Grant: Idea to Innovation

Traditionally, most nickel has been produced from high-grade nickel sulfide ores (e.g., ores of the Sudbury basin in Ontario). However, proven reserves of these ores are dwindling, and future supplies are uncertain. Because of this, the focus has shifted to low-grade nickel laterite ores, which are much more abundant, but which present many economic and technical challenges. Exploitation of these deposits has proven to be marginal at best, as highlighted by the recent closure of the multi-billion dollar Ravensthorpe project in Australia, after less than one year of operation. Alternatively, nickel-iron alloy-bearing serpentinite is a potentially large source of nickel which has been largely ignored by the nickel mining industry. Many such ore deposits exist in Canada and elsewhere, and their efficient exploitation could bring significant economic benefits. A promising new process for selectively leaching nickel from low-grade serpentinite ores containing nickel-iron alloy minerals (e.g., awaruite) has been developed at UBC. The process converts nickel in the form of awaruite (Ni3Fe) to soluble nickel-ammine complexes, using an aerated alkaline ammonium solution in the presence of citrate and thiosulfate. Leaching occurs rapidly, operates under atmospheric conditions, and uses inexpensive, non-corrosive reagents in an efficient and environmentally friendly manner. Such a process, the first of its kind ever reported for extracting nickel from low-grade awaruite deposits, could provide the key for unlocking this important source of mineral wealth. Nickel leaching using ammonia-citrate-thiosulfate has been conclusively demonstrated from a variety of samples. However, further development and optimisation of the process is required before the technology can be licensed and applied commercially. Specifically, the leaching process must be demonstrated in continuous mode, reagent addition and recycle must be optimized, and suitable processes for the purification and recovery of nickel and the recovery or rejection of iron must be selected and demonstrated.