Characterization of Copper Smelter Dust for Copper Recovery

The CSD from Palabora mining company's copper-plant in Limpopo, South Africa was characterized by particle size, chemical and morphological analyses. The dust from the electrostatic precipitator (EPS) attached to the reverberatory furnace was collected and used for this study. The results obtained showed that the dust contains particles mainly in the 53μm size fraction. As regards chemical composition, it is made up of about 18.02 weight % copper, occurring predominantly as cuprospinel and as chalcopyrite. The major impurities in the dust are 42.97, 11.69, 11.45 and 1.6 weight % of mullite, gypsum, silica and magnetite, respectively with traces of lead and bismuth. Morphologically, the particles range from spherical to irregular in shape, with close association occurring between these spherical minerals suspected to be copper and the tabular shaped minerals likely to be gypsum. Smaller copper particles, 1 to 2μm size, were also found embedded in larger spherical particles 8 to 10μm size. The results obtained thus strongly indicate that the CSD as-received is an ultra-fine, copper rich secondary resource that might have been formed in two stages of condensation. Furthermore, the results indicate that physical beneficiation of the CSD in this size fraction of 53μm may be difficult and solvent extraction with prior froth flotation and leaching may be required to efficiently extract the copper value in it.