Method for producing low-potassium industrial-grade ammonium phosphate from medium-low-grade high-potassium phosphorite

Abstract

A method for producing low-potassium industrial-grade ammonium phosphate by utilizing medium-low-grade high-potassium phosphorite comprises the following steps: S1, blending raw material high-potassium ore, producing crude phosphoric acid from phosphoric acid by a sulfuric acid process and a wet process, and cooling and aging to obtain aged acid; s2, carrying out a neutralization reaction on an ammonia source and the aging acid, controlling the reaction pH, and carrying out filter pressing on the reaction slurry after the reaction to obtain a clear liquid; and S3, performing multi-effect evaporation and concentration on the clear liquid, and cooling to obtain supersaturated crystallized crystal slurry. And S4, adjusting the pH value of the supersaturated crystal slurry by using a pH regulator, filtering, and drying the filtered solid to obtain low-potassium industrial-grade diammonium phosphate or adjusting the pH value of the filtered solid back by using phosphoric acid to obtain low-potassium industrial-grade monoammonium phosphate. The method can effectively solve the problem of high potassium content of the finished product caused by high potassium content in the raw material ore in the finished product industrial grade monoammonium phosphate. According to the scheme, the content of the potassium element is reduced by adjusting the pH value of the system and recrystallizing, the technological process is simple, all filtrate generated in the process can be recycled, and the method has extremely high industrialization value.

Description

Technical Field

[0001] The invention relates to the technical field of phosphate preparation, and in particular to a method for producing low-potassium industrial-grade ammonium phosphate by utilizing medium- and low-grade high-potassium phosphate ore. Background Art

[0002] Industrial monoammonium phosphate, also known as ammonium dihydrogen phosphate, is a colorless, transparent tetragonal crystal. It is slightly soluble in alcohol but readily soluble in water. Its aqueous solution is acidic, and its powdered form is somewhat hygroscopic. Industrial monoammonium phosphate does not burn or explode when exposed to acids, bases, high temperatures, or redox substances. It exhibits excellent thermal stability and dehydrates at high temperatures, easily forming viscous chain compounds (such as ammonium polyphosphate and ammonium metaphosphate).

[0003] Industrial-grade monoammonium phosphate is an excellent fire extinguishing agent and flame retardant. It is widely used as a flame retardant for wood, paper, and fabrics, and as a main ingredient in forest fire extinguishing agents and dry powder fire extinguishing agents. It is also used in the dye industry and fiber processing dispersants, as a compounding agent for fire extinguishing coatings, dry powder fire extinguishing agents, and as an ember extinguisher for matchsticks and candle wicks.

[0004] In the food and pharmaceutical industries, it is used as a yeast nutrient, leavening agent, buffer, dough conditioner, brewing fermentation aid, and as an additive in feed production. Industrial monoammonium phosphate can be used as phosphorus nutrition for yeast culture. It is also used in pharmaceutical production.

[0005] In agricultural production, industrial-grade monoammonium phosphate is used as a basic raw material for fertilizers, such as the preparation of N, P, and K ternary compound fertilizers. It is mainly used to produce compound fertilizers and water-soluble fertilizers for direct application to farmland. In the field of environmental protection, it is used to measure sulfide in water and the atmosphere.

[0006] In the new energy field, with the gradual development of new energy vehicles, the market share of battery cell products using iron phosphate as the precursor of the positive electrode material has gradually increased. Ammonium method iron phosphate is the main process for the production of iron phosphate. The demand and quality requirements for industrial-grade monoammonium phosphate are also getting higher and higher. The ammonium method iron phosphate process production market has an increasing demand for industrial-grade monoammonium phosphate with low impurity content, especially potassium content.

[0007] Currently, monoammonium phosphate (MAP) is produced primarily through wet-process phosphoric acid and thermal-process phosphoric acid. Wet-process phosphoric acid production is an effective method for processing phosphate rock. Compared to thermal-process phosphoric acid, wet-process phosphoric acid significantly reduces energy consumption. With increasing energy scarcity, low-energy wet-process phosphoric acid purification technology is gaining attention. Using wet-process phosphoric acid instead of thermal-process phosphoric acid to produce industrial-grade MAP will significantly enhance the technical content of traditional MAP production facilities, expand the deep processing capabilities of wet-process phosphoric acid, and improve economic efficiency.

[0008] However, the current monoammonium phosphate prepared from wet-process phosphoric acid has a technical problem of high K content introduced from the raw materials. In the field of new energy, the high K content of the finished product will have an adverse effect on the performance of the subsequently prepared batteries. Summary of the Invention

[0009] Aiming at the technical problem that monoammonium phosphate prepared by wet-process phosphoric acid has a high K content introduced from the raw materials, the present invention provides a method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate rock.

[0010] A method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore comprises the following steps: S1, blending high-potassium ore as raw material, producing crude phosphoric acid with sulfuric acid wet-process phosphoric acid and cooling and aging to obtain aged acid; S2, neutralizing the ammonia source with the aged acid to control the reaction pH, and filtering the reaction slurry after the reaction to obtain a clear liquid; S3, multi-effect evaporation to concentrate the clear liquid, and cooling to obtain a supersaturated crystal slurry; S4. Adjust the pH of the supersaturated slurry with a pH regulator and then filter. Dry the filtered solid to obtain low-potassium industrial-grade diammonium phosphate, or adjust the pH of the filtered solid with phosphoric acid to obtain low-potassium industrial-grade monoammonium phosphate.

[0011] Preferably, the mass fraction of crude phosphoric acid P2O5 in step S1 is 18%-26%.

[0012] Preferably, the cooling and aging temperature in step S1 is 45-75° C., and the cooling and aging time is 8-12 hours.

[0013] Preferably, the ammonia source in step S2 is one or more of liquid ammonia, aqueous ammonia and gaseous ammonia.

[0014] Preferably, the pH range of the neutralization reaction in step S2 is controlled to be 3.5-4.5.

[0015] Preferably, the temperature of the cooling crystallization in step S3 is 60-75°C.

[0016] Preferably, the pH regulator in step S4 is one or more of liquid ammonia, aqueous ammonia and gaseous ammonia.

[0017] Preferably, the pH of the saturated slurry in step S4 is adjusted to a range of 7-10.

[0018] Preferably, the phosphoric acid used to recover the filtered solids in step S4 is refined phosphoric acid with a mass fraction of 75% or 85%.

[0019] Preferably, the pH range of the filtered solids after phosphoric acid adjustment in step S4 is 3.2-4.8.

[0020] The solution of the present invention reduces the potassium content by adjusting the system pH and recrystallizing. The process flow is simple, and all filtrates produced in the middle can be reused. It has extremely high industrial value, and the obtained industrial-grade monoammonium phosphate with low potassium content can also be directly used to prepare high-purity ferric phosphate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is an operation flow chart of the present invention. DETAILED DESCRIPTION

[0022] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0023] <Example 1> A method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore comprises the following steps: 1. Take medium- and low-grade high-potassium phosphate ore with a potassium content of ≥2000ppm, and produce crude phosphoric acid with a P2O5 mass fraction of 26% through wet-process phosphoric acid using the sulfuric acid method, and age it at 60°C for 8 hours to obtain aged acid.

[0024] 2. Ammonia water and aged acid are neutralized, the pH at the neutralization reaction end point is controlled to be 4.2, and a clear liquid is obtained by filtration.

[0025] 3. The clear liquid was evaporated and concentrated, and then cooled to 60°C to obtain a supersaturated crystal slurry.

[0026] 4. Adjust the pH of the supersaturated crystal slurry to 9.41 with aqueous ammonia at 60°C, filter and dry to obtain low-potassium industrial-grade diammonium phosphate.

[0027] <Example 2> 1. Take medium- and low-grade high-potassium phosphate ore with a potassium content of ≥2000ppm, and produce crude phosphoric acid with a P2O5 mass fraction of 26% through wet-process phosphoric acid using the sulfuric acid method, and age it at 60°C for 8 hours to obtain aged acid.

[0028] 2. Ammonia water and aged acid are neutralized, the pH at the neutralization reaction end point is controlled to be 3.8, and a clear liquid is obtained by filtration.

[0029] 3. The clear liquid was evaporated and concentrated, and then cooled to 70°C to obtain a supersaturated crystal slurry.

[0030] 4. Adjust the pH of the supersaturated crystal slurry to 9.27 with aqueous ammonia at 70°C, filter and dry to obtain low-potassium industrial-grade diammonium phosphate.

[0031] 5. Dissolve low-potassium industrial-grade diammonium phosphate in deionized water and add phosphoric acid to adjust the pH to 4.2. Evaporate and concentrate, then filter to obtain low-potassium industrial-grade monoammonium phosphate.

[0032] <Example 3> A method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore comprises the following steps: 1. Take medium- and low-grade high-potassium phosphate ore with a potassium content of ≥2000ppm, and produce crude phosphoric acid with a P2O5 mass fraction of 18% through wet-process phosphoric acid using the sulfuric acid method, and age it at 70°C for 12 hours to obtain aged acid.

[0033] 2. Ammonia water and aged acid are neutralized, the pH at the neutralization reaction end point is controlled to be 4.0, and a clear liquid is obtained by filtration.

[0034] 3. The clear liquid was evaporated and concentrated, and then cooled to 70°C to obtain a supersaturated crystal slurry.

[0035] 4. Adjust the pH of the supersaturated crystal slurry to 8.77 with aqueous ammonia at 70°C, filter and dry to obtain low-potassium industrial-grade diammonium phosphate.

[0036] <Example 4> A method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore comprises the following steps: 1. Take medium- and low-grade high-potassium phosphate ore with a potassium content of ≥2000ppm, and produce crude phosphoric acid with a P2O5 mass fraction of 18% through wet-process phosphoric acid using the sulfuric acid method, and age it at 70°C for 12 hours to obtain aged acid.

[0037] 2. Ammonia water and aged acid are neutralized, the pH at the neutralization reaction end point is controlled to be 4.0, and a clear liquid is obtained by filtration.

[0038] 3. The clear liquid was evaporated and concentrated, and then cooled to 70°C to obtain a supersaturated crystal slurry.

[0039] 4. Adjust the pH of the supersaturated crystal slurry to 8.77 with aqueous ammonia at 70°C, filter and dry to obtain low-potassium industrial-grade diammonium phosphate.

[0040] 5. Dissolve low-potassium industrial-grade diammonium phosphate in deionized water and add phosphoric acid to adjust the pH to 4.2. Evaporate and concentrate, then filter to obtain low-potassium industrial-grade monoammonium phosphate.

[0041] <Comparative Example> A method for producing industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore comprises the following steps: 1. Take medium- and low-grade high-potassium phosphate ore with a potassium content of ≥2000ppm and produce crude phosphoric acid with a P2O5 mass fraction of 26% through wet-process phosphoric acid using the sulfuric acid method.

[0042] 2. Ammonia water and crude phosphoric acid are neutralized, the pH at the neutralization reaction end point is controlled to 4.2, and a clear liquid is obtained by filtration.

[0043] 3. Evaporate and concentrate the clear liquid, then filter to obtain industrial-grade monoammonium phosphate.

[0044] The comparison results of the K content detection of the low potassium content industrial-grade ammonium phosphate obtained in Examples 1 to 4 and the industrial-grade monoammonium phosphate obtained in the control example are shown in Table 1:

[0045]

[0046] As can be seen from the above table, Examples 1 to 4 using the purification process of this patent can effectively reduce the K content in industrial-grade ammonium phosphate.

[0047] The above implementation cases are only for illustrating the technical solutions and features of the present invention, and their purpose is to enable people familiar with the technology to implement them better. They cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention are within the scope of protection of the present invention. The ones not described in detail are prior art.

Claims

1. A method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore, characterized in that: The following steps are involved: S1, blending raw material high-potassium phosphate ore, producing crude phosphoric acid with sulfuric acid wet-process phosphoric acid and cooling and aging to obtain aged acid; S2, neutralizing the ammonia source with the aged acid to control the reaction pH, and filtering the reaction slurry after the reaction to obtain a clear liquid; S3, multi-effect evaporation to concentrate the clear liquid, and cooling to obtain a supersaturated crystal slurry; S4. Adjust the pH of the supersaturated slurry with a pH regulator and then filter. Dry the filtered solid to obtain low-potassium industrial-grade diammonium phosphate, or adjust the pH of the filtered solid with phosphoric acid to obtain low-potassium industrial-grade monoammonium phosphate.

2. The method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore according to claim 1, wherein: The mass fraction of crude phosphoric acid P2O5 in step S1 is 18%-26%.

3. The method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore according to claim 1, wherein: In step S1, the cooling and aging temperature is 45-75° C., and the cooling and aging time is 8-12 hours.

4. The method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore according to claim 1, wherein: The ammonia source in step S2 comes from one or more of liquid ammonia, aqueous ammonia and gaseous ammonia.

5. The method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore according to claim 1, wherein: In step S2, the pH of the neutralization reaction is controlled to be in the range of 3.5-4.

5.

6. The method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore according to claim 1, wherein: The temperature of the cooling crystallization in step S3 is 60-75°C.

7. The method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore according to claim 1, characterized in that: In step S4, the pH regulator is one or more of liquid ammonia, aqueous ammonia and gaseous ammonia.

8. The method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore according to claim 1, characterized in that: The pH of the saturated slurry in step S4 is adjusted to a range of 7-10.

9. The method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore according to claim 1, characterized in that: The phosphoric acid used for recovering the filtered solid in step S4 is refined phosphoric acid with a mass fraction of 75% or 85%.

10. The method for producing low-potassium industrial-grade ammonium phosphate using medium- and low-grade high-potassium phosphate ore according to claim 1, characterized in that: The pH range of the filtered solids after phosphoric acid adjustment in step S4 is 3.2-4.8.

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