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- Aug 12, 2021
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I have no hands on experience leaching black sands with Cyanide. I have a copy of Zadra's original research papers, but haven't read them in 30 years. The one thing that I do remember, there is a high Cyanide consumption from the base metals. One of these days, I will try to re read his papers, at which time, I would feel more confident speaking about the process, and any possible skirts around the high FeO concentrations.Just a question. Assume we have barrels and barrels of black sands, classified, gold bearing... Could it be cyanide-leached ? Like regular ore processing, but with cons instead of milled ore. As I do not see any obvious problem with it, I do not tried it personally and you just cannot think about everything
Or better, some version of thiosulfate or thiourea leach... I am just curious, and I know that you have good knowledge about mining and stuff... Did you stumbled across something like this ?
Our black sands are running 68% Fe. I have not tried a magnetic separation, but do know that a considerable amount of the residual Au is magnetic. I could run up a considerable lab bill for the hoped for recovery leach technique, for a 1000 tonnes of black sands, which only assay .4 Toz/tonne. My gut is still to find a 7 yard cement mixer, steel balls, caustic soda, and our favorite friend, Mercury. Run over a copper/mercury table (slowly), with a mercury trap, would be the most efficient method. I would think the recovery of the Au and Mercury, would be in the high 99.9% rate.
The huge losses of Mercury in the past, is due to the rampant addition in loose sluice boxes, attachments to Au in gravel, and flat out over feeding of sluice boxes.
A tight set up should not lose even a microgram of Mercury.