in this study, Zn/cu-bearing smelting slag was recycled via an integrated acid dissolution and hematite precipitation method. the slag was dissolved in nitric acid to generate an acid solution containing 23.5 g/L Fe, 4.45 g/L Zn and 2.81 g/L Cu, which was subjected to hydrothermal treatment with the addition of levulinic acid (LA). More than 99.95% of the initial Fe content was removed as hematite particles with diameters of approximately 200 nm, and the residual Fe concentration in the acid was 0.43 mg/L. The generated hematite contained 97.3% Fe 2 o 3 , 0.64% ZnO and 0.58% CuO. Greater than 99% of the initial Zn and Cu was retained in the acid and further precipitated as Zn/Cu-bearing solids by adjusting the solution pH to 9. The precipitated Zn/Cu-bearing solids contained 33.6% Zn and 21.7% Cu, whereas the Fe content was less than 0.2%. This paper is the first report of an environmentally friendly approach for recycling smelting slag without generating any hazardous waste.
The reduction of copper content in converting slag using process control is
significant to copper smelter. In this study, the slags produced from the
Ausmelt Converting Process for copper matte have been analyzed using X-ray
diffraction and chemical analysis. Thermodynamic calculation and effects of
various conditions including the lance submerging depth in molten bath,
the molten bath temperature, the addition of copper matte, and airflow rate
were carried out to lower the content in the slag. Thermodynamic analysis
indicates that the decrease of copper content was achieved by reducing Fe3O4,
CuFe2O4and Cu2O in the slag, decreasing the magnetism of slag and
lowering the viscosity of slag, which is feasible at the operating temperature
of the molten bath. Experiments show that the optimal combination of
operating conditions were found to be the addition of copper matte between
5000 -7000 kg/h, a lance airflow rate of 13000-14000 Nm3/h and a lance
submergence depth into the molten bath of 700-900 mm, in which the copper
content in the slag can be effectively reduced from 22.74 wt. % to 7.70 wt.
%.This study provides a theoretical support and technical guidance for
promoting the utilization of slags from the Ausmelt Converting Process.
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