NL8004840A - METHOD FOR THE THERMAL TREATMENT OF PHOSPHATES - Google Patents

Description

f

** J

4

Process for the thermal treatment of phosphate rock.

The invention relates to a thermal treatment process and in particular to a thermal treatment of phosphate rock.

Calcium phosphate rock contains many contaminants, including organic compounds, for example humic acid. The organic impurities can cause severe foaming when the ore is treated with acid to form calcium sulfate and wet-process phosphoric acid and can also give rise to colored downstream products, for example, phosphoric acid and alkali metal phosphate salts. It is known to remove the organic materials by treatment with activated carbon or by applying oxidizing salts to the phosphoric acid or salts thereof or by calcining the ore. In the calcination, the ore is usually burned to convert the organic materials to carbon dioxide leaving a calcined ore which is substantially free of organic carbon and suitable for conversion to downstream products; temperatures of 750 ° C or higher are useful for this annealing. The foaming can be eliminated by prolonged heating at temperatures above 650 ° C without the need for complete oxidation of the organic compounds (see Chem.Eng. Progress Vol. 58, 1962, pp. 91-93).

It has now been found that by thermal treatment of the ore at temperatures lower than those mentioned above, the organic compounds can be converted at least partially and usually almost completely into insoluble particulate carbon, which can be filtered off with the cabium sulfate at the subsequent next acidification for the 8004840 (»2 formation of wet-process phosphoric acid.

The invention provides a process for the treatment of phosphate rock in which phosphate rock containing organic compounds is heated at 380-600 ° C in order to convert at least a portion of the organic compounds into carbon to form a heated ore containing carbon particles. Preferably, the heated ore containing the carbon particles is reacted with a mixture of sulfuric acid and phosphoric acid to form a solid fraction, containing calcium sulfate and carbon particles, and wet-process phosphoric acid, and the acid is separated from this solid fraction. The phosphate rock is heated to a temperature sufficient to convert at least a portion of said impurities and preferably substantially all of these impurities into particulate carbon, but which is insufficient to effect combustion of all the carbon to a oxide of carbon, so that the treated ore contains carbon particles. When the treated ore is reacted with the acid, a mixture is formed containing phosphoric acid, sulfuric acid, calcium sulfate, usually as gypsum, carbon particles and usually a small amount of unaffected ore; the mixture can be filtered to leave a wet-process acid, which is free from carbon particles and which has a considerably reduced color, for example, yellow instead of the deep brown color of acid from some untreated ores.

The connection of the phosphate rock according to the process of the invention can allow the reaction with the acid to proceed more satisfactorily with less or no foaming than if untreated ore is exposed to the attack, so that the acidification is advantageous is performed in substantially complete absence of any anti-foaming agent. The reaction with ore can also be carried out at a higher filtration rate and ore attack rate than when ore calcined at 950 ° C is attacked. Furthermore, heating in the process of the invention reduces or eliminates the need for the use of activated carbon or oxidizing agents on the acid or its salts to reduce its color. Heating at a lower temperature also represents a significant economic advantage.

The ore is heated at a temperature of 5 at most 600 ° C, i.e. 380-600 ° C, such as 450-600 ° C and especially 510-590 ° C, or 450-550 ° C, e.g. 460-540 ° C; temperatures of 380-500 ° C, for example 380-480 ° C and especially 380-440 ° C or 420-480 ° C can be used, but the rate of conversion of the organic materials to carbon is slower than at higher temperatures . The ore is usually heated at the indicated temperature for 0.01-10 hours, for example 0.1-10 hours, and preferably less than 2 hours, for example 0.6-2 hours, for discontinuous processes or for 1 minute to 1 hour , for example, 2-40 minutes, for continuous processes, where the heating time used is inversely proportional to the temperature used. The time and temperature are chosen such that preferably at least 30% of the organic compounds are converted to carbon and in particular at least 80% of the organic materials are converted. Particularly useful combinations are 40 minutes to 2 hours at 450-550 ° C for Florida or Zin or Oron ore for discontinuous processes or 15 minutes to 2 hours, for example up to 1 hour, at 450-550 ° C for continuous processes, while for Moroccan (for example, Khourigba or white Youssoufia) ores, 30 minutes to 2 hours at 380-440 ° C for discontinuous processes or 15 minutes to 2 hours, for example 15 minutes to 1 hour, at 380-440 ° C for continuous processes are preferred. 380-440 ° C is also advantageous for ores from Syria, Senegal, Algeria and Jordan, while 560-590 ° C is useful for black Youssoufia ore.

Preferably, when the ore is heated in the range of 460-450 ° C, the ore is nothing of Egyptian origin if the heating is carried out at 490-510 ° C or of Russian origin if the heating is carried out at 490-540 ° C and not from Florida if the heating is carried out at 490-510 ° C, unless the heat treatment is carried out continuously rather than discontinuously. When the ore is heated 8004840 J * 4 at 510-590 ° C, it is preferably not from Utah or Morocco if the heating is conducted at 540-560 ° C or from Russia if the heating is conducted at 510-540 ° C and when the heating takes place at 440-460 ° C, the ore is preferably not from Utah or Morocco. In the case of ores from Egypt, Russia, Florida, Utah and Morocco, the above temperatures can be used in continuously running processes. A mixture of ores can be used.

10 Although the usual annealing at 650 ° C

or higher gives a significant amount of hydrogen fluoride in the gaseous effluent obtained upon heating, the heating at the lower temperature according to the invention gives much less fluoride and often no fluoride at all in the effluent, whereby the purification of this effluent is increased. emakke1ij kt.

The heating treatment can be carried out under substantially anaerobic conditions with virtually no free oxygen (or other agent capable of oxidizing the organic contaminant); thus, the ore can be externally heated in the absence of air, for example, in an oven with exclusion of air. However, the ore is advantageously heated in the absence of oxidizing agents (other than oxygen), which can oxidize the organic impurities; for example, the ore can be heated in the presence of air, such as in an oven, or heated, for example, by an oxidizing flame in an oven, to the required temperature. The heating can be carried out with too short of oxygen with respect to the amount required to convert the organic contaminants to carbon, but preferably at least the required amount and in particular an excess is used.

8004840 5 i t

The conditions are usually sufficient to provide a heated ore containing carbon particles and substantially no acid-soluble organic materials (as defined below) and often virtually no other organic compounds.

The heating treatment is preferably carried out continuously, so that the ore is continuously passed through at least one heated zone at 380-600 ° C in order to convert at least a part of the organic compounds into carbon, and a heated ore containing carbon particles is discharged and it is usually allowed to cool.

The heating is usually carried out at 380-600 ° C without subsequently raising the temperature above 600 ° C; the temperature of the ore is then reduced.

Preferably, a rotary furnace is used with a direct or J5 counterflow of ore and hot gases, for example the hot combustion products of a flame, or the ore can be mixed with fuel and the fuel can be burned and the ore heated at the same time during the passage of ore and fuel through an incandescent device. On the other hand, a fluidized bed of 20 ore and hot gases can be used or the ore can be continuously layered under a flame or through an externally heated zone. Ring ovens or tunnel ovens can also be used. Although the heating treatment can be carried out on a large particle particulate ore, the ore particles are preferably less than 5 mm and preferably are ground first, for example to a size of 0.01-1 mm with at least 50% of 0. 01-0.5 mm and preferably by less than 30% of less than 0.1 mm.

The ore may be 0.05-6 wt%, e.g. 0.05-1.0 30 wt% or 0.5-6.0 wt% or 1.0-6 wt% organic material (expressed as weight percent organic carbon) as well as conventional ore impurities. The ore may thus contain 15-45 wt%, for example 25-40 wt%, 2 ^ 5 * ^ 5-35 wt%, or 30-40 wt% or especially 30-35 wt% ^ 5- 55 35 wt%, for example 45-55 or 50-55 wt% Ca, expressed as CaO, 0.01-8 wt%, for example 0.05-0.5 wt% or 0.5-5 wt .% S ^ O ^ with 8004840 6 a total iron and aluminum content of, for example, less than 10 wt.%, For example, less than 4 wt.% (Expressed as Fe20g and A ^ O ^) and 1.0-7 wt.% , for example, 1-3.5 wt% or 3.5-7 wt% carbonate (expressed as C 4). The invention is particularly suitable for the treatment of apatite phosphate ores, for example those which form brown liquids when digested with 27% hydrochloric acid; examples of such ores are those from Zin in Israel and Florida. However, other ores, for example those from the Western States of America, eg Idaho, or elsewhere such as North Carolina, Tennessee, Tunisia, Jordan, Morocco (eg Youssoufia), Algeria, Senegal, Kola, Nauru or Oceania can also be treated . The phosphate rock preferably contains 0.05-0.4 wt% organic materials or a weight ratio of organic materials 15 to: 1; ores with a low organic material content include those from Zin (Israel), Khouribga (Morocco), El Massa (Jordan), Algeria, Tunisia, Senegal or Oron (Israel).

The process of the invention is particularly suitable for the treatment of ores containing acid-soluble organic materials (as defined below). The term "acid-soluble organic materials" as used in this specification refers to organic compounds present in phosphate rock which have such character and are present in an amount that when digested the ore with a 56% mixture sulfuric acid and 20% thermal phosphoric acid (which mixture contains sufficient sulfuric acid to convert the calcium oxide content of the ore into calcium sulfate) a suspension in a liquid containing 25-30% 1 ^ 5 * 30 is formed, which is at least 600 ppm ( e.g. 600-60,000 ppm) of dissolved organic materials (expressed as total carbon), i.e. a weight ratio of dissolved organic materials (expressed as total carbon) to in the liquid of at least 0.002: J, e.g. 0.002-0.2: 1 ; On the other hand, the content of dissolved organic materials in the liquid, expressed as oxidisable carbon, is at least 8004840 * 1 7 100 ppm, for example 100-10,000 ppm, ie a weight ratio of organic materials to from 0 * 0003: 1, for example 0 .0003-0.03: 3 It is these ores, which provide acids, containing the higher amounts of dissolved organic materials, which can be most usefully improved by using the heating treatment of the invention to obtain treated ores from which acid containing smaller amounts of organic materials (e.g., 500 ppm or less total carbon or 50 ppm or less oxidizable carbon) can be prepared.

Ores that can be treated by the method of the invention include those in which the physicians themselves contain a low content of organic materials, for example 0.05-0.4% (total carbon), but these organic levels rials are acid soluble as defined above. Such ores are obtained, for example, from Zin in Israel, Algeria, Tunisia, Jordan and Senegal. Thus, according to another aspect of the invention, there is provided a process for the heat treatment of phosphate ore, wherein a phosphate ore containing a total of 0.05-0.4% organic compounds (expressed as carbon) and acid-soluble organic materials , is subjected to a heat treatment at 380-600 ° C to convert at least a portion of the organic compounds to carbon to form a heated ore containing carbon particles. Preferably, the ore contains 30-40% 1 ^ 5 and ^ 5-55% CaO.

Furthermore, it was found that when phosphate ores are exposed to a heating treatment at 650 ° C, a treated ore is obtained which, upon acidification with an inorganic acid, gives hydrogen sulfide in various amounts depending on the ore and that when the ore is subjected to a heating treatment according to the process of the invention at a lower temperature, for example 380-600 ° C, the amount of the aggressive and toxic hydrogen sulfide formed in the acidification can be reduced, which also applies to the iron content of the acid product. This high temperature effect is believed to be caused by the conversion at the higher temperatures of acid-insoluble iron sulfide present in the ore into acid-soluble iron sulfide, which forms hydrogen sulfide and dissolved iron at the acidification.

The low temperature can also reduce the arsenic content of the product acid compared to that of the acid obtained from high temperature calcined ores.

According to a special embodiment of the method according to the invention, there is thus provided a method for the preparation of phosphoric acid, wherein phosphate rock containing organic impurities and acid-insoluble, heat-labile iron sulfide is heated at 380-600 ° C in order to obtain at least a part converting said organic impurities into carbon particles, but insufficient to cause the conversion of all the acid-insoluble sulfide into acid-soluble iron sulfide, the heating process resulting in a treated ore containing carbon particles and into acid insoluble iron sulfide, and the treated ore is reacted with the mixture of sulfuric acid and phosphoric acid to form a reaction mixture containing phosphoric acid, sulfuric acid, calcium sulfate, carbon particles and acid insoluble, heat-labile iron sulfide, and a solid fraction containing said carbon particles and acid insoluble i iron sulfide and calcium sulfate, usually as gypsum, separate from a wet-process phosphoric acid. The terms "acid-insoluble and acid-soluble iron sulfide" refer to iron sulfides that are insoluble or soluble in a wet process phosphoric acid containing 28% and% SO3. The term "heat labile" iron sulfide, used in this specification, refers to the iron sulfide in the ore, which can be converted from acid insoluble to acid soluble on heating The heating treatment is carried out at 380-600 ° C, eg 380-480 ° G, especially 400-450 ° C or 450-550 ° C, and usually at a temperature below the phase transition temperature in this ore for the conversion of acid insoluble to acid soluble iron-sulfide. generally similar to those described above.

8004840 * * 9

This process is preferably also carried out continuously.

The method comprising preventing hydrogen sulfide formation can be applied to any phosphate rock, such as those described above, but in particular to those containing heat-labile, acid-insoluble iron sulfide, for example in an amount of at least 100 ppm (preferably at least 500 ppm) sulfide (expressed in parts by weight as S), such as 100-20,000, for example 500-10,000, such as 2000-5000 ppm or at least 200 ppm metal sulfide (expressed in 10 wt parts as FeS2), such as 200-40,000, for example 1000-10,000 ppm. The heat-labile, acid-insoluble sulfide content of the unheated ore is obtained from the maximum value of hydrochloric acid-soluble sulfide, present in ores, heated at any temperature in the range of 100-1000 ° C.

15 Such ores are, for example, those from Zin, Youssoufia,

Senegal, Christmas Island and especially Florida, the latter for which the preferred heating temperature is 450-550 ° C; ores from Tennessee, Distress Carolina, Idaho and the other Western States of the United States can also be treated in an analogous manner.

In another aspect, the invention provides a heated phosphate rock, containing carbon particles and acid-insoluble, heat-labile iron sulfide, of which at least 70%, for example at least 80%, such as 80-98% or at least 90%, are acid insoluble and of which the remainder (if any) is acid soluble. Preferably, the ore contains at least 500 ppm, e.g.

500-5000 ppm, of the acid-insoluble, heat-labile iron sulfide (expressed as S).

The ore subjected to heat treatment, containing carbon particles, (whether or not containing iron sulfides) can be reacted with phosphoric acid and / or sulfuric acid to form a calcium phosphate fertilizer. The reaction with phosphoric acid gives a "triple" superphosphate fertilizer, while the reaction with sulfuric acid results in a superphosphate fertilizer containing calcium dihydrogen phosphate and calcium sulfate. Preferably, the amount of acid is at least 80%, eg 80-120%, of the amount needed to react with the calcium in the ore to form calcium dihydrogen phosphate when the acid is phosphoric acid, or the amount of required to form the mixture of calcium dihydrogen phosphate and calcium sulfate (and substantially no free phosphoric acid) when the acid is sulfuric acid. Preferably, the ore is heated to 460-540 ° C and is not from Morocco or Utah unless the heating is conducted at 380-440 ° C or 560-600 ° C or unless the ore is reacted with sulfuric acid or a mixture thereof with phosphoric acid or unless the ore has been heated as part of a continuous operation. In one embodiment, the ore containing carbon particles is reacted with phosphoric or sulfuric acid but not with a mixture thereof. The calcium phosphate fertilizer can be mixed with ammonium nitrate or phosphate in solution or in solid form and optionally potassium chloride to form compound fertilizers after mixing or granulation.

The ore subjected to the heat treatment may also be reacted with an inorganic acid comprising hydrochloric, nitric or sulfuric acid to form a mixture of a calcium salt thereof, phosphoric acid and carbon particles, and a solid fraction containing these particles. separated from the mixture. Preferably, the ore is heated at 380-590 ° C, especially when the acid is hydrochloric acid only, and the ore is preferably not from Florida or Morocco unless the heating was conducted at 380-590 ° C or unless the heating process has been part of a continuous operation. The ore is preferably reacted with an amount of acid equivalent to at least 90% of the calcium content of the ore to convert the phosphate values in the ore into phosphoric acid. Although hydrochloric acid can be used as the attack acid, an acid containing nitric acid or sulfuric acid is preferably used, because the separated solid fraction then also contains calcium nitrate or sulfate, respectively, so that the calcium content of the liquid which remains after the separation, is reduced.

8004840 π

In the conversion of the heat-treated ore to wet-process acid, regardless of whether the ore contains a significant amount of iron sulfides or not, the ore is treated with sulfuric acid and phosphoric acid to form the reaction mixture containing a liquid and a solid fraction. wherein a major amount of the solid fraction includes calcium sulfate and a small amount of carbon particles (and optionally iron sulfide) and usually a small amount of unaffected ore. The amount of sulfuric acid is usually such that at least 90%, for example at least 95%, of the phosphate values in the ore are converted to wet-process phosphoric acid or is equivalent to at least 90% of the calcium oxide content of the ore and preferably 95-105%. The reaction of the treated ore with the mixture of phosphoric acid and sulfuric acid can be carried out at a low temperature and with a low concentration of sulfuric acid to form gypsum or at high temperatures, for example above 90 ° C, and with a high concentration of sulfuric acid to form of calcium sulfate hemihydrate or anhydrite. Appropriately. the ore mixed with sulfuric acid and weak recirculation phosphoric acid 20 and a calcium sulfate recirculation slurry in wet process phosphoric acid to form the calcium sulfate slurry, part of which is recycled and the remainder separated, for example, by filtration, and the filter cake of the calcium sulfate (with carbon particles and possibly iron sulfide) is washed with water to obtain a filtrate of weak phosphoric acid which is recycled to the ore attack step.

The crude wet-process acid, obtained after the treatment with inorganic acid and the separation of the solids, can be used as such, especially when calcium sulfate has separated, or can be further treated, often after concentration, for example up to 40 -60% the case of acid obtained from attack with a sulfuric acid-phosphoric acid mixture.

The crude wet-process phosphoric acid, obtained after the treatment of the heat-treated ore with the an-8004840 12 organic acid and the separation of the solid fraction with or without concentration, can be treated with a water-immiscible organic solvent to form an organic phase and an aqueous phase, acid being recovered from at least one of these phases. The heat treatment process according to the invention reduces the formation of emulsions in this step and increases the phase separation rate compared to that obtained if the ore heat treatment is not carried out. Preferably unless the ore continuously heated as described above, the ore is then heated to 380-590 ° C when the acid is hydrochloric acid only and the organic phase contains dissolved phosphoric acid The solvent may be a solvent in which phosphoric acid is substantially insoluble, or phosphoric acid cannot extract from aqueous phosphoric acid at the given concentration, so that the solvent extracts impurities leaving the large mass of the phosphoric acid in the aqueous phase.The impurities can be simply impurities in the acid, which must be removed, e.g. iron , or can be worth 20 in themselves, such as uranium Examples of solvent Elements for removing iron from the acid, usually without concentration, are long chain amines, alcohols, ethers, esters and chains for the removal from dilute phosphoric acid. Examples of solvents for removing uranium from the acid, usually without concentration, are trialkylphosphine oxides, eg trioctylphosphine oxide, dialkylphosphates, eg di (2-ethylhexyl) phosphate or in particular mixtures thereof or monoalkylpyrophosphates, such as monooctylpyrophosphate and / or dialkyl pyrophosphates or, on the other hand, mono (alkylphenyl) phosphates and / or di (alkylphenyl) phosphates, in particular mixtures thereof, such as mono- and di (octylphenyl) phosphoric acids; in each case, the alkyl groups contain 6-12 carbon atoms. When using phosphine oxide and / or a diester as an extractant, the uranium in the acid must be oxidized to the hexavalent state, and therefore the iron contained in the acid is inevitably oxidized as well; the use of the heating process according to the invention often reduces the iron content of the acid compared to the value obtained from a high-temperature annealed ore, and thus less oxidizing agent may be required for the oxidation of the uranium. A product containing uranium can be recovered from the organic phase, for example by re-extraction in aqueous acid and finally conversion to uranium oxide.

The water-immiscible organic solvent can be a solvent which preferentially extracts phosphoric acid leaving the majority of the impurities in the aqueous raffinate phase, which is separated from the organic phase, containing purified phosphoric acid, and phosphoric acid is recovered from the organic phase such as phosphoric acid or a phosphate salt thereof, for example by contact with water or aqueous phase and optional heating. Examples of suitable solvents are alcohols, ethers, organic esters and ketones, of which those with 4-9 carbon atoms are preferred, for example, butanol, amyl alcohols, isopropyl ether and methyl isobutyl ketone; other esters, such as trialkyl phosphates, eg tributyl phosphate, can also be used. This solvent extraction process is highly desirable when the mineral acid used for the attack is hydrochloric or nitric acid because it separates the phosphoric acid from the calcium salts of the crude reaction mixture. The phosphate values in the extract can be obtained by evaporation or preferably by contacting the extract with water and / or base. The higher carbon solvents are usually used with the acids after concentration to, for example, 50-60 % P2 ° 5 * 30 The wet-process acid, left after the separation of the solid fraction, containing carbon particles, and in particular when it contains calcium nitrate or sulphate, can also be treated, with or without post-concentration to, for example, 40 -60% 1 * 2 ^ 5 * with at least one nitrogen-containing compound, comprising ammonia, to form at least one ammonium phosphate salt, for example, mono- and / or diammonium phosphate, 8004840 14 for use as fertilizer. Often the ammonia is mixed with ammonium nitrate or nitric acid is added first or was the attack acid and the use of the heat-treated ore according to the invention makes it possible to use less nitrate than when untreated ore is used, because the latter and thus the acid therefrom contains organic compounds and these react with the nitrate.

The wet-process acid left after the separation of the solid fraction containing carbon particles, and in particular when this fraction also contains calcium sulfate, can also be treated with an alkali to form at least one phosphate salt, which is separated from the optional solids present, such as heavy metal hydroxides and phosphates, which are also formed. The alkali can be a hydroxide, carbonate or hydroconic carbonate of sodium or potassium. The reaction of the base and the acid can be carried out to a metal: P atomic ratio of 1: 1, 2: 1 or 3: 1 or preferably 1.67: 1, the latter for the subsequent heat treatment to form alkali language tripolyphosphates. The ore heat treatment process makes it possible to reduce or perhaps completely eliminate the amount of oxidizing agent required to decolorize the acid or the phosphate salt liquid and thus the tripolyphosphate.

Particularly when the attack acid is hydrochloric acid, but also in the case of nitric acid and sulfuric acid, the wet-process acid can be successively treated with one or more portions, for example 2-4 portions, of an alkaline earth metal base after separation of the solid fraction. eg a hydroxide or carbonate of calcium or magnesium in order to precipitate a number of fractions of alkaline earth metal (eg calcium) hydrogen phosphate, suitable for use as animal feeds which can be separated from the mother liquor containing calcium chloride or nitrate or water depending on the acid used for the attack,

The invention is further illustrated but not limited by the following examples.

Examples I-III and Comparative Examples A ~ D.

.. Phosphate rock from Zin, Israel, had the following analysis: 32.0 X P-0, 6.0% CO, 2.0% S0, 1.5% SiO, 4.0% F, 51 % Ca (as CaOJ, 0.2% Mgf 0.3% Al as Al ^), 0.2% 8004840 - 15 -

Fe (as Z Na (as Na2O), 0.2% oxidisable organic material (expressed as C).

The ore had a particle size distribution of 6.5% greater than 0.5mm, 27.3% between 0.25 and 0.5mm, 38.9% between 0.15 and 0.25mm and 27.3 7 Less than 0.15 mm.

A layer of the above-mentioned ore was heated in an oven for 1 hour in the presence of air at a temperature as indicated below. The treated ore was examined after cooling. The ores, treated at 400-700 ° C, were dark and showed the presence of carbon particles.

To determine the effect of the heating to remove the organic materials from the ore, the ore (treated by heating or otherwise) (100 g) was gradually added to a mixture of concentrated chloro-15 hydrochloric acid (35%, 205 g) and water (75 g). The temperature of the mixture rose to 40-45 ° C and the mixture was then heated to boiling point for 1 hour. The degree of foaming obtained in the reaction of ore and acid was recorded. The reaction mixture was filtered hot to remove any carbon particles present, unreacted ore and a small amount of calcium salts, then cooled to room temperature and filtered again to yield crude phosphoric acid. The color of the crude acid was recorded and the results are shown below.

25 Table A

Preheat Color of Color of Acid Degree of Image Foam Temp. (° C) ore temperature ._dukt__ A (comp.) No sand color deep red-brown large 30 B (comp.) 200 sand color deep red-brown large. I 400 pale black strong yellow II 450 medium black medium yellow III 500 black light green C (comp.) 700 gray light green small 35 D (comp.) 900 green light green small 8004840 - 16 -

Examples IV-VXIX and Comparative Example D

In the same manner as in Examples I-III, phosphate rock from Zin, Israel, with the same analysis and particle size as described above, was heated at varying temperatures and for varying times. The treated ore was reacted with hydrochloric acid as described above and in separate experiments with a sulfuric acid-phosphoric acid mixture and the color of the liquid was recorded and the organic matter and content was determined. The sulfuric acid-phosphoric acid mixture was a mixture of 200 g of 20 Z's thermal phosphoric acid and a sufficient amount of 56% sulfuric acid to combine with 98% of the calcium content of the phosphate rock used, the amount of which was that it contained 40 g of 1 * 205. The specified amount of ore was mixed with stirring with 200 g of phosphoric acid at 60 ° C. When the foaming ceased, the sulfuric acid was added and the mixture was stirred at 70 ° C for 2 hours to obtain a slurry of gypsum in phosphoric acid. The suspension was filtered hot and the filter cake was washed three times with 50 cm cold tap water. All 20 filtrates were combined to give the product acid, which was analyzed for total carbon and oxidizable carbon contents. The ore before and after the heating was also analyzed for F. The results are shown in Table B. The Zin ore contained before the heat treatment acid insoluble iron sulfide in an amount of 250 ppm (expressed as S). Examples IX-XVIII and Comparative Examples E-J.

In the same manner as in Examples IV-VIII, the same procedures for the heating of phosphate rock and for the reaction of the ore with hydrochloric acid or the sulfuric acid-phosphoric acid mixtures were performed with ores other than Zin. Details regarding the ores and the results obtained are given in Tables C-E below. In either case, the heating treatment was carried out for 1 hour unless otherwise indicated. When unheated Moroccan ore 35 was digested with the ^ SO ^ / H ^ PO ^ mixture, the liquid contained in the filtration) 27.8% ^ 2 ^ 5 '100-200 ppm total carbon and 15-20 8004840 - 17 ppm oxidizable carbon.

Examples XVII-XIX

The Zin ore as in Example IV was continuously subjected to a heating treatment in an inclined rotary annealer, with the ore slowly moving downward in the annealer in countercurrent with an air / burnt gas stream. The residence time was 20-30 minutes. The temperatures of the entering gas, of the solid at the exit point of the annealing device and of the effluent gas were measured. The heated ore was collected and treated with the sulfuric acid-phosphoric acid mixture as described in Example IV; the insoluble materials (including gypsum and carbon particles) were filtered off and the color of the product acid was recorded. The results indicated below were obtained.

Temperatures (° C) _

Emerging Incoming Effluent Acid image solid color gas_gas_ product_ XVII 430 800 - orange yellow 20 XVIII 510 880 210 very light green XIX 520 890 200 very light green 8004840 - 18 - d c • P <u

O I O

I P JS P

3 P U ÖO

to approx

O p ÖO Ό i-l P

cu öd d d · ρ o d <ux cod 3 a p o · ρ 3 o m

S3 · Ρ> N Λ P '3 ÖO · Ρ O

p ü μ I-I -UW

<3 P T) 3 P P P M

COMPOUND M, C | P 3J Μ Ό Ό VJ d 3 p O O ÖO 3 3 3 d O M r-l CM3 M O O · Ρ · Ρ 3 · Ρ 3 '303 3 SJ 3> p Μ P ÖO M N' ^ Ji. 3 3

• 1-ï Λ * P

• P 3 P O P

| 1 — I t — I O CO O

• P 3 3 O CM O

ZS M U> ->

X PO

O 3 P u fd «·

CO> O O

cn »cm 33 m C d ti m p-ι i-i vo 3 · Ρ · Ρ O 3

> N NN * i) M

P M d ti d Ou .O

3 ÖO O ÖO · Ρ * P 3 —PO

P 3 O * P 33 ÖO 6 ^ d O i-1 3 · Ρ P 3 M M 3 303 SS ÖO 3, Χ, Ü · Ρ CU P> 3 P O 3 J2 3 S Μ p

00 N Ό O O

c d p ti p o • p Ό 3 3 3 cn>

pi 3 3 P M

3 P W 3 O «W

no sr> i p o o

d> d O Μ Μ, Χ P

3 3 · Η co 3 3 cn

3 ÖO 3 CNdMOrP

| p S3 3 3 r-l o

Md -O d ^ 3 P 3 O

U3 33 d 3 vf ÖO P .X

S3 r * O 3 0 O S O

O OP P-ι d 3 P d p PI i-llPÖO CO 3 ÖO _ p 3 P 3 ÖO 32 "Ö 3 g 3

3 3, X 3 P P P CU .O

rP 3 P O rPj3 3 3 .X Ό p ï <SN0 33 "O 5 P 3 P 3 -Η 3« 3 CO UiJ PM> 6 ^ Ό • P H Ön

«3 m 3 cn X

cn> O «o M Pp p 00 oo cn co u-t cn 3 dP" I »I» »O Ό · CM g *

X · Ρ 3 CO CO COCO P Μ M CU O

3 W 3 O Μ Ό Ê-i · Ρ 3 P H 3 3 X tn Η · Ό

/ -N O P M> O P

CO · r-l O O Γ-Ν 3

Pd> o o * ü co 3 P · Ρ> .X rP & 3 g 3 3 «> _ / Ό 3 3 3 M ti d Ito O CD O O P3PJ3M3 3 O '- O" CO O 3 3PHT)

> * r-, «W i O> C

• p P P 0 O

ÖOH P Ό 3> Ό r * d M M 3 M 3

.p · Ρ 3 Ό «3 ÖO

rP M 3> 1 fr-5 3 3 3 X) X X «

Ό to P o cn P H

d o »O H

3 3 O d r- O H

X R> 3 CM>> 3 -O tn tc d O Ό • PO · Ρ PW 3

P O

• P · M o O O O O

X Cu ÖO O oooo pg 3 <r sr tn tn m

3 3 ÖO

> H ti o * - I Ό

P rP H

0 3 MM

03fd >> MMM

> X M>>> 8004840 - 19-.

Table C

Phosphate rock analyzes

Source of the ore Morocco Jordan Florida _ (Khourigba) _'__% P205 31.5 33.9 31.3% CaO 51.2 52.8 45.1 ''% Na20 0.7 0.57 0.6% MgO 0.8 0.29 0.75% A1203 0.40 0.28 1.8% Fe203 0.21 0.09 2.4% Sx02 2.4 - 2.37 5.9% S03 2.1 1 .37 3.3 Z CO2 6.4 4.46 3.6% F 4.0 3.88 3.8% Cl * 0.03 0.06 0.005% organic 0.18 0.30 1.56

material like C.

% weight loss 1.1 1.2 0.8 when heated to

105 ° C

Particle size analysis (wt%)> Mesh No._Morocco_Jordan_Florida_

Greater than 1.2 rara 63 t * (+14 mesh) 0.5 mm-1.2 mm 10 38 35 (+30 mesh) 0.25-0.5 mm 7 24 39 (+60 mesh) 0.15 -0.25mm 15 27 23 (+100 mesh)

Less than 0.15mm 5 11 3 (-100 mesh) 8004840 \ - 20 - öo w: s c c 3 • H Cd -rl -rl

3> & N

cd -ri co i 3 * 3 CU 3 00 -rl μ aj £, η <u o cd o 3 r-i • d S w <u ^ p 3 3

N

f — 4 r-4 d) tl 3 ai ai c aj: <u cd cu cu cu g • Η> öo öo o 3 P Ό 3 P AJ | AJ ÖO r-4 • d 3 Λ xi aj <ü ρ cu υ o aj 3 Ό O r-4 -r4 · ι-4 <U -1-4 3> -> W rJ 0 U d .3 ai

.O

d 3 · m i — i <u>

AJ <U T) M

ï-i <3> P _ 0) JZ H W <U Ό

P O X> <! ï H

3 0 d) 3 o 3 <u>> P ai aj cd ca p öo cd aj o cu, o P o öo w <U> o 3 öo o a) 3 cd 3 3 r- <* d · η

> O cd'H P

Yes> ε s cd p co pj <i -h 3 öo cd aii-i 3 O <U 3 1-4 «1-1« 1-4 5 0) Cd 3 μ -u <u -d aj p 3 qn cd mu (UQjcd <u 3i-4 «w £ S co> Eg>« d <u ^ ii o 3 m

d AJ ÖO

, ο cn 0-3 cd PP od H <u 3 ε aj 3 3 1 cd na> »- · S il 1-4 * d 3 3 Q) cu cd 3 o cd d <u P noo> oo 00 ti il 1-1 -ώ. <u JZ * i U X 3d 3> ü 03 P p r-4 r-4 ai'ed po d d d <u öo 5

4Jcdr-4AJ4Jdd3N

ο X U ot w ü O

s .5 3 ÖO 3 3

3 Y3 N

• rl TU ü P

P r-4 CD O

3 CU <4-1 n <u a) co 3 -o öo o

Cd P X ", O" W

<O W Μ X Pd 1-4

O Cd 4J

> <5 .3

<You

* d 3 cd | > o a 30 p Μ ^ T3 3 ÖO r-4

3 3 öO <U

AJ -1-4 3 Ό

Cd AJ -r4 3 p AJ r-4 Cd <U -1-4 CU JZ o o o a3d o o o o E P 3 xi sr ca σ \ <u cu cd 3

H> JZ O

8004840 - 21 - fan cc cc 3 tö · Η · Η · Η> 6 Φ «ι 3 60 · Η I r-l r-j 1 1 Tj 3 3 3 # • Η 4J X.

3 S «Ν I * S 3 3

¢ 0 ^ 1—4 · Η <0 I

«0 3 (U3 Ο Μ 3 <UH Vi 3 <3 · Ν 60, Ο 60 01 Ο 3 1—4 Ö-I 3 * r * 4 4J 4-1 ^ 4« Π 3 3 J3 & Λη 33> μ Ü Ο 60

> · -. I, Ω Ή I I Η CJ

Ό- Μ. <- 4 * -4 Ο 0 3 4J 3 * £ ο ο 3 Ur-ι mow «s, -η u αι α)« ι ω ο Β * κ / 3 3 0) (ί Ο 3 Μ 00 Ν 3 <-4 ω 3 • rl 6 • Η 3 -13 «

ϋ S

<η 4-ΐ 3 3 3.

60 Ο · Η · Η · ι-4 β «033 Ο ΙΌ 330) 4J · ι- | 3 Vl 3 ι — 4 r-1 3 Μ V4> 60 g! , Μ 60 3 3 I Ν 3

3 3 -U

Ό 3 3

• r4 3 S

Vi I

Ο r-4 1-4 U 60 * «S * υ · ι-ι 3 .3 Γ4 Ν 3

Cd J2 3 3 ^ 3 Ό · Η «—4 γΗ 3 3 Ο 3ι-433 φ 3> Ο V4 3 3 3“ 3 4J Vi Jd 3 Ο 60

3 3 Vi I 60 Vi I

t-ι 4J 3 V4 3 60 3 ti 3 3 3 <-) 4J · ι-ι 3 r-Ι ^ · ι-4 3 * 3 1—4 3 «0 ^ 333033 3 Ο Vl Vi · <-4 3 Vi pj Q ί Ο r-4 60 Ο 60 Ό 3

3 · <—> Μ Μ 3 V4 U

Η · η 3 3 V4 3 3 r-4 Η 3 3 3 3 3 «• 3 - - - · - ·

S

δ

JO

(0 / -Ν

60 U

3 Ό • Η ^ ·

4J

4J V4 -! • Η 3 3) J3 3 · Η μ ν) 3 ι.

3 3 0 ι> Vlr-IOOOOO 3 60 Ο Ο Ο Ο Ο ο. 3 ^ ιο ιη ό οι e 60 3 3

Ir1 2 3 Ο 8004840 3 2 VI γ — I Η 3 33 Η> Μ '“Ι 0 3 Η Η>>

>, η XX XX

- 22 -

Examples XX-XXII and comparative examples K-N

Florida ore with analysis as indicated above was heated for 1 hour at varying temperatures and then the treated ore was reacted with the sulfuric acid-phosphoric acid mixture as described in Example IV. A solid, comprising calcium sulfate, carbon particles, and iron sulfide, was separated from the reaction mixture leaving an acid product. The treated ore was treated with 14 hydrochloric acid and analyzed for soluble iron and sulfide.

The results obtained are shown in the table below.

Example Temperature (° C) Analysis of ore_

Sulfide (ppm)% soluble Fe 15 Comparative no heating 70 0.57

Ex. K

XX 400 110 0.73 XXI 500 220 0.76 XXII 600 980 0.94 20 Comparative 650 2180 1.12

Ex. L.

Comparative 750 3360 1.35

Ex, M

Comparative 900 110 1.36 25 Ex. N 1 8004840 23

Example XXIII and. Comparative example P

The acids of Example VIII (heat treatment of the ore for 1 hour at 50 ° C) and Comparative Example E (annealed ore) were mixed separately at 35 ° C in a 5 3: 2 weight ratio with separate solutions of 0.5 M di ( 2-ethylhexyl) phosphoric acid and 0.15 M trioctylphosphine oxide in petroleum ether with a boiling point of 100-120 ° C, followed by phase separation. The phases immediately separate with the acid of Example VIII into an aqueous acid phase and J0 an organic phase which was separated, and the uranium content thereof was recovered therefrom by treatment with aqueous phosphoric acid containing ferrous ions (Example XXIII). With the acid of Comparative Example E, an emulsion was obtained by mixing the acid and petroleum ether solutions, which became clear within 15 minutes to form the organic and aqueous phases (Comparative Example P).

Examples XXIV-XXVI

Ore with analyzes as indicated in Example XXXVIII below was subjected to heat e-20 treatment at 500 ° C for 1 hour as described in Example I. Wet process phosphoric acids were prepared from this ore and also from the unheated treated ore by reaction with a sulfuric acid-phosphoric acid mixture (as in Example IV) and separation of a solid fraction containing gypsum, carbon particles and unaffected ore. In an analogous manner, wet-process acids were prepared from ores with an analysis as indicated in Example I and Example XXVII below. The wet-process acids prepared in Examples XLII-XLIV from heat-treated ores were also used. Each acid was concentrated and oxidized by boiling, passing air through it to reduce the Fe II content. Each of the six acids, containing an amount of 1-5 in the range of 24-29% P2O2, was mixed with a solution in petroleum ether (boiling point 35 100-) with stirring at 35 ° C in a 1: 1 volume ratio. 120 ° G) of 0.5 M di (2-ethylhexyl) phosphoric acid and 0.15 M tri-octylphosphine oxide. After stirring for 5 minutes, the blends 8004840 were allowed to stand. Within 40 seconds, each of the mixtures derived from wet-process acids from the heat-treated ores was separated into an organic phase containing uranium and an aqueous acid phase. With each of the mixtures of acids from 5 unheated treated ore, a substantial amount of solid debris was present at the interface as well as an interface emulsion, which took 10-30 minutes to break leaving an organic phase containing uranium, and an aqueous acid phase. In each case, the two phases were separated and uranium was recovered from the organic phase by extraction with aqueous phosphoric acid containing ferrous ion. Examples XXVII-XXXVIII and Comparative Examples Q-U.

In these examples, the ores below with the indicated analyzes were used. The Florida II ore was from a mine other than the Florida ore used in Examples XIII-XVI.

Florida II Youssoufia Youssoufia Senegal

Black (ge White dried 150 ° C, 20 _0.5 hours _% P205 30.9 29.9 31.0 35.8% CaO 46.0 49.8 51.0 50.1% SO3 1.4 2 .0 1.2 0.33% CO2 4.3 6.7 6.1 1.7 25% SiO2 3.4 4.1% F 3.7 3.9 4.1 3.9% Cl 0.001 0.024 ppm <100% Na2Q 0.7 0.63 0.85 0.18% MgO 0.7 0.61 0.29 500 ppm 30% Al2 O3 0.9 0.32 0.17 0.53% K20 0.2 0.028 <0.1% Fe 2 O 3 S 1.1 0.15 0.13 1.1

Organic Carbon% C 0.5 1.3 0.15 1.08 35 In each of the examples below, the ore was heated in the following manner. The ore in the form of a layer in a silica dish was heated in a muffle furnace, which was vented to atmosphere and kept at a fixed temperature for 1 hour. The treated ore was then reacted with the sulfuric acid-phosphoric acid mixture of Example IV and separately with 14% by weight chlorine-5 hydrochloric acid as in Examples XX-XXII and also with 70% phosphoric acid to separate the insoluble solids containing carbon particles.

Florida II ore

Pre-Temperature Acid-labile Acid-op Color of 10 image (° C) sulfide (ppm) releasable ferric acid after HC1 (% Fe) treatment of ore.

Q untreated 8 0.67 dark brown XXVII 500 230 0.95 lemon green 15 XXVIII 600 1030 1.10 lemon green R 750 3280 1.31 lemon green black ïoussoufia ore S untreated = - dark brown XXIX 400 260 0.11 lemon green 20 xxx 500 220 0, 11 lemon green XXXI 600 120 0.11 lemon green XXXII 580 - - lemon green

7 I White Youssoutia ore _ I

T untreated --- 0.11 blue green 25 XXXIII 400 160 0.12 lemon green XXXIV 450 - - lemon green XXXV 500 220 0.11 lemon green XXXVI 550 215 - lemon green XXXVII 600 220 0.12 lemon green 30 Senegal ore Untreated - - brown XXXVIII 500 - - lemon green

Examples XXXIX-XLI

In these examples, the Florida ore used in Examples XII-XVI was used in Example XXXIX, while in Example XL the Florida II ore of Examples XXVII and XXVIII was used and in Example XLI Moroccan 8004840 26 ore was used as described in Examples IX and X.

For Example XXXIX, the Florida ore of Examples XIII-XVI was subjected to heat treatment in air in an oven at 550 ° C for 1 hour to obtain a gray ore containing carbon particles. This was treated with the sulfuric acid-phosphoric acid mixture of Example IV and a solid fraction containing gypsum and carbon particles was separated leaving a wet process acid, which had a light green color compared to the dark brown color of the acid from the unheated treated ore.

For Example XL, the Florida II ore of Examples XXVII and XXVIII was continuously heat-treated in the manner described in Examples XVII-XIX at a solid exhaust temperature of 500 ° C and supply and effluent gas temperatures of 790, respectively. ° C and 190 ° C with an average residence time of 20-30 minutes. The heated ore was treated with the sulfuric acid-phosphoric acid mixture as described in Example IV and insoluble materials, including gypsum and carbon particles, were separated therefrom leaving a wet-process phosphoric acid of a light green color compared to the dark brown color of the acid from the untreated ore.

For Example XLI, the Moroccan ore was continuously heat-treated in the manner described in Examples 25 XVII-XIX at a solid exhaust temperature of 390 ° C and feed and effluent gas temperatures of 760 and 130 ° C at an average residence time of 20- 30 minutes. The heat-treated ore containing carbon particles was treated with the sulfuric acid-phosphoric acid mixture as in Example IV and wet process acid was separated from the insoluble materials. The color of it. Acid was medium-yellow compared to the strong yellow color of acid from the untreated ore.

Example XLII

Phosphate rock with an analysis as in Example 1 was continuously heat treated as 8004840 27 in Example XIX and the heat treated ore was continuously reacted with a mixture of sulfuric acid and phosphoric acid in the presence of a gypsum suspension to form a wet process phosphoric acid and with separation of a solid fraction containing gypsum, carbon particles and unaffected ore. The reaction was carried out in a single stage stirred tank reactor according to a conventional method and using an amount of sulfuric acid which was 102% of the calcium content in the ore. The product phosphoric acid contained 28-30% 10 and no detectable amount of oxidizable carbon. No anti-foaming agent was required in the attack vessel compared to the addition of 0.6% oleic acid based on the weight of? 2 θ in the ore when the untreated ore was used. The filtration rate of the gypsum slurry was also considerably greater than when unreated ore was used.

Examples XLIII and XLIV

In the same manner as in Example XLII, Florida-II ore continuously subjected to a heat treatment at 500 ° C according to Example XL, and Moroccan (Khouribga) ore continuously subjected to a heat treatment according to Example XLI continuously converted to wet-process acid. The product phosphoric acids contain 28-30% and a detectable amount of oxidizable carbon. No anti-foaming agents were needed in the attack vessel as compared to the addition of 1.0% and 0.6% oleic acid, respectively, based on the weight of 1 * 2 ^ 5 * ore, when not subjected to heat-treated ore used. The filtration rates of the gypsum slurry were also considerably greater than when unheated ore was used,

Example XLV

The wet process phosphoric acid prepared in Example Hill was purified by solvent extraction. It was concentrated to an acid containing 54.7% ^ 2 ^ 5 »1» 51% SO ^, 0.32% Fe, 0.24% Mg and 0.07% Al and less than 50 ppm oxidizable carbon . This acid was purified in a system comprising 8004840 * 28 a two-stage countercurrent extraction, with methyl isobutyl ketone, to obtain an extract and an aqueous raffinate, followed by four countercurrent washes on the extract using purified product -acid as a washing liquid, whereby a purified extract was obtained, as well as used aqueous washing liquid, which was recycled to the extraction and a two-stage countercurrent release with water, whereby an almost acid-free solvent layer was obtained, which was recycled to the extraction, as well as a purified acid containing 41.2%? 2®S> 0> 50% SO4, 40 ppm Fe, 6 ppm Mg and 1 ppm Al and 0.4 ppm As, which acid had a pale yellow color.

The purification procedure was as described in U.S. Pat. No. 3,914,382 with a 65:35 split of between the product acid and the raffinate. The color of the purified acid could be improved, if necessary, by treatment with 1% activated carbon compared to the necessary amount of 5% activated carbon using a corresponding process using a non-heat treated ore. No phase separation difficulties, for example, the formation of long-lasting emulsions at the solvent-water interface occurred, while considerable difficulties were encountered in the use of a process using a heat-treated ore,

Examples XLVI-XLVIII

The wet process phosphoric acids prepared in Examples XLII and XLIV were each converted to sodium phosphates and then sodium tripolyphosphate. Each acid was treated to reduce its sulfate and fluorine impurity content and reacted with sodium carbonate to a Na: P ratio of 5: 3 with a filtration of precipitated solids leaving an aqueous solution of mixed sodium hydrophosphates with a Na: P ratio of 5: 3, which was dried and calcined for 1 hour to form sodium tri-35 polyphosphate. The acid salt of Example XLII was white and had less color than that of the salt prepared from the non-heat-treated ores. The color can be improved by treating the liquids with a Na: P ratio of 5: 3 with up to 0.5% of active substance compared to using 5% or more in the case of the product 5 from the corresponding non- heat-treated ore. The salts of the acids of Examples XLIII and XLIV were white.

Examples XLIX-LI

Ores, prepared as in Examples XIX, XL and 10 XLI, were reacted with 17% hydrochloric acid to form reaction mixtures containing calcium chloride, carbon particles, phosphoric acid, residual hydrochloric acid and unaffected ore. Each reaction mixture was defluorinated by treatment with a portion of an aqueous calcium hydroxide suspension (equivalent to the F content and a small amount of the acid) and subsequent separation of the solids, then a large amount of the calcium hydroxide suspension ( equivalent to the major part of the acid content for the preparation of dicalcium hydrogen phosphate), after which the solid dicalcium hydrogen phosphate, which is suitable as animal feed, was separated. Finally, the remainder of the acid was reacted with a final portion of the calcium hydroxide suspension to form a final fraction of dicalcium hydrogen phosphate which was separated from the mother liquor containing calcium chloride. The amounts of calcium hydroxide suspension added in the three stages were 20%, 70% and 10% of the total amount, respectively.

Examples LII-LIV

Each reaction mixture, containing calcium chloride, carbon particles, phosphoric acid, residual hydrochloric acid and unaffected ore, as prepared in Examples XLIX-XLI, was filtered to remove a solid fraction containing the ore and carbon fractions, leaving an acidic liquid. 5 parts by volume of this liquid were extracted with 10 parts by volume of a mixture of 8 parts by volume of amyl alcohol and 2 parts by volume of 35% hydrochloric acid to form an organic phase, containing 8004840 purified phosphoric acid and hydrochloric acid, and an aqueous phase which was separated. The phases separated quickly and no interface difficulties occurred. The organic phase was mixed with 2.5 parts by volume of water to liberate the acids to form an organic phase with a reduced acid content and an aqueous phase of a mixture of hydrochloric and phosphoric acid; the phases separate again without interface difficulties. The aqueous phase mixture was heated to evaporate hydrochloric acid, leaving purified wet-process phosphoric acid.

Examples IV and LVI

In the same manner as in Example XLV, the wet-process acids of Examples XLIII and XLIV were concentrated and purified by solvent extraction with methyl isobutyl ketone and liberated with water to obtain purified aqueous phosphoric acids. The concentrated wet process acid, obtained from Example XLIII, containing 51.9% SO 2, 1.36% Fe, 0.9% Mg and 1.0% Al, was purified to give an acid of 42.7% P2 ° 5 '^ j54 ^ SO ^, ^ ppm ^ ^ ppm and ^ ppm ^ 20 and a raffinate of 41.3% ^ 2 ^ 5 »2.7% SO ^ j 2.8% Fe, 2.0%

Mg and 1.9% Al at a 68:32 split between purified acid and raffinate. The concentrated wet process acid, obtained from Example XLIV, contained 56.0% SO 2, 0.23% Fe and 0.6%

Mg and was purified to give an acid of 40.5% * 2 5 5 25 0.7% SO SO, 28 ppm Fe 10 10 ppm Mg and a raffinate of 40% ^ 5 1,7 1.7% SOg, 0.6% Fe and 1.4% Mg at a 70:30 split between purified acid and raffinate. In no case did difficulties arise due to the formation of emulsions at the liquid-liquid interface.

30 Examples LVII-LIX

Ores, prepared as in Examples XIX, XL and XLI, were reacted with 24.2 parts of 58% nitric acid per 10.8 parts of heat-treated Moroccan ores and corresponding amounts for the other two ores, in each case obtaining an aqueous mixture of calcium nitrate, carbon particles, unaffected ore, phosphoric acid and residual nitric acid. Each mixture was filtered to remove the carbon particles and ore and cooled to 0 ° C and a solid fraction containing calcium nitrate was separated from the aqueous acid solution containing nitric 5 and phosphoric acids and calcium nitrate. Each aqueous acid solution was treated with 2.55 parts of anhydrous ammonia, which was added continuously. The resulting mixture, containing ammonium nitrate and phosphate and calcium nitrate, was evaporated to form a melt containing 0.5-5% water, which could be used as such as a fertilizer. In each case, the melt was mixed with 5.8 parts of potassium chloride and the mixture was granulated to form a composite fertilizer with an N: P: 1 ratio of 17:17:17.

Examples LX-LXII

The wet-process acids, obtained in Examples XLII-XLIV, were each concentrated to an acid with a ^ 2 ^ 5 content of 54%. Each concentrated acid was treated by bubbling anhydrous ammonia through it to an N: P atomic ratio of 1.35: 1. The temperature rose to 115 ° C and water was added to keep the resulting slurry free flowing (about 20% free water). The hot suspension was partitioned over a bed of fine particulate recycled ammonium phosphate product and the ammoniaation was completed with anhydrous ammonia to a N: P atomic ratio of about 1.8: 1; the re-circularity ratio was 2.5 parts recycled to 1 part removed as product. The product was passed to a dryer and a cooler at 85 ° C and then granulated to give ammonium phosphate in a ratio of 18 : 47: 0, which is suitable as a fertilizer.

Examples LXIII-LXV

The wet process acids, obtained in Examples XLII-XLIV, were each concentrated to an acid with a ^ 2 ^ 5 content of 50%. 50 parts of each concentrated acid were mixed with 12.5 parts of water and passed into a vessel containing an ammonium-phosphate suspension, 8 parts of anhydrous ammonia were added to form a mixture with an N: P ratio of 8004840 32 1.3: 1. Water was evaporated to leave an 80% ammonium phosphate slurry. The slurry could be granulated by mixing with solid recycle product and granulated to form a granular ammonium phosphate-5 fertilizer. The suspension was mixed with solid potassium chloride and an 80% ammonium nitrate solution and granulated to form an N: P: K composite fertilizer.

Examples LXVI-LXVIII

6.2 parts of each concentrated acid with a 50% P2 O2 content, used in Examples LXIII-LXV, was mixed with 7 parts of a 95% ammonium nitrate solution and then 0.8 parts of anhydrous ammonia were added to the mixture Through the heat of reaction, the water was evaporated to leave a concentrated solution with 5% water, which was fed to an evaporator to form a

dry melt. Each melt was mixed with 7.8 parts of potassium chloride and the mixture was granulated to form 20 parts of a composite fertilizer with an N: P: K ratio of 15:15:21. Examples LXIX-LXXI

6 parts of the heat-treated ores of Example XLI (and corresponding amounts of the heat-treated ores of Examples XXX and XL) were each ground to a powder, 80% of which passed through a 150 micron sieve. Each powder was mixed with 4.8 parts of 72% sulfuric acid to form a slurry, which was continuously passed through a curing chamber to form a solid product, which was crushed and heaped for 1 week to allow the reaction to complete superphosphate formation. Any superphosphate as such could be used as a fertilizer. Each superphosphate was mixed with solid potassium chloride and an 80% aqueous solution of ammonium nitrate in 48:17:36 weight ratios, followed by granulation, cooling, and drying to form a free-flowing fertilizer at N: P: K ratio. from 10.5: 10.5: 10.5.

35 Examples LXXII-LXXIV

In the same manner as in examples LXIX-LXXI

8004840 33, 4.1 parts of the heat-treated ore of Example LXI (and corresponding amounts of the heat-treated ores of Examples XIX and XLI) were ground and mixed with 6-8 parts of wet process phosphoric acid, containing 50% P2®5 'and Pro * hkt was prepared as in Examples LXVII-LXIX. Any triple superphosphate obtained could be used as fertilizer as such. Each triple superphosphate was mixed with potassium chloride and an aqueous solution of ammonium nitrate in ratios of 30:25:54 and the mixture was converted into a free-flowing composite fertilizer at a ratio of N: P: K of 15: 10 as described above: 15:15.

8004840

Claims (46)

1. Process for the heat treatment of phosphate rock, characterized in that calcium phosphate rock containing organic compounds is heated at 380-600 ° C in order to convert at least a small amount of the organic compounds into carbon to form a heated ore, which contains carbon particles. 2. Process according to claim 1, characterized in that the ore is heated by continuously passing it through at least one heated zone with a temperature of 380-600 ° C and the heated ore is discharged therefrom. Process according to claims 1 to 2, characterized in that the ore is heated to 380-480 C. 4. Process according to claims 1 or 2, characterized in that the ore is heated to 460-540 ° C, Process according to claim 1, characterized in that the ore does not come from Florida or Egypt if the heating takes place at 490-510 ° C or comes from Russia if the heating takes place at 490-540 ° C and not 20 is from Utah or Morocco if the heating is done at 540-560 ° C. 6. Process according to claims 1-5, characterized in that the ore is heated in the presence of a gas containing molecular oxygen. 7. Process according to claims 1-6, characterized in that the ore contains a total of 0.05-0.4 Z organic compounds (expressed as carbon) and acid-soluble organic materials. 8. Process according to claims 1-7, characterized in that the ore contains 30-40% and ^ 5-55% calcium (expressed as CaO). 9. Process according to claims 1-8, characterized in that the phosphate rock for heating it is an ore, which gives a brown liquid with 27% hydrochloric acid, Process according to claims 1-9, characterized in that the 8004840 ore is from Idaho, North Carolina, Tennessee in the United States of America or Tunisia, Jordan, Algeria, Senegal, Youssoufia in Morocco, Kola, Nauru, Oceania or Fancy Israel. Process according to claims 2.7 or 8, characterized in that Florida ore is heated at 450-550 ° C for 15 minutes to 2 hours in a continuous operation. Process according to claims 2 or 8, characterized in that Moroccan ore is heated at 380-440 ° C for 15 minutes to 2 hours in a continuous operation. Process according to claims 1-12, characterized in that the ore contains organic compounds and acid-insoluble, heat-labile iron sulfide and is heated at a temperature insufficient to convert all the acid-insoluble J5 iron sulfide to acid-soluble iron sulfide, and a heated ore, including phosphate rock, carbon particles, and acid-insoluble iron sulfide, are formed. 14. Process according to claim 13, characterized in that the ore before heating contains at least 500 ppm iron sulfide (expressed as S) insoluble in acid 20, A heat-treated calcium phosphate rock prepared according to the methods of claims 1-14. 16. A heat-treated calcium phosphate rock containing carbon particles and substantially no acid-soluble organic compounds. Ore according to claim 16, which also contains acid-insoluble, heat-labile iron sulfide. Ore according to claim 17, containing at least 30,500 ppm of said iron sulfide (expressed as S). Ore according to claims 17 or 18, characterized in that at least 80% of the iron sulfide is acid insoluble and the remainder, if present, is acid soluble. Process for preparing phosphates from 35 phosphate ore, characterized in that phosphate ore containing carbon particles, as defined in claims 15-19, are reacted 8004840 with at least one of the acids phosphoric and sulfuric acid to form a calcium phosphate fertilizer , 21. Process according to claim 20, characterized in that the ore is not from Morocco or Utah, unless the ore has been heated as part of a continuous process, or has been heated at 380-440 ° C or 460-540 ° C or 560-600 ° C or unless the ore is reacted with sulfuric acid or a mixture thereof with phosphoric acid. Method according to claims 20 or 21, 10, characterized in that the ore is heated to 460-540 C. A method according to claims 21 or 22, characterized in that the ore and its heating are the ore and the heating as defined in claims 2, 11 or 12. 24. Process according to claims 20-23, characterized in that the ore containing carbon particles is reacted with an amount of phosphoric acid which is 80-120% of the amount required to react with the ore under formation ... of calcium dihydrogen phosphate, or with an amount of sulfuric acid that is 80-120% of the amount required to react with the ore to form a mixture of calcium sulfate and calcium dihydrogen phosphate. 25. Process for preparing phosphoric acid from phosphate rock, characterized in that calcium phosphate rock containing carbon particles, prepared by heating phosphate rock at 380-600 ° C or as defined in claims 15-19, is reacted with an inorganic acid, comprising hydrochloric acid, nitric acid or sulfuric acid, to form a mixture of a calcium salt thereof, phosphoric acid and carbon particles, and a solid fraction containing these particles is separated from the mixture, A method according to claim 25, characterized in that the phosphate rock is continuously heated in the manner defined in claim 2, A method according to claims 25 or 26, 35, characterized in that the phosphate rock is heated to 380-590 ° C when the acid is exclusively hydrochloric acid. 8004840? -c 28. A process according to claims 25, 26 or 27, characterized in that the ore containing carbon particles is reacted with an amount of acid equivalent to at least 90% of the calcium content of the ore. A method according to claim 28, characterized in that the ore comes from Florida or Morocco and is heated at 380-550 ° C. 30. Process according to claims 25, 26, 28 or 29, characterized in that the acid is one of the acids nitric acid 10 and sulfuric acid, 31. Process according to claim 30, characterized in that the ore containing carbon particles is reacted with a mixture of sulfuric acid and phosphoric acid to form a solid fraction containing calcium sulfate and carbon particles and wet-process phosphoric acid, and the acid is separated from the solid fraction. 32. Process according to claims 25-31, characterized in that when the heated ore contains the insoluble, heat-labile iron sulfide, the solid fraction contains the carbon particles and the acid-insoluble iron sulfide. 33. Process according to claims 25-32, characterized in that after the separation of the solid fraction, the phosphoric acid is treated with a water-immiscible organic solvent to form an organic phase and an aqueous phase, and acid is recovered from at least one of these phases. 34. Process according to claim 33, characterized in that the phosphoric acid contains uranium and is extracted with or without prior concentration of the acid after separation of the solid fraction with a solvent in order to transfer at least a small amount of the uranium to the organic phase from which a product containing uranium is recovered. 35. A process according to claim 33 or 34, characterized in that the phosphoric acid is extracted with or without a concentration after separation of the solid fraction with a water-immiscible organic solvent to form 8004840 4µ of an organic phase. , containing purified phosphoric acid, and an aqueous raffinate layer, which are separated, and phosphoric acid is recovered from the organic phase in the form of a phosphoric acid or a salt thereof. A method according to claims 25-34, characterized in that after the separation of the solid fraction and with or without concentration of the acid, the phosphoric acid is treated with at least one nitrogen-containing compound, including ammonia, to form at least one ammonium phosphate salt. 37. A process according to claims 25-34, characterized in that after the separation of the solid fraction, the phosphoric acid is treated with an alkali to form at least one alkali metal phosphate salt, which is separated from any solids which are also formed. A method according to claims 25-34, characterized in that after the separation of the solid fraction, the wet-process acid is mixed with calcium hydroxide and precipitated calcium hydrogen phosphate is separated. 39. Process according to claims 20-38, characterized in that the ore is heated by continuously passing it through at least one heated zone at 380-600 ° C and the heated ore is removed from this zone or zones. 40, Calcium phosphate fertilizer, prepared according to the method of claims 20-24 or 39, A liquid mixture containing a calcium salt and phosphoric acid prepared according to the method of claims 25-30 or 39. 42, Wet process phosphoric acid prepared according to the method of claims 30-32 or 39. 43. Purified wet-process phosphoric acid or a salt thereof, prepared according to the method of claims 33-35 or 39. 44. A uranium-containing product obtained by the method of claims 34 or 39, 45, ammonium phosphate, prepared according to the method of claims 36 or 39. 8004840 46. An alkali metal phosphate prepared according to the method of claims 37 or 39. 47. Calcium hydrogen phosphate prepared according to the method of claims 38 or 39. 48. Methods and products as described in the description and / or examples. 8004840