A method for the integrated recycling and utilization of lithium extraction waste from lithium phosphate aluminum ore and phosphate chemical industry waste.

Abstract

This invention discloses a method for the integrated recycling and utilization of lithium phosphate aluminum ore extraction waste residue coupled with phosphate chemical industry. The method includes: reacting fluorosilicic acid, a byproduct of phosphate chemical industry, with ammonia water for ammoniation; refining the filter residue from solid-liquid separation into precipitated silica for recovery; and preparing the filtrate for recycling. The lithium phosphate aluminum ore extraction waste residue is reacted with dilute sulfuric acid, and solid-liquid separation is performed to remove acid-insoluble substances, yielding an acidified solution. The filtrate and acidified solution are mixed and reacted to obtain AlF3 precipitate. After solid-liquid separation, the AlF3 precipitate is further refined to remove impurities such as iron and phosphorus, yielding AlF3. The sulfuric acid phosphoric acid filtrate is added to ammonia water for ammoniation and neutralization to obtain sulfuric acid ammonium slurry. After concentration and drying, fertilizer containing NH4H2PO4+(NH4)2SO4 is produced. This invention features a simple process flow, achieving the industrial-scale integrated utilization of fluorine, silicon, phosphorus, and aluminum elements in the waste residue and byproducts in one step. It provides a new and efficient approach for the comprehensive recycling and utilization of lithium phosphate aluminum ore extraction waste residue for lithium phosphate aluminum ore extraction enterprises and wet-process purified phosphoric acid production enterprises, resulting in significant economic and social benefits.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive recycling and utilization technology of phosphorus chemical and lithium chemical waste, specifically involving a method for the comprehensive recycling and utilization of lithium extraction waste residue from lithium phosphate aluminum ore and phosphorus chemical waste residue. Background Technology

[0002] The development of new energy vehicles and energy storage has driven the demand for lithium resources. While lithium extraction technologies from spodumene and lepidolite are relatively mature, those from lithium phosphate rock are still in the experimental exploration stage. Currently, the method for extracting lithium from lithium phosphate rock involves mixing concentrated sulfuric acid with the ore for acidification and roasting. The roasted product is then leached with water and filtered. The filtrate is used to extract lithium. The main component of the waste residue after lithium extraction is aluminum phosphate (AlPO4), and there are no reports on the high-value recycling and utilization of phosphorus and aluminum from this waste residue.

[0003] In the production of wet-process phosphoric acid by sulfur and phosphorus chemical industry, 40-80 kg of H2SiF6 is produced as a byproduct for every ton of P2O5 produced. Currently, low-cost ammonium fluoride solution is generated while producing silica using H2SiF6. Some of the ammonium fluoride solution is currently used to purify and treat wet-process crude phosphoric acid. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for the comprehensive recovery and utilization of fluorine, silicon, phosphorus, and aluminum elements by coupling lithium extraction waste residue from lithium phosphate aluminate with fluorosilicic acid by-product of wet phosphoric acid production, which is simple in process, can be industrialized, and can be used for integrated production.

[0005] The technical solution adopted in this invention is as follows:

[0006] A method for the integrated recycling and utilization of lithium extraction waste residue from lithium phosphate aluminum ore and phosphate chemical industry waste residue includes the following steps:

[0007] Step 1: The fluorosilicic acid, a byproduct of phosphorus chemical industry, is ammonified with ammonia water. The filter residue from solid-liquid separation is refined into precipitated silica for recovery, and the filtrate is to be recovered.

[0008] Step 2: The lithium extraction waste residue from lithium phosphate aluminum ore is reacted with dilute sulfuric acid, and the solid-liquid separation is performed to remove acid-insoluble substances and obtain an acidified solution.

[0009] Step 3: Mix the filtrate from Step 1 with the acidified solution from Step 2 to obtain AlF3 precipitate. After solid-liquid separation, further refine the AlF3 precipitate to remove impurities such as iron and phosphorus to obtain AlF3. The thiophosphoric filtrate is to be recovered.

[0010] Step 4: Add the sulfur-phosphoric acid filtrate from Step 3 to ammonia water for ammoniation and neutralization to obtain sulfur-phosphoric ammonium slurry. After concentration and drying, produce fertilizer containing NH4H2PO4+(NH4)2SO4.

[0011] Furthermore, the fluorosilicic acid byproduct of the phosphoric acid chemical industry mentioned in step 1 is a fluorosilicic acid byproduct of the wet-process phosphoric acid production process, with a concentration of 8% to 20%.

[0012] Furthermore, in the ammoniation reaction described in step 1, the ammonia water is in 8-fold excess according to the chemical reaction molar ratio, the reaction temperature is 75℃, the reaction endpoint pH is 9, and the aging time is 6h.

[0013] Furthermore, the concentration of ammonia in the ammoniation reaction described in step 1 is 10% to 26%.

[0014] Furthermore, the concentration of the dilute sulfuric acid mentioned in step 2 is 20% to 35%.

[0015] The main chemical equations for this invention are as follows:

[0016] 2LiAlPO4 (OH, F) + H2SO4 = Li2SO4 + 2AlPO4 + 2H2O (2HF) ↑

[0017] H2SiF6 + 6NH3 + 2H2O = 6NH4F + SiO2↓

[0018] AlPO4+ H2SO4 + 3NH4F = AlF3↓+ NH4H2PO4+ (NH4)2SO4

[0019] The beneficial effects of this invention are:

[0020] This invention utilizes a low-cost ammonium fluoride solution generated during the production of silica from H2SiF6, a byproduct of wet-process phosphoric acid, and couples it with acidified lithium extraction waste (mainly AlPO4) to generate AlF3 precipitate for the separation and recovery of phosphorus and aluminum elements. The sulfur-phosphoric acid solution after aluminum recovery is neutralized with NH3 water to produce sulfur-phosphoric acid ammonium fertilizer. This invention achieves the comprehensive industrial utilization of fluorine, silicon, phosphorus, and aluminum elements from waste and byproducts in one step. The process of this invention is simple and provides a new and efficient way for lithium phosphate aluminum extraction enterprises and wet-process purified phosphoric acid production enterprises to recover and utilize lithium phosphate aluminum extraction waste, resulting in significant economic and social benefits. Attached Figure Description

[0021] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Example 1

[0023] like Figure 1As shown, a method for recycling lithium extraction waste residue from lithium phosphate aluminum ore and waste from phosphate chemical industry includes the following steps:

[0024] Step 1: Mix 1 ton of fluorosilicic acid containing 20% ​​H2SiF6 with 4.36 tons of ammonia water containing 26% NH3 (reaction molar ratio 8 times excess) and add to a desilication reaction tank. Heat to 75℃ for ammoniation reaction, control the final pH of the reaction to be 9, keep at this temperature for 6 hours, let stand and filter, refine the filter residue, spray dry to obtain 0.081 tons of silica. The DBP value of silica was tested to be 3.52 ml / g. The filtrate (main component NH4F) enters the next process for recycling.

[0025] Step 2: 0.41 tons of waste residue from lithium extraction from lithium phosphate rock (tested to be 48.82% P2O5, 11.04% SiO2, and 35.19% Al2O3) are reacted with 0.78 tons of 35% dilute sulfuric acid. The solid-liquid separation removes acid-insoluble matter to obtain an acidified solution.

[0026] Step 3: The filtrate from Step 1 is mixed with the acidified solution from Step 2 to obtain AlF3 precipitate. After solid-liquid separation, the AlF3 precipitate is further refined to remove impurities such as iron and phosphorus, yielding 0.22 tons of AlF3 product. Analysis shows the following composition: F: 61.3%, Al: 31.6%, SiO2: 0.07%, Fe2O3: 0.05%, P2O5: 0.02%, SO42-. 2- The concentration was 0.08%, meeting the industrial-grade standard GB / T4292-2017. The thiophosphoric acid filtrate is to be recovered.

[0027] Step 4: Add the sulfur-phosphoric acid filtrate from Step 3 to ammonia water for ammoniation and neutralization reaction to obtain sulfur-phosphoric ammonium slurry. The amount of ammonia water added is controlled to a slurry pH of 7-8 as the endpoint. The sulfur-phosphoric ammonium slurry is concentrated and dried to obtain 0.66 tons of fertilizer containing NH4H2PO4+(NH4)2SO4. The fertilizer contains 15.2% nitrogen, 24.4% available P2O5, and 11.9% sulfur. The NH3-containing tail gas generated during the concentration and drying process is recovered and recycled. Example 2

[0028] like Figure 1 As shown, a method for recycling lithium extraction waste residue from lithium phosphate aluminum ore and waste from phosphate chemical industry includes the following steps:

[0029] Step 1: Mix 1 ton of fluorosilicic acid containing 14% H2SiF6 with 4.41 tons of ammonia water containing 18% NH3 (reaction molar ratio 8 times excess) and add to a desilication reaction tank. Heat to 75℃ for ammoniation reaction, control the final pH of the reaction to be 9, keep at this temperature for 6 hours, let stand and filter, refine the filter residue, spray dry to obtain 0.058 tons of silica. The DBP value of silica was tested to be 3.53 ml / g. The filtrate (main component NH4F) enters the next process for recycling.

[0030] Step 2: React 0.41 tons of waste residue (tested to be 48.82% P2O5, 11.04% SiO2, and 35.19% Al2O3) from lithium extraction from lithium phosphate aluminum ore with 0.71 tons of 27% dilute sulfuric acid. Separate the solid and liquid phases to remove acid-insoluble substances and obtain an acidified solution.

[0031] Step 3: The filtrate from Step 1 is mixed with the acidified solution from Step 2 to obtain AlF3 precipitate. After solid-liquid separation, the AlF3 precipitate is further refined to remove impurities such as iron and phosphorus, yielding 0.16 tons of AlF3 product. Analysis shows the following composition: F: 60.8%, Al: 31.3%, SiO2: 0.22%, Fe2O3: 0.08%, P2O5: 0.02%, SO42-. 2- The concentration was 0.3%, meeting the industrial-grade standard GB / T4292-2017. The thiophosphoric acid filtrate is to be recovered.

[0032] Step 4: Add the sulfur-phosphoric acid filtrate from Step 3 to ammonia water for ammoniation and neutralization reaction to obtain sulfur-phosphoric ammonium slurry. The amount of ammonia water added is controlled to a slurry pH of 7-8 as the endpoint. The sulfur-phosphoric ammonium slurry is concentrated and dried to obtain 0.66 tons of fertilizer containing NH4H2PO4+(NH4)2SO4. The fertilizer contains 15.21% nitrogen, 24.0% available P2O5, and 11.7% sulfur. The NH3-containing tail gas generated during the concentration and drying process is recovered and recycled. Example 3

[0033] like Figure 1 As shown, a method for recycling lithium extraction waste residue from lithium phosphate aluminum ore and waste from phosphate chemical industry includes the following steps:

[0034] Step 1: Mix 2 tons of fluorosilicic acid containing 68% H2SiF with 9.07 tons of ammonia water containing 10% NH3 (reaction molar ratio 8 times excess) and add to a desilication reaction tank. Heat to 75℃ for ammoniation reaction, control the final pH of the reaction to be 9, keep at this temperature for 6 hours, let stand and filter, refine the filter residue, spray dry to obtain 0.066 tons of silica. The DBP value of silica was tested to be 3.51 ml / g. The filtrate (main component NH4F) enters the next process for recycling.

[0035] Step 2: 0.33 tons of waste residue from lithium extraction from lithium phosphate aluminate ore (tested to contain 48.82% P2O5, 11.04% SiO2, and 35.19% Al2O3) are reacted with 1.09 tons of 20% dilute sulfuric acid. The solid-liquid separation removes acid-insoluble matter to obtain an acidified solution.

[0036] Step 3: The filtrate from Step 1 is mixed with the acidified solution from Step 2 to obtain AlF3 precipitate. After solid-liquid separation, the AlF3 precipitate is further refined to remove impurities such as iron and phosphorus, yielding 0.18 tons of AlF3 product. The product composition is as follows: F: 60.5%, Al: 31.2%, SiO2: 0.25%, Fe2O3: 0.07%, P2O5: 0.03%, SO42-. 2- The concentration was 0.4%, meeting the industrial-grade standard GB / T4292-2017. The thiophosphoric acid filtrate is to be recovered.

[0037] Step 4: Add the sulfur-phosphoric acid filtrate from Step 3 to ammonia water for ammoniation and neutralization reaction to obtain sulfur-phosphoric ammonium slurry. The amount of ammonia water added is controlled to the pH of the slurry at 7-8. The sulfur-phosphoric ammonium slurry is concentrated and dried to obtain 0.54 tons of fertilizer containing NH4H2PO4+(NH4)2SO4. The fertilizer contains 15.3% nitrogen, 24.1% available P2O5, and 11.5% sulfur. The NH3-containing tail gas generated during the concentration and drying process is recovered and recycled.

[0038] This invention couples the byproducts of phosphorus chemical industry with the waste residue of lithium chemical industry, and comprehensively recovers and utilizes phosphorus, aluminum, silicon and fluorine elements in phosphorus chemical byproducts and lithium chemical waste residue. It has extremely high economic and social benefits and is worth promoting.

[0039] Unless otherwise stated, all percentages mentioned in this invention are mass percentages.

[0040] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations included within the equivalent meaning and scope of the claims be encompassed within the protection scope of the present invention.

Claims

1. A method for the integrated recycling and utilization of lithium extraction waste residue from lithium phosphate aluminum ore and waste residue from phosphate chemical industry, characterized in that, Includes the following steps: Step 1: The fluorosilicic acid, a byproduct of phosphorus chemical industry with a concentration of 8% to 20%, is ammonified with ammonia water. The filter residue after solid-liquid separation is refined into precipitated silica for recovery, and the filtrate is to be recovered. Step 2: The lithium extraction waste residue from lithium phosphate aluminum ore is reacted with dilute sulfuric acid, and the solid-liquid separation is performed to remove acid-insoluble substances and obtain an acidified solution. Step 3: Mix the filtrate from Step 1 with the acidified solution from Step 2 to obtain AlF3 precipitate. After solid-liquid separation, further refine the AlF3 precipitate to remove iron and phosphorus impurities to obtain AlF3. The thiophosphoric filtrate is to be recovered. Step 4: Add the sulfur-phosphoric acid filtrate from Step 3 to ammonia water for ammoniation and neutralization to obtain sulfur-phosphoric ammonium slurry. After concentration and drying, produce fertilizer containing NH4H2PO4+(NH4)2SO4.

2. The method as described in claim 1, characterized in that, The ammoniation reaction described in step 1 involves an 8-fold excess of ammonia water according to the chemical reaction molar ratio, a reaction temperature of 75°C, a final reaction pH of 9, and an aging time of 6 hours.

3. The method as described in claim 2, characterized in that, The ammonia concentration in the ammoniation reaction described in step 1 is 10% to 26%.

4. The method as described in claim 1, characterized in that, The concentration of the dilute sulfuric acid mentioned in step 2 is 20% to 35%.

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