Method for preparing lithium carbonate by recycling lithium through synergistic treatment of lithium-containing waste

Abstract

The invention belongs to the technical field of lithium-containing waste treatment, and particularly discloses a method for preparing lithium carbonate by recycling lithium through cooperative treatment of lithium-containing waste. The method specifically comprises the following steps: mixing a lithium amide waste material, a lithium sulfide waste material and water, then mixing with a hydrogen peroxide solution and a sulfuric acid solution, and carrying out an acid dissolution reaction to obtain a lithium-containing acid solution and an insoluble substance; mixing the lithium-containing acid solution with alkali liquor, and carrying out alkalization reaction to obtain insoluble impurities and alkalized feed liquid; concentrating the alkalized feed liquid to obtain concentrated alkalized feed liquid, and mixing the concentrated alkalized feed liquid with a sodium carbonate solution for lithium precipitation reaction to obtain lithium precipitation mother liquor and lithium carbonate; extracting the lithium element in the lithium precipitation mother liquor, and evaporating and concentrating the raffinate to separate out sodium sulfate and ammonium sulfate; ammonium sulfate and the lithium iron phosphate waste are mixed and then sequentially subjected to roasting and leaching, and a leaching solution and a lithium-containing acid solution are mixed for alkalization. The method has the characteristics of high process integration level, high economic value and less environmental pollution, and conforms to the new concept of chemical green atom economy.

Description

Technical Field

[0001] The invention relates to the technical field of lithium-containing waste treatment, and in particular to a method for preparing lithium carbonate by co-processing lithium-containing waste to recover lithium. Background Art

[0002] Solid electrolytes are the core components of solid-state lithium-ion batteries. Sulfide electrolytes have attracted much attention from industry insiders due to their excellent electrical conductivity, high energy density, and long cycle life, and are considered to be the most promising type of solid electrolytes. Lithium sulfide is the core material for synthesizing sulfide electrolytes. Currently, the main preparation methods for lithium sulfide include mechanical ball milling, high-temperature reduction, and solvent methods. Waste is inevitably generated during the production process of lithium sulfide, so lithium sulfide waste recycling technology is particularly important.

[0003] Lithium amide has the appearance of white glossy crystals or powder, melting point of 390℃, density of 1.78g / cm 3 , insoluble in kerosene, soluble in liquid ammonia, soluble in cold water and strongly hydrolyzed in hot water. Lithium amide is mainly used in organic synthesis and drug manufacturing. It is a good hydrogen storage material together with lithium hydride and lithium imide. Lithium amide can be used as a condensation promoter, reducing agent, dehydrating agent, drying agent, dehalogenating agent, alkylating agent, and aminolysis reactant in organic synthesis. It is also used as an initiator for anionic polymerization of vinyl compounds, and can also be used to manufacture azide compounds and cyanides. In the pharmaceutical industry, it is used as a synthesis catalyst for vitamin A, vitamin D3 and anti-AIDS drugs, and as an efficient catalyst for the alkylation of nitriles and ketones in the production of antioxidants 1010 and 1076. Based on the wide application of lithium amide, many companies have built corresponding production lines, but the subsequent lithium amide will produce a large amount of lithium amide waste due to the difficulty in accurately controlling the calcination temperature in the actual production process, so the reprocessing of lithium amide waste is also worthy of attention.

[0004] With the continuous development of the market, more and more companies are entering the lithium iron phosphate battery industry, and market competition is becoming increasingly fierce. As the use time of new energy vehicles increases, the number of retired lithium iron phosphate batteries will face explosive growth. Retired lithium iron phosphate batteries will become an important urban mineral, so the recycling of lithium iron phosphate waste is imminent.

[0005] Based on this, it is particularly important to disclose a treatment method for synergistically treating lithium amide, lithium sulfide and lithium iron phosphate wastes and recovering the lithium and valuable elements therein. Summary of the invention

[0006] In view of this, the present invention provides a method for preparing lithium carbonate by co-processing lithium-containing waste to recover lithium, so as to solve the problem that there is no solution for co-processing lithium amide, lithium sulfide and lithium iron phosphate waste in the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for preparing lithium carbonate by co-processing lithium-containing waste materials to recover lithium comprises the following steps:

[0009] 1) mixing lithium amide waste and lithium sulfide waste with water to obtain a waste mixed solution, then mixing the waste mixed solution with a hydrogen peroxide solution and a sulfuric acid solution to obtain an acid-soluble mixed solution, performing an acid-soluble reaction, and obtaining a lithium-containing acid solution and insoluble matter after solid-liquid separation;

[0010] 2) mixing the lithium acid solution with an alkali solution to carry out an alkalization reaction, and after the reaction is completed, separating the solid and the liquid to obtain insoluble impurities and an alkalized feed solution;

[0011] 3) concentrating the alkalized feed liquid to obtain a concentrated alkalized feed liquid, mixing the concentrated alkalized feed liquid with a sodium carbonate solution to carry out a lithium precipitation reaction, and after the reaction is completed, solid-liquid separation is performed to obtain a lithium precipitation mother liquor and lithium carbonate;

[0012] 4) extracting lithium from the lithium precipitation mother liquor, stripping the extract with sulfuric acid to obtain lithium sulfate, evaporating and concentrating the raffinate, and precipitating sodium sulfate and ammonium sulfate in steps;

[0013] 5) The ammonium sulfate and lithium iron phosphate waste are mixed, and then roasted and leached in sequence to obtain a leachate, which is mixed with the lithium acid solution in step 2) to perform an alkalization reaction.

[0014] Preferably, the mass ratio of the lithium amide waste, lithium sulfide waste, water, hydrogen peroxide solution and sulfuric acid solution in step 1) is 45-55:45-55:600-1000:80-120:280-320;

[0015] The mass concentration of the hydrogen peroxide solution is 30-60%;

[0016] The mass concentration of the sulfuric acid solution is 80-98%.

[0017] Preferably, the acid dissolution reaction time in step 1) is 0.5 to 2 hours.

[0018] Preferably, the pH value of the system of the alkalization reaction in step 2) is 10 to 12;

[0019] The alkali solution includes sodium hydroxide solution;

[0020] The mass concentration of the alkali solution is 30-35%.

[0021] Preferably, the alkalization reaction time in step 2) is 0.5 to 1 h.

[0022] Preferably, the mass concentration of Li in the concentrated alkalized liquid in step 3) is 15-25 g / L;

[0023] In step 3), the molar ratio of Li in the concentrated alkalized liquid to sodium carbonate in the sodium carbonate solution is 1.8 to 2.2:1;

[0024] The mass concentration of the sodium carbonate solution is 200-250 g / L.

[0025] Preferably, the lithium precipitation reaction time in step 3) is 0.5 to 1 h, and the lithium precipitation reaction temperature is 80 to 95°C.

[0026] Preferably, the extractant in step 4) comprises an oil phase and an aqueous phase, and the volume ratio of the oil phase to the aqueous phase is 0.8 to 1.5:1; the oil phase comprises a Li alkaline extractant and a diluent, and the volume ratio of the Li alkaline extractant to the diluent is 0.8 to 1.2:1; the diluent comprises sulfonated kerosene;

[0027] The number of stages of extraction in step 4) is 3.

[0028] Preferably, in step 5), the mass ratio of ammonium sulfate to lithium iron phosphate waste is 0.6 to 1:1.

[0029] Preferably, the calcination temperature in step 5) is 250-350°C, the calcination time is 10-15 min, the liquid-solid mass ratio of the leaching is 2-4:1, and the leaching temperature is 40-60°C.

[0030] It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following beneficial effects:

[0031] Compared with the prior art, the present invention utilizes three kinds of lithium-containing waste materials to synergistically process and recover lithium to prepare lithium carbonate. Lithium sulfide and lithium amide waste materials are synergistically acid-dissolved to generate lithium sulfate and ammonium sulfate at the same time. Ammonium sulfate is used as a roasting aid for lithium iron phosphate waste materials. After roasting and leaching, lithium in the lithium iron phosphate waste materials is extracted. Alkalinization and impurity removal are then completed at the same time. The target product, lithium carbonate, is obtained by lithium precipitation process.

[0032] The specific reaction equation is: 2LiNH2(s)+Li2S(s)+H2O2(aq)+3H2SO4(aq)=2Li2SO4(aq)+(NH4)2SO4(aq)+S(s)+2H2O(aq)

[0033] 2LiFePO4(s)+0.5O2(g)+(NH4)2SO4(s)=2Li2SO4(s)+2FePO4(s)+2NH3(g)+H2O(g)

[0034] Li2SO4(aq)+Na2CO3(aq)=Li2CO3(s)+Na2SO4(aq)

[0035] The present invention uses lithium sulfide waste, lithium amide waste and lithium iron phosphate waste as raw materials, and utilizes lithium amide and lithium sulfide to generate lithium sulfate and ammonium sulfate in sulfuric acid solution. The lithium sulfate is used to produce industrial-grade lithium carbonate, and the ammonium sulfate is used to roast lithium iron phosphate waste to generate lithium sulfate solution, thereby realizing the process of coordinating the three wastes and producing lithium carbonate at the same time. It has the characteristics of high process integration, small construction area, high economic value, no waste acid generation in the whole process, and less environmental pollution, avoiding single waste treatment, high comprehensive resource utilization rate, and conforming to the new concept of chemical green atomic economy. DETAILED DESCRIPTION

[0036] The present invention provides a method for preparing lithium carbonate by co-processing lithium-containing waste materials to recover lithium, comprising the following steps:

[0037] 1) mixing lithium amide waste and lithium sulfide waste with water to obtain a waste mixed solution, then mixing the waste mixed solution with a hydrogen peroxide solution and a sulfuric acid solution to obtain an acid-soluble mixed solution, performing an acid-soluble reaction, and obtaining a lithium-containing acid solution and insoluble matter after solid-liquid separation;

[0038] 2) mixing the lithium acid solution with an alkali solution to carry out an alkalization reaction, and after the reaction is completed, separating the solid and the liquid to obtain insoluble impurities and an alkalized feed solution;

[0039] 3) concentrating the alkalized feed liquid to obtain a concentrated alkalized feed liquid, mixing the concentrated alkalized feed liquid with a sodium carbonate solution to carry out a lithium precipitation reaction, and after the reaction is completed, solid-liquid separation is performed to obtain a lithium precipitation mother liquor and lithium carbonate;

[0040] 4) extracting lithium from the lithium precipitation mother liquor, stripping the extract with sulfuric acid to obtain lithium sulfate, evaporating and concentrating the raffinate, and precipitating sodium sulfate and ammonium sulfate in steps;

[0041] 5) The ammonium sulfate and lithium iron phosphate waste are mixed, and then roasted and leached in sequence to obtain a leachate, which is mixed with the lithium acid solution in step 2) to perform an alkalization reaction.

[0042] In the present invention, the mass ratio of the lithium amide waste, lithium sulfide waste, water, hydrogen peroxide solution and sulfuric acid solution in step 1) is 45-55:45-55:600-1000:80-120:280-320, preferably 48-52:48-52:700-900:90-110:290-310, and more preferably 50:50:800:100:300.

[0043] In the present invention, the mass concentration of the hydrogen peroxide solution is 30-60%, specifically 35%, 40%, 45%, 50%, 55%.

[0044] In the present invention, the mass concentration of the sulfuric acid solution is 80-98%, specifically 82%, 84%, 85%, 86%, 88%, 90%, 92%, 95%, 96%.

[0045] In the present invention, the time of the acid dissolution reaction in step 1) is 0.5 to 2 hours, specifically 0.6 hours, 0.8 hours, 1 hour, 1.2 hours, 1.5 hours, or 1.8 hours.

[0046] In the present invention, the pH value of the system of the alkalization reaction in step 2) is 10-12, specifically 10, 10.5, 11, 11.5, 12.

[0047] In the present invention, the alkali solution includes sodium hydroxide solution.

[0048] In the present invention, the mass concentration of the alkali solution is 30-35%, specifically 31%, 32%, 33%, 34%.

[0049] In the present invention, the time of the alkalization reaction in step 2) is 0.5 to 1 h, specifically 0.6 h, 0.7 h, 0.8 h, or 0.9 h.

[0050] In the present invention, the mass concentration of Li in the concentrated alkalized liquid in step 3) is 15-25 g / L, specifically 16 g / L, 18 g / L, 20 g / L, 22 g / L, or 24 g / L.

[0051] In the present invention, the molar ratio of Li in the concentrated alkalized liquid to sodium carbonate in the sodium carbonate solution in step 3) is 1.8 to 2.2:1, preferably 1.9 to 2.1:1, and more preferably 2:1.

[0052] In the present invention, the mass concentration of the sodium carbonate solution is 200-250 g / L, specifically 210 g / L, 220 g / L, 230 g / L, and 240 g / L.

[0053] In the present invention, the time of the lithium precipitation reaction in step 3) is 0.5-1h, specifically 0.6h, 0.7h, 0.8h, 0.9h; the temperature of the lithium precipitation reaction is 80-95°C, specifically 82°C, 84°C, 85°C, 86°C, 88°C, 90°C, 92°C, 94°C.

[0054] In the present invention, the extractant in step 4) comprises an oil phase and an aqueous phase, and the volume ratio of the oil phase to the aqueous phase is 0.8 to 1.5:1, preferably 0.9 to 1.2:1, and more preferably 1:1; the oil phase comprises a Li alkaline extractant and a diluent, and the volume ratio of the Li alkaline extractant to the diluent is 0.8 to 1.2:1, preferably 0.9 to 1.1:1, and more preferably 1:1; the diluent comprises sulfonated kerosene.

[0055] In the present invention, the number of extraction stages in step 4) is 3.

[0056] In the present invention, the raffinate in step 4) is evaporated and concentrated preferably to a Baume degree of 38°Bé, sodium sulfate is precipitated at 80-90°C, and ammonium sulfate is precipitated at 50-60°C.

[0057] In the present invention, the temperature for precipitating sodium sulfate can be specifically 82°C, 84°C, 85°C, 86°C, or 88°C, and the temperature for precipitating ammonium sulfate can be specifically 52°C, 54°C, 55°C, 56°C, or 58°C.

[0058] In the present invention, in step 5), the mass ratio of ammonium sulfate to lithium iron phosphate waste is 0.6-1:1, preferably 0.7-0.9:1, and more preferably 0.8:1.

[0059] In the present invention, the roasting temperature in step 5) is 250-350°C, specifically 260°C, 280°C, 300°C, 320°C, and 340°C; the roasting time is 10-15min, specifically 11min, 12min, 13min, and 14min; the liquid-to-solid mass ratio of the leaching is 2-4:1, preferably 2.5-3.5:1, and more preferably 3:1; the leaching temperature is 40-60°C, specifically 42°C, 45°C, 48°C, 50°C, 52°C, 55°C, and 58°C.

[0060] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] Example 1

[0062] Step A: Acid dissolution of lithium amide and lithium sulfide waste materials. At room temperature, 50 g of lithium amide waste and 50 g of lithium sulfide waste are added to a reaction container, and 800 g of deionized water is added while stirring. At the same time, 300 g of H2SO4 solution with a mass concentration of 98% and 100 g of H2O2 solution with a mass concentration of 50% are added. After reacting for 1 hour, a lithium-containing acidified slurry is obtained and solid-liquid separation is performed to obtain a lithium-containing acid solution and a sulfur element precipitate. The sulfur element can be further purified and refined into sulfur.

[0063] Step B: Alkalization: adjust the pH of the lithium acid solution obtained in step A to 12 with a sodium hydroxide solution having a mass concentration of 32%, stir the reaction for 1 hour, and filter it with a sand core funnel with a pore size of 2 μm to obtain insoluble impurities (mainly iron hydroxide after the lithium iron phosphate leachate is returned) and an alkalized feed solution.

[0064] Step C: lithium precipitation. The alkaline and impurity-removing solution obtained in step B is concentrated to a Li mass concentration of 20 g / L. A sodium carbonate solution with a mass concentration of 230 g / L is added at 95°C (the molar ratio of Li in the concentrated alkaline solution to sodium carbonate in the sodium carbonate solution is 1.95:1). The reaction is stirred for 1 hour. The lithium precipitation mother liquor and crude lithium carbonate are obtained by filtration. The crude lithium carbonate is filtered, rinsed and dried to obtain 278 g of industrial-grade lithium carbonate (including the conversion amount of the raw material lithium iron phosphate), with a main content of 99.1%.

[0065] Step D: Extraction: Li extraction is performed on the lithium precipitation mother liquor obtained in step C, the volume ratio of the extractant oil phase to the water phase is 1:1, the oil phase includes HB121 alkaline extractant and sulfonated kerosene in a volume ratio of 1:1, and the lithium extraction rate is 99.5% after three-stage countercurrent extraction at room temperature. The raffinate is evaporated and concentrated, and when the raffinate is evaporated to a Baume degree of 38°Bé, 435g of sodium sulfate is thermally precipitated at 85°C, and 327g of ammonium sulfate is precipitated at 55°C.

[0066] Step E: calcination, calcining 327g of ammonium sulfate and 409g of lithium iron phosphate waste obtained in step D, i.e., the mass ratio of ammonium sulfate to lithium iron phosphate waste is 0.8:1, at 300°C for 10min, cooling after calcination, leaching with 3 times the mass of water at 50°C, obtaining 1150g of leachate, circulating to step B for lithium precipitation for standby use, and repeating the above operation.

[0067] Example 2

[0068] Step A: Acid dissolution of lithium amide and lithium sulfide waste materials. At room temperature, 50 g of lithium amide waste and 50 g of lithium sulfide waste are added to a reaction container. While stirring, 600 g of deionized water is added, and 300 g of a 98% H2SO4 solution and 100 g of a 50% H2O2 solution are added. After reacting for 1 hour, a lithium-containing acidified slurry is obtained and solid-liquid separation is performed to obtain a lithium-containing acid solution and a sulfur element precipitate. The sulfur element can be further purified and refined into sulfur.

[0069] Step B: Alkalization: adjust the pH of the lithium acid solution obtained in step A to 12 with a sodium hydroxide solution having a mass concentration of 32%, stir the reaction for 1 hour, and filter it with a sand core funnel with a pore size of 5 μm to obtain insoluble impurities (mainly iron hydroxide after the lithium iron phosphate leachate is returned) and an alkalized feed solution.

[0070] Step C: lithium precipitation. The alkaline and impurity-removing solution obtained in step B is concentrated to a Li mass concentration of 18 g / L. A sodium carbonate solution with a mass concentration of 230 g / L is added at 95° C. (the molar ratio of Li in the concentrated alkaline solution to sodium carbonate in the sodium carbonate solution is 2:1). The reaction is stirred for 1 hour. The lithium precipitation mother liquor and crude lithium carbonate are obtained by filtration. The crude lithium carbonate is filtered, rinsed, and dried to obtain 278 g of industrial-grade lithium carbonate (including the conversion amount of the raw material lithium iron phosphate), with a main content of 99.1%.

[0071] Step D: Extraction: Li extraction is performed on the lithium precipitation mother liquor obtained in step C, the volume ratio of the extractant oil phase to the water phase is 1:1, the oil phase includes HB121 alkaline extractant and sulfonated kerosene at a volume ratio of 1.2:1, and the lithium extraction rate is 99.3% after three-stage countercurrent extraction at room temperature. The raffinate is evaporated and concentrated, and when the raffinate is evaporated to a Baume degree of 38°Bé, 395g of sodium sulfate is thermally precipitated at 80°C, and 295g of ammonium sulfate is precipitated at 55°C.

[0072] Step E: calcination, calcining 295g of ammonium sulfate and 295g of lithium iron phosphate waste obtained in step D, that is, the mass ratio of ammonium sulfate to lithium iron phosphate waste is 1:1, calcining at 280°C for 10min, cooling after calcination, leaching with 2.5 times the mass of water at 50°C, obtaining 575g of leachate, circulating to step B for lithium precipitation for standby use, and repeating the above operation.

[0073] Example 3

[0074] Step A: Acid dissolution of lithium amide and lithium sulfide waste materials. At room temperature, 50 g of lithium amide waste and 50 g of lithium sulfide waste are added to a reaction container. 1000 g of deionized water is added while stirring. At the same time, 300 g of H2SO4 solution with a mass concentration of 98% and 100 g of H2O2 solution with a mass concentration of 50% are added. After reacting for 1 hour, a lithium-containing acidified slurry is obtained and solid-liquid separation is performed to obtain a lithium-containing acid solution and a sulfur element precipitate. The sulfur element can be further purified and refined into sulfur.

[0075] Step B: Alkalization, the pH of the lithium acid solution obtained in step A is adjusted to 11 with a sodium hydroxide solution having a mass concentration of 32%, and after stirring the reaction for 0.5 hours, it is filtered with a sand core funnel with a pore size of 3 μm to obtain insoluble impurities (the lithium iron phosphate leachate is mainly iron hydroxide after returning) and an alkalized feed solution.

[0076] Step C: lithium precipitation. The alkaline and impurity-removing solution obtained in step B is concentrated to a Li mass concentration of 23 g / L. A sodium carbonate solution with a mass concentration of 230 g / L is added at 95°C (the molar ratio of Li in the concentrated alkaline solution to sodium carbonate in the sodium carbonate solution is 1.95:1). The reaction is stirred for 1 hour. The lithium precipitation mother liquor and crude lithium carbonate are obtained by filtration. The crude lithium carbonate is filtered, rinsed and dried to obtain 267 g of industrial-grade lithium carbonate (including the conversion amount of the raw material lithium iron phosphate), with a main content of 99.3%.

[0077] Step D: Extraction: Li extraction is performed on the lithium precipitation mother liquor obtained in step C, the volume ratio of the extractant oil phase to the water phase is 1:1, the oil phase includes HB121 alkaline extractant and sulfonated kerosene at a volume ratio of 0.8:1, and the lithium extraction rate is 99.2% after three-stage countercurrent extraction at room temperature. The raffinate is evaporated and concentrated, and when the raffinate is evaporated to a Baume degree of 38°Bé, 408g of sodium sulfate is thermally precipitated at 82°C, and 276g of ammonium sulfate is precipitated at 57°C.

[0078] Step E: calcination, calcining 276g of ammonium sulfate and 307g of lithium iron phosphate waste obtained in step D, i.e., the mass ratio of ammonium sulfate to lithium iron phosphate waste is 0.9:1, at 300°C for 10min, cooling after calcination, leaching with 3 times the mass of water at 50°C, obtaining 895g of leachate, circulating to step B for lithium precipitation for standby use, and repeating the above operation.

[0079] The analytical data of the industrial-grade lithium carbonate obtained in Examples 1 to 3 of the present invention are shown in Table 1.

[0080] Table 1 Analysis data of industrial grade lithium carbonate

[0081]

[0082]

[0083] It can be seen from Table 1 that the lithium carbonate prepared in Examples 1-3 all meet the industrial grade requirements.

[0084] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0085] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing lithium carbonate by co-processing lithium-containing waste to recover lithium, characterized in that: The steps include: 1) mixing lithium amide waste and lithium sulfide waste with water to obtain a waste mixed solution, then mixing the waste mixed solution with a hydrogen peroxide solution and a sulfuric acid solution to obtain an acid-soluble mixed solution, performing an acid-soluble reaction, and obtaining a lithium-containing acid solution and insoluble matter after solid-liquid separation; 2) mixing the lithium acid solution with an alkali solution to carry out an alkalization reaction, and after the reaction is completed, separating the solid and the liquid to obtain insoluble impurities and an alkalized feed solution; 3) concentrating the alkalized feed liquid to obtain a concentrated alkalized feed liquid, mixing the concentrated alkalized feed liquid with a sodium carbonate solution to carry out a lithium precipitation reaction, and after the reaction is completed, solid-liquid separation is performed to obtain a lithium precipitation mother liquor and lithium carbonate; 4) extracting lithium from the lithium precipitation mother liquor, stripping the extract with sulfuric acid to obtain lithium sulfate, evaporating and concentrating the raffinate, and precipitating sodium sulfate and ammonium sulfate in steps; 5) The ammonium sulfate and lithium iron phosphate waste are mixed, and then roasted and leached in sequence to obtain a leachate, which is mixed with the lithium acid solution in step 2) to perform an alkalization reaction.

2. The method for preparing lithium carbonate by co-processing lithium-containing waste materials to recover lithium according to claim 1, characterized in that: The mass ratio of the lithium amide waste, lithium sulfide waste, water, hydrogen peroxide solution and sulfuric acid solution in step 1) is 45-55:45-55:600-1000:80-120:280-320; The mass concentration of the hydrogen peroxide solution is 30-60%; The mass concentration of the sulfuric acid solution is 80-98%.

3. The method for preparing lithium carbonate by co-processing lithium-containing waste materials to recover lithium according to claim 2, characterized in that: The time of the acid dissolution reaction in step 1) is 0.5 to 2 hours.

4. A method for preparing lithium carbonate by co-processing lithium-containing waste materials to recover lithium according to any one of claims 1 to 3, characterized in that: The pH value of the alkalization reaction system in step 2) is 10 to 12; The alkali solution includes sodium hydroxide solution; The mass concentration of the alkali solution is 30-35%.

5. The method for preparing lithium carbonate by co-processing lithium-containing waste materials to recover lithium according to claim 4, characterized in that: The alkalization reaction time in step 2) is 0.5 to 1 h.

6. The method for preparing lithium carbonate by co-processing lithium-containing waste materials to recover lithium according to claim 5, characterized in that: The mass concentration of Li in the concentrated alkalized liquid in step 3) is 15-25 g / L; In step 3), the molar ratio of Li in the concentrated alkalized liquid to sodium carbonate in the sodium carbonate solution is 1.8 to 2.2:1; The mass concentration of the sodium carbonate solution is 200-250 g / L.

7. A method for preparing lithium carbonate by co-processing lithium-containing waste to recover lithium according to claim 5 or 6, characterized in that: The lithium precipitation reaction time in step 3) is 0.5 to 1 hour, and the lithium precipitation reaction temperature is 80 to 95°C.

8. The method for preparing lithium carbonate by co-processing lithium-containing waste materials to recover lithium according to claim 7, characterized in that: In step 4), the extractant comprises an oil phase and an aqueous phase, and the volume ratio of the oil phase to the aqueous phase is 0.8 to 1.5:1; the oil phase comprises a Li alkaline extractant and a diluent, and the volume ratio of the Li alkaline extractant to the diluent is 0.8 to 1.2:1; the diluent comprises sulfonated kerosene; The number of stages of extraction in step 4) is 3.

9. The method for preparing lithium carbonate by co-processing lithium-containing waste materials to recover lithium according to claim 8, characterized in that: In step 5), the mass ratio of ammonium sulfate to lithium iron phosphate waste is 0.6 to 1:

1.

10. The method for preparing lithium carbonate by co-processing lithium-containing waste materials to recover lithium according to claim 9, characterized in that: The calcination temperature in step 5) is 250-350°C, the calcination time is 10-15 minutes, the liquid-solid mass ratio of the leaching is 2-4:1, and the leaching temperature is 40-60°C.

Images