DE102007014906A1 - Method for producing pre-product for calcium phosphate fertilizers, involves using metallurgical process engineering of pig iron and cast iron, where granular material is added to phosphorous containing waste - Google Patents

Abstract

Calcium phosphate fertilizers pre-product production involves using metallurgical process engineering of pig iron and cast iron. A granular material is added to phosphorus containing waste. The granular material contains iron or iron compounds, and phosphorus or phosphorus compounds. The phosphorus containing waste is sewage sludge, animal flour, meat mash or grinded bones. Coal briquet is melted in a coke-fired melting furnace directly with oxygen and combustion air as burning medium for a fusible slag and a metal alloy. Low-boiling metals like mercury, cadmium and zinc, present in the ingredients are reduced extensively and escapes from a part over the gaseous phase and precipicate in the purification of waste gas. High boiling heavy metals like copper, chromium and nickel are reduced to a large extent, and are dissolved in the hearth to a part as alloying elements in iron-metallic melting bath acting as heavy metal-sink. Metals like lead are collected in the hearth of the core melting furnace as liquid pool below the iron-metallic melting bath. The phosphorus pentoxide present in the molten slag is bonded in the typical structure of the slag. An independent claim is also included for a calcium phosphate fertilizer, which has ferric oxide and phosphorus pentoxide.

Description

The The invention relates to a heavy metal lime phosphate fertilizer and a method of producing a precursor for the same Fertilizers from phosphorus-containing waste under Admixture of further dusty and / or grainy Substances containing iron or iron compounds and also phosphorus or May contain phosphorus compounds.

By DE 28 20 729 discloses a process for the production of granulated fertilizers from sludge of biological wastewater treatment plants, wherein the mechanically thickened sludge with solid contents between 5-60 wt .-% in a mechanically stirred fluidized bed zone with high swirl in high dilution in direct contact with above 150 ° C. hot gases ie, for example, 250 ° C to 750 ° C hot flue gases, brought, wherein the granulated and dried product is discharged by means of the exhaust gas pneumatically from the fluidized bed zone and separated in a separator. The water content of the granulated fertilizer is less than 5% by weight. It contains, based on the dry matter, chemically bound 3 to 10% N and about 1.5-4.5% P. The disadvantage is that a possible heavy metal contamination of the starting materials can not be reduced by this method.

To DE 195 45 122 A1 Further, a method for producing a calcium- and phosphate-containing substance is known in which a natural or artificial calcium-containing mineral or a phosphorus-poor slag with artificial iron phosphate is reacted at elevated temperatures, the calcium-containing mineral is a low-phosphorus slag, z. B. may be a metallurgical slag from the production of iron or steel and the calcium-containing mineral or low-phosphorus slag still oxides of Si, Al, Mg, Mn, Fe and optionally P and CaS and beyond at least 25 wt .-%, in particular Contain 30 to 60 wt .-% CaO. These calcium-containing minerals or low-phosphorus slags are reacted with artificial iron phosphate, calculated as FePO ₄ in a weight ratio between 5: 1 and 0.5: 1, at temperatures greater than 600 ° C, in particular over 1000 ° C, but at most 1700 ° C. Alternatively, the reaction is additionally carried out with annealing, in particular with sintering or melting at least one of the mineral ingredients. The artificial iron phosphate is thereby introduced into a liquid slag, and by the reaction, a phosphate fertilizer is obtained. The ratio between low-phosphorus slag or calcium-containing mineral to artificial iron phosphate, the reaction temperature and / or reaction time are chosen such that at least 30 wt .-%, in particular at least 50% by weight of the artificial iron phosphate after the reaction in 2% ( % By weight) of the citric acid solution, according to the determination of the phosphate solubility customary for Thomasschlacke.

The artificial iron phosphate is in a phosphating process iron-containing parts, in particular from phosphatizing sludge recycling, receive. The addition of artificial iron phosphate can for example, to molten basic slag with temperatures between 1000 ° C and 1600 ° C by immediate Contact when parting or by heating a mixture the fine-grained fraction of the cooled metal slag and the artificial iron phosphate in the rotary kiln to preferably at least 1000 ° C take place.

adversely This is not the usual with Thomasschlacke citrate solubility phosphate of more than 90%.

adversely is further that a possible heavy metal contamination of the starting materials with this method can not be reduced and that artificial Iron phosphate a crucial role for the produced Fertilizer plays.

Thereby This procedure may not be for processing suitable heavy metal materials and by the necessary Production of artificial iron phosphate in advance economically disadvantaged.

Of the Invention is based on the object, the production of a heavy metal Calcium phosphate fertilizer and a method for producing a Pre-product for this fertilizer from phosphorus-containing Waste with the addition of further dusty and / or granular substances containing iron or iron compounds and may also contain phosphorus or phosphorus compounds without the compulsory addition of artificial material to be prepared beforehand To realize iron phosphate.

These Task becomes by the use of metallurgical processing techniques of pig iron, cast iron and mineral wool generation accordingly the characterizing parts of claims 1, 2, 3 and 4 solved.

advantageously, become the metallurgical reactions during the reducing melting used in a coke-fired shaft melting furnace.

Thus, in the melting of iron and heavy metal containing, briquetted in advance phosphorus-containing waste, such as sewage sludge, meat-and-bone meal, meat mash, ground bones, in mixture with those incurred in the combustion of these substances Ash, such. As filter dusts from the exhaust gas treatment of Monoverbrennungsanlagen to a liquid slag, the high-boiling heavy metals such as Cu, Cr, Ni, reduced and largely alloyed in the liquid iron, which thus acts as a heavy metal sink.

The low-boiling heavy metals, such as Zn, Cd, Hg, also become reduced; they evaporate and are largely over the Gas phase deposited in the exhaust gas purification. Contained in the starting materials, however, in liquid iron as well as in liquid Slag largely insoluble metals, such as Pb, collect as a swamp under the iron-metallic molten bath in the hearth of the Shaft furnace.

Further It is advantageous that the remaining contained in the starting materials Metals and metal oxides, d. H. the proportion that is not reduced and was not discharged via the exhaust, only a small Percentage. Characteristic of the very low Concentration of the metals or metal oxides contained in the slag is the low iron oxide content of the slag, which is less than 5%, preferably less than 2%.

Of the introduced phosphorus is distributed according to the P-solubility on metal and slag, it being advantageous that accordingly the mass ratio of metal bath to slag is the largest Proportion of phosphorus as a slag ingredient, preferably as a phosphate is bound.

From Another advantage is that the rest contained in the starting materials Metals and metal oxides as well as the phosphate in the rapid Cooling involved typical amorphous structures of the slag become.

advantageously, is by regulating the cooling rate of the liquid Slag at sufficiently slow solidification of this slag the Integration into the resulting crystalline slag structures technically and procedurally easy to implement.

The Heavy metal low calcium phosphate fertilizer according to the invention and a method of producing a precursor for the same Fertilizers from phosphorus-containing waste explained in more detail below with examples.

Example 1:

briquettes from 60% sewage sludge (30% TM) and 40% filter dust with cement as binders are used with a Kokstoffatz of 120 kg / t briquette under limestone addition or an adapted slag guide in a coke-fired Melting furnace smelted with an oxygen propellant nozzle system is operated for combustion wind supply. The slag will tapped at about 1450 ° C and granulated in a water bath.

• – Die Schlacke enthält 5,9% P₂O₅, davon 90,8% citratlöslich (als Maß für die Pflanzenverfügbarkeit des Phosphors).
• – Der CaO-Gehalt der Schlacke beträgt 42,5%.
• – Der FeO-Gehalt der Schlacke beträgt 1,5%.

From the granules, a mineral product is produced by fine grinding, which shows the expected properties of a lime phosphate fertilizer with the following parameters:

• - The slag contains 5.9% P ₂ O ₅ , of which 90.8% citrate soluble (as a measure of the plant availability of phosphorus).
• The CaO content of the slag is 42.5%.
• - The FeO content of the slag is 1.5%.

These Slag can thus serve as the basis for a lime phosphate fertilizer or a "mineral composite fertilizer" accordingly Nomenclature of DüMV with 4 to 7 wt .-% citrate-soluble Phosphate can be used.

Example 2:

briquettes from the filter ashes of a mono-incinerator for sewage sludge are made with cement as a binder and with a coke kit of 140 kg / t briquette with limestone addition or an adapted Slag run in a coke-fired shaft melting furnace melted down with an oxygen propellant nozzle system is operated for combustion wind supply. The slag will tapped at about 1500 ° C and by air cooling cooled to about 200 ° C.

• – Die Schlacke enthält 11,7% P₂O₅, davon 92,6% citratlöslich (als Maß für die Pflanzenverfügbarkeit des Phosphors).
• – Der CaO-Gehalt der Schlacke beträgt 44,3%.
• – Der FeO-Gehalt der Schlacke beträgt 1,7%.

From the granules, a mineral product is produced by fine grinding, which can be used with the following parameters as a precursor for a lime phosphate fertilizer:

• - The slag contains 11.7% P ₂ O ₅ , of which 92.6% citrate soluble (as a measure of the plant availability of phosphorus).
• The CaO content of the slag is 44.3%.
• - The FeO content of the slag is 1.7%.

Example 3:

Briquettes from the filter bag of a mono-incineration plant for sewage sludge are made with cement as a binder and melted under limestone addition or an adapted slag guide in a coke-fired shaft melting furnace, which is operated with an oxygen blowing nozzle system for combustion wind supply. The combustion wind additionally injects 50 kg of animal meal per ton of briquette. This reduces coke consumption by 20 kg / t briquette and increases the P ₂ O ₅ content of the slag by 0.8%.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 2820729 [0002]
• - DE 19545122 A1 [0003]

Claims (6)

Heavy metal low calcium phosphate fertilizer and method for producing a precursor for this fertilizer from phosphorus-containing wastes with the addition of other dusty and / or granular substances that may contain iron or iron compounds and also phosphorus or phosphorus compounds, by using metallurgical process techniques of pig iron, cast iron and mineral wool -Production, characterized in that - the phosphorus-containing waste, such as sewage sludge, animal meal, meat mash, ground bones, in mixture with the resulting in the combustion of these substances ashes, such. As the filter dust from the exhaust gas purification of mono-combustion plants, briquetted with the addition of binders or processed by other molding processes into moldings, - the briquettes or moldings in a coke-fired shaft melting furnace with oxygen directly, oxygen and combustion air or combustion air as a combustion agent to a molten slag and a Melted metal alloy, - the low-boiling metals contained in the starting materials, such as Hg, Cd, Zn largely reduced and escape to a part of the gas phase and are deposited in the exhaust gas purification, - the high-boiling heavy metals contained in the starting materials, such as Cu, Cr Ni are largely reduced and partly dissolved as alloying elements in the iron-metal melt bath acting as heavy metal sink in the hearth, metals which are contained in the starting materials but are largely insoluble in liquid iron, such as Pb Collect under the iron - metallic molten bath in the hearth of the shaft melting furnace, - the remaining metals and metal oxides contained in the starting materials, ie the portion, which was not reduced and not discharged over the exhaust gas, into the typical structures of the slag are integrated, that in the liquid slag contained P ₂ O _{5 are incorporated} into the typical structures of the slag, Heavy metal low calcium phosphate fertilizer and method for producing a precursor for this fertilizer by using metallurgical process techniques of pig iron, cast iron and mineral wool production according to claim 1, characterized in that the heavy metals contained in the liquid slag and the P contained in the liquid slag ₂ O _{5 are incorporated} into their crystalline structures during rapid cooling and solidification into the typical amorphous structures of the slag or, with slow solidification of this slag. Heavy metal low calcium phosphate fertilizer and method for producing a precursor for this fertilizer by using metallurgical process techniques of pig iron, cast iron and mineral wool production according to claim 1 or 2, characterized in that the citrate solubility contained in the fertilizer or in the precursor for this fertilizer P ₂ O _{5 is} greater than 85%, preferably greater than 90%. Heavy metal low calcium phosphate fertilizer and a method of producing a precursor for the same Fertilizers using metallurgical process techniques of pig iron, cast iron and mineral wool production according to claim 1 or 2 and claim 3, characterized in that the fertilizer or the precursor for this fertilizer less contains 5%, preferably less than 2% iron oxides. Process for producing a precursor for this fertilizer by using metallurgical processing techniques of pig iron, cast iron and mineral wool production according to claim 1, characterized in that in the coke-fired shaft melting furnace with oxygen directly, oxygen and combustion air or combustion air as a combustion medium additionally high calorific value and / or phosphorus-rich and / or other fertilizer-relevant elements contained, dust and / or fine-grained materials injected and / or be supplied in lumps. Process for producing a precursor for this fertilizer by using metallurgical processing techniques of pig iron, cast iron and mineral wool production according to claim 1, characterized in that the melting unit is a metallurgical Processes of pig iron, cast iron and mineral wool production using furnace or mixing and / or Abstichaggregat.