Research On Utilization Of Boron & Lithium From Coipasa Salt Lake Brine,Bolivia

The Coipasa Salt Lake,located in South America,Bolivia,is abundant with sodium,potassium,magnesium,boron,lithium and other chemical resources.It has high content and a large amount of reserves,and it is reported that its potential economic value is over ten billion dollars.According to the results of isothermal evaporation experiment by Coipasa Salt Lake brine,it has a higher salinity at the later stage of the evaporation process,and enriched with boron and magnesium after the point of potassium precipitation.Due to the special components,the brine system is quite different with the other salt lake brine which has been reported.So far,the research of the salt lake has stayed on the basic stage due to lacking knowledge about the brine including borate,lithium and double salt crystallization properties and crystallization rule.For the same reason,the research about the comprehensive utilization of boron,lithium and other resource in this salt lake is also scarce.This research chooses the extracting potassium brine in Coipasa Salt Lake as raw materials.Through isothermal evaporation brine at 25 ? experiment and summer natural evaporation brine experiment,the metastable phase diagram of quatemary system Li+?Mg2+//Cl-?SO42-—H2O at 25 ? was used for a theoretical basis,we systematic studied the brine in evaporation experiment of the elements enrichment regularity and salt crystallization law,and provide a basic theoretical for the development of boron and lithium resources in Coipasa Salt Lake brine.According to the result of evaporation experiment,we found the optimal condition of boron extracted from brine.On this condition,we studied on the extraction of boric acid by HCl acidification experiment and found the optimal add amounts of HCl which the mole ratio of HCl and B2O3 is 1.23:1.Pure boric acid canbe gained finally by heating dissolution and cooling crystallization.Finally we determined a blueprint for the process of extracting boron.Due to the high boron content in the extracting boron brine which will affect the extraction of lithium,we studied extraction and back extraction of boron removal in aqueous solutions.The experimental conditions include the concentration of extraction,extraction time and back extraction time,extraction phase ratio and back extraction phase ratio,extraction stages and back extraction stages were investigated,and the results showed as the following: the ratio of extraction volume and thinner volume is 1:1,extraction phase ratio(O/A)is 1.2:1,extraction time is 5 minutes,extraction stages is 6;back extraction phase ratio(O/A)is 1:1,back extraction time is7 minutes,back extraction stages is 5.The optimal conditions of extraction and back extraction were finally determined.Roasting-leaching was used to separate magnesium and lithium from extraction phase.The experimental conditions including roasting temperature,roasting time and leaching volume were studied for the influence of lithium recovery rates and magnesium residual rates,and the results showed as the following: roasting temperature is 650 ?,roasting time is 3 hours,the ratio of leaching volume and roasting products volume is 1.2:1.The optimal condition of lithium extracted and the blueprint for the process of extracting lithium were determined.