Study on Lithium Extraction from Salt Lake Brines

Abstract

The purpose of the present study is to investigate the extraction of lithium from southern Tunisian brines. Density and concentration of Lithium in those brines were reported. Also, pondered rates of Lithium and the major elements in brines were investigated. Obtained results indicate that Lithium exist in those brines as traces. The optimization of certain parameters is required in this study. To extract Lithium from natural brines two steps were investigated. Firstly, we have used Ammonium Oxalate ((NH4)2(C2O4)⋅2H2O) to precipitate only Magnesium ion: in this procedure, three parameters were investigated (Mg/Oxalate, T (°C) and tstirring). The maximum values were found to be Mg/Ox = 0.66, T = Treflux = 100°C and tstirring ≥ 30 min. Secondly, we have used Aluminum Chloride (AlCl3⋅6H2O) in order to adsorbing lithium ions by Aluminum hydroxide. In this procedure, four parameters were investigated (pH, Al/Li, tstirring and T (°C)). Maximum values of these parameters are 7.2, 4.7, 3 h and 25°C respectively. Finally, to separate Lithium from Aluminum solution, we have used an exchange ion resin. This solution including two ions under cationic form (Al3+ and Li+). Al3+ was complexed into [Al(C2O4)3]3– using Ammonium Oxalate ions ( $${{{\text{C}}}_{{\text{2}}}}{\text{O}}_{4}^{{2 - }}$$ ) and removed from solution using an anion exchange resin (Amberlite IRA-402). Thus, a theoretical study was carried out to determine the appropriate pH for separation. After Aluminum ions complexation by ammonium oxalate, Ox/Al molar ratio and pH was studied. Optimal values of these parameters are 3 and 4 respectively and the recovery of Li+ is set to be 98.5%.