Abstract

LOTTERING, C.  and  DORFLING, C. Investigation of secondary zinc oxides as an alternative feed to the Skorpion Zinc process: Part 2 - Process considerations and economic analysis. J. S. Afr. Inst. Min. Metall. [online]. 2018, vol.118, n.7, pp.715-722. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2018/v118n7a5.

Skorpion Zinc is investigating the possibility of using secondary zinc oxides as an alternative feed to supplement the zinc oxide ore feed and to extend the life of mine. Part 1 of this communication provides the technical background on the leaching performance at the typical Skorpion Zinc operating conditions. This study reports on the process modelling and economic analysis that were performed to determine appropriate feed blending strategies for electric arc furnace (EAF) dust, zinc dross, and zinc fume dust based on process limitations and economic considerations. The zinc fume dust had the highest zinc and lowest impurity content of the alternative oxide sources investigated; as a result, this alternative source resulted in the highest zinc production and profitability. At a blending ratio of 50% zinc fume in the solids feed, more than three times the current zinc production from ore could theoretically be achieved. Production from the zinc dross samples was limited by the amount of contained nickel; the maximum production was achieved at a blending ratio of 10% and was 20% higher than the current production from ore. Zinc production from EAF dust was very low at blending ratios exceeding 30%, due to Mg and Mn impurity limitations as well as the relatively low zinc content. Both zinc dross and EAF dust can also be processed economically to yield profit for Skorpion Zinc and the alternative oxide suppliers. Zinc dross was generally more profitable to process than EAF dust, despite its higher freight costs.

Keywords : leaching; process economics; secondary zinc oxide.

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