Efficient Leaching of Rubidium from Biotite by Ion Exchange without Destroying the Lamellar Crystal Structure

Both the rare metal in the mica and the mica minerals are valuable resources. However, in order to obtain the rare metal during the conventional extraction process, the mica crystal has to be destroyed, which results in a lot of solid waste being generated and inefficient utilization of mica minerals. In this work, rubidium-bearing biotite (Rb-BB) was adopted to efficiently extract Rb through ion exchange. The influences of experimental conditions on the Rb leaching efficiency (Le(Rb)) were explored in detail. Under the optimal conditions of 0.6 g/g Mg(NO3)2, 1.5 mol/L H2SO4, leaching temperature 363 K, leaching time 6 h, and liquid–solid rate 5:1 (mL/g), Le(Rb) reached 95.6%. The microscopic process was characterized by virous characterization techniques. The results clearly revealed that the lamellar structure of biotite was still retained complete and Mg2+ was enriched in the biotite layers after leaching. Compared with direct acid leaching, this process could reduce the consumption of H2SO4 by 54.73% with the same Le(Rb). Furthermore, the leaching kinetics analyses showed that the enhanced extraction of Rb was a chemical-controlled process with an activation energy (Ea) of 43.62 kJ/mol. Therefore, this process provides a promising strategy for the efficient extraction of metals occurring in phyllosilicate minerals.