Effective Extraction Of Lithium And Beryllium From Flourite Flotation Tailing

Lithium and beryllium are important rare metal elements,which are regarded as strategic energy sources at home and abroad.With the increasing market demand for lithium and beryllium,the research on the extraction of lithium and beryllium from low-grade lithium and beryllium ores has been paid more and more attention.In this paper a flotation tailing of fluorite containing lithium and beryllium in Chenzhou city was studied.The new technique for lithium and beryllium extraction,including the following steps as microwave roasting,sulfuric acid leaching,removal of harmful metals,extraction of lithium,extraction of beryllium,was explored.The related factors in the process such as leaching time and temperature,dosage of sulfuric acid,impurity removal of leaching solution,extraction were examined.The optimum process condition was determined and the purpose of high efficiency extraction of lithium beryllium was realized.（1）In the leaching process of ore samples,the conventional acid leaching and microwave roasting acid leaching were used for comparative study.The best experimental conditions of conventional acid leaching:acid ratio was 110%,liquid solid ratio was 2∶1,leaching temperature was 95°C,leaching time was 28 h.The results showed that the leaching rate of direct acid leaching was low,the leaching rate of lithium was about 53%,and the leaching rate of beryllium was about 42%.Microwave roasting acid leaching can significantly improve the leaching rate and achieve the ideal leaching effect.The samples were roasted in industrial microwave for 120 min at 750℃,and the best experimental conditions of Microwave roasting acid leaching:acid ore ratio was 80%,liquid solid ratio was 1.5∶1,leaching temperature was 90℃,leaching time was 20 h.The leaching rate of lithium was about 95%,and the leaching rate of beryllium was about 85%.（2）In the process of purification and impurity removal of leaching solution.Due to the higher content of iron and aluminum,it was easy to generate iron hydroxide and aluminum hydroxide colloid by adjusting the pH,which was not only difficult to filter,but also caused the adsorption loss of lithium and beryllium.In this paper,the method of removing iron was jarosite method,the method of removing aluminum were potassium alum method and sodium benzoate method.It could achieve the better purification and impurity removal effect with almost no loss of lithium and beryllium.The best experimental conditions for the removal of iron by jarosite process:pH 2.0,reaction temperature 95℃,reaction time 4 h,the amount of sodium sulfate was 1.4 times of the theoretical amount.At this condition,the removal rate of ferric ions in the leaching solution was more than 98%,and the loss of lithium and beryllium was less than 3%.The best conditions of aluminum removal by potassium alum method:pH 2.5,reaction temperature 25℃,stirring time 3 h,and the amount of potassium sulfate was the 1.6 times of the theoretical amount,it was about 65%of aluminum precipitated in the form of potassium alum.The best conditions of aluminum removal by sodium benzoate method:pH 3.5,reaction temperature 25℃,reaction time 25 min,the amount of sodium benzoate was 1.2 times of the theoretical amount,the removal rate of aluminum was more than 95%,and the loss rate of lithium and beryllium was less than 3%.（3）In the process of extraction and reverse extraction,this paper mainly studies the extraction of lithium from leach solution by TBP-kerosene-FeCl₃system,and the mechanism of extraction reaction was discussed.The best extraction conditions was:extraction concentration was 75%,[Cl^-]was 285 g/L,[SO₄^2-]was below 40 g/L,V_O/V_Awas 2∶1,[Fe³⁺]/[Li⁺]was 2.5,pH was 1.5,extraction temperature 25℃,extraction time 15 min,the single-stage extraction rate of lithium was about 78%,through five-stage countercurrent extraction,the extraction rate of lithium could reach about 99%.The best reverse extraction conditions was:hydrochloric acid as the reverse extractant,[H⁺]was 1.5 mol/L,V_O/V_Awas 8∶1,reverse extraction temperature 25℃,reverse extraction time 9 min,and the single-stage reverse extractant rate of lithium is about 82%.After four-stage countercurrent reverse extractant,the reverse extraction rate of lithium could reach about 97%.By chemical analysis,slope method,and IR spectra could prove the composition of extraction complex was Li FeCl₄·2TBP.（4）In the process of extraction of beryllium from raffinate.Sodium hydroxide precipitation and sodium oleate precipitation were used to prepare beryllium product.The results show that qualified beryllium concentrate product could not be obtained by sodium hydroxide precipitation method,and by the sodium oleate precipitation method,a satisfactory product could be prepared,with a BeO grade of 32.5%.