High Purity Tungsten Oxide Production from Low Grade Scheelite Concentrates at Pilot Plant Scale

Tungsten is a critical raw material with growing importance in electronics, military, and automotive industries. It is primarily found in minerals like scheelite and wolframite (0.5% W), which are processed in the mine site to produce a high-grade scheelite concentrate (60% W). This process results in significant tungsten losses as tailings, currently unvalorized at EU level. Ionic liquids were proposed in previous author’s publications [1] for tungsten valorization from low grade scheelite concentrates, obtaining tungsten oxide (96% purity) at 80% global yield. In this paper, an optimized ionic liquid-based process (involving leaching, solvent extraction, crystallization and calcination) was developed at laboratory scale. Important issues as flammability of solvents or the commercial availability of ionic liquids are dealt to guarantee the safety and industrial feasibility of the process. Further on, a pilot plant was designed, constructed and operated for a significant period (3 days). Tungsten oxide was produced at improved purity (> 99%) and global yield (91.6%) on continuous operation. 1. Nieto, J.; Yurramendi, L.; Aldana, J.L.; del Río, C.; Siriwardana, A. A Process Based on Ionic Liquids for Tungsten Valorization from Low Grade Scheelite Concentrates . Proceedings of the ISEC 2022 Gothenburg Sweden 2023.