Method for extracting valuable metal from waste lithium-containing polishing powder

Abstract

The invention provides a method for extracting valuable metals from waste lithium-containing polishing powder. The method comprises the following steps: (1) carrying out acid leaching treatment on the waste lithium-containing polishing powder to obtain acid leaching residues and an acid leaching solution; (2) adjusting the pH value of the acid leaching solution to a first pH value, mixing the acid leaching solution with a first precipitator, and carrying out lanthanum precipitation treatment to obtain a lanthanum-precipitated solution and lanthanum-precipitated slag; (3) mixing the alum-forming reagent and the lanthanum-deposited liquid, heating and dissolving, and then carrying out aluminum removal treatment to obtain alum and a first aluminum-removed liquid; (4) mixing the first aluminum-removed liquid with a pH regulator, and carrying out impurity removal treatment to obtain an impurity-removed liquid; and (5) carrying out calcium removal treatment on the impurity-removed solution to obtain a lithium-rich solution. According to the method provided by the invention, valuable metals such as lithium, lanthanum and aluminum in the waste lithium-containing polishing powder are effectively recycled under the low-temperature condition, and the method is high in recycling and extracting rate, low in energy consumption and cost, simple in technological process, free of a complicated roasting treatment process and suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of recycling and treatment of waste lithium-containing polishing powder, and relates to a method for extracting valuable metals from waste lithium-containing polishing powder. Background Art

[0002] With the development of technology, the polishing precision requirements for electronic devices such as touch screen mobile phones, liquid crystal display devices, and precision instrument glass devices are getting higher and higher. Therefore, the demand for polishing powder with characteristics such as high polishing efficiency, high chemical activity, and long service life is increasing continuously. In traditional technology, waste rare earth polishing powder is treated as solid waste. However, the waste rare earth polishing powder contains a large amount of rare earth oxides and other chemical components. Direct landfill or stacking will cause serious pollution to soil and water bodies. Through recycling and treatment, the pollution of these harmful substances to the environment can be effectively reduced. On the other hand, recycling and utilization of waste polishing powder can effectively ensure the supply-demand balance of rare earth polishing powder resources.

[0003] Currently, the methods for resource utilization of waste polishing powder include physical methods and chemical methods. The physical method is to go through processes such as cyclone separation, flotation separation, drying, and pulverization, and then mix and use it with new rare earth polishing powder. However, the service life of the rare earth polishing powder obtained by this method is low. The chemical method for recycling waste polishing powder is mainly divided into sulfation roasting method and selective alkali leaching for impurity removal. Currently, there are few research reports on the recovery of valuable elements from waste lithium-containing polishing powder, and the commonly used recovery method is to roast with additives and then acid-leach to stepwise extract valuable elements. CN118207432A roasts waste polishing powder with a roasting additive and then finely grinds it, adds sulfuric acid solution to leach at a certain liquid-solid ratio, temperature, and time, and then adds a precipitant and crystal seeds to stepwise precipitate lanthanum, aluminum, and lithium from the leaching solution. CN118127350A roasts waste polishing powder with carbonate and then mixes it with crystal seeds, leaches it at low temperature in sulfuric acid-sulfate solution, and the leaching solution produces lithium phosphate products after precipitation and impurity removal.

[0004] The existing recovery technologies for waste lithium-containing polishing powder are mostly roasting-acid leaching methods. This method has high roasting energy consumption and large environmental pollution; and introducing benzoate organic matter to recover aluminum in the form of aluminum slag results in high costs for organic wastewater treatment and aluminum slag landfill. At the same time, the conventional process for removing aluminum in the solution is mostly to adjust the pH with liquid alkali to remove it, resulting in relatively high lithium entrainment loss.

[0005] Therefore, developing a process for recovering valuable metals from waste lithium-containing polishing powder under low-temperature conditions is of great significance for reducing energy consumption, achieving environmental protection, and reducing costs. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a method for extracting valuable metals from waste lithium-containing polishing powder. The method provided by the present invention realizes the effective recycling of valuable metals such as lithium, lanthanum and aluminum in waste lithium-containing polishing powder under low-temperature conditions, with high recovery rates, low energy consumption and costs, simple process flow, no need for complex roasting treatment process, and is suitable for large-scale industrial production.

[0007] To achieve the purpose of this invention, the following technical solutions are adopted:

[0008] In the first aspect, the present invention provides a method for extracting valuable metals from waste lithium-containing polishing powder, and the method includes the following steps:

[0009] (1) Acid-leach the waste lithium-containing polishing powder to obtain an acid-leached residue and an acid-leached solution;

[0010] (2) After adjusting the acid-leached solution to a first pH value, mix the acid-leached solution and a first precipitant, and perform lanthanum precipitation treatment to obtain a post-lanthanum-precipitation solution and a lanthanum-precipitation residue;

[0011] (3) Mix a vanning reagent with the post-lanthanum-precipitation solution, heat and dissolve, and then perform aluminum removal treatment to obtain alum and a first post-aluminum-removal solution;

[0012] (4) Mix the first post-aluminum-removal solution and a pH regulator, and perform impurity removal treatment to obtain a post-impurity-removal solution;

[0013] (5) Perform calcium removal treatment on the post-impurity-removal solution to obtain a lithium-rich solution.

[0014] It should be noted that the low temperature in the present invention refers to a temperature lower than (≤) 80 °C.

[0015] It should be noted that the waste lithium-containing polishing powder in the present invention comes from the polishing process of lithium-containing glass, belongs to lithium-containing rare earth polishing powder, and its main components include lithium, aluminum, cerium dioxide and lanthanum oxyfluoride, and also includes elements such as calcium, magnesium, iron and silicon.

[0016] The method provided by the present invention realizes the basic leaching of valuable metals lithium, aluminum and lanthanum in waste lithium-containing polishing powder under low-temperature conditions through acid leaching treatment, and cerium dioxide and silicon dioxide are retained in the acid-leached residue. Through the precipitation and lanthanum precipitation process, the effective recovery of lanthanum is realized; then the vanning process is used to realize the conversion of aluminum from impurities to finished products and reduce the loss of lithium; after further impurity removal treatment, the high-purity enrichment of lithium is realized. The present invention recycles valuable metals such as lithium, lanthanum and aluminum through step-by-step extraction under low-temperature conditions, with high extraction and recovery efficiency and simple process flow; and there is no need for additional roasting treatment process, low recovery cost, taking into account both environmental protection and economic benefits, realizing the high-value-added green recycling of waste lithium-containing polishing powder, and is suitable for large-scale industrial production.

[0017] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical purpose and beneficial effects of the present invention can be better achieved and realized.

[0018] Preferably, the median particle size D50 of the waste lithium-containing polishing powder in step (1) is ≤74 μm.

[0019] In the present invention, regulating the particle size of the waste lithium-containing polishing powder to D50≤74 μm is more conducive to the full contact and reaction of valuable elements with acid during the subsequent leaching process, and promotes the leaching of valuable elements.

[0020] It should be noted that in the present invention, there is no special limitation on the method for adjusting the particle size of the waste lithium-containing polishing powder. Any conventional method that does not affect the composition of the waste lithium-containing polishing powder and can obtain the required particle size is applicable to the present invention; for example, the waste lithium-containing polishing powder that does not meet the particle size requirements can be dried, crushed and screened to obtain the waste lithium-containing polishing powder with the required particle size.

[0021] Preferably, the acid solution used in the acid leaching treatment in step (1) includes a sulfuric acid solution.

[0022] In the acid leaching process of the present invention, sulfuric acid is preferably used as the acid leaching solution, which can better realize the leaching of valuable metals in the waste lithium-containing polishing powder; at the same time, the solubility differences of different valuable metal sulfates are obvious, and it is more conducive to separating lanthanum and cerium in the form of acid leaching solution and acid leaching residue in the sulfuric acid system.

[0023] Preferably, the concentration of the sulfuric acid solution is 1.25 - 2.5 mol / L, such as 1.25 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L or 2.5 mol / L, etc.

[0024] In the present invention, a sulfuric acid solution with a lower concentration is selected, especially preferably a sulfuric acid solution with a concentration of 1.25 - 2.5 mol / L, which can better extract valuable elements under the condition of low acid consumption.

[0025] Preferably, in step (1), the mass ratio of the acid solution used in the acid leaching treatment to the waste lithium-containing polishing powder is (3 - 6):1, such as 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1 or 6:1, etc.

[0026] In the present invention, the mass ratio of the acid solution used in the acid leaching treatment to the waste lithium-containing polishing powder is (3-6):1, which is more conducive to separating lanthanum and cerium in the form of acid leaching solution and acid leaching residue according to the solubility differences of lanthanum and cerium sulfates at this sulfate concentration.

[0027] Preferably, the leaching temperature of the acid leaching treatment in step (1) is 40-80 °C, such as 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C or 80 °C, etc.

[0028] The present invention can achieve acid leaching treatment at low temperature, reducing energy consumption compared with high-temperature roasting.

[0029] Preferably, the leaching time of the acid leaching treatment is 2-4 h, such as 2 h, 3 h or 4 h, etc.

[0030] Preferably, the first pH value in step (2) is 1-3, such as 1, 1.3, 1.5, 1.8, 2, 2.3, 2.5, 2.4, 2.5, 2.8 or 3, etc.

[0031] In the present invention, the precipitation of rare earth elements is carried out in an acidic environment system, and other valuable elements to be extracted in the acid leaching solution will not be precipitated, improving the rare earth content in the rare earth precipitate; it should also be noted that the method for regulating the pH value of the acid leaching solution in the present invention can be accurately regulated by adding a certain amount of liquid alkali.

[0032] Preferably, in step (2), the mass dosage of the first precipitating agent is 1-1.3 times the theoretical dosage, such as 1 time, 1.1 times, 1.2 times or 1.3 times, etc.

[0033] It should be noted that the theoretical dosage of the first precipitating agent is that the molar ratio of the precipitating agent to lanthanum in the acid leaching solution is 3:2. Based on the theoretical dosage, the mass dosage of the first precipitating agent is regulated, that is, the actual dosage.

[0034] Preferably, the first precipitating agent in step (2) includes any one or a combination of at least two of oxalic acid, sodium hydroxide or sodium phosphate.

[0035] In the present invention, in addition to the above-defined types of the first precipitating agent, conventional precipitating agent types that can achieve the precipitation reaction of rare earth elements in a specific acidic environment are also applicable to the present invention.

[0036] Preferably, the temperature of the lanthanum precipitation treatment in step (2) is 20-60 °C, such as 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C or 60 °C, etc.

[0037] Preferably, the alum-forming reagent in step (3) includes potassium sulfate and / or ammonium sulfate.

[0038] In the present invention, valuable metal aluminum is recovered in the form of alum finished products through the alum crystallization method, reducing the loss of lithium. This process can be achieved without any additional regulation treatment of the post-lanthanum precipitation solution. While improving the extraction recovery rate of aluminum, it also simplifies the extraction and recovery process; furthermore, it reduces the loss of lithium and controls the mass loss of lithium during the aluminum removal process to ≤4%.

[0039] Preferably, the mass dosage of the alum reagent in step (3) is 1 to 1.5 times the theoretical dosage, such as 1 time, 1.1 times, 1.2 times, 1.3 times, 1.4 times, or 1.5 times, etc.

[0040] It should be noted that the theoretical dosage of the alum reagent in the present invention is the molar ratio of the alum reagent to aluminum in the post-lanthanum precipitation solution of 0.5:1; the mass dosage is regulated according to the obtained theoretical dosage, that is, the actual dosage.

[0041] Preferably, the temperature of the aluminum removal treatment in step (3) is 10 to 35 °C, such as 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, or 35 °C, etc.

[0042] In the present invention, preferably, the temperature of the aluminum removal treatment in step (3) is 10 to 35 °C, which is more conducive to increasing the supersaturation of the solution, thereby promoting the precipitation of alum crystals and improving the comprehensive recovery rate of aluminum in alum.

[0043] Preferably, the time of the aluminum removal treatment is 3 to 6 h, such as 3 h, 4 h, 5 h, or 6 h, etc.

[0044] Preferably, the pH regulator in step (4) includes any one or a combination of at least two of liquid alkali, calcium oxide, or calcium hydroxide.

[0045] Preferably, the pH value of the impurity removal treatment in step (4) is 12 to 14, such as 12, 12.3, 12.5, 12.8, 13, 13.5, 13.8, or 14, etc.

[0046] In the present invention, in step (4), the pH regulator is added for impurity removal, so that impurities such as magnesium, silicon, and residual aluminum in the first post-aluminum removal solution are removed in the form of a precipitate with basically no adsorptivity, thereby reducing the entrainment of lithium during the impurity removal process and reducing the loss rate of lithium in this process.

[0047] Preferably, the temperature of the impurity removal treatment in step (4) is 20 to 85 °C, such as 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, or 85 °C, etc.

[0048] Preferably, the method of the calcium removal treatment in step (5) includes the precipitation method, and the precipitant of the precipitation method includes carbonate.

[0049] Furthermore, the carbonate includes sodium carbonate and / or potassium carbonate, etc.

[0050] Preferably, the lithium-rich solution in step (5) is subjected to lithium precipitation treatment to obtain a lithium salt.

[0051] The present invention is also applicable to the type of effectively extracting valuable element lithium through simple lithium precipitation treatment in the lithium-rich solution after calcium removal; for example, lithium phosphate is obtained through phosphate precipitation; or the lithium-rich solution is subjected to carbonation treatment to obtain battery-grade lithium carbonate.

[0052] As a preferred technical solution, the method includes the following steps:

[0053] (1) The waste lithium-containing polishing powder with a median particle size D50 ≤ 74 μm is subjected to acid leaching treatment with a sulfuric acid solution having a concentration of 1.25 - 2.5 mol / L, the leaching temperature is 40 - 80 °C, and the leaching time is 2 - 4 h to obtain an acid leaching residue and an acid leaching solution;

[0054] (2) The acid leaching solution is adjusted to a first pH value of 1 - 3, the acid leaching solution and a first precipitant are mixed, and the mass dosage of the first precipitant is 1 - 1.3 times the theoretical dosage, and lanthanum precipitation treatment is carried out at 20 - 60 °C to obtain a post-lanthanum precipitation solution and a lanthanum precipitation residue;

[0055] (3) A vanadium reagent is mixed with the post-lanthanum precipitation solution, and after heating and dissolving, aluminum removal treatment is carried out at a temperature of 10 - 35 °C for 3 - 6 h to obtain alum and a first post-aluminum removal solution;

[0056] (4) The first post-aluminum removal solution and a pH regulator are mixed, and impurity removal treatment is carried out at a temperature of 20 - 85 °C under the condition that the pH value is 12 - 14 to obtain a post-impurity removal solution;

[0057] (5) The post-impurity removal solution is subjected to calcium removal treatment by carbonate precipitation method, the carbonate includes sodium carbonate and / or potassium carbonate, to obtain a lithium-rich solution, and the lithium-rich solution is subjected to lithium precipitation treatment to obtain a lithium salt.

[0058] The numerical ranges described in the present invention not only include the point values exemplified above, but also any point values between the above numerical ranges not exemplified. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the ranges.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] The method provided by the present invention realizes the basic leaching of valuable metals lithium, aluminum, and lanthanum in waste lithium-containing polishing powder under low-temperature conditions through acid leaching treatment. Cerium dioxide and silicon dioxide are retained in the acid leaching residue. Through the precipitation and lanthanum precipitation process, the effective recovery of lanthanum is realized; then, the conversion of aluminum from impurities to finished products is realized by using the alum process, and the loss of lithium is reduced; after further impurity removal treatment, the high-purity enrichment of lithium is realized. The present invention recovers and utilizes valuable metals such as lithium, lanthanum, and aluminum through stepwise extraction under low-temperature conditions, with high extraction and recovery efficiency and a simple process flow; moreover, no additional roasting treatment process is required, the recovery cost is low, both environmental protection and economic benefits are taken into account, and the high-value green recovery and utilization of waste lithium-containing polishing powder are realized, which is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 Process flow chart of the method for extracting valuable metals from waste lithium-containing polishing powder provided in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0062] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusion.

[0064] In the description of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order, or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality of" means more than two unless otherwise specifically defined.

[0065] In a specific embodiment, the present invention provides a waste lithium-containing polishing powder, and the specific components and mass contents of the waste polishing powder are as follows: Ce: 32.82%, La: 17.32%, Al: 9.70%, Li: 0.79%, Si: 1.82%.

[0066] The following examples and comparative examples all use the waste lithium-containing polishing powder provided in the above specific embodiment to extract valuable elements.

[0067] Example 1

[0068] This embodiment provides a method for extracting valuable metals from waste lithium-containing polishing powder at low temperature, such as Figure 1 shown below:

[0069] (1) The waste lithium-containing polishing powder is dried, crushed and sieved to obtain waste lithium-containing polishing powder with a particle size D50 below 74 μm; 2 mol / L dilute sulfuric acid is mixed with the waste lithium-containing polishing powder with a particle size below 74 μm in a liquid-solid mass ratio of 5:1 for pulping, and acid leaching is carried out at 50 °C for 4 h to obtain acid leaching residue and acid leaching solution;

[0070] (2) After adjusting the acid leaching solution to a first pH value of 1.5 with liquid caustic soda, the first precipitant oxalic acid and the acid leaching solution are mixed. The actual added mass of oxalic acid is 1.2 times the theoretical dosage, and then lanthanum precipitation treatment is carried out at 60 °C, followed by solid-liquid separation to obtain the solution after lanthanum precipitation and lanthanum precipitation residue;

[0071] (3) Ammonium sulfate as the alum-forming agent and the solution after lanthanum precipitation are mixed. The actual added mass of the alum-forming agent is 1.3 times the theoretical dosage. After heating and dissolving, aluminum removal treatment is carried out at 10 °C for 4 h, followed by solid-liquid separation to obtain alum and the first solution after aluminum removal;

[0072] (4) The first solution after aluminum removal is mixed with the pH regulator calcium hydroxide and adjusted to pH 13 for impurity removal treatment at 40 °C to obtain the solution after impurity removal;

[0073] (5) The solution after impurity removal is mixed with sodium carbonate for calcium removal to obtain a lithium-rich solution, and the lithium-rich solution is subjected to carbonation lithium precipitation to obtain lithium carbonate.

[0074] Example 2

[0075] This embodiment provides a method for extracting valuable metals from waste lithium-containing polishing powder at low temperature. The method is as follows:

[0076] (1) The waste lithium-containing polishing powder is dried, crushed and sieved to obtain waste lithium-containing polishing powder with a particle size D50 below 74 μm; 2.25 mol / L dilute sulfuric acid is mixed with the waste lithium-containing polishing powder with a particle size D50 below 74 μm in a liquid-solid mass ratio of 4:1 for pulping, and acid leaching is carried out at 60 °C for 4 h to obtain acid leaching residue and acid leaching solution;

[0077] (2) After adjusting the acid leaching solution to a first pH value of 1.2 with liquid caustic soda, the first precipitant oxalic acid and the acid leaching solution are mixed. The actual added mass of oxalic acid is 1.1 times the theoretical dosage, and then lanthanum precipitation treatment is carried out at 60 °C, followed by solid-liquid separation to obtain the solution after lanthanum precipitation and lanthanum precipitation residue;

[0078] (3) Mix the alum-making agent ammonium sulfate and the solution after lanthanum precipitation. The actual added mass of the alum-making agent is 1.4 times the theoretical dosage. After heating and dissolving, perform aluminum removal treatment at 30 °C for 4 h, then carry out solid-liquid separation to obtain alum and the first solution after aluminum removal;

[0079] (4) Mix the first solution after aluminum removal with the pH regulator calcium hydroxide and adjust the pH to 12 for impurity removal treatment at 40 °C to obtain the solution after impurity removal;

[0080] (5) Mix the solution after impurity removal with sodium carbonate for calcium removal to obtain a lithium-rich solution, and carry out carbonation lithium precipitation on the lithium-rich solution to obtain lithium carbonate.

[0081] Example 3

[0082] This example provides a method for low-temperature extraction of valuable metals from waste lithium-containing polishing powder. The method is as follows:

[0083] (1) Dry, crush and screen the waste lithium-containing polishing powder to obtain waste lithium-containing polishing powder with a particle size D50 lower than 74 μm; Mix 1.8 mol / L dilute sulfuric acid and waste lithium-containing polishing powder with a particle size lower than 74 μm in a liquid-solid mass ratio of 6:1 for pulping, and carry out acid leaching at 40 °C for 3 h to obtain acid leaching residue and acid leaching solution;

[0084] (2) After adjusting the acid leaching solution to the first pH value of 1.8 with liquid caustic soda, mix the first precipitant oxalic acid and the acid leaching solution. The actual added mass of oxalic acid is 1.2 times the theoretical dosage, carry out lanthanum precipitation treatment at 30 °C, and carry out solid-liquid separation to obtain the solution after lanthanum precipitation and lanthanum precipitation residue;

[0085] (3) Mix the alum-making agent ammonium sulfate and the solution after lanthanum precipitation. The actual added mass of the alum-making agent is 1.2 times the theoretical dosage. After heating and dissolving, perform aluminum removal treatment at 35 °C for 6 h, then carry out solid-liquid separation to obtain alum and the first solution after aluminum removal;

[0086] (4) Mix the first solution after aluminum removal with the pH regulator calcium oxide and adjust the pH to 12.5 for impurity removal treatment at 65 °C to obtain the solution after impurity removal;

[0087] (5) Mix the solution after impurity removal with sodium carbonate for calcium removal to obtain a lithium-rich solution, and carry out carbonation lithium precipitation on the lithium-rich solution to obtain lithium carbonate.

[0088] Example 4

[0089] This example provides a method for low-temperature extraction of valuable metals from waste lithium-containing polishing powder. The method is as follows:

[0090] (1) The waste lithium-containing polishing powder is dried, crushed and screened to obtain waste lithium-containing polishing powder with a particle size D50 below 74 μm; 2.5 mol / L dilute sulfuric acid is mixed with the waste lithium-containing polishing powder with a particle size below 74 μm in a liquid-solid mass ratio of 4:1 for pulping, and acid leaching is carried out at 50 °C for 2 h to obtain acid leaching residue and acid leaching solution;

[0091] (2) After adjusting the acid leaching solution to a first pH value of 1.5 with liquid caustic soda, the first precipitant oxalic acid and the acid leaching solution are mixed. The actual added mass of oxalic acid is 1.2 times the theoretical dosage, and then lanthanum precipitation treatment is carried out at 60 °C. After solid-liquid separation, the solution after lanthanum precipitation and lanthanum precipitation residue are obtained;

[0092] (3) The alum-making agent ammonium sulfate and the solution after lanthanum precipitation are mixed. The actual added mass of the alum-making agent is 1.3 times the theoretical dosage. After heating and dissolving, aluminum removal treatment is carried out at 30 °C for 4 h. After solid-liquid separation, alum and the first aluminum-removed solution are obtained;

[0093] (4) The first aluminum-removed solution is mixed with the pH regulator calcium hydroxide and adjusted to pH 13 for impurity removal treatment at 40 °C to obtain the solution after impurity removal;

[0094] (5) The solution after impurity removal is mixed with sodium carbonate for calcium removal to obtain a lithium-rich solution, and the lithium-rich solution is subjected to carbonation lithium precipitation to obtain lithium carbonate.

[0095] Example 5

[0096] This example provides a method for low-temperature extraction of valuable metals from waste lithium-containing polishing powder. The method is as follows:

[0097] (1) The waste lithium-containing polishing powder is dried, crushed and screened to obtain waste lithium-containing polishing powder with a particle size D50 below 74 μm; 1.25 mol / L dilute sulfuric acid is mixed with the waste lithium-containing polishing powder with a particle size below 74 μm in a liquid-solid mass ratio of 6:1 for pulping, and acid leaching is carried out at 50 °C for 4 h to obtain acid leaching residue and acid leaching solution;

[0098] (2) After adjusting the acid leaching solution to a first pH value of 3 with liquid caustic soda, the first precipitant oxalic acid and the acid leaching solution are mixed. The actual added mass of oxalic acid is 1.3 times the theoretical dosage, and then lanthanum precipitation treatment is carried out at 60 °C. After solid-liquid separation, the solution after lanthanum precipitation and lanthanum precipitation residue are obtained;

[0099] (3) The alum-making agent ammonium sulfate and the solution after lanthanum precipitation are mixed. The actual added mass of the alum-making agent is 1 times the theoretical dosage. After heating and dissolving, aluminum removal treatment is carried out at 15 °C for 3 h. After solid-liquid separation, alum and the first aluminum-removed solution are obtained;

[0100] (4) The first aluminum-removed solution is mixed with the pH regulator calcium hydroxide and adjusted to pH 14 for impurity removal treatment at 40 °C to obtain the solution after impurity removal;

[0101] (5) The post - mixing impurity - removing solution is subjected to calcium removal with sodium carbonate to obtain a lithium - rich solution, and the lithium - rich solution is subjected to lithium precipitation by carbonation to obtain lithium carbonate.

[0102] Example 6

[0103] The difference between this example and Example 1 is that in step (1) of this example, the concentration of the dilute sulfuric acid solution is 0.9 mol / L.

[0104] The remaining extraction methods and parameters are the same as those in Example 1.

[0105] Example 7

[0106] The difference between this example and Example 1 is that in step (1) of this example, the concentration of the dilute sulfuric acid solution is 3 mol / L.

[0107] The remaining extraction methods and parameters are the same as those in Example 1.

[0108] Example 8

[0109] The difference between this example and Example 1 is that in step (1) of this example, the particle size D50 of the waste lithium - containing polishing powder is > 74 μm, that is, the waste lithium - containing polishing powder is directly subjected to acid leaching treatment without drying, crushing and sieving.

[0110] The remaining extraction methods and parameters are the same as those in Example 1.

[0111] Example 9

[0112] The difference between this example and Example 1 is that in step (1) of this example, the leaching temperature for acid leaching treatment is room temperature 25 °C.

[0113] The remaining extraction methods and parameters are the same as those in Example 1.

[0114] Example 10

[0115] The difference between this example and Example 1 is that in step (1) of this example, the leaching temperature for acid leaching treatment is 95 °C.

[0116] The remaining extraction methods and parameters are the same as those in Example 1.

[0117] Example 11

[0118] The difference between this example and Example 1 is that in step (2) of this example, the first pH value is 0.8.

[0119] The remaining extraction methods and parameters are the same as those in Example 1.

[0120] Example 12

[0121] The difference between this example and Example 1 is that the pH value in step (2) of this example is 4.

[0122] The remaining extraction methods and parameters are the same as those in Example 1.

[0123] Example 13

[0124] The difference between this example and Example 1 is that the temperature of the aluminum removal treatment in step (3) of this example is 45 °C.

[0125] The remaining extraction methods and parameters are the same as those in Example 1.

[0126] Example 14

[0127] The difference between this example and Example 1 is that the pH value in step (4) of this example is adjusted to 8.5.

[0128] The remaining extraction methods and parameters are the same as those in Example 1.

[0129] Comparative Example 1

[0130] The difference between this example and Example 1 is that the acid used in step (1) of this example is dilute hydrochloric acid instead of dilute sulfuric acid.

[0131] The remaining extraction methods and parameters are the same as those in Example 1.

[0132] Comparative Example 2

[0133] The difference between this comparative example and Example 1 is that after adjusting the pH value to 4 with liquid caustic soda in step (3) of this comparative example, the reaction is carried out at room temperature of 25 °C for 4 h to directly remove aluminum.

[0134] The remaining extraction methods and parameters are the same as those in Example 1.

[0135] The lithium leaching rate (step (1)), lanthanum leaching rate, cerium leaching rate, lanthanum precipitation rate, comprehensive aluminum recovery rate, comprehensive lithium recovery rate, and main content of alum in the methods provided in Examples 1-14 and Comparative Example 1 were measured (the element content was detected by ICP-OES after sample dissolution, and the main amount of aluminum alum was detected by lead nitrate back titration method). The obtained results are shown in Table 1.

[0136] Table 1

[0137]

[0138]

[0139] In summary, the method provided by the present invention realizes the basic leaching of valuable metals lithium, aluminum and lanthanum in waste lithium-containing polishing powder under low temperature conditions through acid leaching treatment, and cerium dioxide and silicon dioxide are retained in the acid leaching residue. After the precipitation and precipitation of lanthanum, the effective recovery of lanthanum is achieved; then the alum formation process is used to realize the conversion of aluminum from impurities to finished products, and the loss of lithium is reduced; and after further impurity removal treatment, high-purity enrichment of lithium is achieved. The present invention recycles valuable metals such as lithium, lanthanum and aluminum through step-by-step extraction under low temperature conditions, with high extraction and recovery efficiency and simple process flow; and no additional roasting process is required, the recovery cost is low, and environmental protection and economic benefits are taken into account, and high-value-added green recycling of waste lithium-containing polishing powder is achieved, which is suitable for large-scale industrial production.

[0140] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for extracting valuable metals from waste lithium-containing polishing powder, characterized in that, The method comprises the following steps: (1) Acid-leach the waste lithium-containing polishing powder to obtain an acid-leached residue and an acid-leached solution; (2) After adjusting the acid-leached solution to a first pH value, mix the acid-leached solution and a first precipitant, and perform lanthanum precipitation treatment to obtain a post-lanthanum-precipitation solution and a lanthanum-precipitation residue; (3) Mix a vanning reagent with the post-lanthanum-precipitation solution, dissolve it by heating, and then perform aluminum removal treatment to obtain alum and a first post-aluminum-removal solution; (4) Mix the first post-aluminum-removal solution and a pH regulator, and perform impurity removal treatment to obtain a post-impurity-removal solution; (5) Perform calcium removal treatment on the post-impurity-removal solution to obtain a lithium-rich solution.

2. The method for extracting valuable metals from waste lithium-containing polishing powder according to claim 1, wherein In step (1), the median particle size D50 of the waste lithium-containing polishing powder is ≤74 μm.

3. The method for extracting valuable metals from waste lithium-containing polishing powder according to claim 1, characterized in that, In step (1), the acid solution used for the acid-leaching treatment includes a sulfuric acid solution, and the concentration of the sulfuric acid solution is 1.25 - 2.5 mol / L.

4. The method for extracting valuable metals from waste lithium-containing polishing powder according to claim 1, characterized in that, In step (1), the mass ratio of the acid solution used for the acid-leaching treatment to the waste lithium-containing polishing powder is (3 - 6):1; Preferably, in step (1), the leaching temperature of the acid-leaching treatment is 40 - 80°C, and the leaching time of the acid-leaching treatment is 2 - 4 h.

5. The method for extracting valuable metals from waste lithium-containing polishing powder according to claim 1 or 3, characterized in that, The first pH value in step (2) is 1 - 3; Preferably, in step (2), the mass dosage of the first precipitant is 1 - 1.3 times the theoretical dosage; Preferably, in step (2), the temperature of the lanthanum precipitation treatment is 20 - 60°C.

6. The method for extracting valuable metals from waste lithium-containing polishing powder according to claim 1 or 3, characterized in that, The vanning reagent in step (3) includes potassium sulfate and / or ammonium sulfate; Preferably, in step (3), the mass dosage of the vanning reagent is 1 - 1.5 times the theoretical dosage; Preferably, in step (3), the temperature of the aluminum removal treatment is 10 - 35°C, and the time of the aluminum removal treatment is 3 - 6 h.

7. The method for extracting valuable metals from waste lithium-containing polishing powder according to claim 1 or 3, characterized in that, The pH regulator in step (4) includes any one or a combination of at least two of liquid alkali, calcium oxide, or calcium hydroxide; Preferably, in step (4), the pH value of the impurity removal treatment is 12 - 14; Preferably, in step (4), the temperature of the impurity removal treatment is 20 - 85°C.

8. The method for extracting valuable metals from waste lithium-containing polishing powder according to claim 1, wherein The calcium removal treatment method in step (5) includes a precipitation method, and the precipitant of the precipitation method includes carbonate.

9. The method for extracting valuable metals from waste lithium-containing polishing powder according to claim 1, characterized in that, Perform lithium precipitation treatment on the lithium-rich solution in step (5) to obtain a lithium salt.

10. The method for extracting valuable metals from waste lithium-containing polishing powder according to claim 1, characterized in that, The method comprises the following steps: (1) Acid-leach the waste lithium-containing polishing powder with a median particle size D50 ≤74 μm using a sulfuric acid solution with a concentration of 1.25 - 2.5 mol / L, with a leaching temperature of 40 - 80°C and a leaching time of 2 - 4 h to obtain an acid-leached residue and an acid-leached solution; (2) Adjust the acid-leached solution to a first pH value of 1 - 3, mix the acid-leached solution and a first precipitant, the mass dosage of the first precipitant is 1 - 1.3 times the theoretical dosage, and perform lanthanum precipitation treatment at 20 - 60°C to obtain a post-lanthanum-precipitation solution and a lanthanum-precipitation residue; (3) Mix a vanning reagent with the post-lanthanum-precipitation solution, dissolve it by heating, and then perform aluminum removal treatment at a temperature of 10 - 35°C for 3 - 6 h to obtain alum and a first post-aluminum-removal solution; (4) Mix the first post-aluminum-removal solution and a pH regulator, and perform impurity removal treatment at a temperature of 20 - 85°C under the condition that the pH value is 12 - 14 to obtain a post-impurity-removal solution; (5) The post-impurity removal solution is subjected to calcium removal treatment by carbonate precipitation method. The carbonate includes sodium carbonate and / or potassium carbonate to obtain a lithium-rich solution, and the lithium-rich solution is subjected to lithium precipitation treatment to obtain a lithium salt.

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