Processing of PGM containing Ni/Cu bulk concentrates in a sustainable way by Outotec Direct Nickel Flash Smelting process

摘要

Large deposits of low grade mixed Ni/Cu sulphide ores with important PGM values exist in North America and elsewhere. The challenge is producing saleable concentrates at acceptable recovery degrees. Producing bulk concentrates and treating them by Outotec Direct Nickel Flash Smelting (DON) to matte and then hydrometallurgical refining, offers a reliable route from concentrate to product. In the DON process high grade matte with low Fe-content is produced in the Flash smelting furnace (FSF) and metal values in slag are recovered in an electric furnace (EF). Matte refining is based on atmospheric pre-leaching and total pressure leaching. Nickel, cobalt and iron are leached leaving a leaching residue containing small amount of gangue minerals and PGM's. Iron is removed from the leach solution in an autoclave to produce high quality hematite as by-product. Cobalt and nickel will be recovered with standard methods. Overall ＞ 95% metal recovery can be expected with low energy consumption and low environmental impact.