Method for preparing lithium carbonate and lithium phosphate by extracting lithium from glass polishing waste residues

Abstract

The invention discloses a method for preparing lithium carbonate and lithium phosphate by extracting lithium from glass polishing waste residues. The method comprises the following steps: (1) wet leaching; (2) acid recovery; (3) nanofiltration and impurity removal; (4) deeply removing impurities; (5) concentrating and precipitating lithium: evaporating and concentrating the filtrate obtained in the step (4) until the concentration of Li is greater than or equal to 20g / L, then heating, adding a sodium carbonate solution, carrying out lithium precipitation reaction to obtain a lithium carbonate solid and a mother solution after lithium precipitation, and drying the lithium carbonate solid to obtain an industrial-grade lithium carbonate product; and then preserving heat of the mother liquor after lithium precipitation, adding a phosphate solution into the mother liquor after lithium precipitation, reacting, filtering and drying to obtain a lithium phosphate product. According to the invention, lithium in the glass polishing waste residue is recycled to obtain lithium carbonate and lithium phosphate products; more than 70% of the used acid is recycled, so that the operation cost is greatly reduced; high-temperature roasting is not needed, the energy consumption is low, and the method is an efficient and energy-saving technology.

Description

Technical Field

[0001] The invention belongs to the field of resource utilization of glass polishing waste residue, and in particular relates to a method for extracting lithium from glass polishing waste residue to prepare lithium carbonate and lithium phosphate. Background Art

[0002] In recent years, with the continuous development of electronic products such as computers, digital cameras, and mobile phones, lithium has become the largest consumer area in the battery industry. At the same time, various new roles of lithium in glass are constantly being discovered, and various lithium-containing glasses appear in daily life. As the surface quality and polishing accuracy requirements of glass substrates become more and more stringent, polishing powder is used in large quantities. The large-scale application of polishing powder has also led to an increase in the amount of glass polishing waste residue in my country year by year. Relevant data show that the annual amount of glass polishing waste residue in my country exceeds 100,000 tons. These glass polishing waste residues contain a certain amount of lithium elements, so recycling them to achieve the recycling and reuse of lithium resources can not only reduce resource waste, but also comprehensively solve the shortage of raw materials such as lithium.

[0003] With the development of new energy vehicles, the demand for battery positive electrode materials has increased by leaps and bounds. The demand for lithium carbonate and lithium phosphate as important positive electrode raw materials has also increased sharply. From 2017 to 2030, global lithium demand will increase from 238,000 tons (lithium carbonate, the same below) to 2.56 million tons. In 2017, my country's lithium resource consumption was 125,000 tons, accounting for 52% of the world. In 2030, my country's lithium resource consumption will reach 1.44 million tons.

[0004] At present, there are few development and research in this field. There are some studies on lithium extraction from glass powder. For example, Chinese patent application with application number 202211392554.1 discloses a method and process for recovering lithium from lithium-containing glass powder, which is not suitable for treating glass polishing waste. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for extracting lithium from glass polishing waste residue to prepare lithium carbonate and lithium phosphate.

[0006] The technical solution adopted by the present invention to solve the technical problem is a method for extracting lithium from glass polishing waste residue to prepare lithium carbonate and lithium phosphate, comprising the following steps:

[0007] (1) Wet leaching:

[0008] The glass polishing waste residue is subjected to an acid leaching reaction to transfer lithium in the glass polishing waste residue to a liquid phase to obtain a leachate;

[0009] The lithium ion content in the glass polishing waste residue is ≥0.2wt%.

[0010] In this specification, unless otherwise specified, the percentages are by mass.

[0011] Furthermore, in step (1), the acid used for acid leaching is at least one of hydrochloric acid, sulfuric acid, nitric acid, etc. The mass concentration of the acid is ≤50% (preferably 10-40%).

[0012] Furthermore, in step (1), the leaching reaction solid-liquid ratio is 1:1-5 (g / ml), the temperature is 20-80°C, and the reaction time is 1-6h. Within a certain range, appropriate heating and prolonged reaction time can promote the leaching reaction and increase the leaching rate of lithium ions.

[0013] (2) Acid recovery:

[0014] The acid concentration in the leachate obtained in step (1) is relatively high, and a diffusion dialysis membrane is used to recover the acid to obtain a diffusion dialysis tail liquid;

[0015] The recovered acid can be reused in step (1) after being configured to a corresponding concentration. The acidity in the diffusion dialysis tail liquid is reduced by more than 70% compared to the original leaching liquid, and there is basically no loss of lithium.

[0016] Furthermore, in step (2), the diffusion dialysis membrane is an anionic membrane.

[0017] Furthermore, in step (2), pure water is used as the water in the diffusion dialysis process, the flow rate is 1-2 L / h, and the flow rate of the leaching liquid is 0.8-2 L / h. It is preferably carried out at room temperature.

[0018] (3) Nanofiltration removal:

[0019] The diffusion dialysis tail liquid obtained in step (2) is subjected to impurity removal using an acid-resistant nanofiltration membrane, so that divalent and higher ions are retained in the nanofiltration concentrated water, and lithium ions and hydrogen ions enter the nanofiltration clear water;

[0020] Furthermore, in step (3), the acid-resistant nanofiltration membrane is a commercially available product with an acid resistance of ≤50%.

[0021] Furthermore, in step (3), the nanofiltration pressure is 1-4 MPa and the reaction temperature is 20-40°C.

[0022] By using diffusion dialysis membrane to recover acid and acid-resistant nanofiltration membrane to remove impurities, the amount of acid and alkali used can be effectively reduced, the process cost can be greatly reduced, and better economic benefits can be obtained.

[0023] (4) Deep impurity removal:

[0024] Add an alkaline solution to the nanofiltration clear water obtained in step (3), adjust the solution pH to 11.5-12.5 (preferably 12) and then filter.

[0025] The filtrate is obtained;

[0026] Furthermore, the alkaline solution in step (3) is at least one of a sodium hydroxide solution and a potassium hydroxide solution.

[0027] (5) Concentrated lithium precipitation:

[0028] The filtrate obtained in step (4) is evaporated and concentrated to a Li concentration of ≥20 g / L, then heated, and sodium carbonate solution is added to carry out lithium precipitation reaction to obtain lithium carbonate solid and mother liquor after lithium precipitation, and the lithium carbonate solid is dried to obtain an industrial-grade lithium carbonate product; then the mother liquor after lithium precipitation is kept warm, a phosphate solution is added to the mother liquor after lithium precipitation, and the reaction is carried out for 20-60 minutes (preferably the reaction time is more than 25 minutes), filtered, and dried to obtain a lithium phosphate product.

[0029] Furthermore, in the step (4), the lithium precipitation reaction is heated to a temperature of 60-100°C.

[0030] Furthermore, in step (4), the concentration of the sodium carbonate solution is 200-280 g / L, and the molar amount of carbonate ions contained in the sodium carbonate solution is 1-1.5 times the molar amount of lithium ions.

[0031] Furthermore, in the step (4), the temperature of the mother liquor after lithium precipitation is kept at 80-90°C.

[0032] Furthermore, in step (4), the phosphate solution is at least one of a Na2HPO4 solution and a NaH2PO4 solution. The molar amount of phosphate ions contained in the phosphate solution is 1-1.5 times the molar amount of lithium ions.

[0033] The advantages of the present invention are:

[0034] 1. Reuse lithium in glass polishing waste to obtain lithium carbonate and lithium phosphate products;

[0035] 2. The present invention recycles more than 70% of the acid used, greatly reducing the operating cost;

[0036] 3. The present invention does not require high-temperature roasting and has low energy consumption. It is a new high-efficiency and energy-saving technology.

[0037] The method of extracting lithium from glass polishing waste residue to prepare lithium carbonate and lithium phosphate of the present invention can significantly improve the lithium leaching rate and lower the reagent cost; using appropriate heating and extending the reaction time can promote the leaching reaction and improve the leaching rate of lithium ions. At the same time, by using diffusion dialysis membrane to recover acid and acid-resistant nanofiltration membrane to remove impurities, the amount of acid and alkali can be effectively reduced, the process cost is greatly reduced, and better economic benefits are obtained. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with specific embodiments.

[0039] Example 1

[0040] The raw material of this embodiment is glass polishing waste residue from a domestic glass production company, and the component analysis is as follows:

[0041] index Li / % Al / ％ Ca / % Mg / % Fe / % K / ％ Na / % <![CDATA[Cl - / %]]> content 0.6879 6.6610 0.9847 0.6048 0.3153 0.9750 0.2401 0.6320

[0042] The method for extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate in this embodiment comprises the following steps:

[0043] (1) Wet leaching: 1 kg of polishing mud (glass polishing waste residue) was stirred with a 20% sulfuric acid solution at a solid-liquid ratio of 1:3 g / ml, and the leaching temperature was 50°C for 2 hours. After the leaching reaction, the filtrate (leaching solution) was filtered to obtain 2.78 kg of filtrate (leaching solution) and 1.16 kg of filter residue. The filtrate contained 1.34% Li + 0.22%,Al 3+ Mass concentration 1.93%, Li + Leaching rate: 88.64%;

[0044] (2) Acid recovery: The acid in the leachate was recovered using the CR-DD-4 diffusion dialysis membrane produced by Hangzhou Cree. The leachate flow rate was 0.8 L / h and the pure water flow rate was 1 L / h. 2.48 kg of acid recovery liquid and 3.06 kg of diffusion dialysis tail liquid were obtained. The recovered acid concentration was 14.16%, the acid recovery rate was 71.44%, the lithium retention rate was 99.91%, and the aluminum retention rate was 99.93%;

[0045] (3) Nanofiltration impurity removal: The diffusion dialysis tail liquid obtained after acid recovery in step (2) was passed through an acid-resistant nanofiltration membrane at a pressure of 3.5 MPa and a temperature of 25° C. to obtain 2.46 kg of nanofiltration clear water and 0.57 kg of nanofiltration concentrated water, with an aluminum retention rate of 99.5%;

[0046] The acid-resistant nanofiltration membrane is a commercially available product with an acid resistance of ≤50%;

[0047] (4) deep impurity removal: adding sodium hydroxide solution to the nanofiltration clear water obtained in step (3), adjusting the pH of the solution to 12 and filtering to obtain a filtrate;

[0048] (5) Concentration of lithium precipitation: The filtrate obtained in step (4) is evaporated and concentrated to a Li concentration of ≥ 20 g / L, and then the concentration is adjusted according to the Li / CO3 2- Molar ratio 1:1.2, heating, adding 250g / L sodium carbonate solution 900g to carry out lithium precipitation reaction, reaction temperature 85°C, obtaining wet lithium carbonate solid and mother liquor after lithium precipitation, the wet lithium carbonate solid is dried to obtain 26.35g 99.23% industrial grade lithium carbonate product; keeping the temperature at 90°C, adding Li / PO4 3-75.52 g of NaH2PO4 solution with a mass concentration of 20% was added at a molar ratio of 1:1.1, reacted for 30 min, filtered, and dried to obtain 4.62 g of 95.23% lithium phosphate.

[0049] Example 2

[0050] The raw material of this embodiment is glass polishing waste produced by a domestic electronic product screen manufacturing company, and the component analysis is as follows:

[0051] index Li / % Al / ％ Ca / % Mg / % Fe / % K / ％ Na / % <![CDATA[Cl - / %]]> content 0.5467 6.3698 0.9638 0.5493 0.2567 2.0692 2.3652 1.6528

[0052] The method for extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate in this embodiment comprises the following steps:

[0053] (1) Wet leaching: 1 kg of polishing mud (glass polishing waste residue) was stirred with 15% hydrochloric acid at a solid-liquid ratio of 1:3 g / ml, and the leaching temperature was 50°C for 2 hours. After the leaching reaction, the filtrate was filtered to obtain 2.69 kg of filtrate and 1.21 kg of filter residue. The filtrate contained 0.18% Li and 0.28% Al. 3+ Mass concentration 1.97%, Li + Leaching rate: 88.56%;

[0054] (2) Acid recovery: The acid in the leachate was recovered using the CR-DD-4 diffusion dialysis membrane produced by Hangzhou Cree. The leachate flow rate was 1 L / h, and the pure water flow rate was 1.1 L / h. 2.25 kg of acid recovery liquid and 2.86 kg of tail liquid were obtained. The recovered acid concentration was 13.51%, the acid recovery rate was 70.55%, the lithium retention rate was 99.92%, and the aluminum retention rate was 99.95%;

[0055] (3) Nanofiltration impurity removal: The diffusion dialysis tail liquid obtained after acid recovery in step (2) was passed through an acid-resistant nanofiltration membrane at a pressure of 3 MPa and a temperature of 25° C. to obtain 2.31 kg of nanofiltration clear water and 0.54 kg of nanofiltration concentrated water, with an aluminum retention rate of 99.2%;

[0056] The acid-resistant nanofiltration membrane is a commercially available product with an acid resistance of ≤50%;

[0057] (4) deep impurity removal: adding sodium hydroxide solution to the nanofiltration clear water obtained in step (3), adjusting the pH of the solution to 12 and filtering to obtain a filtrate;

[0058] (5) Concentration of lithium precipitation: The filtrate obtained in step (4) is evaporated and concentrated to a Li concentration of ≥ 20 g / L, and then the concentration is adjusted according to the Li / CO3 2-The molar ratio was 1:1.15, and 675 g of 250 g / L sodium carbonate solution was added to the solution for lithium precipitation reaction at a reaction temperature of 85 ° C to obtain wet lithium carbonate solid, which was then dried to obtain 20.62 g of 99.26% industrial grade lithium carbonate product. The mother liquor after lithium precipitation was kept at 90 ° C and added to the mother liquor after lithium precipitation according to the Li / PO4 3- 65.34 g of 20% NaH2PO4 solution was added at a molar ratio of 1:1, reacted for 30 min, filtered, and dried to obtain 3.85 g of 96.36% lithium phosphate.

[0059] Example 3

[0060] The raw material of this embodiment is the polishing waste residue of mobile phone glass back panel produced by a domestic electronic product manufacturing company. The component analysis is as follows:

[0061] index Li / % Al / ％ Ca / % Mg / % Fe / % K / ％ Na / % <![CDATA[Cl - / %]]> content 0.6515 6.1270 0.5987 0.5265 0.1748 2.5090 2.1800 1.3860

[0062] The method for extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate in this embodiment comprises the following steps:

[0063] (1) Wet leaching: 1 kg of polishing mud (i.e. glass polishing waste residue) was stirred with 20% sulfuric acid at a solid-liquid ratio of 1:4 g / ml, and the leaching temperature was 40°C for 1.5 h. After the leaching reaction, 3.71 kg of filtrate and 1.13 kg of filter residue were obtained. The filtrate contained 0.16% Li and 0.6% Al. 3+ Mass concentration 1.56%, Li + Leaching rate: 91.11%;

[0064] (2) Acid recovery: The acid in the leachate was recovered using the CR-DD-4 diffusion dialysis membrane produced by Hangzhou Cree. The leachate flow rate was 0.8 L / h and the pure water flow rate was 1.0 L / h. 3.65 kg of acid recovery liquid and 3.89 kg of tail liquid were obtained. The recovered acid concentration was 14.62%, the acid recovery rate was 71.27%, the lithium retention rate was 99.91%, and the aluminum retention rate was 99.93%;

[0065] (3) Nanofiltration impurity removal: The diffusion dialysis tail liquid obtained after acid recovery in step (2) is passed through an acid-resistant nanofiltration membrane at a pressure of 3 MPa and a temperature of 25° C. to obtain 2.31 kg of nanofiltration clear water and 0.54 kg of nanofiltration concentrated water, with an aluminum retention rate of 99.2%; the acid-resistant nanofiltration membrane is a commercially available product with an acid resistance of ≤50%;

[0066] (4) Deep impurity removal: adding sodium hydroxide solution to the nanofiltration clear water obtained in step (3), adjusting the solution pH to 12 and filtering, and concentrating the filtrate to precipitate lithium;

[0067] (5) Concentration of lithium precipitation: The filtrate obtained in step (4) is evaporated and concentrated to a Li concentration of ≥ 20 g / L, and then the concentration is adjusted according to the Li / CO32- The molar ratio was 1:1.25, and 988 g of 250 g / L sodium carbonate solution was added to the solution for lithium precipitation reaction at a reaction temperature of 90 ° C to obtain wet lithium carbonate solid, which was then dried to obtain 28.78 g of 99.31% industrial grade lithium carbonate product. The mother liquor after lithium precipitation was kept at 90 ° C, and the mother liquor after lithium precipitation was added according to the Li / PO4 3- 82.47 g of 20% NaH2PO4 solution was added at a molar ratio of 1:1.35, reacted for 30 min, filtered, and dried to obtain 4.87 g of 95.86% lithium phosphate.

[0068] Comparative Example 1

[0069] The steps and raw material ratios of this comparative example are the same as those of Example 1, except that: the leaching temperature in step (1) is 15°C and the reaction time is 1h; the leaching liquid flow rate in step (2) is 1L / h and the pure water flow rate is 2L / h. The lithium leaching rate of this comparative example is only 72.31%.

[0070] Comparative Example 2

[0071] The method for extracting lithium from glass polishing waste residue to prepare lithium carbonate and lithium phosphate provided in this comparative example is basically the same as that in Example 1, except that: step (2) acid recovery and step (3) nanofiltration impurity removal are not performed. Due to the lack of acid recovery and nanofiltration impurity removal, the amount of acid used is greatly increased, and the amount of alkali used in step (4) is increased at the same time, and aluminum ions cannot be effectively removed. The purity of lithium carbonate obtained in this comparative example is only 80.21%, and industrial-grade lithium carbonate products cannot be obtained.

[0072] According to the above-mentioned Examples 1 to 3 and Comparative Examples 1 to 2, it can be seen that the method of extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate in the present application has a significantly improved lithium leaching rate and a lower reagent cost compared to Comparative Examples 1 to 2; appropriate heating and prolonged reaction time can promote the leaching reaction and increase the leaching rate of lithium ions; at the same time, by using diffusion dialysis membranes to recover acids and acid-resistant nanofiltration membranes to remove impurities, the amount of acid and alkali used can be effectively reduced, the process cost can be greatly reduced, and better economic benefits can be obtained.

Claims

1. A method for extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate, characterized in that: The following steps are involved: (1) Wet leaching: The glass polishing waste residue is subjected to an acid leaching reaction to transfer lithium in the glass polishing waste residue to a liquid phase to obtain a leachate; The lithium ion content in the glass polishing waste residue is ≥ 0.2wt%; (2) Acid recovery: The leachate obtained in step (1) is subjected to acid recovery using a diffusion dialysis membrane to obtain a diffusion dialysis tail liquid; (3) Nanofiltration removal: The diffusion dialysis tail liquid obtained in step (2) is subjected to impurity removal using an acid-resistant nanofiltration membrane, so that divalent and higher ions are retained in the nanofiltration concentrated water, and lithium ions and hydrogen ions enter the nanofiltration clear water; (4) Deep impurity removal: Add an alkaline solution to the nanofiltration clear water obtained in step (3), adjust the pH of the solution to 11.5-12.5, and then filter to obtain a filtrate; (5) Concentrated lithium precipitation: The filtrate obtained in step (4) is evaporated and concentrated to a Li concentration of ≥20 g / L, then heated, and a sodium carbonate solution is added to carry out a lithium precipitation reaction to obtain a lithium carbonate solid and a mother liquor after lithium precipitation, and the lithium carbonate solid is dried to obtain an industrial-grade lithium carbonate product; then the mother liquor after lithium precipitation is kept warm, a phosphate solution is added to the mother liquor after lithium precipitation, reacted, filtered, and dried to obtain a lithium phosphate product.

2. The method for extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate according to claim 1, characterized in that: In step (1), the acid used for acid leaching is at least one of hydrochloric acid, sulfuric acid and nitric acid; and the mass concentration of the acid is ≤50%.

3. The method for extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate according to claim 1 or 2, characterized in that: In step (1), the leaching reaction solid-liquid ratio is 1:1-5; the temperature is 20-80°C; and the reaction time is 1-6h.

4. The method for extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate according to claim 1 or 2, characterized in that: In step (2), the diffusion dialysis membrane is an anionic membrane.

5. The method for extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate according to claim 1 or 2, characterized in that: In step (2), pure water is used in the diffusion dialysis process at a flow rate of 1-2 L / h, and the flow rate of the leaching solution is 0.8-2 L / h.

6. The method for extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate according to claim 1 or 2, characterized in that: The nanofiltration pressure in step (3) is 1-4 MPa, and the reaction temperature is 20-40°C.

7. The method for extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate according to claim 1 or 2, characterized in that: The alkaline solution in step (3) refers to at least one of a sodium hydroxide solution and a potassium hydroxide solution.

8. The method for extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate according to claim 1 or 2, characterized in that: In step (4), the lithium precipitation reaction is heated to a temperature of 60-100°C.

9. The method for extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate according to claim 1 or 2, characterized in that: In step (4), the concentration of the sodium carbonate solution is 200-280 g / L; the molar amount of carbonate ions contained in the sodium carbonate solution is 1-1.5 times the molar amount of lithium ions.

10. The method for extracting lithium from glass polishing waste to prepare lithium carbonate and lithium phosphate according to claim 1 or 2, characterized in that: In step (4), the mother liquor is kept warm at a temperature of 80-90°C after lithium precipitation; and / or in step (4), the phosphate solution is at least one of a Na2HPO4 solution and a NaH2PO4 solution; and / or the molar amount of phosphate ions contained in the phosphate solution is 1-1.5 times the molar amount of lithium ions.