Abstract
Imperial Mining Group Ltd is developing its Crater Lake scandium project in North East Quebec. The Crater Lake Intrusive Complex is a 6 km diameter olivine quartz ferrosyenite deposit within Mistastin Batholith. The metallurgical process being developed includes mineral beneficiation which uses magnetic separation technique to produce a scandium / rare earth elements (REE) mineral concentrate. The mineral concentrate is subjected to a patent pending two-stage hydrometallurgical extraction process which entails a high-pressure caustic leach (HPC) followed by hydrochloric acid leach of the HPC residue which resulted in 96% scandium extraction. Optimization testing conducted at the laboratory scale included evaluating caustic leach temperature and acidity of acid leach. Following the optimization testwork, 66 kg of concentrate was caustic cracked using a 20 L Monel batch autoclave and the cracked and washed residue was subjected to bulk batch atmospheric leaching.