2014 Volume 55 Issue 6 Pages 958-963
In recent years, while Cu production has increased, ore quality has degraded. Consequently, copper smelting industries generate large amounts of byproducts and wastes, including slag. However, the use of these byproducts and wastes involve high costs and most of the wastes are discarded in landfills after processing. In some cases, these byproducts and wastes contain valuable components, which may be profitable to recover. In other cases, toxic or hazardous chemicals are required in the treatment of these wastes to prevent their release. Therefore, the processing of byproducts is a significant activity, which determines the profitability of copper production facilities.
Magnetic separation of precipitated magnetite (Fe3O4) crystals in the copper slag is one of the most effective methods to recover iron resources. It is preferable to convert molten fayalite slag to magnetite during the cooling of the slag with oxidation.
With a time-temperature-transformation (TTT) diagram, the microstructure of the slag obtained after heat treatment could be estimated through a designed cooling path according to the purpose for which the slag is to be used. Slag recycling, mainly the recovery of the precipitated magnetite crystals, will be enhanced by controlling the slag cooling conditions.
In the present study, using an infrared furnace, the crystallization behavior of copper smelter slag with regard to obtaining a TTT diagram was assessed by X-ray diffraction (using an internal standard), scanning electron microscopy and energy dispersive spectroscopy. Moreover, the distribution behaviors of the heavy metals such as Cu, Zn, As, and Cr were also studied.