step c), in step d) the filtrate 2 or supernatant 2 resulting from step c) is subjected to purification in an ion exchanger, yielding an eluate 3; e) following step d), in step e) the eluate 3 eluted from the ion exchanger is recovered as collected phosphoric acid; f) following step e), in step f) the collected phosphoric acid (and/or the eluate 3) is at least partially subjected to volume reduction to concentrate the collected phosphoric acid, resulting in concentrated phosphoric acid; g) in step g) following step b), step c), step d), step e) and/or step f) the filtrate, supernatant, eluate and/or collected phosphoric acid is at least partially recycled for use in step a); characterized in that in at least one turbidity separation step, step h), during or following step b), c), d), e) and/or f) and/or before recycling to step g) for use in step a), at least one turbidity precipitating reagent is added to the filtrate, the supernatant, the eluate and/or the collected phosphoric acid or a part thereof, and subsequently the at least one turbidity precipitating reagent and/or turbidity compounds bound to the turbidity precipitating reagent are separated again from the filtrate, the supernatant, the eluate and/or the collected phosphoric acid, and characterized in that the precipitating reagent added in at least one of the turbidity separation steps, step h), is a cationic polymer or a non-ionic polymer. 2. Method according to claim 1, characterized in that no turbidity separation step, step h), is performed during or directly following step b) or before step c). 3. Method according to claim 1 or 2, characterized in that in at least one turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably in at least one turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter. 4. Method according to claim 3, characterized in that in each turbidity separation step, step h), the separation is carried out by applying an artificial gravity, for example by utilizing the specific density, a gravity separation; preferably in each turbidity separation step, step h), the separation is carried out by an aggregate, such as a centrifuge or a decanter. 5. Method according to one of claims 1 to 4, characterized in that the turbidity compounds are silicon compounds. 6. Method according to any one of claims 1 to 5, characterized in that at least one of these turbidity separation steps, step h), is carried out following step f); or at least one of these turbidity separation steps, step h), is carried out before step g). 7. Method according to one of claims 1 to 5, characterized in that at least one of these turbidity separation steps, step h), is carried out following step f) and before step g). 8. Method according to any one of claims 1 to 7, characterized in that at least one of these turbidity separation steps, step h), is carried out following step c); or at least one of these turbidity separation steps, step h), is carried out following step c) and before step d); or at least one of these turbidity separation steps, step h), is carried out following step d); or at least one of these turbidity separation steps, step h), is carried out following step d) and before step f). 9. Method according to any one of claims 1 to 7, characterized in that at least one of these turbidity separation steps, step h), is performed following step c) and at least one of these turbidity separation steps, step h), is performed following step d); or at least one of these turbidity separation steps, step h), is performed following step c) and before step d) and at least one of these turbidity separation steps, step h), is performed following step d) and before step f). 0. A method according to any one of claims 1 to 9, characterized in that at least one of these turbidity separation steps, step h), is performed following step c) and before step d) or at least one of these turbidity separation steps, step h), is performed following step d) and before step f); and that at least one of these turbidity separation steps, step h), is performed following step f); or at least one of these turbidity separation steps, step h), is performed before step g); or at least one of these turbidity separation steps, step h), is performed following step f) and before step g); OR that at least one of these turbidity separation steps, step h), is performed following step c) and at least one of these turbidity separation steps, step h), is performed following step d); and that at least one of these turbidity separation steps, step h), is performed following step f); or at least one of these turbidity separation steps, step h), is performed before step g); or at least one of these turbidity separation steps, step h), is performed following step f) and before step g); OR that at least one of these turbidity separation steps, step h), is performed following step c) and before step d), and at least one of these turbidity separation steps, step h), is performed following step d) and before step f); and that at least one of these turbidity separation steps, step h), is performed following step f); or at least one of these turbidity separation steps, step h), is performed before step g); or at least one of these turbidity separation steps, step h), is performed following step f) and before step g). 1. A method according to any one of claims 6 to 10, characterized in that the precipitation reagent added in any one of these turbidity separation steps, step h), is a cationic polymer, a cationic synthetic polymer, or a synthetic polyelectrolytic cationic polymer, preferably that the precipitation reagent added in at least one of the turbidity separation steps, step h), is a synthetic polyelectrolytic cationic polymer; or that the precipitation reagent added in any one of these turbidity separation steps, step h), is a cationic polymer, a cationic synthetic polymer, or a synthetic polyelectrolytic cationic polymer, preferably that the precipitation reagent added in one of the turbidity separation steps, step h), is a synthetic polyelectrolytic cationic polymer; or that the precipitation reagent added in each of these turbidity separation steps, step h), is a cationic polymer, a cationic synthetic polymer or a synthetic polyelectrolytic cationic polymer, preferably that the precipitation reagent added in each of the turbidity separation steps, step h), is a synthetic polyelectrolytic cationic polymer. 12. A method according to any one of claims 1 to 11, characterized in that the phosphate-containing ash is obtained by incinerating phosphate-containing sewage sludge, biodegradable waste, biowaste and/or animal waste in a waste incineration plant or sewage sludge incineration plant, in particular characterized in that the phosphate-containing ash is obtained by incinerating phosphate-containing sewage sludge and/or animal waste in a waste incineration plant or sewage sludge incineration plant, preferably characterized in that the phosphate-containing ash is obtained by incinerating phosphate-containing sewage sludge in a sewage sludge incineration plant. 13. Method according to any one of claims 1 to 12, characterized in that in step a) the reaction between the ash and the phosphoric acid lasts 2 to 300 minutes, preferably 10 to 60 minutes, or less than 10 minutes, preferably in step a) the reaction between the ash and the phosphoric acid lasts less than 5 minutes, or particularly preferably in step a) the reaction between the ash and the phosphoric acid lasts less than 2 minutes, wherein the reaction between the ash and the phosphoric acid preferably lasts between 1 and 2 minutes, less than 1.75 minutes, less than 1.5 minutes, less than 1 minute, or less than 30 seconds; and/or characterized in that in step a) the reaction between the ash and the phosphoric acid takes place at room temperature, or at temperatures between 20°C and 30°C, or at temperatures between 15°C and 70°C, or at temperatures between 25°C and 50°C; and/or characterized in that in step a) the reaction between the ash and the phosphoric acid is carried out with dilute phosphoric acid, preferably in aqueous dilution, preferably in step a) the reaction between the ash and the phosphoric acid is carried out with a dilute phosphoric acid in a concentration of 5 wt.% to 50 wt.%, preferably 10 wt.% to 30 wt.%, preferably in aqueous dilution, particularly preferably with a dilute phosphoric acid with a concentration between 25 wt.% to 35 wt.%, preferably in aqueous dilution; and/or characterized in that in step a) in the reaction between the ash and the phosphoric acid the proportion of ash is 5 wt.% to 50 wt.%, preferably 20 wt.% to 30 wt.% or 25 wt.% to 35 wt.% or 20 wt.% to 35 wt.% or 25 wt.% based on the ash-phosphoric acid suspension; and/or characterized in that in step a) the reaction between the ash and the phosphoric acid takes place in a reactor. 14. A method according to any one of claims 1 to 13, characterized in that in step c) a pH value <1 is adjusted by adding the sulfuric acid to the filtrate 1 or supernatant 1; and/or characterized in that in step c) sulfuric acid is added in a dilution of 10 to 98 wt.%, preferably 40 to 80 wt.%; and/or characterized in that in step c) the sulfuric acid is added in a molar ratio corresponding to the dissolved calcium concentration of 0.5 Ca to 1.5 SO4 (sulfate), preferably 1.0 Ca to 1.0 SO4 (sulfate); and/or characterized in that in step c) the sulfuric acid is added in a stirred reactor; and/or characterized in that in step c) the reaction temperature during the precipitation of calcium sulfate after the addition of sulfuric acid in the stirred reactor is 20° to 90°C, preferably 60° to 90°C; and/or characterized in that in step c) the calcium sulfate precipitate is separated by mechanical filtration and/or dehydration processes; and/or characterized in that in step c) the separation of the calcium sulfate precipitate is carried out using dewatering units, preferably characterized in that in step c) the separation of the calcium sulfate precipitate is carried out using a vacuum belt filter, a chamber filter press, a membrane filter press, a belt filter press or a centrifuge, particularly preferably characterized in that in step c) the separation of the calcium sulfate precipitate is carried out using a vacuum belt filter; and/or characterized in that in step c) after separation of the calcium sulfate precipitate the residue is washed with water, preferably in step c) after separation of the calcium sulfate precipitate the residue is washed with water in the dewatering units, wherein optionally the wash water is recycled for use in step a) or the wash water is combined with the filtrate 2 or supernatant 2 before step d). 15. Method according to any one of claims 1 to 14, characterized in that, following step e), the eluate 3 and optionally the eluate 4, or the collected phosphoric acid, are at least partially subjected to a volume reduction in step f). The collected phosphoric acid is subjected to concentration so that concentrated phosphoric acid is obtained; preferably following step e), the eluate 3 and the eluate 4 eluted from the ion exchanger after at least one washing step, preferably with water, or the collected phosphoric acid is subjected in step f) to a volume reduction to concentrate the collected phosphoric acid, so that concentrated phosphoric acid is obtained, and/or characterized in that the phosphoric acid collected following step e) or the phosphoric acid concentrated in step f) is concentrated to 65-85 wt.% by volume reduction; or characterized in that the phosphoric acid collected following step e) or the phosphoric acid concentrated in step f) is divided into part A and part B, and part A of the phosphoric acid is recycled for use in step a), wherein preferably this part A of the collected or concentrated phosphoric acid has a concentration of 25–35 wt.% or is concentrated to 25–35 wt.% by volume reduction, and preferably part B of the collected or concentrated phosphoric acid is concentrated to 65–85 wt.%, wherein part A preferably comprises at least 20%, more preferably 20% to 80%, and even more preferably 40% to 66% or 80% to 85%, based on the total volume of the collected or concentrated phosphoric acid from part A and part B, wherein the volume reduction is preferably achieved by evaporation, in particular vacuum evaporation.