Abstract
Co-grinding nonferrous metal (Cu, Pb, Cd, and Zn) oxides with sulphur (S) in the presence of a reducer such as iron (Fe) powder was conducted to stimulate their solid-state reactions, forming nonferrous metal sulphides in the product. The co-grinding induces the sulphidizing reaction and the yield is improved with an increase in grinding periods of time. Any hazardous gaseous substances are not generated during the grinding. The Fe plays a significant role to reduce the metal oxides, and it has been oxidized to form magnetite (Fe3O4). The necessary conditions to sulphidize the oxides have been clarified based on the thermodynamic discussion. Separation of the sulphidized materials from the product can be achieved by flotation, when it is suspended in water. In the present stage, we have intensively conducted a feasibility study to recover the nonferrous metals from a combustion dust or its relevant wastes emitted from an incineration facilities. This process could be also applicable to remove heavy metals such as lead (Pb), cadmium (Cd) from their contaminated wastes.
