Waste lithium metal battery valuable metal recycling technology

First, dry technology

Dry isolated by reducing roasting cobalt, aluminum, a lithium ion battery separator leaching recycling of cobalt and acetylene black. This method will keep the battery isolated from moisture and air environments, typically in a nitrogen or ammonia environment, lithium ion batteries are incinerated at a high temperature, separating various metals. Wen Junjie, et al. proposed a process for recovering metallic cobalt by high temperature roasting. First, the lithium ion waste battery is subjected to discharge treatment, the outer casing is peeled off, and the metal material is recovered; the electric core is mixed with coke and limestone , and is subjected to calcination for reduction roasting. The organic matter is burned to generate carbon dioxide and other gases. Lithium cobaltate is reduced to metallic cobalt and lithium oxide. The fluorine and phosphorus elements are fixed by sediment, and the aluminum is oxidized to Al ₂ O ₃ slag. Most of the lithium oxide escapes as a vapor, absorbs it with water, forms a carbon-containing alloy of copper , lithium, nickel , etc., and then performs deep processing by conventional hydrometallurgical techniques. The dry process is short, the process of fluorine pollution is considered in the process, and lithium is recovered.

In foreign countries, Sony and Sumitomo Metal Mining Co., Ltd. have jointly developed technologies for recovering cobalt and other elements from used lithium-ion batteries. The battery is first incinerated, the organic matter is removed, and after removing iron and copper, the residual powder is heated and dissolved in the acid, and the cobalt oxide is extracted with an organic solvent.

Churl Kyoung Lee, etc. first broke the used lithium-ion battery and heat-treated it in different temperature ranges to convert the combustible materials such as carbon powder and binder into gas, leaving LiCoO ₂ . LiCoO ₂ was dissolved in a constant temperature water bath (75 ° C), liquid solid mass ratio of 20 L / g, nitric acid concentration of 1 mol / L, 1.7% H ₂ O ₂ solution, and the leaching rates of Co and Li were both 85%.

The dry process is relatively simple. The disadvantage is that the energy consumption is high, and the electrolyte solution and other components in the electrode are converted into CO ₂ or other harmful components such as P ₂ O ₅ by combustion. The method of incinerating and removing organic matter easily causes air pollution, and the purity of the alloy is low. The subsequent hydrometallurgical process still requires a series of purification and impurity removal steps.

Second, wet technology

The wet method is obtained by leaching the valuable components in the used battery with a mineral acid solution, and then recovering by a complex exchange method, an alkali boiling-acid solution method, an acid solution-extraction-precipitation method, or the like.

Zhang Pingwei, etc., leaching the cathode waste of lithium ion secondary battery with 4mol/L hydrochloric acid solution at 80 °C, the leaching rate of Co and Li are more than 99%, and then using 0.9mol/L PC-88A (2-ethyl The phosphite-mono-2-ethylhexyl ether is extracted with Co, and after stripping, cobalt is recovered as cobalt sulfate. The lithium in the solution was recovered by adding a saturated sodium carbonate solution and precipitated as lithium carbonate at 100 ° C, and the recovery was close to 80%. Kudo Mistuhiko, etc., soaked the lithium ion battery positive waste with acid, added an amphoteric metal to the leachate, changed Co ^{2 +} to Co, and then added alkali to remove the amphoteric metal to obtain metal Co. Hayashi, etc. is leached with sulfuric acid or hydrochloric acid, an alkali metal carbonate is added to the leachate, and the precipitated substance is calcined to obtain a more pure positive electrode active material. Supasan, etc., leaches the lithium ion battery cathode waste with HNO3 solution, adds LiOH to the mixed leachate, precipitates hydroxide of each metal, and the precipitate is filtered and calcined to obtain a mixture of metal oxides.

Wang Xiaofeng, etc. First dissolve the electrode material in dilute hydrochloric acid at 80 ° C, filter out insoluble matter, adjust pH = 4 with ammonia water, selectively precipitate aluminum hydroxide, then add ammonia water containing NH ₄ Cl to adjust the pH to At about 10, a complex of ammonia and cobalt is formed, and then pure oxygen is introduced to oxidize CO ²⁺ and Ni ²⁺ to trivalent ions, and the solution is repeatedly passed through a weakly acidic cation exchange resin, and the saturated resin is used at different concentrations. Cobalt and nickel were eluted with ammonium sulfate solution, and cobalt and nickel were precipitated from the eluate with oxalate. Shen Yongfeng uses cobalt leaching-electrolysis process to recover cobalt. With 10mol / L sulfuric acid solution at 70 deg.] C under leaching cobalt, lithium, solution pH was adjusted to 2.0 ~ 3.0,90 ℃ blowing stirring, hydrolysis and removal of the impurities, and then at 55 ~ 60 ℃ for titanium plate The anode was electrolyzed at a current density of 235 A/m ² using a cobalt plate as a cathode to obtain an electroconductive cobalt in accordance with national standards. Zhong Haiyun, etc. The recovery of cobalt from the lithium ion secondary battery positive waste-aluminum cobalt film is a full wet process using alkali leaching-acid solution-purification-sinking cobalt. First, the aluminum-cobalt film waste is leached with 100g/L NaOH solution to prepare aluminum hydroxide, and then diluted H ₂ SO ₄ and H ₂ O ₂ are added to the remaining waste, and the acid-soluble solution is adjusted to pH 5.0 to purify and remove impurities, and then The ammonium oxalate solution was added to precipitate cobalt, and finally a cobalt oxalate product was obtained. Wu Fang uses alkali to dissolve the battery material, preliminarily removes about 90% of the aluminum, and then leaches the residue with H ₂ SO ₄ +H ₂ O ₂ system. The filtrate after leaching contains impurities such as Fe ^{2 +} , Ca ^{2 +} , Mn ^{2 + ,} etc. The mixture of cobalt and lithium is extracted by P ₂ O ₄ solvent, and then cobalt and lithium are separated by P507 solvent extraction, cobalt sulfate is obtained after back extraction, and lithium carbonate is precipitated and precipitated, and the obtained lithium carbonate reaches zero-order product requirement, lithium The recovery rate was 76.5%. The patent "a new process for the efficient extraction of cobalt compounds from drilled scraps" provides another idea. The cobalt manganese material was dissolved in industrial reactor sulfuric acid in a reaction vessel to remove the insoluble organic residue, and a clear mixed solution of CoSO ₄ and MnSO ₄ was obtained. The solution was added to an ammoniazer containing industrial ammonia water to maintain the pH at 9 or more. After a certain period of time, the precipitate was separated by a centrifuge and the filtrate was sent to the reaction vessel. A NaOH solution was added to the kettle and heated to boiling for 5 min. The suspension of the heat sink was cooled to 60 ° C and the cobalt compound was separated by a centrifuge. The cobalt compound was dissolved in concentrated sulfuric acid in a reaction vessel, diluted, and filtered to obtain a cobalt sulfate clear liquid. The clear liquid was sent to a sedimentation tank, and the sodium carbonate solution was added to adjust the pH to 8.0 to form a purple-red precipitate. The precipitate was stirred and washed several times, and then dried to obtain a basic cobalt carbonate product. Jin Yongxun, et al. studied the recovery of lithium cobalt oxide from waste lithium ion batteries by flotation, but the recovered lithium cobalt oxide contains impurities such as graphite and cannot be used to make lithium ion batteries. Wen Junjie, etc. used alkali leaching-acid solution-purification-sinking process to recover aluminum and drill in the positive waste of lithium ion battery, and obtained chemically pure aluminum hydroxide. The recovery rate was 94.89%. The cobalt was recovered in the form of cobalt oxalate. The rate is 94.23%.

The waste lithium ion battery is treated by the wet method, the leaching liquid needs to be strictly purified, consumes a large amount of electric energy, the organic reagent also has an adverse effect on the environment and human health, and the process flow is long, the equipment requirements are high, and the cost is high. The current wet process is complicated, the resource recovery rate is low, and there are secondary pollution problems. Some researchers have proposed the AEA process, although it has the advantages of simple process, low secondary pollution and high resource recovery rate, its economic feasibility needs further study.

McLaughlin proposed that the Toxco method (combination of fire method and wet method) firstly cools the waste material in liquid nitrogen, and after mechanical crushing, deionized water is added to react lithium with water to form lithium hydroxide, which is used as the main Product, but the law does not address the recovery of other elements such as cobalt.

Kim, etc. conducted a direct exploration on the direct repair of the electrode material, but its processing efficiency can not be guaranteed, and whether the electrode material after repair has good charge and discharge and safety performance, and whether it can be directly used as an electrode material of a lithium ion battery. , yet to be further researched.

In short, countries have started late in the research on recycling and recycling of waste lithium-ion batteries, and because lithium-ion batteries have less environmental pollution than other types of batteries and high recycling costs, there has been no efficient, economical and environmentally friendly recycling process. Therefore, it is necessary to seek a reasonable, effective and clean way of recycling metals and resources.

Third, the bioleaching process

The so-called microbial leaching is the use of microorganisms to convert the useful components of the system into soluble compounds and selectively dissolve them to obtain a metal-containing solution, to separate the target component from the impurity components, to obtain a metal-containing solution, and to achieve the target component. Separation from the impurity component ultimately recovers the useful metal. Bioleaching technology is a multidisciplinary cross-technology of biology, metallurgy, chemistry, etc. It is a complex process, including the biology of bacterial growth and metabolism, surface chemistry and kinetics of interaction between bacteria and mineral surfaces, chemical oxidation, biooxidation and original Battery reactions often occur simultaneously. Among them, the special effects of microorganisms on bacterial leaching are generally considered to have three kinds of oxidation mechanisms: direct oxidation reaction, chemical oxidation reaction of Fe ^{3 +} oxidized sulfide, and primary battery reaction. Among the three leaching mechanisms, microorganisms play a vital role. The main strains in bioleaching include Thiobacillus oxidans, Iron oxide bacillus, Thiobacillus ferrooxidans and Polythiobacillus. They are all autotrophic bacteria and can grow in strong acidic media where common microorganisms are difficult to survive. Oxidation of inorganic compounds such as S, Fe, and N obtains energy, carbon is taken from CO ₂ , and nitrogen is taken from the ammonium salt to form self-cells. In the case of many acidic waters, such bacilli are grown. Once a certain water is taken back for domestication and cultivation, it can be inoculated into the slag to be leached for bacterial leaching. This method has the advantages of low cost, low energy consumption, no pollution, and has been widely used in the mining industry.

Bioleaching technology has been successfully applied to extract metals from low-grade, difficult-to-treat ore, used in wastewater treatment and recycling metals from various wastes such as waste circuit boards, dry batteries, nickel- cadmium batteries, etc. It is also a very popular research. Question. Drawing on biometallurgical technology, the microorganisms directly or indirectly participate in the reduction and recovery of manganese dioxide in the waste battery powder, and the final leaching rate of manganese dioxide can reach 93%. Compared with traditional battery recycling technology, its special advantage is that it is environmentally friendly and can realize comprehensive treatment of organic waste and waste batteries. Research on the application of bioleaching technology to dispose of waste lithium-ion batteries has just begun. Xin Baoping, et al. studied the recovery of cobalt from waste lithium ion batteries by bioleaching dissolution. Firstly, the used batteries were split and screened, and the cobalt in the waste lithium ion battery was eluted by leaching with a solution containing microorganisms. The culture conditions, sulfur concentration, initial pH value and electrode material addition amount were investigated for bioleaching of cobalt. The effects and methods of improving the biodissolution efficiency of cobalt ions were discussed. The mixed bacteria of Thiobacillus ferrooxidans and Thiobacillus thiooxidans were used for the test. For cobalt in lithium ion batteries, bioleaching has higher dissolution efficiency than chemical leaching. Recently, foreign countries have also reported the results of experimental studies on the extraction of cobalt and lithium from waste lithium ion batteries using Thiobacillus acidophilus. Due to the use of a single strain, the leaching rate is very low, no recovery of other metals has been studied, and studies on leaching mechanism and kinetics have not been conducted.