Rubidium and Potassium Extraction from Granitic Rubidium Ore: Process Optimization and Mechanism Study

Thus far, little is known about the use of granitic rubidium ore for the extraction of rubidium. Herein, we examined the extractability of rubidium and potassium from granitic rubidium ore via sulfuric acid baking, reductive decomposition, and alkaline leaching. In addition, the extraction mechanism was studied by using interdisciplinary approaches based on the mineralogy and thermodynamics. Under the optimum conditions, more than 94% and 92% of Rb and K were extracted, respectively. Mineralogical analysis suggests that the Rb is scatted in micas (biotite and muscovite) and potassium feldspar in the form of isomorphism. Micas were transformed into sulfates during the sulfuric acid baking process. Increasing the dosage of coal, the decomposition temperature, and the time was conducive to the decomposition of sulfates. The sulfates were transformed into aluminum oxide and potassium sulfate during the reductive decomposition process. The basic structure of potassium feldspar was unchanged in the stages of baking and decomposition. The feldspar was finally altered to cancrinite and zeolite in alkaline leaching. These phase transformations reveal the release approach of Rb and K from micas and feldspar