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

The process of ion exchange-enhancedextracting Rb can reduceacid consumption and eliminate solid waste. Both the rare metal in the mica and the mica mineralsare valuableresources. However, in order to obtain the rare metal during the conventionalextraction process, the mica crystal has to be destroyed, which resultsin a lot of solid waste being generated and inefficient utilizationof mica minerals. In this work, rubidium-bearing biotite (Rb-BB) wasadopted to efficiently extract Rb through ion exchange. The influencesof experimental conditions on the Rb leaching efficiency (L (e)(Rb)) were explored in detail. Under the optimalconditions of 0.6 g/g Mg(NO3)(2), 1.5 mol/L H2SO4, leaching temperature 363 K, leaching time6 h, and liquid-solid rate 5:1 (mL/g), L (e)(Rb) reached 95.6%. The microscopic process was characterizedby virous characterization techniques. The results clearly revealedthat the lamellar structure of biotite was still retained completeand Mg2+ was enriched in the biotite layers after leaching.Compared with direct acid leaching, this process could reduce theconsumption of H2SO4 by 54.73% with the same L (e)(Rb). Furthermore, the leaching kinetics analysesshowed that the enhanced extraction of Rb was a chemical-controlledprocess with an activation energy (E (a))of 43.62 kJ/mol. Therefore, this process provides a promising strategyfor the efficient extraction of metals occurring in phyllosilicateminerals.