Method for synergistically extracting lithium from multi-source lithium-containing waste

Abstract

The invention belongs to the technical field of lithium-containing waste treatment, and provides a method for synergistically extracting lithium from multi-source lithium-containing waste. The collaborative lithium extraction method comprises the following steps: mixing a multi-source lithium-containing waste material, sulfuric acid and water, and carrying out an acid dissolution reaction to obtain acidified slurry; mixing the acidified slurry with a magnesium salt, and transforming to obtain a lithium salt solution and a solid precipitate; the method comprises the following steps: mixing a lithium salt solution and a sodium carbonate solution, and carrying out a neutralization impurity removal reaction to obtain an impurity-removed filtrate and insoluble impurities; adding a sodium carbonate solution into the impurity-removed filtrate, and carrying out lithium precipitation reaction to obtain lithium precipitation mother liquor and lithium carbonate; the variety of multi-source lithium-containing waste is defined. According to the method, the multi-source lithium-containing waste is subjected to cooperative treatment, heat required for transformation of lithium fluoride is provided by utilizing exothermic reaction of the lithium sulfide waste, the lithium amide waste and the acid, and the reaction energy consumption is reduced; by-products comprise ammonium sulfate and sodium sulfide, and the economic value is high; industrial-grade lithium carbonate can be directly obtained, so that reasonable utilization of resources is realized, and a new concept of green chemical economy is met.

Description

Technical Field

[0001] This invention relates to the field of lithium-containing waste treatment technology, and in particular to a method for synergistic lithium extraction from multi-source lithium-containing waste. Background Technology

[0002] With the booming development of the new energy industry, the demand for lithium fluoride is constantly rising. However, the production and use of lithium fluoride inevitably generate lithium fluoride waste, and how to recycle and reuse this waste is a problem that all manufacturers need to face. At present, the recycling and treatment of lithium fluoride waste is difficult and costly, and the recycling methods are difficult to promote and apply industrially. For economic reasons, manufacturers generally pile up or bury substandard lithium fluoride waste, which is both wasteful of resources and prone to environmental pollution.

[0003] All-solid-state lithium batteries possess high safety due to their use of non-flammable solid electrolytes. Among several types of solid electrolytes, sulfide solid electrolytes have attracted attention due to their high ionic conductivity and are considered the most promising type. Lithium sulfide, as an essential precursor material for the synthesis of sulfide solid electrolytes, is undeniably important. However, lithium sulfide is unstable and extremely sensitive to water and air, readily undergoing hydrolysis and releasing highly toxic hydrogen sulfide gas. Therefore, the production and storage of lithium sulfide have been the biggest limitations to its industrialization. Hydrolyzed lithium sulfide no longer meets the requirements for solid electrolytes and is classified as substandard lithium sulfide waste, making the harmless treatment and recycling of this waste a challenging problem.

[0004] Lithium amine is an inorganic strong base, appearing as a white, lustrous crystalline powder with an ammonia odor. It slowly decomposes in air, but reacts rapidly with water or moisture, releasing heat and ammonia gas. It is highly corrosive and flammable, requiring sealed storage in an anhydrous, light-protected, inert atmosphere. Lithium amine can be used as a condensation accelerator, reducing agent, dehydrating agent, desiccant, dehalogenating agent, alkylating agent, and ammonolysis agent in organic synthesis. It can also be used as an initiator for the anionic polymerization of ethylene compounds. The synthesis of lithium amine is primarily pyrometallurgical, involving the high-temperature calcination of metallic Li and ammonia under an inert N2 atmosphere. This method is simple and suitable for industrial production; however, due to its gas-solid reaction, it may result in uneven reaction, producing a large amount of lithium amine waste.

[0005] Therefore, it is crucial to find a way to co-process lithium fluoride waste, lithium amino acid waste, and lithium sulfide waste to extract lithium and recover lithium elements. Summary of the Invention

[0006] The purpose of this invention is to provide a method for synergistic lithium extraction from multi-source lithium-containing waste, addressing the shortcomings of existing technologies.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for synergistic lithium extraction from multi-source lithium-containing waste, comprising the following steps: 1) Mix multi-source lithium-containing waste, sulfuric acid and water, and carry out an acid dissolution reaction to obtain an acidified slurry; 2) The acidified slurry and magnesium salt are mixed and transformed to obtain a lithium salt solution and a solid precipitate; 3) Mix the lithium salt solution and sodium carbonate solution to carry out a neutralization and impurity removal reaction, and obtain the purified filtrate and insoluble impurities; 4) Add sodium carbonate solution to the purified filtrate to carry out the lithium precipitation reaction, and obtain lithium precipitation mother liquor and lithium carbonate; The multi-source lithium-containing waste includes lithium fluoride waste, lithium amino acid waste, and lithium sulfide waste.

[0008] Preferably, the mass ratio of the lithium fluoride waste, lithium amino acid waste, and lithium sulfide waste is 25~35:25~35:25~35.

[0009] Preferably, in step 1), the mass ratio of the multi-source lithium-containing waste, sulfuric acid, and water is 1:2~3:6~10, and the mass fraction of the sulfuric acid is 90~99%.

[0010] Preferably, the acid dissolution reaction in step 1) is carried out at a temperature of 30~95℃ and for a time of 0.5~2h.

[0011] Preferably, the magnesium salt in step 2) comprises one or more of magnesium chloride, magnesium sulfate, and magnesium nitrate; The mass ratio of the lithium fluoride waste to the magnesium salt in step 2) is 1:1.5~2.

[0012] Preferably, the temperature for the transformation in step 2) is 50~100℃ and the transformation time is 1~3h.

[0013] Preferably, the amount of sodium carbonate solution added in step 3) is such that the pH value of the lithium salt solution reaches 6-7; Step 3) The concentration of the sodium carbonate solution is 200~250 g / L; The neutralization and impurity removal reaction in step 3) takes 0.5 to 2 hours.

[0014] Preferably, the sodium carbonate solution in step 4) is added at a time of 10-60 minutes, and the concentration of the sodium carbonate solution in step 4) is 200-250 g / L.

[0015] Preferably, the temperature of the lithium precipitation reaction in step 4) is 80~95℃, and the reaction time is 0.5~2h.

[0016] The beneficial effects of this invention are: This invention co-processes lithium-containing waste from multiple sources, utilizing the exothermic reaction of lithium sulfide waste, lithium amino waste, and acid to provide the heat required for lithium fluoride conversion, thereby reducing reaction energy consumption. The method is simple, and the byproducts include ammonium sulfate and sodium sulfide, which have high economic value. Industrial-grade lithium carbonate can be obtained directly, realizing the rational utilization of resources and conforming to the new concept of green chemical economy. Attached Figure Description

[0017] Figure 1 This is a flowchart of the multi-source lithium-containing waste synergistic lithium extraction method of the present invention. Detailed Implementation

[0018] This invention provides a method for synergistic lithium extraction from multi-source lithium-containing waste, comprising the following steps: 1) Mix multi-source lithium-containing waste, sulfuric acid and water, and carry out an acid dissolution reaction to obtain an acidified slurry; 2) The acidified slurry and magnesium salt are mixed and transformed to obtain a lithium salt solution and a solid precipitate; 3) Mix the lithium salt solution and sodium carbonate solution to carry out a neutralization and impurity removal reaction, and obtain the purified filtrate and insoluble impurities; 4) Add sodium carbonate solution to the purified filtrate to carry out the lithium precipitation reaction, and obtain lithium precipitation mother liquor and lithium carbonate; The multi-source lithium-containing waste includes lithium fluoride waste, lithium amino acid waste, and lithium sulfide waste.

[0019] In this invention, the mass ratio of lithium fluoride waste, lithium amino acid waste and lithium sulfide waste is preferably 25~35:25~35:25~35, more preferably 28~34:28~34:28~34, and even more preferably 30~32:30~32:30~32.

[0020] In this invention, the mass ratio of the multi-source lithium-containing waste, sulfuric acid and water in step 1) is preferably 1:2~3:6~10, more preferably 1:2.2~2.8:7~9, and even more preferably 1:2.5:8; the mass fraction of the sulfuric acid is preferably 90~99%, more preferably 93~98%, and even more preferably 95%.

[0021] In this invention, the temperature of the acid dissolution reaction in step 1) is preferably 30~95℃, more preferably 40~80℃, and even more preferably 50~70℃; the time of the acid dissolution reaction is preferably 0.5~2h, more preferably 0.8~1.5h, and even more preferably 1~1.2h.

[0022] In this invention, stirring is preferably performed during the acid dissolution reaction in step 1), and the stirring speed is preferably 300~500 rpm, more preferably 350~450 rpm.

[0023] In this invention, the magnesium salt in step 2) preferably comprises one or more of magnesium chloride, magnesium sulfate, and magnesium nitrate; The mass ratio of the lithium fluoride waste to the magnesium salt in step 2) is preferably 1:1.5~2, more preferably 1:1.6~1.9, and even more preferably 1:1.7~1.8.

[0024] In this invention, the temperature of the transformation in step 2) is preferably 50~100℃, more preferably 70~95℃, and even more preferably 75~90℃; the transformation time is preferably 1~3h, more preferably 1.5~2.5h, and even more preferably 2h.

[0025] In this invention, stirring is preferably performed during the transformation process described in step 2), and the stirring speed is preferably 300~500 rpm, and more preferably 350~450 rpm.

[0026] In this invention, the amount of sodium carbonate solution added in step 3) is preferably such that the pH value of the lithium salt solution reaches 6-7, and more preferably reaches 6.5; Step 3) The concentration of the sodium carbonate solution is preferably 200~250 g / L, more preferably 210~240 g / L, and even more preferably 220~230 g / L; The neutralization and impurity removal reaction time in step 3) is preferably 0.5-2h, more preferably 0.8-1.5h, and even more preferably 1-1.2h.

[0027] In this invention, stirring is preferably performed during the neutralization and impurity removal reaction in step 3), and the stirring speed is preferably 300~500 rpm, more preferably 350~450 rpm.

[0028] In this invention, the addition time of the sodium carbonate solution in step 4) is preferably 10-60 min, more preferably 12-40 min, and even more preferably 20-35 min; the concentration of the sodium carbonate solution in step 4) is preferably 200-250 g / L, more preferably 210-240 g / L, and even more preferably 220-230 g / L.

[0029] In this invention, the amount of sodium carbonate solution added in step 4) is preferably 0-10% excess based on lithium, more preferably 2-8% excess, and even more preferably 3-7% excess.

[0030] In this invention, the temperature of the lithium precipitation reaction in step 4) is preferably 80~95℃, more preferably 83~93℃, and even more preferably 85~90℃; the time of the lithium precipitation reaction is preferably 0.5~2h, more preferably 0.8~1.5h, and even more preferably 1~1.2h.

[0031] In this invention, stirring is preferably performed during the lithium precipitation reaction in step 4), and the stirring speed is preferably 300~500 rpm, more preferably 350~450 rpm.

[0032] In this invention, after the acid dissolution reaction in step 1) is completed, it is preferable to further treat the generated waste gas using sulfuric acid solution and sodium hydroxide solution.

[0033] In this invention, the specific reactions occurring in the method for synergistic lithium extraction from multi-source lithium-containing waste are as follows: 2LiNH2(s)+Li2S(s)+2LiF(s)+MgCl2+2H2SO4(aq)=2Li2SO4(aq)+2NH3(g)+H2S(g)+2LiCl(aq)+MgF2(S) 2NH3(g)+H2SO4(aq)=(NH4)2SO4(aq) Li2SO4(aq)+Na2CO3(aq)=Li2CO3(s)+Na2SO4(aq) H2S(g)+2NaOH(aq)=Na2S(aq)+H2O.

[0034] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0035] The lithium fluoride waste used in the embodiments and comparative examples of the present invention is the floor material generated from the lithium fluoride workshop of Ganfeng Lithium Industry Group, the lithium amino acid waste comes from the Xinyu Ganfeng production workshop, and the lithium sulfide waste comes from the lithium sulfide production workshop of Ganfeng Lithium Industry Group.

[0036] Example 1

[0037] 50g of lithium fluoride waste, 50g of lithium amino acid waste, and 50g of lithium sulfide waste were added to a reactor. While stirring at 400 rpm, 1500g of deionized water and 330g of 98% sulfuric acid were added. The mixture was then stirred at 400 rpm at 80°C for 1 hour to carry out an acidification reaction, yielding an acidified slurry. 264g of 35% magnesium chloride solution was added to the acidified slurry, and the temperature was raised to 95°C. The mixture was stirred at 400 rpm for 2 hours to carry out a transformation reaction. After filtration, a lithium salt solution and a solid precipitate were obtained. A 230g / L sodium carbonate solution was added to the lithium salt solution until the pH of the lithium salt solution reached 7. The mixture was stirred at 400 rpm for 1 hour to carry out a neutralization and impurity removal reaction. After filtration, a purified filtrate and insoluble impurities were obtained. At 95°C, a 230g / L sodium carbonate solution (10% excess based on lithium content) was added to the purified filtrate over a controlled addition time of 60 minutes. After addition, the lithium precipitation reaction was carried out by stirring at 400 rpm for 1 hour. After filtration, lithium precipitation mother liquor and crude lithium carbonate were obtained. The crude lithium carbonate was washed sequentially with pure water by stirring and rinsing, and then dried at 140℃ for 14 hours to obtain 389g of lithium carbonate.

[0038] Example 2

[0039] 50g of lithium fluoride waste, 50g of lithium amino acid waste, and 50g of lithium sulfide waste were added to a reactor. While stirring at 400 rpm, 1350g of deionized water and 320g of 98% sulfuric acid were added. The mixture was then stirred at 70℃ for 1 hour at 400 rpm to carry out an acidification reaction, yielding an acidified slurry. 251g of 35% magnesium chloride solution was added to the acidified slurry, and the temperature was raised to 95℃. The mixture was stirred at 400 rpm for 2 hours to carry out a transformation reaction. After filtration, a lithium salt solution and a solid precipitate were obtained. A 230g / L sodium carbonate solution was added to the lithium salt solution until the pH reached 6.5. The mixture was stirred at 400 rpm for 0.5 hours to carry out a neutralization and impurity removal reaction. After filtration, a purified filtrate and insoluble impurities were obtained. A sodium carbonate solution with a concentration of 230 g / L was added to the purified filtrate at 95 °C (5% excess sodium carbonate solution based on lithium), with the addition time controlled at 40 min. After addition, the mixture was stirred at 400 rpm for 1 h to induce lithium precipitation. After filtration, lithium precipitation mother liquor and crude lithium carbonate were obtained. The crude lithium carbonate was sequentially washed with pure water by stirring and rinsing, and then dried at 140 °C for 14 h to obtain 385 g of lithium carbonate.

[0040] Example 3

[0041] 50g of lithium fluoride waste, 50g of lithium amino acid waste, and 50g of lithium sulfide waste were added to a reactor. While stirring at 400 rpm, 1200g of deionized water and 315g of 98% sulfuric acid were added. The mixture was then stirred at 400 rpm at 90°C for 1 hour to carry out an acidification reaction, yielding an acidified slurry. 251g of 35% magnesium chloride solution was added to the acidified slurry, and the temperature was raised to 95°C. The mixture was stirred at 400 rpm for 2 hours to carry out a transformation reaction. After filtration, a lithium salt solution and a solid precipitate were obtained. A 230g / L sodium carbonate solution was added to the lithium salt solution until the pH reached 6. The mixture was stirred at 400 rpm for 0.5 hours to carry out a neutralization and impurity removal reaction. After filtration, a purified filtrate and insoluble impurities were obtained. A sodium carbonate solution with a concentration of 230 g / L was added to the purified filtrate at 95 °C (5% excess sodium carbonate solution based on lithium), with the addition time controlled at 40 min. After addition, the mixture was stirred at 400 rpm for 1 h to induce lithium precipitation. After filtration, lithium precipitation mother liquor and crude lithium carbonate were obtained. The crude lithium carbonate was sequentially washed with pure water by stirring and rinsing, and then dried at 140 °C for 14 h to obtain 378 g of lithium carbonate.

[0042] Comparative Example 1

[0043] Replace the magnesium chloride solution in Example 1 with a calcium chloride solution, and otherwise remain the same as in Example 1.

[0044] The amount of lithium carbonate obtained in this comparative example was 377g.

[0045] Comparative Example 2

[0046] The difference from Example 1 is that 50g of lithium fluoride waste, 50g of lithium amino acid waste and 50g of lithium sulfide waste were added to the reactor, and 1500g of deionized water, 300g of 98% sulfuric acid and 50g of 50% hydrogen peroxide solution were added while stirring at 400 rpm. Then, the acid dissolution reaction was carried out at 80°C and stirred at 400 rpm for 1 hour to obtain acidified slurry.

[0047] The amount of lithium carbonate obtained in this comparative example was 376g.

[0048] The elemental content of lithium carbonate obtained in Examples 1-3 and Comparative Examples 1-2 was analyzed using an ICP spectrometer. The results are shown in Table 1.

[0049] Table 1. Elemental analysis results of lithium carbonate

[0050] As shown in Table 1, this invention uses only sulfuric acid for acid dissolution and magnesium salts for the conversion of lithium fluoride waste, which improves lithium leaching and yields high-purity lithium carbonate that meets industrial-grade standards and can be directly used industrially. This is because Mg The smaller hydration radius of the ions results in faster diffusion, higher contact and reaction efficiency with LiF particles, shorter reaction time, and milder reaction conditions; the byproduct produced is magnesium fluoride (Mg). Calcium fluoride (Ca) is an important inorganic chemical raw material with high purity and can be directly applied in industry. Comparative Example 1 uses calcium salts to transform lithium fluoride waste, producing calcium fluoride (Ca). Although fluorite is also an important mineral, the Ca obtained from it... Typically, the purity is low, and it contains impurities, so it can only be sold as low-grade fluorite, with limited utilization value and restricted disposal or sales channels. Comparative Example 2 uses sulfuric acid and hydrogen peroxide solution for acid dissolution. On the one hand, the raw material hydrogen peroxide is expensive, resulting in high process costs. On the other hand, it produces elemental sulfur as a byproduct, which may form a colloid that is difficult to filter, affecting the solid-liquid separation efficiency as well as the yield and purity of lithium carbonate.

[0051] As can be seen from the above embodiments, the present invention provides a method for synergistic lithium extraction from multi-source lithium-containing waste. The multi-source lithium-containing waste is acid-dissolved with sulfuric acid and transformed with magnesium salts to improve the leaching of lithium in the waste. After impurity removal and lithium precipitation, the resulting lithium carbonate has high purity, reaches industrial grade, and can be directly used in industrial applications.

[0052] 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 method for synergistic lithium extraction from multi-source lithium-containing waste, characterized in that, It includes the following steps: 1) Mix multi-source lithium-containing waste, sulfuric acid and water, and carry out an acid dissolution reaction to obtain an acidified slurry; 2) The acidified slurry and magnesium salt are mixed and transformed to obtain a lithium salt solution and a solid precipitate; 3) Mix the lithium salt solution and sodium carbonate solution to carry out a neutralization and impurity removal reaction, and obtain the purified filtrate and insoluble impurities; 4) Add sodium carbonate solution to the purified filtrate to carry out the lithium precipitation reaction, and obtain lithium precipitation mother liquor and lithium carbonate; The multi-source lithium-containing waste includes lithium fluoride waste, lithium amino acid waste, and lithium sulfide waste.

2. The method for synergistic lithium extraction from multi-source lithium-containing waste according to claim 1, characterized in that, The mass ratio of the lithium fluoride waste, lithium amino acid waste, and lithium sulfide waste is 25~35:25~35:25~35.

3. The method for synergistic lithium extraction from multi-source lithium-containing waste according to claim 2, characterized in that, Step 1) The mass ratio of the multi-source lithium-containing waste, sulfuric acid and water is 1:2~3:6~10, and the mass fraction of the sulfuric acid is 90~99%.

4. The method for synergistic lithium extraction from multi-source lithium-containing waste according to any one of claims 1 to 3, characterized in that, The acid dissolution reaction in step 1) takes place at a temperature of 30~95℃ and for a time of 0.5~2h.

5. The method for synergistic lithium extraction from multi-source lithium-containing waste according to claim 4, characterized in that, Step 2) The magnesium salt comprises one or more of magnesium chloride, magnesium sulfate, and magnesium nitrate; The mass ratio of the lithium fluoride waste to the magnesium salt in step 2) is 1:1.5~2.

6. The method for synergistic lithium extraction from multi-source lithium-containing waste according to claim 5, characterized in that, Step 2) The transformation temperature is 50~100℃, and the transformation time is 1~3h.

7. The method for synergistic lithium extraction from multi-source lithium-containing waste according to claim 1 or 6, characterized in that, Step 3) The amount of sodium carbonate solution added is such that the pH value of the lithium salt solution reaches 6-7; Step 3) The concentration of the sodium carbonate solution is 200~250 g / L; The neutralization and impurity removal reaction in step 3) takes 0.5 to 2 hours.

8. The method for synergistic lithium extraction from multi-source lithium-containing waste according to claim 7, characterized in that, The sodium carbonate solution in step 4) is added over a period of 10 to 60 minutes, and the concentration of the sodium carbonate solution in step 4) is 200 to 250 g / L.

9. The method for synergistic lithium extraction from multi-source lithium-containing waste according to claim 8, characterized in that, Step 4) The temperature of the lithium precipitation reaction is 80~95℃, and the reaction time is 0.5~2h.

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