| Microflotation, laboratory batch, and continuous in-plant minicell tests were conducted to determine if copper ions not only activate sphalerite but also depress pyrite when the minerals are together.;Microflotation was performed on mineral samples over a pH range of 3.5--11. It was found that pyrite recovery increased with addition of copper ions when alone, but decreased by more than 25% (absolute) when sphalerite was also present for the pH range 6--9.5.;Bench flotation tests were performed on Louvicourt Mine ore and Red Dog Mine ore. The results for Red Dog showed that upon addition of copper, pyrite recovery decreased significantly. Pyrite recovery decreased from ca. 70% (no copper) to ca. 10% (4.5 g Cu/kg Zn) at a sphalerite recovery of ca. 70%.;Continuous in-plant minicell tests at Louvicourt Mine also showed that pyrite recovery decreased with addition of copper and further indicated that with excess copper (20 g Cu/kg Zn) pyrite recovery can increase.;The mechanism responsible for the depression of pyrite seems to be competition first for copper then xanthate that favours sphalerite over pyrite. To take advantage of this competition it may be necessary to control the sequence and rate of copper, collector, and lime addition. |
