Extraction of lithium, rubidium and cesium from lithium porcelain stone

Abstract

The anticipated increase in demand for Li, Rb, and Cs raises growing concern due to the expected shortage in alkali metals available for extraction from ores. In this study, two kinds of additives (Na2SO4 and CaCl2) were used to selectively extract alkali metals from lithium porcelain stone. HSC modelling was used to simulate the process of roasting the ore in the presence of these additives, and to predict the temperature effect in addition to the ore/Na2SO4/CaCl2 mass ratio. Under the optimized conditions, the Li, Na, K, Rb, and Cs extraction efficiencies were 98.70, 49.80, 37.90, 97.27, and 98.40%, respectively. The optimal roasting conditions were found to be an ore/Na2SO4/CaCl2 mass ratio of 1/0.2/0.2 with heating at 850 °C for 60 min, while the optimal water leaching conditions were a liquid/solid ratio of 1/1 and a stirring speed of 300 rpm at room temperature for 60 min. Upon analysis of the calcined and leaching residues, the extraction mechanism was demonstrated to involve a highly chemoselective ion-exchange process between the alkali metals present in the ore, the Na+ in Na2SO4, and the Ca2+ in CaCl2. After this process, the concentrations of the alkali metals in lixivium were approximately 3.43 g/L Li, 25.50 g/L Na, 11.00 g/L K, 1.35 g/L Rb, and 0.56 g/L Cs, thereby indicating the feasibility of this process.