Abstract: Batch flotation tests showed that a simple xanthate gold float using one cleaning stage would yield acceptable gold and silver recoveries for the Rainbow zone mineralization.

The bioleach testwork indicated that a 4-day bioleach retention time provides adequate dissolution of sulphides to render contained refractory gold and silver amenable to cyanide extraction. Extended bioleaching (to a 6-day retention time) appeared to result in losses of gold and silver to the bioleachate solution which in turn led to poorer cyanide extraction efficiencies.

Flotation testing of the Rainbow zone composite provided for this test program indicates that flotation recoveries of 92% for gold and 88% for silver should be achievable, into a flotation concentrate assaying 40 to 45 g Au/tonne and 4,000 to 5,000 g Ag/tonne, depending on the head grade of the material being processed.

Achievable cyanide extractions on washed bioleach residue appear to be 92% for gold and 88% for silver. These extraction values will need to be confirmed in the second phase of work planned for this test program. Suitable cyanidation conditions appear to be a 36 to 48-hour leach retention time on washed bioleach residue, pH 10 to 10.5, a target cyanide concentration of 1 g NaCN/L, and reagent consumptions of 10 to 15 kg NaCN/tonne and 35 to 45 kg Ca(OH)2/tonne of cyanidation feed.

Authors: Melis Engineering for Wheaton River Minerals Ltd.

Map Scale: 1 : 0

Citation: Melis Engineering for Wheaton River Minerals Ltd., 1993. Skukum Creek Gold/Silver Deposit - Rainbow Zone Bioleach and Cyanidation Gold/Silver Recovery Phase 1 Test Program. Yukon Geological Survey, Report 1993-10(T).

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