Test Your Knowledge – Generalized Metallurgical Flowsheet

A simplified flowsheet for a flotation process on a copper-nickel ore is shown below (p. 7). This process would produce two valuable concentrates, one containing primarily chalcopyrite and the other containing primarily pentlandite, i.e. (Ni,Fe)9S8 (the sum of Fe + Ni is 9 moles per 8 moles sulfur). The ore also contains pyrrhotite, i.e. Fe1-xS (x  0.05) and other gangue minerals. The ore is crushed to -8 inch at the mine site, then transported to the size reduction/flotation plant. The ore after primary crushing is first screened; -1/2 inch undersize is directed to product. Oversize goes through secondary and tertiary crushing, with -1/2 inch size being the final crushed product. The crushed ore is directed to a two-stage grinding circuit. The ground ore is then sent to flotation for copper and nickel concentrates. There are many possible variations on this theme and actual flowsheets are more complex. Amyl xanthate is commonly used, but for this question assume ethyl xanthate is the collector.

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In either case most of the feed (ore in the first case; bulk concentrate in the second) passes through the first stage. Two concentrates are obtained from the second stage, one a flotation concentrate and the other the tailings from that operation.

For the purposes of this discussion, the copper concentrate product the copper roughers is a flotation concentrate product. It then becomes the feed to the cleaners, from which two concentrates are obtained, one a flotation product and the other the tailings.

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