Novel technology for comprehensively utilizing multiple elements of white fertilizer

Abstract

The invention discloses a novel technology for comprehensive utilization of multiple elements of a white fertilizer, and relates to the technical field of phosphorus chemical resource recycling. The process comprises the following steps: acid leaching: leaching the white fertilizer by using an acid leaching agent, and carrying out solid-liquid separation to obtain a filtrate containing phosphorus, fluorine, iron and aluminum and a calcium-containing filter residue; defluorination: mixing the filtrate with sodium sulfate, and carrying out defluorination reaction to obtain sodium fluosilicate precipitate and filtrate; extraction: adding an alcohol extraction agent into the filtrate to obtain an extraction phase and a raffinate phase; preparing ferric phosphate and aluminum phosphate: respectively dropwise adding ammonia water into the extraction phase and the raffinate phase, controlling the pH value, and filtering to obtain ferric phosphate filter residues, aluminum phosphate filter residues and filtrate; and preparation of monoammonium phosphate: collecting the filtrate, dropwise adding ammonia water into the filtrate, controlling the pH value, and filtering to obtain fertilizer-grade monoammonium phosphate filter residues. According to the method, resource utilization of phosphorus, calcium, fluorine, iron and aluminum in the white fertilizer is achieved, the method is simple and easy to implement, the utilization rate of phosphorus, calcium, fluorine, iron and aluminum can be effectively increased, and fluorine pollution is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of phosphorus chemical resource recycling, and in particular to a new process for comprehensive utilization of "multi-elements" of white fertilizer. Background Art

[0002] Phosphorus and its associated fluorine in phosphate rock are both strategic non-renewable resources. In recent years, with the rapid development of my country's phosphorus chemical industry, high-grade phosphate rock resources have gradually been exhausted. Currently, most phosphoric acid companies using wet process technology use medium-low grade phosphate rock. The initial concentration and purity of the obtained wet process phosphoric acid are getting lower and lower, and the impurity content is getting higher and higher, which makes the purification cost of wet process phosphoric acid increase year by year. Therefore, the neutralization method is used to prepare feed-grade calcium hydrogen phosphate, which has a great cost advantage, but it produces white fertilizer as a by-product. P in white fertilizer is generally 2 O 5 The content is 20-35%, the fluorine content is 4-12%, and the CaO content is 18-25%. In addition, it also contains a certain amount of iron and aluminum. The application range of white fertilizer is narrow and the price is very low. The traditional application method is to use it as an auxiliary material for providing phosphorus in compound fertilizer or directly apply it to the soil as a low-cost fertilizer. However, the fluorine content of white fertilizer is high and it has strong acidity. If it is directly used as fertilizer, the fluorine in it will have a certain toxic effect on crops and the ecological environment. Therefore, how to achieve the comprehensive utilization of the main elements of white fertilizer such as phosphorus, calcium, fluorine, iron and aluminum is a major problem that the phosphorus chemical industry urgently needs to solve. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a new process for the comprehensive utilization of "multi-elements" of white fertilizer. The method provided by the present invention can convert phosphorus, iron and aluminum in white fertilizer into industrial-grade iron phosphate, aluminum phosphate and fertilizer-grade monoammonium phosphate, and at the same time convert fluorine contained in the white fertilizer into sodium fluorosilicate and calcium into calcium sulfate, thereby realizing the comprehensive utilization of "multi-elements" of white fertilizer.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The invention discloses a new process for comprehensive utilization of "multi-elements" of white fertilizer, comprising the following steps:

[0006] (1) Acid leaching: The white fertilizer is leached with an acidic leaching agent, and after solid-liquid separation, a filtrate containing phosphorus, fluorine, iron, and aluminum and a filter residue containing calcium are obtained;

[0007] (2) defluorination: mixing the phosphorus, fluorine, iron and aluminum filtrate of step (1) with sodium sulfate to carry out a defluorination reaction to obtain a sodium fluorosilicate precipitate and a filtrate;

[0008] (3) Extraction: adding an alcohol extractant to the filtrate obtained in step (2) to perform multi-stage extraction, and after the reaction is completed, obtaining an extraction phase containing phosphorus and iron and a raffinate phase containing phosphorus and aluminum;

[0009] (4) Preparation of iron phosphate: adding aqueous ammonia to the extraction phase of step (3) to control the pH, filtering after the reaction to obtain a filter residue and a filtrate, further drying, grinding, and sieving the filter residue to obtain industrial-grade iron phosphate;

[0010] (5) Preparation of aluminum phosphate: Ammonia water is added dropwise to the raffinate phase of step (3) to control the pH value. After the reaction is completed, the filter is filtered to obtain a filter residue and a filtrate. The filter residue is further dried, ground, and sieved to obtain industrial-grade aluminum phosphate;

[0011] (6) Preparation of monoammonium phosphate: Collect the filtrate from steps (4) and (5), add aqueous ammonia to the filtrate, control the pH value, and filter, dry, grind and sieve to obtain fertilizer-grade monoammonium phosphate after the reaction is completed.

[0012] In a preferred embodiment of the present invention, the leaching agent and the P in the white fertilizer raw material 2 O 5 The molar ratio is 0.5-2.0, the leaching temperature is 30-80°C, and the leaching time is 40-120min.

[0013] In a preferred embodiment of the present invention, the leaching agent is sulfuric acid with a concentration of 1 to 14%, and the calcium-containing filter residue is calcium sulfate filter residue.

[0014] In a preferred embodiment of the present invention, the initial particle size of the white fertilizer is 80-300 meshes.

[0015] In a preferred embodiment of the present invention, the acid leaching step and the defluorination step also include a cyclic acid leaching step, wherein the cyclic acid leaching step is: the phosphorus, fluorine, iron and aluminum filtrate obtained in step (1) is supplemented with a leaching agent and then recycled to treat the next batch of white fertilizer, and after repeating this step 2 to 6 times, the solid and liquid are separated to obtain a calcium-containing filter residue and a filtrate enriched with phosphorus, fluorine, iron and aluminum.

[0016] In a preferred embodiment of the present invention, when the white fertilizer is circulated, the liquid-to-solid mass ratio is 1 to 4:1, and the solid-liquid separation is performed after the acid leaching step is repeated 3 to 5 times.

[0017] In a preferred embodiment of the present invention, the molar ratio of the amount of sodium sulfate added in the defluorination reaction to the amount of fluorine contained in the white fertilizer is 0.2-1.0, the defluorination reaction temperature is 30-80° C., the defluorination reaction time is 30-120 min, and the stirring rate during the defluorination reaction is 0-400 rpm.

[0018] In a preferred embodiment of the present invention, the extractant added in the extraction reaction is one or a mixture of n-octanol, n-hexanol, n-butanol, n-propanol, isooctyl alcohol, the volume ratio of the amount of the added extractant to the amount of the phosphorus, iron and aluminum filtrate is 0.5 to 3:1, the extraction reaction temperature is 20 to 40°C, the extraction reaction time is 10 to 40 minutes, and the number of multi-stage extraction stages is 2 to 4.

[0019] In a preferred embodiment of the present invention, in the preparation of the iron phosphate, the reaction temperature is 30-50°C, and the pH value at the reaction end point is 1-2; in the preparation of the aluminum phosphate, the reaction temperature is 30-55°C, and the pH value at the reaction end point is 1.5-2.5; in the preparation of the monoammonium phosphate, the reaction temperature is 30-55°C, and the pH value at the reaction end point is 4.2-4.5.

[0020] In a preferred embodiment of the present invention, the sodium fluorosilicate content in the sodium fluorosilicate product is greater than 98.5wt%, and the free acid is H 2 SO 4 less than 0.15 wt%, sulfate as SO 4 The content of aluminum oxide in the aluminum phosphate product is greater than 15wt%, the content of phosphorus pentoxide is greater than 30wt%, the content of water-insoluble matter is less than 5wt%, and the content of available phosphorus in the monoammonium phosphate is greater than 45wt%, the content of total nitrogen is greater than 9wt%, and the content of total nutrients, as N+P 2 O 5 The content is greater than 56wt%, and the percentage of water-soluble phosphorus in available phosphorus is greater than 75%.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The invention provides a new process for comprehensive utilization of "multi-elements" of white fertilizer, comprising the following steps: using sulfuric acid as a leaching agent to leach the white fertilizer, filtering and separating to obtain a filtrate containing phosphorus, fluorine, iron and aluminum and a calcium sulfate filter residue, circulating the leaching solution for 2 to 6 times, and then performing solid-liquid separation to obtain a calcium sulfate filter residue and a filtrate enriched in phosphorus, fluorine, iron and aluminum; mixing the filtrate enriched in phosphorus, fluorine, iron and aluminum with sodium sulfate to carry out a defluorination reaction to obtain a sodium fluorosilicate precipitate and a filtrate; adding an alcohol extractant to the filtrate to obtain an extraction phase containing phosphorus and iron and a raffinate phase containing phosphorus and aluminum through a multi-stage extraction reaction; dripping ammonia water into the extraction phase for a neutralization reaction to obtain industrial-grade iron phosphate and fertilizer-grade monoammonium phosphate; dripping ammonia water into the raffinate phase for a neutralization reaction to obtain industrial-grade aluminum phosphate and fertilizer-grade monoammonium phosphate. Phosphorus-containing substances in white fertilizer are generally calcium hydrogen phosphate, calcium dihydrogen phosphate and a small amount of phosphoric acid, and the pH value is usually 2-3, while fluorine-containing substances in white fertilizer are generally calcium fluorosilicate, and some of them exist in the form of calcium fluoride, calcium fluoroaluminate and hydrofluoric acid. By leaching white fertilizer with sulfuric acid, the calcium in the white fertilizer can be converted into calcium sulfate, which can be used to prepare gypsum powder, gypsum board, calcium sulfate whiskers and other products, and phosphorus, fluorine, iron and aluminum are leached in the form of solution. After defluorination, the leaching solution enriched with phosphorus, fluorine, iron and aluminum can be converted into sodium fluorosilicate (sodium fluorosilicate content is greater than 98.5wt%, free acid (in the form of H 2 SO 4 less than 0.15 wt% and sulfate (in terms of SO 4 The filtrate is extracted with an alcoholic substance to obtain an organic phase and a saturated aqueous phase, and the organic phase is reacted with ammonia water to be converted into iron phosphate (Fe content is greater than 30wt%, P content is greater than 20wt%, iron-phosphorus ratio (Fe: P) is 0.93-1.05, Al content is not more than 0.05wt%, and water content is not more than 1wt%); the saturated aqueous phase is reacted with ammonia water to be converted into aluminum phosphate (aluminum oxide (Al 2 0 3 ) content is greater than 15wt%, phosphorus pentoxide (P 2 O 5 ) content is greater than 30wt%, and the moisture content is not greater than 5wt%. ); further adjusting the pH, monoammonium phosphate (the content of available phosphorus is greater than 45wt%, the content of total nitrogen is greater than 9wt%, and the content of total nutrients (N+P 2 O 5 ) content is greater than 56wt%, and the percentage of water-soluble phosphorus to effective phosphorus is greater than 75%. ). The present invention realizes the comprehensive utilization of white fertilizer, and the method is simple and easy to implement. The utilization rates of phosphorus, calcium, iron and aluminum in the white fertilizer can reach more than 90%, and the utilization rate of fluorine can reach more than 80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention provides a flow chart of a new process for comprehensive utilization of "multi-elements" in white fertilizer. DETAILED DESCRIPTION

[0024] The present invention provides a new process for comprehensive utilization of "multi-element" white fertilizer, such as Figure 1 As shown, the following steps are included:

[0025] (1) Acid leaching: The white fertilizer is leached with an acidic leaching agent, and after solid-liquid separation, phosphorus, fluorine, iron, aluminum filtrate and calcium-containing filter residue are obtained;

[0026] In the present invention, sulfuric acid is preferably used as a leaching agent to leach the white fertilizer, and phosphorus, fluorine filtrate and calcium sulfate filter residue are obtained after filtration and separation. 2 SO 4 P in white fertilizer raw materials 2 O 5 The molar ratio is 0.5-2.0, specifically 0.5, 1.0, 1.5 or 2.0; the leaching temperature is 30-80°C, specifically 30°C, 40°C, 50°C, 60°C, 70°C or 80°C; the leaching time is 40-120min, specifically 40min, 60min, 80min, 100min or 120min; the sulfuric acid concentration is 1-14%, specifically 4%, 8% or 12%; the initial particle size of the white fertilizer raw material is 80-300 mesh, specifically 100 mesh, 200 mesh or 300 mesh; the phosphorus-containing substance in the white fertilizer is generally calcium hydrogen phosphate, calcium dihydrogen phosphate and a small amount of phosphoric acid, and the pH value is usually 2-3, and the fluorine-containing substance in the white fertilizer is generally calcium fluorosilicate, and a part of it exists in the form of calcium fluoride, calcium fluoroaluminate and hydrofluoric acid. By leaching white fertilizer with sulfuric acid, phosphorus in the white fertilizer can be leached out in the form of solution, and calcium can be converted into calcium sulfate. The reactions involved are as follows:

[0027] CaHPO 4 +H 2 SO 4 →CaSO 4 +H 3 PO 4 ;

[0028] Ca(H 2 PO 4 ) 2 +H 2 SO 4 →CaSO 4 +2H 3 PO 4 .

[0029] The calcium sulfate prepared in this step can be used to prepare products such as gypsum powder, gypsum board, and calcium sulfate whiskers.

[0030] (2) Defluorination: mixing the phosphorus, fluorine, iron and aluminum filtrates from step (1) with sodium sulfate to carry out a defluorination reaction to obtain a sodium fluorosilicate precipitate and a filtrate;

[0031] After obtaining the leachate, the present invention conducts a defluorination reaction between the leachate of the phosphorus, fluorine, iron, and aluminum filtrate and sodium sulfate to obtain a fluorine-containing precipitate and a filtrate. In the present invention, the molar ratio of the amount of sodium sulfate added to the leachate of the phosphorus, fluorine, iron, and aluminum filtrate to the amount of fluorine contained in the white fertilizer in the defluorination reaction is 0.2 to 1.0, specifically 0.4, 0.8 or 1.0; the defluorination reaction temperature is 30 to 80°C, specifically 30°C, 40°C, 50°C, 60°C, 70°C or 80°C; the defluorination reaction time is 30 to 120min, specifically 30min, 60min, 90min or 120min; the defluorination reaction stirring rate is 0 to 400rpm, specifically 100rpm, 200rpm, 300rpm or 400rpm. In the present invention, the fluorine and silicon elements in the leachate can react with sodium sulfate to form a sodium fluorosilicate precipitate, and the reaction formula involved is: 6F - +SiO 3 2- +2Na + +6H + →Na 2 SiF 6 ↓+3H 2 In the present invention, the sodium fluorosilicate product satisfies the requirement that the sodium fluorosilicate content is greater than 98.5 wt %, the free acid (in terms of H 2 SO 4 less than 0.15 wt% and sulfate (in terms of SO 4 The content of phosphorus pentoxide is less than 0.02wt%, and the content of water-insoluble matter is less than 0.5wt%.

[0032] (3) Extraction: adding an alcohol extractant to the filtrate obtained in step (2) to carry out multi-stage extraction, and after the reaction is completed, obtaining an extraction phase containing phosphorus and iron and a raffinate phase containing phosphorus and aluminum. In the present invention, the alcohol extractant of the extraction reaction is one or a mixture of n-octanol, n-hexanol, n-butanol, n-propanol, isooctyl alcohol; the volume ratio of the amount of the added extractant to the amount of the filtrate containing phosphorus, iron and aluminum in the extraction reaction is 0.5-3:1, specifically 0.5:1, 1:1, 2:1 or 3:1; the extraction reaction temperature is 20-40°C, specifically 20°C, 25°C, 30°C or 40°C; the extraction reaction time is 10-40 min, specifically 10 min, 20 min, 30 min or 40 min; the multi-stage extraction level of the extraction reaction is 2-4, specifically 2, 3 or 4. In the present invention, an alcohol extractant is added to the defluorination filtrate to achieve separation and enrichment of iron and aluminum elements in a complex solution, and an extraction phase containing phosphorus and iron and a raffinate phase containing phosphorus and aluminum are obtained respectively.

[0033] (4) Preparation of iron phosphate: After obtaining the extraction phase after multi-stage extraction reaction, the present invention drips ammonia water into the extraction phase for neutralization reaction, controls the pH, and filters after the reaction to obtain filter residue and filtrate. The filter residue is further dried, ground, and sieved to obtain industrial-grade iron phosphate. In the present invention, the reaction temperature of the neutralization reaction is 30 to 50°C; the pH value of the neutralization reaction at the reaction end point is 1 to 2. Through the neutralization reaction, phosphorus and iron in the extraction phase after multi-stage extraction reaction can be converted into industrial-grade iron phosphate. The reaction formula involved is: FeSO 4 +NH 4 H 2 PO 4 →FeP0 4 +NH 4 HSO 4 In the present invention, the Fe content is greater than 30wt%, the P content is greater than 20wt%, the iron-phosphorus molar ratio (Fe:P) is 0.93-1.05, the Al content is not greater than 0.05wt%, and the moisture content is not greater than 1wt%, which can meet the requirements of the qualified products of the iron phosphate industry standard HG / T 6262-2024. The present invention can effectively reduce the loss of phosphorus and iron resources in white fertilizers and improve the utilization rate of phosphorus and iron resources.

[0034] (5) Preparation of aluminum phosphate: After obtaining the raffinate phase after multi-stage extraction reaction, the present invention drips ammonia water into the raffinate phase to carry out a neutralization reaction, controls the pH, and filters after the reaction to obtain filter residue and filtrate. The filter residue is further dried, ground, and sieved to obtain industrial-grade aluminum phosphate. In the present invention, the reaction temperature of the neutralization reaction is 30 to 55°C; the pH value of the reaction end point of the neutralization reaction is 1.5 to 2.5. Through the neutralization reaction, the phosphorus and aluminum in the raffinate phase after multi-stage extraction reaction can be converted into industrial-grade aluminum phosphate. The reaction formula involved is: Al 2 (SO 4 ) 3 +NH 4 H 2 PO 4 →AlP0 4 +NH 4 HSO 4 In the present invention, aluminum oxide (Al 2 0 3 ) content is greater than 15wt%, phosphorus pentoxide (P 2 O 5 ) content is greater than 30wt%, and the moisture content is not greater than 5wt%, which can meet the requirements of the national standard GB / T10602-2008 for aluminum phosphate qualified products. The present invention can effectively reduce the loss of phosphorus and aluminum resources in white fertilizer and improve the utilization rate of phosphorus and aluminum resources.

[0035] (6) Preparation of monoammonium phosphate: Collect the filtrate from steps (4) and (5), and add ammonia water to the filtrate for neutralization reaction, control the pH, filter, dry, grind, and sieve after the reaction to obtain fertilizer-grade monoammonium phosphate. In the present invention, the reaction temperature of the neutralization reaction is 30 to 55°C; the pH value of the neutralization reaction at the reaction end point is 4.2 to 4.5. Fertilizer-grade monoammonium phosphate can be prepared by the neutralization reaction, and the reaction formula involved is: H 3 PO 4 +NH 3 →NH 4 H 2 PO 4 In the present invention, P 2 O 5 The content of available phosphorus in the fertilizer-grade monoammonium phosphate is greater than 45wt%, the content of total nitrogen is greater than 9wt%, and the content of total nutrients (N+P 2 O 5 ) content is greater than 56wt%, the percentage of water-soluble phosphorus in effective phosphorus is greater than 75%, and the requirements of the national standard GB / T 10205-2009 for monoammonium phosphate qualified products can be met. The present invention can effectively reduce the loss of phosphorus resources in white fertilizers and improve the utilization rate of phosphorus resources.

[0036] In addition, the acid leaching step (1) and the defluorination step (2) also include a cyclic acid leaching step, wherein the cyclic acid leaching step is: the phosphorus and fluorine filtrate obtained in step (1) is supplemented with a leaching agent and then recycled to treat the next batch of white fertilizer, and the solid-liquid separation is performed after repeating this step 2 to 6 times to obtain a calcium-containing filter residue and a phosphorus, fluorine, iron, and aluminum filtrate enriched. Preferably, when the white fertilizer is cyclically treated, the liquid-solid mass ratio is 1 to 4:1, specifically 1:1, 2:1, 3:1 or 4:1, and the solid-liquid separation is preferably performed after the cyclic acid leaching step is repeated 3 to 5 times, specifically 3, 4, or 5 times.

[0037] The method provided by the present invention can convert the fluorine resources in the white fertilizer into sodium fluorosilicate, and convert the phosphorus, iron and aluminum resources into monoammonium phosphate, iron phosphate and aluminum phosphate, and at the same time convert the calcium therein into calcium sulfate, thereby realizing the comprehensive utilization of the white fertilizer, and the method is simple and easy to implement.

[0038] The novel process for comprehensive utilization of "multi-elements" of white fertilizer provided by the present invention is described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0039] Example 1

[0040] The white fertilizer from the factory includes the following raw materials by mass fraction: 2 O 5 :25.33%,CaO:20.11%,Fe 2 O 3 :5.12%,Al 2 O 3 :8.29%, MgO: 0.81%, F: 4.18%.

[0041] 10% sulfuric acid was added to the 200 mesh white fertilizer for acid leaching, wherein H 2 SO 4 P 2 O 5 The molar ratio of 1.5:1 was 1.5:1, and the reaction was carried out at 60°C for 60 minutes. After solid-liquid separation, a filtrate containing phosphorus, fluorine, iron, and aluminum and a calcium sulfate filter residue were obtained. The above leachate was supplemented with sulfuric acid and then recycled to treat the white fertilizer raw material (liquid-solid mass ratio was 1:1). After repeating the same conditions for 3 times, the components of the filtrate enriched in phosphorus, fluorine, iron, and aluminum obtained after solid-liquid separation were: P 2 O 5 :16.17%,CaO:1.45%,Fe 2 O 3 :3.11%,Al 2 O 3 :5.51%, MgO: 0.68%, F: 2.55%.

[0042] Sodium sulfate in a molar ratio of 0.4 to the amount of fluorine contained in the white fertilizer is added to the filtrate enriched with phosphorus, fluorine, iron and aluminum, and the reaction is carried out at 200 rpm and 30° C. for 60 min to obtain a fluorine-containing precipitate and a filtrate; after the precipitate is treated, a sodium fluorosilicate product is obtained, and the indicators are as follows: the sodium fluorosilicate content is 98.64wt%, the free acid (in terms of H 2 SO 4 The content of sulfate (in terms of SO 4 The content of phosphorus pentoxide is 0.02wt% and the content of water-insoluble matter is 0.44wt%.

[0043] The extractant n-octanol is added to the filtrate, the volume of the organic phase and the volume of the filtrate are controlled to be 1:1, the reaction temperature is about 30°C, the reaction time is 25min, the multi-stage extraction level is 2, and after the reaction is completed, an extraction phase containing phosphorus and iron and a raffinate phase containing phosphorus and aluminum are obtained.

[0044] Ammonia water is dropped into the extraction phase, the reaction temperature is controlled at about 40°C, the end point pH is 1.5, and the suspension is filtered after the reaction is completed, the filtrate is set aside, the filter residue is washed, and dried to constant weight to obtain iron phosphate; the iron phosphate product indicators are: Fe content is 36.4wt%, P content is 20.77wt%, iron-phosphorus molar ratio (Fe:P) is 0.988, Al content is 0.01wt%, and water content is 0.42wt%.

[0045] Ammonia water is dripped into the raffinate phase, the reaction temperature is controlled at about 30°C, and the pH at the end point is 2.0. After the reaction is completed, the suspension is filtered and the filtrate is set aside. The filter residue is washed and dried to constant weight to obtain aluminum phosphate; the aluminum phosphate product indicators are: aluminum oxide (Al 2 0 3 ) content is 16.57wt%, phosphorus pentoxide (P 2 O 5 ) content is 33.21wt%, and the moisture content is 3.29wt%.

[0046] Combine the filtrates from the preparation of iron phosphate and aluminum phosphate, drip ammonia water into the filtrate, control the reaction temperature at about 40°C, and the pH at the end point is 4.2. After the reaction is completed, the filter residue is washed and dried to a constant weight to obtain monoammonium phosphate; the monoammonium phosphate product index is: P 2 O 5 The content of available phosphorus is 46.52wt%, the content of total nitrogen is 9.62wt%, and the content of total nutrients (N+P 2 O 5 ) content is 56.14wt%, and the percentage of water-soluble phosphorus in available phosphorus is 77.23%.

[0047] Example 2

[0048] The white fertilizer from the factory includes the following raw materials by mass fraction: 2 O 5 :25.85%,CaO:19.88%,Fe 2 O 3 :5.34%,Al 2 O 3 :8.15%, MgO: 0.77%, F: 4.37%.

[0049] 10% sulfuric acid was added to the 200 mesh white fertilizer for acid leaching, wherein H 2 SO 4 P 2 O 5 The molar ratio of 2:1 was 2:1, and the reaction was carried out at 70°C for 60 minutes. After solid-liquid separation, a filtrate containing phosphorus, fluorine, iron, and aluminum and a calcium sulfate filter residue were obtained; sulfuric acid was added to the above leachate and then recycled to treat the white fertilizer raw material (liquid-solid mass ratio was 2:1). After repeating the same conditions for 4 times, the components of the filtrate enriched in phosphorus, fluorine, iron, and aluminum obtained after solid-liquid separation were: P 2 O 5 :16.24%,CaO:1.22%,Fe 2 O 3 :3.35%,Al 2 O 3 :5.64%, MgO: 0.64%, F: 2.62%.

[0050] Sodium sulfate in a molar ratio of 0.4 to the amount of fluorine contained in the white fertilizer is added to the leachate, and the mixture is reacted at 200 rpm and 40° C. for 70 min to obtain a fluorine-containing precipitate and a filtrate; after treatment, the precipitate is treated to obtain a sodium fluorosilicate product, and the indicators are as follows: the sodium fluorosilicate content is 98.66 wt %, the free acid (in terms of H 2 SO 4 The content of sulfate (in terms of SO 4 The content of phosphorus pentoxide is 0.02wt%, and the content of water-insoluble matter is 0.43wt%.

[0051] The extractant n-hexanol is added to the filtrate, the volume of the organic phase and the volume of the filtrate are controlled to be 2:1, the reaction temperature is about 30°C, the reaction time is 30 minutes, the multi-stage extraction level is 2, and after the reaction is completed, an extraction phase containing phosphorus and iron and a residual phase containing phosphorus and aluminum are obtained.

[0052] Ammonia water is dropped into the extraction phase, the reaction temperature is controlled at about 40°C, the end point pH is 1.8, and the suspension is filtered after the reaction is completed, the filtrate is set aside, the filter residue is washed, and dried to constant weight to obtain iron phosphate; the iron phosphate product indicators are: Fe content is 36.53wt%, P content is 20.89wt%, iron-phosphorus molar ratio (Fe:P) is 0.981, Al content is 0.005wt%, and water content is 0.34wt%.

[0053] Ammonia water is dripped into the residual phase, the reaction temperature is controlled at about 35°C, and the pH at the end point is 2.5. After the reaction is completed, the suspension is filtered and the filtrate is set aside. The filter residue is washed and dried to constant weight to obtain aluminum phosphate; the aluminum phosphate product indicators are: aluminum oxide (Al 2 0 3 ) content is 17.42wt%, phosphorus pentoxide (P 2 O 5 ) content is 34.25wt%, and the moisture content is 2.56wt%.

[0054] Combine the filtrates from the preparation of iron phosphate and aluminum phosphate, drip ammonia water into the filtrate, control the reaction temperature at about 40°C, and the pH at the end point is 4.3. After the reaction is completed, the filter residue is dried to a constant weight to obtain monoammonium phosphate; the monoammonium phosphate product index is: P 2 O 5 The content of available phosphorus is 46.68wt%, the content of total nitrogen is 9.88wt%, and the content of total nutrients (N+P 2 O 5 ) content is 56.64wt%, and the percentage of water-soluble phosphorus in available phosphorus is 78.14%.

[0055] Example 3

[0056] The white fertilizer from the factory includes the following raw materials by mass fraction: 2 O 5 :26.01%,CaO:20.98%,Fe 2 O 3 :3.66%,Al 2 O 3 : 7.95%, MgO: 0.88%, F: 4.07%.

[0057] 10% sulfuric acid was added to the 200 mesh white fertilizer for acid leaching, wherein H 2 SO 4 P 2 O 5The molar ratio of 1.5:1 was 1.5:1, and the reaction was carried out at 60°C for 60 minutes. After solid-liquid separation, a filtrate containing phosphorus, fluorine, iron, and aluminum and a calcium sulfate filter residue were obtained. The above leachate was supplemented with sulfuric acid and then recycled to treat the white fertilizer raw material (liquid-solid mass ratio was 3:1). After repeating the same conditions for 5 times, the components of the filtrate enriched in phosphorus, fluorine, iron, and aluminum obtained after solid-liquid separation were: P 2 O 5 :16.33%,CaO:1.21%,Fe 2 O 3 :2.85%,Al 2 O 3 :5.04%, MgO: 0.56%, F: 2.32%.

[0058] Sodium sulfate in a molar ratio of 0.4 to the amount of fluorine contained in the white fertilizer is added to the leachate, and the reaction is carried out at 200 rpm and 40° C. for 90 min to obtain a fluorine-containing precipitate and a filtrate; the precipitate is treated to obtain a sodium fluorosilicate product, and the indicators are as follows: the sodium fluorosilicate content is 98.60wt%, the free acid (as H 2 SO 4 The content of sulfate (in terms of SO 4 The content of phosphorus pentoxide is 0.017wt% and the content of water-insoluble matter is 0.47wt%.

[0059] The extractant n-butanol is added to the filtrate, the volume of the organic phase and the volume of the filtrate are controlled to be 3:1, the reaction temperature is about 35°C, the reaction time is 40min, the multi-stage extraction level is 3, and after the reaction is completed, an extraction phase containing phosphorus and iron and a residual phase containing phosphorus and aluminum are obtained.

[0060] Ammonia water is dropped into the extraction phase, the reaction temperature is controlled at about 40°C, the end point pH is 1.8, the suspension is filtered after the reaction is completed, the filtrate is set aside, the filter residue is washed and dried to constant weight to obtain iron phosphate; the iron phosphate product indicators are: Fe content is 36.15wt%, P content is 20.95wt%, iron-phosphorus molar ratio (Fe:P) is 0.966, Al content is 0.008wt%, and water content is 0.21wt%.

[0061] Ammonia water is dripped into the raffinate phase, the reaction temperature is controlled at about 40°C, and the pH at the end point is 2.0. After the reaction is completed, the suspension is filtered and the filtrate is set aside. The filter residue is washed and dried to constant weight to obtain aluminum phosphate; the aluminum phosphate product indicators are: aluminum oxide (Al 2 0 3 ) content is 18.23wt%, phosphorus pentoxide (P 2 O 5 ) content is 33.56wt%, and the moisture content is 2.87wt%.

[0062] Combine the filtrates from the preparation of iron phosphate and aluminum phosphate, drip ammonia water into the filtrate, control the reaction temperature at about 45°C, and the pH at the end point is 4.4. After the reaction is completed, the filter residue is dried to a constant weight to obtain monoammonium phosphate; the monoammonium phosphate product index is: P 2 O 5 The content of available phosphorus is 46.73wt%, the content of total nitrogen is 10.11wt%, and the content of total nutrients (N+P 2 O 5 ) content is 56.84wt%, and the percentage of water-soluble phosphorus in available phosphorus is 78.24%.

[0063] Example 4

[0064] The white fertilizer from the factory includes the following raw materials by mass fraction: 2 O 5 :25.02%,CaO:20.23%,Fe 2 O 3 :4.33%,Al 2 O 3 :8.05%, MgO: 0.84%, F: 4.35%.

[0065] 10% sulfuric acid was added to the 200 mesh white fertilizer for acid leaching, wherein H 2 SO 4 P 2 O 5 The molar ratio of 2:1 was 2:1, and the reaction was carried out at 60°C for 60 minutes. After solid-liquid separation, a filtrate containing phosphorus, fluorine, iron, and aluminum and a calcium sulfate filter residue were obtained; sulfuric acid was added to the above leachate and then recycled to treat the white fertilizer raw material (liquid-solid mass ratio was 4:1). After repeating the same conditions for 5 times, the components of the phosphorus and fluorine enriched filtrate obtained after solid-liquid separation were: P 2 O 5 :17.05%,CaO:1.45%,Fe 2 O 3 :3.11%,Al 2 O 3 : 6.51%, MgO: 0.74%, F: 2.55%.

[0066] Sodium sulfate in a molar ratio of 0.4 to the amount of fluorine contained in the white fertilizer is added to the leachate, and the reaction is carried out at 200 rpm and 30° C. for 60 min to obtain a fluorine-containing precipitate and a filtrate; the precipitate is treated to obtain a sodium fluorosilicate product, and the indicators are as follows: the sodium fluorosilicate content is 98.62wt%, the free acid (as H 2 SO 4 The content of sulfate (in terms of SO4 The content of phosphorus pentoxide is 0.018wt%, and the content of water-insoluble matter is 0.47wt%.

[0067] The extractant n-propanol is added to the filtrate, the volume of the organic phase and the volume of the filtrate are controlled to be 2.5:1, the reaction temperature is about 40°C, the reaction time is 30 minutes, the multi-stage extraction level is 4, and after the reaction is completed, an extraction phase containing phosphorus and iron and a residual phase containing phosphorus and aluminum are obtained.

[0068] Ammonia water is dripped into the extraction, the reaction temperature is controlled at about 40°C, the end point pH is 2.0, and the suspension is filtered after the reaction is completed, the filtrate is set aside, the filter residue is washed, and dried to constant weight to obtain iron phosphate; the iron phosphate product indicators are: Fe content is 36.42wt%, P content is 20.85wt%, iron-phosphorus molar ratio (Fe:P) is 0.969, Al content is 0.007wt%, and water content is 0.14wt%.

[0069] Ammonia water is dripped into the raffinate phase, the reaction temperature is controlled at about 40°C, and the pH at the end point is 1.8. After the reaction is completed, the suspension is filtered and the filtrate is set aside. The filter residue is washed and dried to constant weight to obtain aluminum phosphate; the aluminum phosphate product indicators are: aluminum oxide (Al 2 0 3 ) content is 18.56wt%, phosphorus pentoxide (P 2 O 5 ) content is 32.98wt%, and the moisture content is 2.56wt%.

[0070] Combine the filtrates from the preparation of iron phosphate and aluminum phosphate, drip ammonia water into the filtrate, control the reaction temperature at about 40°C, and the pH at the end point is 4.5. After the reaction is completed, the filter residue is dried to a constant weight to obtain monoammonium phosphate; the monoammonium phosphate product index is: P 2 O 5 The content of available phosphorus is 46.82wt%, the content of total nitrogen is 10.21wt%, and the content of total nutrients (N+P 2 O 5 ) content is 57.03wt%, and the percentage of water-soluble phosphorus in available phosphorus is 78.23%.

[0071] Example 5

[0072] The white fertilizer from the factory includes the following raw materials by mass fraction: 2 O 5 :25.47%,CaO:20.24%,Fe 2 O 3 :2.97%,Al 2 O 3:7.75%, MgO: 0.74%, F: 4.52%.

[0073] 10% sulfuric acid was added to the 200 mesh white fertilizer for acid leaching, wherein H 2 SO 4 P 2 O 5 The molar ratio of 1.5:1 was 1.5:1, and the reaction was carried out at 60°C for 90 minutes. After solid-liquid separation, a filtrate containing phosphorus, fluorine, iron, and aluminum and a calcium sulfate filter residue were obtained. The above leachate was supplemented with sulfuric acid and then recycled to treat the white fertilizer raw material (liquid-solid mass ratio was 4:1). After repeating the same conditions for 4 times, the components of the filtrate enriched in phosphorus, fluorine, iron, and aluminum obtained after solid-liquid separation were: P 2 O 5 :17.03%,CaO:1.44%,Fe 2 O 3 :2.21%,Al 2 O 3 :5.44%, MgO: 0.66%, F: 2.74%.

[0074] Sodium sulfate in a molar ratio of 0.4 to the amount of fluorine contained in the white fertilizer is added to the leachate, and the reaction is carried out at 200 rpm and 40° C. for 90 min to obtain a fluorine-containing precipitate and a filtrate; the precipitate is treated to obtain a sodium fluorosilicate product, and the indicators are as follows: the sodium fluorosilicate content is 98.57wt%, the free acid (as H 2 SO 4 The content of sulfate (in terms of SO 4 The content of phosphorus pentoxide is 0.014wt% and the content of water-insoluble matter is 0.45wt%.

[0075] The extractant isooctyl alcohol is added to the filtrate, the volume of the organic phase and the volume of the filtrate are controlled to be 0.5:1, the reaction temperature is about 35°C, the reaction time is 25min, the multi-stage extraction level is 3, and after the reaction is completed, an extraction phase containing phosphorus and iron and a raffinate phase containing phosphorus and aluminum are obtained.

[0076] Ammonia water is dropped into the extraction phase, the reaction temperature is controlled at about 40°C, the end point pH is 2.0, and the suspension is filtered after the reaction is completed, the filtrate is set aside, the filter residue is washed, and dried to constant weight to obtain iron phosphate; the iron phosphate product indicators are: Fe content is 36.06wt%, P content is 21.02wt%, iron-phosphorus molar ratio (Fe:P) is 0.951, Al content is 0.006wt%, and water content is 0.24wt%.

[0077] Ammonia water is dripped into the residual phase, the reaction temperature is controlled at about 40°C, and the pH at the end point is 1.5. After the reaction is completed, the suspension is filtered and the filtrate is set aside. The filter residue is washed and dried to constant weight to obtain aluminum phosphate; the aluminum phosphate product indicators are: aluminum oxide (Al 2 0 3 ) content is 17.88wt%, phosphorus pentoxide (P 2 O 5 ) content is 34.67wt%, and the moisture content is 2.46wt%.

[0078] Combine the filtrates from the preparation of iron phosphate and aluminum phosphate, drip ammonia water into the filtrate, control the reaction temperature at about 45°C, and the pH at the end point is 4.5. After the reaction is completed, the filter residue is dried to a constant weight to obtain monoammonium phosphate; the monoammonium phosphate product index is: P 2 O 5 The content of available phosphorus is 47.23wt%, the content of total nitrogen is 10.43wt%, and the content of total nutrients (N+P 2 O 5 ) content is 57.66wt%, and the percentage of water-soluble phosphorus in available phosphorus is 78.22%.

[0079] It can be seen from the above embodiments that the new process for comprehensive utilization of "multi-elements" of white fertilizer provided by the present invention can convert the phosphorus, iron and aluminum resources in the white fertilizer into qualified industrial-grade iron phosphate and aluminum phosphate and fertilizer-grade monoammonium phosphate, and convert the fluorine resources into sodium fluorosilicate, and at the same time convert the calcium in the white fertilizer into calcium sulfate, thereby realizing the comprehensive utilization of the white fertilizer.

[0080] The above content is only a preferred implementation method of the present invention. For those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A new process for comprehensive utilization of "multi-element" white fertilizer, characterized in that: The following steps are involved: (1) Acid leaching: The white fertilizer is leached with an acidic leaching agent, and after solid-liquid separation, a filtrate containing phosphorus, fluorine, iron, and aluminum and a filter residue containing calcium are obtained; (2) defluorination: mixing the phosphorus, fluorine, iron and aluminum filtrate of step (1) with sodium sulfate to carry out a defluorination reaction to obtain a sodium fluorosilicate precipitate and a filtrate; (3) Extraction: adding an alcohol extractant to the filtrate of step (2) to perform multi-stage extraction, and after the reaction is completed, obtaining an extract phase containing phosphorus and iron and a raffinate phase containing phosphorus and aluminum; (4) Preparation of iron phosphate: adding aqueous ammonia to the extraction phase of step (3) to control the pH, filtering after the reaction to obtain a filter residue and a filtrate, further drying, grinding, and sieving the filter residue to obtain industrial-grade iron phosphate; (5) Preparation of aluminum phosphate: Ammonia water is added dropwise to the raffinate phase of step (3) to control the pH value. After the reaction is completed, the filter is filtered to obtain a filter residue and a filtrate. The filter residue is further dried, ground, and sieved to obtain industrial-grade aluminum phosphate; (6) Preparation of monoammonium phosphate: Collect the filtrate from steps (4) and (5), add aqueous ammonia to the filtrate, control the pH value, and filter, dry, grind and sieve to obtain fertilizer-grade monoammonium phosphate after the reaction is completed.

2. The new process for comprehensive utilization of white fertilizer "multi-element" according to claim 1, characterized in that: The molar ratio of the leaching agent to P2O5 in the white fertilizer raw material is 0.5-2.0, the leaching temperature is 30-80°C, and the leaching time is 40-120 minutes.

3. The new process for comprehensive utilization of white fertilizer "multi-element" according to claim 1 is characterized in that: The leaching agent is sulfuric acid with a concentration of 1 to 14%, and the calcium-containing filter residue is calcium sulfate filter residue.

4. The new process for comprehensive utilization of white fertilizer "multi-element" according to claim 1 is characterized in that: The initial particle size of the white fertilizer is 80 to 300 meshes.

5. The new process for comprehensive utilization of white fertilizer "multi-element" according to claim 1 is characterized in that: The acid leaching step and the defluorination step also include a cyclic acid leaching step, which comprises: adding a leaching agent to the phosphorus, fluorine, iron and aluminum filtrate obtained in step (1) and recycling it to treat the next batch of white fertilizer, and after repeating this step 2 to 6 times, the solid and liquid are separated to obtain a calcium-containing filter residue and a filtrate enriched with phosphorus, fluorine, iron and aluminum.

6. The new process for comprehensive utilization of white fertilizer "multi-element" according to claim 5 is characterized in that: When the white fertilizer is recycled, the liquid-to-solid mass ratio is 1-4:1, and the solid-liquid separation is performed after the acid leaching step is repeated 3-5 times.

7. The new process for comprehensive utilization of white fertilizer "multi-element" according to claim 1 is characterized in that: The molar ratio of the amount of sodium sulfate added in the defluorination reaction to the amount of fluorine contained in the white fertilizer is 0.2-1.0, the defluorination reaction temperature is 30-80° C., the defluorination reaction time is 30-120 min, and the stirring rate during the defluorination reaction is 0-400 rpm.

8. The new process for comprehensive utilization of white fertilizer "multi-element" according to claim 1 is characterized in that: The alcohol extractant is one or a mixture of n-octanol, n-hexanol, n-butanol, n-propanol, and isooctyl alcohol. The volume ratio of the amount of the extractant added to the extraction reaction to the amount of the filtrate containing phosphorus, iron, and aluminum is 0.5 to 3:

1. The extraction reaction temperature is 20 to 40° C., the extraction reaction time is 10 to 40 minutes, and the number of multi-stage extraction stages is 2 to 4.

9. The new process for comprehensive utilization of white fertilizer "multi-element" according to claim 1 is characterized in that: In the preparation of the iron phosphate, the reaction temperature is 30-50°C, and the pH value at the reaction end point is 1-2; in the preparation of the aluminum phosphate, the reaction temperature is 30-55°C, and the pH value at the reaction end point is 1.5-2.5; in the preparation of the monoammonium phosphate, the reaction temperature is 30-55°C, and the pH value at the reaction end point is 4.2-4.

5.

10. The new process for comprehensive utilization of "multi-element" white fertilizer according to claim 1 is characterized in that: The sodium fluorosilicate content in the sodium fluorosilicate product is greater than 98.5wt%, the free acid is less than 0.15wt% in terms of H2SO4, the sulfate is less than 0.50% in terms of SO4, the phosphorus pentoxide content is less than 0.02wt%, and the water-insoluble matter content is less than 0.5wt%; the Fe content in the ferric phosphate product is greater than 30wt%, the P content is greater than 20wt%, the iron-phosphorus molar ratio is 0.93-1.05, the Al content is not greater than 0.05wt%, and the moisture content is not greater than 1wt%; the aluminum phosphate product has an aluminum oxide content greater than 15wt%, a phosphorus pentoxide content greater than 30wt%, and a moisture content less than 5wt%; in the monoammonium phosphate product, the effective phosphorus content in terms of P2O5 is greater than 45wt%, the total nitrogen content is greater than 9wt%, the total nutrient content in terms of N+P2O5 is greater than 56wt%, and the percentage of water-soluble phosphorus in effective phosphorus is greater than 75%.

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