Recovery Of Cobalt And Lithium From Spent Lithium-ions Batteries By Sequentially Polyvinyl Chloride Chloridizing Calcination-aqueous Leaching Process

Based on the great demand for precious metals in the current new energy market,and the increasingly prominent problems of ecological environment caused by e-waste,the waste lithium-ion batteries have become the focus of urban mineral resources research.The traditional recycling technologies are mainly composed of pyrometallurgy and hydrometallurgy,in which exists serious energy consumption and secondary pollution of acid and alkali waste liquid,as a result,developing a kind of technology that is environmental friendly and is able to recycle energy efficiently can not only realize the aim of recycling waste lithium-ions battery,but also promote the sustainable development of the industry.This paper proposes a resource disposal technology for waste lithium-ion batteries,in which the polyvinyl chloride serves as chlorination agent and the chloridizing calcination-aqueous leaching act as the core technology,combined with chemical precipitation method to extract Co and Li from waste lithium-ion batteries.In the experiment,the effects of the roasting temperature,heating rate,holding time and material ratio on the chlorination and the optimum combination of conditions were explored through the single factor experiment and orthogonal experiment.By analyzing calcined product and water leaching residue under each experimental conditions,the state changes and transformation path of Li and Co in LiCoO₂ were explored,as well as the main reactions during the chlorination process.Based on the stability analysis of LiCoO₂ and the thermodynamic study of chlorination reaction,the chlorination reaction mechanism and the influence of side reaction on the chlorination effect of metal in the roasting process were verified.After the metal leaching solution was obtained,the Co²⁺and Li⁺in the leaching solution were recovered step by step by using NaOH and Na₃PO₄ as precipitants.The influence of temperature,stirring rate,dosage of precipitant and other factors on the metal precipitation was explored.The composition of the precipitation product was determined by XRD phase analysis.The experimental results showed that when the chloridizing roasting temperature was 500?,the holding time was 120 min,the heating rate was 5?/min,and the material ratio was n(PVC):n(LiCoO₂)=5:1,there was around 95%cobalt in LiCoO₂ material that had been converted to Co Cl₂,and nearly 100%lithium had been converted to Li Cl,which made the chlorination result ideal.In separation recycling process,when the water bath temperature was 40?,the stirring speed was 600 r/min,cobalt ion deposition efficiency was close to 100%,the efficiency of comprehensive recovery reached 95%.When the water bath temperature was 90?,the stirring speed was 500 r/min,and the dosage of Na₃PO₄ was 1.3 times of the theoretical dosage,lithium ion precipitation rate reached 98%,comprehensive recovery efficiency reached 98%.The overall recovery efficiency was excellent.This research results proved the feasibility of chlorination roasting-aqueous leaching method in recycling precious metals of waste lithium batteries.Compared with the traditional pyrometallurgy technology,it can reduce the energy consumption.Compared with the hydrometallurgical technology,it can avoid the use of acid and reduce the pollution of secondary acid and alkali waste liquid.At the same time,the whole recycling process is simple and efficient,which provides theoretical basis and experimental support for large-scale industrial application.