CN108751156B - Method for preparing high-purity triple superphosphate by decomposing phosphorite with ammonium chloride - Google Patents
Method for preparing high-purity triple superphosphate by decomposing phosphorite with ammonium chloride Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/32—Phosphates of magnesium, calcium, strontium, or barium
- C01B25/321—Methods for converting an alkaline earth metal ortho-phosphate into another ortho-phosphate
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05B—PHOSPHATIC FERTILISERS
- C05B1/00—Superphosphates, i.e. fertilisers produced by reacting rock or bone phosphates with sulfuric or phosphoric acid in such amounts and concentrations as to yield solid products directly
- C05B1/04—Double-superphosphate; Triple-superphosphate; Other fertilisers based essentially on monocalcium phosphate
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- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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- C01P2006/80—Compositional purity
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Abstract
The invention relates to industrial solid wasteThe technical field of material utilization, in particular to a method for preparing high-purity triple superphosphate by decomposing phosphorite with ammonium chloride. In the invention, CaCl2The molten salt system adopts ammonium chloride as a stealth acid medium, uses ground phosphate rock as a raw material, reacts with the ammonium chloride in a calcium chloride molten salt system to generate a heavy calcium product and release ammonia gas, does not consume sulfuric acid and discharge phosphogypsum, dissolves heavy calcium superphosphate containing acid-insoluble impurities and having low purity in hydrochloric acid, removes precipitates, takes filtrate, and puts the filtrate in CaCl2In the state of a sub-molten salt system, the reaction is carried out at the temperature of more than 140 ℃, so that a large amount of HCl formed by the reaction is volatilized, and the reaction is rapidly carried out in the forward direction, so as to obtain a large amount of high-purity triple superphosphate. The method is a method for preparing high-purity triple superphosphate by decomposing phosphorite with ammonium chloride, and the triple superphosphate has high purity without sulfuric acid consumption and phosphogypsum discharge.
Description
Technical Field
The invention relates to the technical field of phosphorite treatment, in particular to a method for preparing high-purity triple superphosphate by decomposing phosphorite with ammonium chloride.
Background
The traditional heavy calcium adopts an additive production process, and at least 0.46 ton of sulfuric acid is consumed for producing 1 ton of heavy calcium, so that 0.93 ton of phosphogypsum is produced.
Phosphogypsum is industrial waste residue generated in the production process of wet-process phosphoric acid. For each 1 ton of phosphoric acid produced (in P)2O5Meter), typically 4-5 tons of phosphogypsum are produced. The main components of the phosphogypsum are calcium sulfate dihydrate or calcium sulfate hemihydrate, and a small amount of quartz, undecomposed apatite and water-soluble P2O5Insoluble P2O5Eutectic crystal P2O5Fluoride, and phosphate and sulfate salts of fluorine, aluminum, magnesium, and the like. At present, the phosphogypsum is mainly used for producing building material products, including cement retarder (setting retarder), building gypsum powder, paper-faced gypsum board, fiber gypsum board, pit filler, road bed material and the like. Soluble phosphorus, fluorine and other impurities in the phosphogypsum have adverse effects on the performance of a phosphogypsum building material product, such as prolonged gypsum setting time, reduced strength of a hardened body, loose crystal structure and the like, and the water content is high, so that the phosphogypsum prepared building material product has poor quality, low additional value and short market transportation radius. In addition, because the solubility products of calcium sulfate and calcium carbonate in ammonium sulfate differ by more than 3000 times, the calcium sulfate is easily converted into solid product calcium carbonate through the carbonation reaction process and synchronously produces ammonium sulfate mother liquor, and the ammonium sulfate mother liquor can be further converted to prepare sulfur-based compound fertilizer products such as potassium sulfate, ammonium chloride and the like. On one hand, however, almost all impurities in the phosphogypsum enter solid products, so that the obtained calcium carbonate product has fine particles, poor purity and whiteness and low added value and is difficult to utilize on a large scale; on the other hand, the conversion of calcium sulphate in phosphogypsum to calcium carbonate requires the consumption of large amounts of ammonia, whereasThe consumed ammonia is finally converted into low value-added products such as ammonium sulfate or ammonium chloride, and the whole technology is difficult to be economic.
Based on this, aiming at the outstanding problems of large amount of phosphogypsum produced in the prior phosphoric acid extraction process by the dihydrate wet method and poor economy of the technology for preparing calcium carbonate by carbonating and converting the phosphogypsum, a method for decomposing phosphate rock by using the phosphorus-free gypsum needs to be found.
The triple superphosphate is colorless triclinic crystals or white crystalline powder. The relative density was 2.22(16 ℃). Slightly hygroscopic, easily soluble in hydrochloric acid and nitric acid, slightly soluble in cold water, and hardly soluble in ethanol. At 30 ℃, 1.8g of monocalcium phosphate can be dissolved in 100ml of water. The aqueous solution is acidic, and the calcium hydrogen orthophosphate is hydrolyzed by adding hot aqueous solution. At 109 ℃ the water of crystallization is lost and at 203 ℃ it decomposes to calcium metaphosphate. Triple superphosphate (triple superphosphate), component Ca (H)2PO4)2Soluble in water, has higher fertilizer efficiency than calcium superphosphate (ordinary calcium superphosphate), is preferably mixed with farmyard manure, but cannot be mixed with alkaline substances, and can react with the following substances H2PO4(-)+2OH(-)＝2H2O+PO4(3-) Insoluble calcium phosphate is generated to reduce the fertilizer efficiency. The triple superphosphate is suitable for fertilizer, is used for various soils and crops, and can be used as a base fertilizer, a top dressing and a compound (mixed) fertilizer raw material. Is widely applicable to various grain crops and economic crops such as rice, wheat, corn, sorghum, cotton, melons, fruits, vegetables and the like. It is also used for glass manufacture, plastic stability, and supplementary feed for livestock.
At present, the production of calcium superphosphate mainly adopts two processes of a dilute acid ore powder method and a concentrated acid ore pulp method. The traditional process for producing triple superphosphate is to decompose phosphorite with sulfuric acid, obtain dilute phosphoric acid through leaching and filtering, and decompose secondary phosphorite with higher quality with the concentrated phosphoric acid after concentration to obtain secondary phosphorite with higher P content2O5Heavy superphosphate. The traditional production process has high requirements on phosphorite, namely secondary ore, for producing the triple superphosphate, but high-grade phosphorite is less and less along with the long-term exploitation and consumption of phosphorite resources. In addition, the sulfur resource in China is insufficient, the sulfuric acid is mainly prepared by pyrite,thus, the supply of sulfuric acid is short. Since 2008, the international sulfur price is continuously rising, and the domestic sulfuric acid price is stimulated to be vigorously raised. And the resources of the middle-low grade phosphorite in China are more, hydrochloric acid is a byproduct of many enterprises, the hydrochloric acid is abundant, and the price is low. Therefore, many enterprises use hydrochloric acid to replace sulfuric acid to decompose phosphorite to produce triple superphosphate and co-produce calcium chloride, but the method consumes a large amount of hydrochloric acid to produce a large amount of calcium chloride, and the calcium chloride is associated with phosphoric acid, so that the economic benefit of the calcium chloride is low.
In conclusion, it is urgent to find a method for preparing triple superphosphate by decomposing phosphate ore without generating phosphate-free gypsum.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides
A method for preparing high-purity triple superphosphate by decomposing phosphorite with ammonium chloride comprises the following steps:
(1) crushing phosphate rock, mixing with ammonium chloride solution, stirring and pulping;
(2) adding ground phosphate rock slurry into CaCl2Carrying out reaction in a sub-molten salt;
(3) after full reaction, adding water into the reactant for dilution, discharging and filtering to respectively obtain filtrate and filter cake;
(4) washing the filter cake with water for dechlorination, and then drying the filter cake to obtain triple superphosphate;
(5) adding the obtained triple superphosphate into water, stirring to form slurry, adding hydrochloric acid into the slurry, and reacting;
(6) filtering after the slurry is fully reacted to respectively obtain filtrate and filter cake,
(7) heating the filtrate to obtain a stable sub-molten salt system, and reacting at the temperature of more than 140 ℃;
(8) and after the reaction is finished, collecting a solid product to obtain the high-purity triple superphosphate.
Preferably, the phosphorite is smashed into powder. The powdered phosphorite is easier to react with ammonium chloride solution, so that the reaction is faster and slurry is easier to be formed.
Preferably, the ammonium chloride solution is a supersaturated ammonium chloride solution. More preferably, the supersaturated ammonium chloride solution is a supersaturated solution at 60 ℃. The supersaturated ammonium chloride solution contains more ammonium chloride, and can be timely supplemented after the ammonium chloride in the solution is consumed by the reaction with the ore, the solubility of the ammonium chloride is higher under the condition of 60 ℃, the ammonium chloride in the supersaturated ammonium chloride solution is also more, and the loss caused by the increase of the hydrolysis amount of the ammonium chloride due to overhigh temperature can be avoided.
Preferably, CaCl of said step (2)2A sub-molten salt is prepared by mixing CaCl2Mixing with water 50-150 wt%, stirring, heating to 170-180 deg.c and maintaining the temperature stably. In this case, CaCl2The sub-molten salt system is relatively stable.
Preferably, in the step (2), the ground phosphate rock slurry is added into CaCl2In the process of sub-melting the salt, the ground phosphate rock slurry is slowly added. So as to avoid overflowing and influencing the reaction speed caused by the rapid generation of a large amount of foam due to the rapid addition of the ground phosphate rock slurry.
Preferably, in the step (2), the reaction time is controlled to be more than 2 h. So that the reaction proceeds sufficiently.
Preferably, in the step (3), water is added for dilution, and the water accounts for 15-40% of the weight of the reactants. At the moment, the dilution effect is better, the dosage is moderate, and the loss of the triple superphosphate caused by the increase of the amount of the triple superphosphate dissolved in water due to more water is avoided.
Preferably, the step (7) is carried out at 160 ℃. The reaction speed is high when the reaction is carried out at 160 ℃, and the change of phosphoric acid and the loss of materials can not be caused.
Preferably, in the step (7), the gas released during the reaction is absorbed by using an alkaline solution. The gas released in the reaction process is mainly HCl gas and cannot be directly discharged into the air.
Preferably, in the step (7), the condensation reflux is carried out during the reaction. The condensation reflux can reduce the loss of water and phosphoric acid, so that the reaction consumption is reduced.
Preferably, in the step (7), the released gas is collected during the reaction. The gas released in the reaction process is mainly HCl gas, and can be collected and utilized.
The method of the invention is in CaCl2The molten salt system adopts ammonium chloride as a stealth acid medium, uses ground phosphate rock as a raw material, and reacts with the ammonium chloride in a calcium chloride molten salt system to generate a heavy calcium carbonate product and release ammonia gas, so that the consumption of sulfuric acid and the emission of phosphogypsum are avoided.
The main reaction equation of the invention is as follows:
when decomposing the phosphate ore ammonium chloride:
2Ca5(PO4)3F+12NH4Cl＝3Ca(H2PO4)2+CaF2+12NH3↑+6CaCl2
(reaction conditions: 160 ℃ C., 180 ℃ C., CaCl)2Sub-molten salt system)
CaCO3+CaSiO3+2NH4Cl＝2NH3↑+H2O+CaCl2+CO2↑+SiO2·2H2O
(reaction conditions: 160 ℃ C., 180 ℃ C., CaCl)2Sub-molten salt system)
Ca (H) formed by the reaction at this time2PO4)2Is a slightly soluble substance, SiO2·2H2O is insoluble matter, the filter cake obtained in the step (3) mainly consists of the two components, so that the purity of the triple superphosphate is not high, and therefore, the filter cake is separated by using free hydrochloric acid and then CaCl is added2And carrying out reverse reaction in a molten salt system state to obtain the triple superphosphate with higher purity.
When the triple superphosphate is purified:
3Ca(H2PO4)2-acid insoluble residue +2HCl ═ 2H3PO4+CaCl2+ acid insoluble residue ↓
(reaction conditions: < 100 ℃ C.)
2H3PO4+CaCl2＝Ca(H2PO4)2+2HCl
(reaction conditions: CaCl > 140 ℃ C.)2Sub-molten salt system)
In solution, HCl is more acidic than H3PO4Thus H3PO4With CaCl2No reaction takes place and Ca (H)2PO4)2But reacts with HCl to form H3PO4With CaCl2Therefore, CaCl is generally regarded as2And H3PO4It is not feasible to directly prepare triple superphosphate, Ca (H) in solution2PO4)2Reaction with HCl to form H3PO4With CaCl2The specific reaction equation of (a) is as follows:
Ca(H2PO4)2+2HCl＝2H3PO4+CaCl2
(in solution strong acid and weak acid reaction)
In CaCl2In the state of a sub-molten salt system, the reaction can be performed reversely, and the specific reaction equation is as follows:
2H3PO4+CaCl2＝Ca(H2PO4)2+2HCl
(reaction conditions: CaCl > 140 ℃ C.)2Sub-molten salt system)
In this case, the reactions are reversible and can be carried out via CaCl2And H3PO4Reaction to obtain Ca (H)2PO4)2With HCl, but in the same time the reaction takes place in the forward direction, in the reverse direction, triple superphosphate can be obtained, but the triple superphosphate still contains more CaCl2Resulting in lower purity of triple superphosphate.
In this case, by controlling the reaction temperature to be more than 140 ℃, a large amount of HCl formed by the reaction can be volatilized, the reaction speed is high when the reaction is carried out at 160 ℃, the material loss due to the change of phosphoric acid is not caused, and the reaction is rapidly carried out in the forward direction, so that a large amount of triple superphosphate can be obtained, and the purity of the triple superphosphate obtained is high.
Compared with the prior art, the invention has the technical effects that:
in the invention, CaCl2The molten salt system adopts ammonium chloride as a stealth acid medium, uses ground phosphate rock as a raw material, reacts with the ammonium chloride in a calcium chloride molten salt system to generate a heavy calcium product and release ammonia gas, does not consume sulfuric acid and discharge phosphogypsum, dissolves heavy calcium superphosphate containing acid-insoluble impurities and having low purity in hydrochloric acid, removes precipitates, takes filtrate, and puts the filtrate in CaCl2In the state of a sub-molten salt system, the reaction is carried out at the temperature of more than 140 ℃, so that a large amount of HCl formed by the reaction is volatilized, and the reaction is rapidly carried out in the forward direction, so as to obtain a large amount of high-purity triple superphosphate. The method has the advantages of no sulfuric acid consumption and phosphogypsum discharge, high purity of the obtained triple superphosphate, elimination of the problems of consumption of a large amount of sulfuric acid and discharge of a large amount of phosphogypsum in the traditional production process of the triple superphosphate, no consumption of sulfuric acid and discharge of the phosphogypsum, and high purity of the obtained triple superphosphate.
Detailed Description
The technical solution of the present invention is further defined below with reference to the specific embodiments, but the scope of the claims is not limited to the description.
Example 1
(1) Crushing 200g of phosphate rock into powder, mixing the powder with an ammonium chloride solution, and stirring the mixture to form slurry, wherein the ammonium chloride solution is an ammonium chloride saturated solution obtained by dissolving 230g of ammonium chloride in 280ml of water at 60 ℃;
(2) adding ground phosphate rock slurry into CaCl2In a sub-molten salt, reacting for 2 hours, wherein the CaCl is2Sub-molten salt is prepared by mixing 800gCaCl2Mixing with 100 wt% water, stirring, heating to 175 deg.C, and keeping stable to obtain the final product;
(3) after full reaction, adding water accounting for 25 percent of the weight of the reactant into the reactant for dilution, discharging and filtering to respectively obtain filtrate and filter cake;
(4) washing the filter cake with water for dechlorination, and then drying the filter cake to obtain triple superphosphate;
(5) adding the obtained triple superphosphate into water, stirring to form slurry, adding hydrochloric acid into the slurry, and reacting;
(6) filtering after the slurry is fully reacted to respectively obtain filtrate and filter cake,
(7) heating the filtrate to obtain a stable sub-molten salt system, reacting at 160 ℃, and absorbing the gas released by the reaction by using an alkaline solution;
(8) and after the reaction is finished, collecting a solid product to obtain the high-purity triple superphosphate.
P in the phosphate ore2O5The content of CaO is 35.62 percent and the content of CaO is 50.84 percent.
Example 2
(1) Crushing 200g of phosphate rock into powder, mixing the powder with an ammonium chloride solution, and stirring and slurrying, wherein the ammonium chloride solution is an ammonium chloride supersaturated solution obtained by dissolving 230g of ammonium chloride in 400ml of water at 40 ℃;
(2) adding ground phosphate rock slurry into CaCl2In a sub-molten salt, reacting for 1h, the CaCl2Sub-molten salt is prepared by mixing 800gCaCl2Mixing with water 50% of the weight of the raw materials, stirring uniformly, heating to 180 ℃, and keeping stable to obtain the product;
(3) after full reaction, adding water accounting for 15 percent of the weight of the reactant into the reactant for dilution, discharging and filtering to respectively obtain filtrate and filter cakes;
(4) washing the filter cake with water for dechlorination, and then drying the filter cake to obtain triple superphosphate;
(5) adding the obtained triple superphosphate into water, stirring to form slurry, adding hydrochloric acid into the slurry, and reacting;
(6) filtering after the slurry is fully reacted to respectively obtain filtrate and filter cake,
(7) heating the filtrate to obtain a stable sub-molten salt system, reacting at 140 ℃, and absorbing the gas released by the reaction by using an alkaline solution;
(8) and after the reaction is finished, collecting a solid product to obtain the high-purity triple superphosphate.
P in the phosphate ore2O5The content of CaO is 35.62 percent and the content of CaO is 50.84 percent.
Example 3
(1) Crushing 200g of phosphate rock into powder, mixing the powder with an ammonium chloride solution, and stirring and slurrying, wherein the ammonium chloride solution is an ammonium chloride supersaturated solution obtained by dissolving 230g of ammonium chloride in 230ml of water at 80 ℃;
(2) adding ground phosphate rock slurry into CaCl2In a sub-molten salt, reacting for 3 hours, wherein the CaCl is2Sub-molten salt is prepared by mixing 800gCaCl2Mixing with water 150 wt%, stirring, heating to 170 deg.C, and keeping stable to obtain the final product;
(3) after full reaction, adding water accounting for 40 percent of the weight of the reactant into the reactant for dilution, discharging and filtering to respectively obtain filtrate and filter cakes;
(4) washing the filter cake with water for dechlorination, and then drying the filter cake to obtain triple superphosphate;
(5) adding the obtained triple superphosphate into water, stirring to form slurry, adding hydrochloric acid into the slurry, and reacting;
(6) filtering after the slurry is fully reacted to respectively obtain filtrate and filter cake,
(7) heating the filtrate to obtain a stable sub-molten salt system, reacting at 180 ℃, and absorbing the gas released by the reaction by using an alkaline solution;
(8) and after the reaction is finished, collecting a solid product to obtain the high-purity triple superphosphate.
P in the phosphate ore2O5The content of CaO is 35.62 percent and the content of CaO is 50.84 percent.
Example 4
(1) Crushing 200g of phosphate rock into powder, mixing the powder with an ammonium chloride solution, and stirring the mixture to form slurry, wherein the ammonium chloride solution is an ammonium chloride saturated solution obtained by dissolving 230g of ammonium chloride in 280ml of water at 60 ℃;
(2) adding the ground phosphate rock slurry into CaCl slowly2In a sub-molten salt, reacting for 2 hours, wherein the CaCl is2Sub-molten salt is prepared by mixing 800gCaCl2Mixing with 100 wt% water, stirring, heating to 175 deg.C, and keeping stable to obtain the final product;
(3) after full reaction, adding water accounting for 25 percent of the weight of the reactant into the reactant for dilution, discharging and filtering to respectively obtain filtrate and filter cake;
(4) washing the filter cake with water for dechlorination, and then drying the filter cake to obtain triple superphosphate;
(5) adding the obtained triple superphosphate into water, stirring to form slurry, adding hydrochloric acid into the slurry, and reacting;
(6) filtering after the slurry is fully reacted to respectively obtain filtrate and filter cake,
(7) heating the filtrate to obtain a stable sub-molten salt system, reacting at 160 ℃, and absorbing the gas released by the reaction by using an alkaline solution;
(8) and after the reaction is finished, collecting a solid product to obtain the high-purity triple superphosphate.
P in the phosphate ore2O5The content of CaO is 35.62 percent and the content of CaO is 50.84 percent.
Example 5
(1) Crushing 200g of phosphate rock into powder, mixing the powder with an ammonium chloride solution, and stirring the mixture to form slurry, wherein the ammonium chloride solution is an ammonium chloride saturated solution obtained by dissolving 230g of ammonium chloride in 280ml of water at 60 ℃;
(2) adding ground phosphate rock slurry into CaCl2In a sub-molten salt, reacting for 2 hours, wherein the CaCl is2Sub-molten salt is prepared by mixing 800gCaCl2Mixing with 100 wt% water, stirring, heating to 175 deg.C, and keeping stable to obtain the final product;
(3) after full reaction, adding water accounting for 25 percent of the weight of the reactant into the reactant for dilution, discharging and filtering to respectively obtain filtrate and filter cake;
(4) washing the filter cake with water for dechlorination, and then drying the filter cake to obtain triple superphosphate;
(5) adding the obtained triple superphosphate into water, stirring to form slurry, adding hydrochloric acid into the slurry, and reacting;
(6) filtering after the slurry is fully reacted to respectively obtain filtrate and filter cake,
(7) heating the filtrate to obtain a stable sub-molten salt system, reacting at 160 ℃, carrying out condensation reflux in the reaction process, and absorbing the gas released by the reaction by using an alkaline solution;
(8) and after the reaction is finished, collecting a solid product to obtain the high-purity triple superphosphate.
P in the phosphate ore2O5The content of CaO is 35.62 percent and the content of CaO is 50.84 percent.
Example 6
(1) Crushing 200g of phosphate rock into powder, mixing the powder with an ammonium chloride solution, and stirring the mixture to form slurry, wherein the ammonium chloride solution is an ammonium chloride saturated solution obtained by dissolving 230g of ammonium chloride in 280ml of water at 60 ℃;
(2) adding ground phosphate rock slurry into CaCl2In a sub-molten salt, reacting for 2 hours, wherein the CaCl is2Sub-molten salt is prepared by mixing 800gCaCl2Mixing with 100 wt% water, stirring, heating to 175 deg.C, and keeping stable to obtain the final product;
(3) after full reaction, adding water accounting for 25 percent of the weight of the reactant into the reactant for dilution, discharging and filtering to respectively obtain filtrate and filter cake;
(4) washing the filter cake with water for dechlorination, and then drying the filter cake to obtain triple superphosphate;
(5) adding the obtained triple superphosphate into water, stirring to form slurry, adding hydrochloric acid into the slurry, and reacting;
(6) filtering after the slurry is fully reacted to respectively obtain filtrate and filter cake,
(7) heating the filtrate to obtain a stable sub-molten salt system, reacting at 160 ℃, and collecting released gas in the reaction process;
(8) and after the reaction is finished, collecting a solid product to obtain the high-purity triple superphosphate.
P in the phosphate ore2O5The content of CaO is 35.62 percent and the content of CaO is 50.84 percent.
The examples were compared and the results were as follows:
from the above, the method of the present invention can effectively purify the triple superphosphate, remove the acid insoluble impurities therein, and obtain the triple superphosphate with high purity.
Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the technical solution of the present invention is not limited to the above-described embodiments, and many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.
Claims (9)
1. A method for preparing high-purity triple superphosphate by decomposing phosphorite with ammonium chloride is characterized by comprising the following steps:
(1) crushing phosphate rock, mixing with ammonium chloride solution, stirring and pulping;
(2) adding ground phosphate rock slurry into CaCl2In a sub-molten salt, the reaction is carried out, the CaCl2A sub-molten salt is prepared by mixing CaCl2Mixing with water 50-150 wt%, stirring, heating to 170-180 deg.C, and keeping stable to obtain the final product;
(3) after full reaction, adding water into the reactant for dilution, discharging and filtering to respectively obtain filtrate and filter cake;
(4) washing the filter cake with water for dechlorination, and then drying the filter cake to obtain triple superphosphate;
(5) adding the obtained triple superphosphate into water, stirring to form slurry, adding hydrochloric acid into the slurry, and reacting;
(6) filtering after the slurry is fully reacted to respectively obtain filtrate and filter cake,
(7) heating the filtrate to obtain a stable sub-molten salt system, and reacting at the temperature of more than 140 ℃;
(8) and after the reaction is finished, collecting a solid product to obtain the high-purity triple superphosphate.
2. The method of claim 1, wherein the phosphate ore is broken up into powder.
3. The method of claim 1, wherein the ammonium chloride solution is a supersaturated ammonium chloride solution.
4. The method for preparing high-purity triple superphosphate by decomposing phosphate ore with ammonium chloride according to claim 3, wherein the supersaturated ammonium chloride solution is a supersaturated solution at 60 ℃.
5. The method for preparing high-purity triple superphosphate by decomposing phosphate ore with ammonium chloride as claimed in claim 1, wherein in the step (2), the powdered phosphate ore slurry is added into CaCl2In the process of sub-melting the salt, the ground phosphate rock slurry is slowly added.
6. The method for preparing high-purity triple superphosphate by decomposing phosphate ore with ammonium chloride as claimed in claim 1, wherein the dilution with water in step (3) is performed by adding water in an amount of 15-40% by weight of the reactants.
7. The method for preparing high-purity triple superphosphate by decomposing phosphate ore with ammonium chloride as claimed in claim 1, wherein in the step (7), the gas released during the reaction is absorbed by using alkaline solution.
8. The method for preparing high-purity triple superphosphate by decomposing phosphate ore with ammonium chloride according to claim 1, wherein the step (7) is carried out by condensing and refluxing during the reaction.
9. The method for preparing high-purity triple superphosphate by decomposing phosphate ore with ammonium chloride according to claim 1 or 8, wherein the step (7) is carried out by collecting the released gas during the reaction.
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| CN85107209B (en) * | 1985-09-24 | 1987-06-10 | 路文兴 | Method of chemical sepn. of low grade calcareous phosphorous ore |
| CN1122635C (en) * | 1999-08-22 | 2003-10-01 | 李怀然 | novel process for preparing fodder grade calcium hydrophosphate and by-product calcium carbonate and ammonium chloride by hydrochloric acid method |
| CN1962421B (en) * | 2006-11-19 | 2010-04-14 | 武善东 | Phosphorite acidolysis method |
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