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The chemistry of the Olympic Dam concentrate leaching process and viability of reductive leaching

University of British Columbia

The WMC Olympic Dam currently mines ore containing chalcocite, bornite, and hematite. The ore is expected to downgrade from chalcocite/bornite to chalcopyrite in the future. The result is increased strain on the direct smelter to blister process currently in operation and a necessary change to a two-step smelter-converter process. The chemistry of the concentrate leaching process was studied with the purpose of applying a reductive leach to enrich the concentrate. Enrichment increases the Cu:S ratio and would allow the current smelting process to continue in the future. Reductive leaching was conducted in acid sulfate media with iron reductant and WMC concentrate over a range of acidity (0.15 M - 0.60 M), reductant to chalcopyrite ratio (0.5 - 2.1), temperature range (25°C - 70°C), and % solids (4 % - 20 %). Select tests were repeated on chalcopyrite and a mixture of chalcopyrite and hematite for comparison. When hematite was present, reduction was modestly successful and most of the iron was consumed by side reactions within the first 10 minutes. Leaching with just chalcopyrite produced much better results. Copper reductant was used but produced minimal results unless high acidity and temperature were applied. Copper was consumed in hematite reduction as well. 77% of the hematite in WMC concentrate was removed by treating the concentrate in 200 g/L sulfuric acid at 90°C over 24 hours. Reductive leaching after this treatment should be investigated as a two-stage process.

Thesis/Dissertation

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2009-11-20

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http://hdl.handle.net/2429/15309

Materials Engineering

University of British Columbia

UBCV

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