Low-cost utilization method of low-lithium solution and nickel-cobalt intermediate product treatment solution

Abstract

The application provides a low-cost utilization method of a low-lithium solution and a nickel-cobalt intermediate product treatment solution. The method uses the low-lithium solution and the nickel-cobalt intermediate product treatment solution as raw materials, first fixes the low-lithium solution with lithium phosphate, then reacts the lithium phosphate with sulfuric acid and the nickel-cobalt intermediate product treatment solution to convert into magnesium phosphate slag and a low-acid solution, further converts the magnesium phosphate slag into product magnesium hydroxide and sodium phosphate, and purifies the low-acid solution, then obtains product lithium carbonate through lithium precipitation. The method not only realizes high-value and efficient utilization of waste resources, but also reduces the cost of auxiliary materials in the lithium resource recovery process and the cost of recycling and processing the low-value raw material nickel-cobalt intermediate product treatment solution. The whole process realizes the cyclic utilization of phosphorus resources, and the technical and economic benefits, environmental protection benefits and resource regeneration benefits are remarkable.

Description

Technical Field

[0001] This invention belongs to the field of resource recycling technology. Specifically, this invention relates to a low-cost utilization method for low-lithium solutions and nickel-cobalt intermediate processing solutions. Background Technology

[0002] In recent years, influenced by multiple factors such as energy, environment, technology, and policy, the new energy vehicle industry has experienced explosive growth, directly driving the rapid increase in the production and installation scale of lithium-ion power batteries. Power batteries typically reach their end-of-life after five to eight years, and it is projected that the number of used power batteries will surge by 2050, creating enormous recycling pressure.

[0003] Used power batteries contain large amounts of heavy metals and organic chemicals, posing a serious threat to ecosystems and human health. At the same time, valuable metals such as nickel, cobalt, manganese, lithium, copper, and aluminum in used power batteries are important urban mineral resources. The recycling of valuable metals and the harmless disposal of toxic components from used power batteries are crucial for the sustainable development of the new energy vehicle industry.

[0004] Currently, there are two main processes for lithium recovery from spent power batteries in China: priority lithium extraction and raffinate lithium extraction. Priority lithium extraction involves using a roasting-water leaching process to extract lithium first, separating it from nickel, cobalt, and manganese. After purification of the leaching solution, lithium is precipitated with sodium carbonate to obtain lithium carbonate. Raffinate lithium extraction involves using a leaching-purification-extraction separation process to extract nickel, cobalt, and manganese first, and then extracting lithium from the raffinate. Both processes produce low-lithium, high-sodium solutions (lithium carbonate mother liquor and raffinate, with a lithium concentration of 2-3 g / L and a sodium concentration of 60-80 g / L). For such solutions, direct carbonate precipitation cannot be used. Generally, mechanical vapor recompression (MVR) evaporation is used to concentrate the solution before lithium carbonate precipitation, or trisodium phosphate is used to directly precipitate lithium to prepare lithium phosphate for lithium recovery.

[0005] The method of recovering lithium carbonate from low-lithium, high-sodium solutions using MVR evaporation and concentration is not only costly and involves large investments, but also results in significant lithium loss due to the co-crystallization of lithium with sodium sulfate during the evaporation process (the lithium recovery rate in this portion of the low-lithium solution is only about 60%), making it economically unfeasible. While the process of recovering lithium by precipitating low-lithium, high-sodium solutions to produce lithium phosphate requires less investment, lithium phosphate has relatively low economic value and needs to be further processed into lithium carbonate. This requires conversion into lithium-containing solutions through calcium, iron, and magnesium salts, generating phosphorus-containing waste residue, consuming large amounts of auxiliary materials, and producing phosphorus-containing waste residue as a byproduct, increasing disposal costs. Therefore, it is necessary to research a low-cost, high-recovery method for preparing high-quality lithium carbonate from low-lithium, high-sodium solutions to meet the demands of the lithium carbonate market.

[0006] When nickel-cobalt intermediates are used as raw materials to prepare nickel-cobalt sulfate products using a hydrometallurgical process, the raw materials contain multiple metal elements such as nickel, cobalt, copper, manganese, and magnesium. In actual production and metal recovery, the industry first recovers magnesium, usually by extraction, enrichment, and removal to produce magnesium sulfate solution. Then, through purification and crystallization, low-chemical-purity, low-value magnesium sulfate is produced. This magnesium sulfate product has low added value and no economic benefit. Moreover, purification and crystallization require a large amount of energy consumption and are costly, thus making it uneconomical. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a low-cost method for utilizing low-lithium solutions and nickel-cobalt intermediate processing solutions.

[0008] To achieve the above objectives, the present invention proposes the following solution:

[0009] A low-cost method for utilizing low-lithium solutions and nickel-cobalt intermediate processing solutions includes:

[0010] (1) The lithium phosphate solution is reacted with a soluble phosphate, and after solid-liquid separation, lithium phosphate solid and precipitated liquid are obtained; the soluble phosphate is sodium phosphate or potassium phosphate.

[0011] (2) The lithium phosphate solid is mixed with sulfuric acid and nickel-cobalt intermediate treatment solution and then reacted to obtain magnesium phosphate slag and low acid solution; the nickel-cobalt intermediate treatment solution is magnesium sulfate solution;

[0012] (3) The magnesium phosphate slag is reacted with sodium hydroxide solution or potassium hydroxide solution, and the reaction product is subjected to solid-liquid separation to obtain solid magnesium hydroxide byproduct, and sodium phosphate solution or potassium phosphate solution; and

[0013] The low-acid solution is reacted with an alkaline substance to remove impurities, and the purified lithium sulfate solution is obtained by solid-liquid separation.

[0014] (4) The lithium sulfate purification solution is reacted with sodium carbonate, and the lithium carbonate product is obtained by solid-liquid separation.

[0015] Preferably, in step (3), the resulting sodium phosphate solution or potassium phosphate solution is returned to step (1) for use.

[0016] Preferably, in step (1), the lithium content in the low-lithium solution is 0.2~4 g / L.

[0017] Preferably, in step (1), the low-lithium solution is one or more of the following: lithium recovery mother liquor from battery recycling, lithium recovery mother liquor from salt lake, lithium recovery mother liquor from ore and lithium carbonate precipitation, and battery recycling raffinate.

[0018] In this technical solution, the nickel-cobalt intermediate processing liquid is an intermediate product produced during the production process of nickel-cobalt intermediate products.

[0019] Preferably, in step (2), the molar ratio of the lithium phosphate solid, sulfuric acid, and nickel-cobalt intermediate treatment solution (calculated as phosphate ions) is 1:0.6~1.2:0.9~1.5.

[0020] Preferably, in step (2), the solid-liquid ratio of the reaction is 1:5 to 1:10 t / m³. A liquid-solid ratio that is too low or too high will reduce the yield of precipitated lithium carbonate. During their research, the inventors discovered that controlling the solid-liquid ratio of the reaction in step (2) within the range of 1:5 to 10 t / m³ can achieve a higher lithium recovery rate while ensuring the purity of lithium carbonate.

[0021] Preferably, in step (2), the reaction temperature is 60~95℃ and the reaction time is 0.5~2.5h. If the reaction temperature is too low, it is difficult to guarantee the proportion and efficiency of lithium phosphate being converted into magnesium phosphate slag; if the temperature is too high, a large amount of solution will volatilize.

[0022] Preferably, in step (2), the pH value of the low-acid solution is 3 to 4.

[0023] Preferably, in step (3), the reaction temperature is 90~95℃ and the reaction time is 1~3h. If the temperature is too low, magnesium phosphate is difficult to convert into magnesium hydroxide, resulting in low efficiency; if the temperature is too high, the solution will evaporate in large quantities. However, the inventors unexpectedly discovered that controlling the reaction temperature in step (2) within the range of 90~95℃ makes it easier for magnesium phosphate to be converted into magnesium hydroxide, thereby significantly improving the magnesium recovery rate.

[0024] Preferably, in step (3), the concentration of the sodium hydroxide solution or potassium hydroxide solution is 1~2 mol / L.

[0025] Preferably, in step (3), the alkaline substance is one or more of NaOH, Na2CO3, and NaHCO3.

[0026] Preferably, in step (3), the final pH of the reaction between the low-acid solution and the alkaline substance is 10-12, and the reaction time is 0.5-2 hours.

[0027] Preferably, in step (4), the amount of sodium carbonate is determined by adding 200-300g to 1L of lithium sulfate purification solution.

[0028] Preferably, in step (4), the reaction temperature is 80~95℃ and the reaction time is 0.5~2 hours.

[0029] In step (1), the soluble phosphate is added at a amount slightly higher than the theoretical amount, which is sufficient to achieve sufficient precipitation of lithium in the low-lithium solution. For example, it can be 1.05-1.2 times the theoretical amount.

[0030] In step (4), the amount of sodium hydroxide solution or potassium hydroxide solution used should be slightly higher than the theoretical amount, which is sufficient to meet the theoretical conversion requirements of magnesium phosphate slag. It can be 1.2-1.5 times the theoretical amount.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention utilizes magnesium sulfate solution from low-value nickel-cobalt intermediates as a raw material to convert lithium phosphate into resource-rich lithium carbonate. This reduces the cost of processing magnesium-containing solutions from nickel-cobalt intermediates and achieves magnesium resource recovery. It also reduces the cost of auxiliary materials used in lithium phosphate conversion. Furthermore, by further converting phosphorus-containing waste into sodium phosphate and magnesium hydroxide, it eliminates waste disposal costs while recovering phosphorus resources. Therefore, this process, through the organic combination of its steps, optimizes the value of waste resources and processing costs. The process achieves a lithium recovery rate of over 95% in low-lithium solutions, far exceeding the recovery rate of lithium carbonate produced after MVR evaporation and concentration. It also recovers phosphorus resources in the form of sodium phosphate or potassium phosphate to further recover lithium resources from low-lithium solutions (phosphate recycling), avoiding pollution while significantly improving the recovery rate of phosphorus and lithium. Therefore, the processing method of this invention has significant technical, economic, environmental, and resource regeneration benefits.

[0033] In the processing method of this invention, the low-lithium raw material solution has a wide range of applications, including battery recycling, salt lakes, lithium extraction from ore, lithium carbonate mother liquor, and battery recycling raffinate. The low-chemical-purity, low-value magnesium sulfate solution generated in the production of nickel and cobalt intermediates can be used as another raw material, which can not only reduce the cost of auxiliary materials, but also achieve low-cost and low-energy-consumption effective utilization of low-chemical-purity, low-value magnesium sulfate. Furthermore, this processing method can realize the resource utilization of phosphorus-containing waste residue. The phosphorus resource recovery product sodium phosphate solution can be returned to the lithium phosphate precipitation process for recycling, further reducing the cost of auxiliary materials and improving environmental value. The by-product magnesium hydroxide can be sold to generate economic value. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a process flow diagram illustrating the low-cost utilization of the low-lithium solution and nickel-cobalt intermediate processing solution of the present invention. Detailed Implementation

[0036] To facilitate understanding of the present invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0037] Example 1

[0038] A low-cost method for utilizing low-lithium solutions and nickel-cobalt intermediate processing solutions includes:

[0039] (1) At 85°C, add trisodium phosphate to the battery recovery raffinate (lithium content is 0.774 g / L, composition is shown in Table 1). The amount of trisodium phosphate is 1.1 times the theoretical reaction amount. Start stirring and react for 1 hour. Then centrifuge the lithium phosphate slurry to obtain solid lithium phosphate.

[0040] (2) Add sulfuric acid and magnesium sulfate solution from nickel-cobalt intermediate treatment solution to lithium phosphate solid to carry out lithium phosphate low acid replacement reaction. The solid-liquid ratio of the reaction is 1:6t / m³, the temperature is 80℃, and the molar ratio of lithium phosphate solid:sulfuric acid:magnesium sulfate based on phosphate ions is 1:0.87:1.5. After reacting for 1.5h, filter under pressure to obtain low acid solution and magnesium phosphate slag. The composition of low acid solution is shown in Table 2.

[0041] (3) Add the magnesium phosphate slag obtained above to a sodium hydroxide solution with a concentration of 1.5 mol / L. The sodium hydroxide solution is 1.2 times the theoretical reaction amount. Heat to 93°C and react for 2 hours. Then filter under pressure to obtain solid magnesium hydroxide by-product and trisodium phosphate solution. Return the trisodium phosphate solution to step (1) to react with the battery recovery raffinate.

[0042] (4) Add NaOH to the low acid solution obtained by pressure filtration for purification, turn on the stirring to control the final pH to 11, remove impurities, and filter after 1 hour of reaction to obtain lithium sulfate purified solution.

[0043] (5) Add sodium carbonate solution to the purified lithium sulfate solution obtained from the purification and separation at a dosage of 250g sodium carbonate per 1L of purified lithium sulfate solution to precipitate lithium. React at 90℃ for 1.5h and then centrifuge to obtain crude lithium carbonate product. The composition of lithium carbonate is shown in Table 3. The lithium recovery rate of the whole process is 96.15%. The composition of magnesium hydroxide is shown in Table 4. The magnesium recovery rate is 85.3%.

[0044] Table 1. Composition of Battery Material Extraction Liquid

[0045]

[0046] Table 2. Composition of Low Acid Solution

[0047]

[0048] Table 3 Lithium Carbonate Composition Table

[0049]

[0050] Table 4. Composition of Magnesium Hydroxide

[0051]

[0052] Example 2

[0053] A low-cost method for utilizing low-lithium solutions and nickel-cobalt intermediate processing solutions includes:

[0054] (1) At 90°C, trisodium phosphate was added to the lithium carbonate mother liquor (lithium content is 3.217 g / L, composition is shown in Table 5) from the lithium extraction of ore. The amount of trisodium phosphate was 1.1 times the theoretical reaction amount. The machine was turned on and stirred. After reacting for 1 hour, the lithium phosphate slurry was centrifuged and the solid lithium phosphate was obtained by centrifugation.

[0055] (2) Add sulfuric acid and magnesium sulfate solution from nickel-cobalt intermediate treatment solution to lithium phosphate to carry out low acid replacement reaction of lithium phosphate. Under the conditions of solid-liquid ratio of 1:5t / m³, reaction temperature of 70℃, and molar ratio of lithium phosphate solid:sulfuric acid:magnesium sulfate of 1:0.75:1.25 based on phosphate ions, filter under pressure after reaction for 1h to obtain low acid solution and magnesium phosphate slag. The composition of low acid solution is shown in Table 6.

[0056] (3) Add the obtained magnesium phosphate slag to a sodium hydroxide solution with a concentration of 2 mol / L. The sodium hydroxide solution is 1.2 times the theoretical reaction amount. React at 95℃ for 1 h and then filter to separate. The sodium phosphate solution is used to return to step (1) to prepare lithium phosphate. Solid magnesium hydroxide is used as a by-product.

[0057] (4) Add NaOH to the low acid solution obtained by pressure filtration for purification, turn on the stirring to control the final pH to 11, and filter after 1 hour of reaction to obtain lithium sulfate purified solution.

[0058] (5) Add sodium carbonate solution to the lithium sulfate purification solution at a dosage of 300g sodium carbonate per 1L of lithium sulfate purification solution to precipitate lithium. React at 90℃ for 2h and then centrifuge to obtain crude lithium carbonate product. The composition of the obtained lithium carbonate product is shown in Table 7. The lithium recovery rate of the whole process is 96.23%. The composition of magnesium hydroxide is shown in Table 8. The magnesium recovery rate is 86.8%.

[0059] Table 5. Composition of Mother Lithium Extraction and Lithium Carbonate Precipitation Lithium ...

[0060]

[0061] Table 6. Composition of Low-Acid Solution

[0062]

[0063] Table 7 Lithium Carbonate Composition Table

[0064]

[0065] Table 8. Composition of Magnesium Hydroxide

[0066]

[0067] Example 3

[0068] The only difference between this embodiment and Example 1 is that in step (2), the reaction temperature is 60℃, the reaction time is 2.5h, and the solid-liquid ratio is 1:10t / m³. The composition of the recovered lithium carbonate is shown in Table 9, and the lithium recovery rate is 95.01% throughout the process. The composition of magnesium hydroxide is shown in Table 10, and the magnesium recovery rate is 84.3%.

[0069] Table 9. Lithium Carbonate Composition Table

[0070]

[0071] Table 10 Composition of Magnesium Hydroxide

[0072]

[0073] Example 4

[0074] The only difference between this embodiment and Example 2 is that in step (2), the solid-liquid ratio is 1:15 t / m³, the reaction temperature is 40℃, and the reaction time is 3h. The composition of the recovered lithium carbonate is shown in Table 11. The lithium recovery rate of the entire process is 90.21%, indicating that a low solid-liquid ratio and low temperature will increase the lithium loss rate and reduce the purity of lithium carbonate. The composition of magnesium hydroxide is shown in Table 12, and the magnesium recovery rate is 85.1%.

[0075] Table 11 Lithium Carbonate Composition Table

[0076]

[0077] Table 12 Composition of Magnesium Hydroxide

[0078]

[0079] Example 5

[0080] The only difference between this embodiment and Example 1 is that in step (2), the solid-liquid ratio is 1:3 t / m³, and the composition of the recovered lithium carbonate is shown in Table 13. The lithium recovery rate of the entire process is 93.41%, indicating that the solid-liquid ratio is too high, which reduces the purity of lithium carbonate and the lithium recovery rate. The composition of magnesium hydroxide is shown in Table 14, and the magnesium recovery rate is 84.8%.

[0081] Table 13 Lithium Carbonate Composition Table

[0082]

[0083] Table 14 Composition of Magnesium Hydroxide

[0084]

[0085] Example 6

[0086] The only difference between this embodiment and Example 2 is that in step (5), the reaction temperature is 70°C and the reaction time is 3 hours. The composition of the recovered lithium carbonate is shown in Table 15. The lithium recovery rate of the whole process is 89.22%. Due to the low temperature of the lithium carbonate precipitation process, the solubility of lithium carbonate is worse, so the yield is reduced.

[0087] Table 15 Lithium Carbonate Composition Table

[0088]

[0089] Example 7

[0090] The only difference between this embodiment and Example 2 is that in step (3), the reaction temperature is 90°C and the reaction time is 3 hours. The composition of the obtained magnesium hydroxide is shown in Table 16, and the magnesium recovery rate is 87.05%.

[0091] Table 16 Composition of Magnesium Hydroxide

[0092]

[0093] Example 8

[0094] The only difference between this embodiment and Example 2 is that in step (3), the reaction temperature is 60°C and the reaction time is 3 hours. The composition of the obtained magnesium hydroxide is shown in Table 17. The magnesium recovery rate is 79.47%, indicating that at too low a temperature, magnesium phosphate is difficult to convert into magnesium hydroxide.

[0095] Table 17 Composition of Magnesium Hydroxide

[0096]

[0097] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-cost method for utilizing low-lithium solution and nickel-cobalt intermediate processing solution, characterized in that, include: (1) The low-lithium solution is reacted with a soluble phosphate, and after solid-liquid separation, lithium phosphate solid and precipitated liquid are obtained; the soluble phosphate is sodium phosphate or potassium phosphate; (2) The lithium phosphate solid is mixed with sulfuric acid and nickel-cobalt intermediate treatment solution and then reacted to obtain magnesium phosphate slag and low acid solution; the nickel-cobalt intermediate treatment solution is magnesium sulfate solution; (3) The magnesium phosphate slag is reacted with sodium hydroxide solution or potassium hydroxide solution, and the reaction product is separated into solid and liquid to obtain solid magnesium hydroxide by-product, as well as sodium phosphate solution or potassium phosphate solution. The reaction temperature is 90~95℃. The low acid solution is reacted with alkaline substances, and lithium sulfate purified solution is obtained by solid-liquid separation. The sodium phosphate solution or potassium phosphate solution obtained in step (3) is returned to step (1) for use. (4) The lithium sulfate purification solution is reacted with sodium carbonate, and the lithium carbonate product is obtained by solid-liquid separation.

2. The low-cost utilization method of the low-lithium solution and nickel-cobalt intermediate processing solution as described in claim 1, characterized in that, In step (1), the lithium content in the low-lithium solution is 0.2~4 g / L.

3. The low-cost utilization method of the low-lithium solution and nickel-cobalt intermediate processing solution as described in claim 1, characterized in that, In step (1), the low-lithium solution is one or more of the following: lithium recovery mother liquor from battery recycling, lithium recovery mother liquor from salt lake, lithium recovery mother liquor from ore and lithium carbonate precipitation, and battery recycling raffinate.

4. The low-cost utilization method of the low-lithium solution and nickel-cobalt intermediate processing solution as described in any one of claims 1 to 3, characterized in that, In step (2), the molar ratio of the lithium phosphate solid, sulfuric acid, and nickel-cobalt intermediate treatment solution (calculated as phosphate ions) is 1:0.6~1.2:0.9~1.

5.

5. A low-cost utilization method for the low-lithium solution and nickel-cobalt intermediate processing solution as described in any one of claims 1 to 3, characterized in that, In step (2), the solid-liquid ratio of the reaction is 1:5~1:10t / m³.

6. A low-cost utilization method for the low-lithium solution and nickel-cobalt intermediate processing solution as described in any one of claims 1 to 3, characterized in that, In step (2), the reaction temperature is 60~95℃.

7. A low-cost utilization method for the low-lithium solution and nickel-cobalt intermediate processing solution as described in any one of claims 1 to 3, characterized in that, In step (2), the reaction time is 0.5~2.5h.

8. A low-cost utilization method for the low-lithium solution and nickel-cobalt intermediate processing solution as described in any one of claims 1 to 3, characterized in that, In step (2), the pH value of the low acid solution is 3 to 4.

9. A low-cost utilization method for the low-lithium solution and nickel-cobalt intermediate processing solution as described in any one of claims 1 to 3, characterized in that, In step (3), the reaction time is 1 to 3 hours.

10. A low-cost utilization method for the low-lithium solution and nickel-cobalt intermediate processing solution as described in any one of claims 1 to 3, characterized in that, In step (3), the concentration of the sodium hydroxide solution or potassium hydroxide solution is 1~2 mol / L.

11. A low-cost utilization method for the low-lithium solution and nickel-cobalt intermediate processing solution as described in any one of claims 1 to 3, characterized in that, In step (1), the reaction temperature is 80~95℃; the reaction is carried out under stirring conditions.

12. A low-cost utilization method for the low-lithium solution and nickel-cobalt intermediate processing solution as described in any one of claims 1 to 3, characterized in that, In step (3), the alkaline substance is one or more of NaOH, Na2CO3, and NaHCO3.

13. A low-cost utilization method for the low-lithium solution and nickel-cobalt intermediate processing solution as described in any one of claims 1 to 3, characterized in that, In step (3), the final pH value of the reaction between the low acid solution and the alkaline substance is 10-12, and the reaction time is 0.5-2 hours.

14. A low-cost utilization method for the low-lithium solution and nickel-cobalt intermediate processing solution as described in any one of claims 1 to 3, characterized in that, In step (4), the amount of sodium carbonate is determined by adding 200-300g to 1L of lithium sulfate purification solution.

15. The low-cost utilization method of low-lithium solution and nickel-cobalt intermediate processing liquid as described in any one of claims 1 to 3, wherein in step (4), the reaction temperature is 80 to 95°C and the reaction time is 0.5 to 2 hours.

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