Efficient and clean extraction and separation of rubidium from low-grade rubidium ore via stepwise acid treatment and crystallization

A novel process was proposed for efficient extraction from low-grade rubidium ore. • The pickling process enhanced extraction efficiency and reduced waste generation. • A simple low-temperature sulfidation process enables transformation of Rb-containing phase. • The leaching residue was able to prepare high-purity silicon products. Rubidium is an important strategic metal. In this study, rubidium was efficiently extracted and separated from low-grade rubidium ore via stepwise acid leaching and crystallization. The main phase composition of low-grade rubidium ore was determined as muscovite, calcite, and quartz. This paper adopted hydrochloric acid pickling to remove calcium, and then extracted the valuable elements by sulfation-water leaching. The removal of calcium reached 99.3% under the optimum pickling conditions of 70 °C, 0.5 mol/L HCl, 1.5 h, and 2 mL/g Liquid-solid (L/S) ratio. The average particle size of low-grade rubidium after pickling was decreased from 5.74 μm to 4.84 μm. Compared with direct sulfation, the process combined with pickling and sulfation could increase the extraction of rubidium by around 10%. The production of CaSO 4 waste residues was avoided. The systematic sulfation and water leaching experiments indicated that the extraction of rubidium reached 85.4% under the optimal conditions. However, 92.8% of aluminum and 87.1% of potassium were also extracted simultaneously. Subsequently, the preliminary separation of rubidium and potassium could be achieved by crystallization, which laid the foundation for the subsequent preparation of high-purity rubidium products. The content of SiO 2 in leaching residue reached 94.4%. Download: Download high-res image (403KB) Download: Download full-size image