The Theory Of Reduction Roasting-water Leaching Process Of Waste Ternary Lithium Battery Cathode Material Handicraft Research

Lithium-ion batteries are widely used in mobile electronic devices and new energy vehicles because of their high energy density,good cycle performance,and low self-discharge rate.Since 2010,our country's demand for lithium-ion batteries has been showing a trend of rapid growth.Improper handling of scrapped lithium-ion batteries will cause organic pollution,heavy metal pollution,fluorine pollution,dust pollution and other pollution,which will cause great harm to the environment.At the same time,lithium-ion batteries contain a variety of valuable metals such as Ni,Co,Mn,Li,Cu,the efficient recycling of waste lithium-ion batteries can effectively alleviate the demand for strategic metal resources such as Li and Co,and at the same time solve the problem of environmental pollution,which is of great significance to promote the sustainable development of China's lithium-ion battery industry.This paper takes waste ternary lithium battery cathode materials as the research object,and carries out the theoretical and technological research on the recovery of valuable metals in the"reduction roasting-carbonized water leaching"process,which is the recovery of Li and other valuable metals in waste ternary lithium ion cathode materials.Provide basic theories and technical prototypes.The research results obtained in the thesis are as follows:(1)On the basis of the composition and phase analysis of the raw materials,alkali pretreatment is used to dealuminate,and the composition characteristics of the waste ternary materials after dealumination are determined.The main substance is LiNi_0.5Co_0.2Mn_0.3O₂,which also contains A small amount of Al and C impurities.The thermodynamic theory calculation of the reduction roasting process was carried out,and the corresponding Li-Me-C-O thermodynamically stable area map was drawn using Factsage software.The research results showed that the difficulty of forming Li₂CO₃ below 650°C decreases with the increase of temperature,and exceeds 650°C As the temperature rises,it becomes more difficult to generate.With increasing temperature,the stable regions of Ni and Co change from NiO and CoO to Ni and Co respectively.The stable zone of Mn will be transformed into Mn O with increasing temperature and will continue to increase.(2)Based on the results of thermodynamic calculations,the selective separation of lithium by carbonized water leaching was carried out on the reduction roasting process,and the phase and morphology of the roasted products were characterized.The research results show that the valuable metals in the calcined products with increasing temperature are Li₂CO₃,Ni,Co,Mn O.As the calcining time increases and the carbon content increases,the reduction reaction proceeds more thoroughly,and the main reduction products are It is Li₂CO₃,Ni,Co simple substance and Mn O.The optimal calcination conditions are determined as follows:calcination temperature 650°C,calcination time 3 h,and calcination material carbon content 20%.Under this roasting condition,the maximum Li leaching rate can reach 90.33%,and the leaching rate of other valuable metals is less than 2%,achieving the purpose of selective leaching of Li.(3)Based on the thermodynamic calculation of the carbonization water immersion process,the carbonization countercurrent water immersion process was systematically studied.The results show that the carbonization water immersion reaction can proceed spontaneously when the temperature is lower than 57°C?G^?<0,and cannot proceed when the temperature is higher than 57°C?G^?>0.The optimal carbonization water leaching conditions were determined as follows:CO₂aeration rate 200 m L/min,leaching time 1.5 h,leaching liquid-solid ratio 15:1,leaching temperature 15°C.The results of multi-stage countercurrent leaching show that the multi-stage counter-current leaching of the leaching residue and the leaching solution under different liquid-solid ratios can efficiently leaching Li in the slag and effectively increase the Li+concentration in the leaching solution.The slag can be leached four times under the condition of a liquid-solid ratio of 15:1.The post Li leaching rate is as high as 98.17%,the Li⁺concentration after four cycles of the leaching solution exceeds 7.1 g/L,and the impurity metal ion concentration is less than 100 mg/L.The high Li⁺leachate obtained by the countercurrent leaching is recovered by the pyrolysis evaporation crystallization method,and the obtained lithium carbonate has a purity of 99.6%,which can meet the requirements for the Li purity of battery-grade lithium carbonate.Through this research,a new process for the recovery of valuable metals in the cathode materials of waste ternary lithium batteries based on"reduction roasting-carbonized water leaching"has been determined,and the efficient recovery of Li and the separation and enrichment of valuable metals have been achieved.The recovery of the cathode material of the ternary lithium battery by the"reduction roasting-carbonized water immersion"process provides a theoretical basis.