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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How to recover gold and Iridium in this element (3 replies and 2 comments)

6 years ago
Parmanand 6 years ago

I want to recover gold and iridium from element with below combination.

CU - 63%

Ir - 17.61%

Ag - 16.20%

Au - 3.04%

Nickel - 0.13%

Mercury (Hg) - 0.002%

6 years ago
Rheomet 6 years ago
2 likes by David and Parmanand

Is this a recycled material? I would try to hammer-crush it down to about 10 mesh and leach the copper with sulfuric acid and oxygen, preferably in a drum-reactor...could take 12 - 24 hours, test and see. Filter the residue, process the liquor by evaporation and simple crystallization of copper sulfate penta-hydrate, the cheapest route. 

Try intensive cyanidation (20 g/L NaCN, 80C, 6 hours) for the copper leach residue still containing the AuAgIr, and/or any other PGMs you may have. If works, filter, and use AVR to precipitate the AuAgPGM, filter and wash well the discharge - it is your final product. This is a very risky unit operation, as it mixes sulfuric acid with cyanide, in closed reactors with pH control. A caustic scrubbing unit is needed to recover the cyanide and recycle it into the process, so you can afford it. The precipitate is a saleable product on its own. Look up the Lonmin process  for more details (run their pilot with a good crew, for 30 days 7/24 about ~ 13 years ago). Suggest hiring a robust testing lab for this. Even better, crunch the numbers and evaluate the amount of feed you have, to have a sense for the economics. High but not excessive  process risk overall, again, needs robust testing.



6 years ago

What is 'AVR'?

6 years ago
(unknown) 6 years ago
6 years ago

From what I read, it looks like the cyanide waste is deliberately acidified to drive off HCN gas. Like they say, do not try this at home. I can see why doing so safely requires a substantial investment in apparatus, and therefore only economical in large plants. Am I right?

6 years ago
Bhaduri 6 years ago
1 like by David

Addendum to Alex's response: Intensive ammoniacal oxidation @60C or below should solubilize Cu, Ni & Ag depending upon particle size & mineralogy; there are means to separate the solubilized metals via SX, IX or precipitation.The ammoniacal residue may be cyanided.

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