Tungsten-based scrap such as used cemented carbide requires oxidation roasting treatment. However, in the past, the scrap could not efficiently be oxidized into the inside, requiring high energy consumption. We have established the technology of molten salt dissolution using NaNO3, an exothermic reaction.
Because powdered scrap can also be dissolved into the molten product, simultaneous treatment of solid and powder scraps is possible. We also have developed a method of converting Na2WO4 to (NH4)2WO4 through ion exchange with high efficiency while removing impurities. We refine (recycle) with a small environmental load using efficient molten salt dissolution, ion exchange, NH 3 recovery/regeneration, and environmental treatment technology.