Direct Pressure Alkaline Leaching of Scheelite Ores and Concentrates

The average global recovery rates for processing scheelite ores by physical methods typically range from 50 to 70%, and achieving a minimum grade of 60% WO3 in concentrates poses significant challenges. This research aimed to explore direct hydrometallurgical processing as a viable economic alternative for low-grade concentrates and medium- to high-grade ores, thereby enhancing recovery rates while minimizing penalties associated with concentrate grades. Specifically, the study focused on sodium carbonate leaching, which offers advantages like selective dissolution of problematic metals while facing challenges related to high temperature and pressure requirements. To assess feasibility, various operational parameters—including temperature, pressure, and reagent concentration—were rigorously tested using samples from both skarn and chalcopyrite-scheelite ore bodies. Results indicated that optimized operating conditions, despite being milder than industry norms, resulted in higher carbonate consumption but allowed for effective leaching. This research paves the way for potential industrial application by facilitating straightforward scale-up to pilot-plant design and optimization, making alkaline pressure leaching a promising method for scheelite processing.