Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction

Hydrometallurgy: Leaching in Heap, Vat, CIL, CIP, Merrill–Crowe, SX Solvent Extraction

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Recover gold from 1980's botched heap leach (2 replies)

3 years ago
JdmJeremy 3 years ago

I came across an old operation on government property that appears open to claim (I will verify before removing any minerals).

Background: I know nearly nothing about cyanide leach.

Here are a few details that I found in mining reports and other documents.

1980's - 1.5 Million tons of gold and silver bearing ore removed from open pit for heap leach operation.

Mine report mentions milling to 1/2" minus, gravity seperation, then leach with carbon column collection. No reports of refractory gold or sulphides.

Mining report also mentions start-up issues, operator errors, and lower than expected recovery.

Assays show gold range 1.5 - 0.01oz/t. Average 0.1 oz/t.

150,000 oz reserve (low estimate)

30,000 oz recovered. I'm not sure how much silver was recovered or if 30,000 was the combined total.

Seems to me that there is still some gold to be recovered. Would a heap leach be safe to sample after 25 years?

I assume the cyanide has dried and decomposed. Would the gold even be gold anymore? Or some sort of unidentifiable powder salt?

Todd H
3 years ago
Todd H 3 years ago

Yes it is safe to sample, and the gold would be still there because if it leached the rain would have washed it out years ago.

Cyanide breaks down to carbon and nitrogen species and any gold complex would become elemental gold again if it was a cyanide complex.  Unlikely that any significant amount of gold was just sitting there leached and not flowing out in the leach solution, rain water etc...


Todd Harvey - Global Resource Engineering http://www.global-resource-eng.com

3 years ago
JdmJeremy 3 years ago

Update: I collected some samples from the mining area. There is no visible gold in the ore. However I tossed a few chunks into a fire pit and the next morning there were significant gold color specs. When. I crushed it, and panned it, the specs did not act like gold. Some floated, they were flakey and seemed too light to be gold.I am going to try my luck with fire assay. I also have photos (I attempted to attach them here). Either way I send update after assay.

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