Research The Process Of High Pressure Extraction Of Lithium From Spodumene And Production Of Lithium Hydroxide

Lithium hydroxide is a kind of important lithium compounds,widely applied in national defense,chemical industry,battery and other fields.Especially in recent years,wiht the rapid development of new energy vehicles,the market demand for lithium hydroxide is very strong.Present technologies of leaching lithium from mineral usually have a large energy consumption and complex processes.Therefore it is meangingful to explore a process of leaching lithium from mineral and producing lithium hydroxide with low cost.Spodumene is a kind of important lithium mineral,which has a large number of lithium and at the same time has few impurity,therefore it is usually used to produce high purity lithium hydroxide.This paper focuses on the high pressure extraction of lithium from spodumene and production of lithium hydroxide,by autoclaving the spodumene with water and lime and sodium hydroxide or sodium sulfate.We can not get a good lithium extraction rate from the a-spodumene by autoclaving with sodium sulfate or sodium hydroxide and lime.Mechanical disrupt the a-spodumene deeply first,mixed it with sodium sulfate or sodium hydroxide and lime,autoclaved in high pressure and high temperature.However,the extraction rate was low,so that the process can not be applied in industry,as the best extraction ratio is only 37.2%.Calcined the α-spodumene at 1100℃,that it transform into β-spodumene which has a relatively loose structure.Sodium hydroxide and lime react with the P-spodumene in high temperature,that the reaction assistants destroy the structure of quartz and aluminosilicate,produced calcium silicate and calcium aluminum silicate.The leaching conditions are as follow:the raction temperature is 230℃，the agition speed is 300r/min,reaction time is 2h and the optimal mass ratio of P-spodumene and sodium hydroxide and lime is 10:5:20,while the reaction conversion efficiency can reach more than 92%.Evaporate the filtrate of the process,of which the the main component is sodium hydroxide and lithium hydroxide,and we can get the solid lithium hydroxide.We can get lithium from(3-spodumene by autoclaving with sodium sulfate and a little lime.Lithium is replaced from the β-spodumene by sodium sulfate in the reaction,produced analcite instead of destroying the structure of aluminosilicate.The optimal leaching conditions are as follow:the raction temperature is 230 1C,the agition speed is 300r/min,reaction time is 2h and the mass ratio of β-spodumene and sodium sulfate and lime is 10:15:1,that the reaction conversion efficiency is as much as 92.7%.The thermodynamic analysis showed that the reaction is exothermic,and spontaneous.The main component of filtrate is sodium sulfate and lithium sulfate,contained a little calcium ion.Concentrate the filtrate,after that cool it,as a lot of sodium sulfate is isolated.Than evaporate the solution,produced the solid lithium hydroxide.This study provides two technical routes,which leach lithium from spodumene and produce lithium hydroxide.The two can make most of spodumene,as the reaction assistant is cheap and friendly to the environment.Moreover,the processes have less energy consumption and are relatively simple,as the product has higher added value.Consequently the processes will have a good application prospect.