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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Cinnabar Ore Process Flow (4 replies)

Bob Mathias
8 years ago
Bob Mathias 8 years ago

I got a junior mining client want to extract Gold and Mercury out of Cinnabar.ore. The ore content about 1500 ppm Gold and 60% Hg. Does anyone could share experience on process flow that may suit medium scale operation?  Any help or information on how is mercury extracted from cinnabar ore?

(unknown)
8 years ago
(unknown) 8 years ago
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If your numbers are correct, cinnabar content is ~70% w/the rest as gangue...is this a concentrate? Grinding in water would be a serious risk to health, life & liberty; you might attempt grinding or leaching (if this is a concentrate) in a combination of caustic (0.5-wt%) & sodium sulfide (10-wt%) as this will soluabilize the Hg as a double sulfide...it will also suppress Hg vapor formation; HgS + Na2S = HgS.Na2S (soluble) 

I do not know the deportment of Au in your concentrate...assuming it is free, you could perform a solid-liquid separation & leach the Au out of the gangue w/cyanide at ~pH 11. The Hg may be precipitated out of solution w/Al or Zn powder: 3(HgS.Na2S) + 8NaOH + 2Al = 3Hg + 6Na2S + NaAlO2 + 4H2O
MERCURY VAPORS ARE HIGHLY TOXIC and all safety precautions including full face respirators must be adopted!

(unknown)
8 years ago
(unknown) 8 years ago
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First words of advice would be read USBM report from 1956

Second advice would be walk away from the proposal.

Mercury extraction from cinnabar is a tried and tested process and has been used in Spain for millennia. But what are the other impurities?

Keep all "concentrates" Under water containing pine oil. Remove the mercury using a retort, it will leave the gold behind but is 1500 ppm gold significant on a small deposit? It may cost you more o extract than the gold is worth.

Helena Russell
8 years ago
Helena Russell 8 years ago
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What tonnage is available to process? I would recommend retort recovery of the Hg. This is standard practice in the gold processing. The Hg is recovered as liquid metal. The retorted residue would be processed for the gold content. The use of a retort is preferred to liquid processing. Any spillage of the slurry will result in Hg vapor in the work place. Retorts are available from small to large capacities

(unknown)
8 years ago
(unknown) 8 years ago
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Mercury is a designated substance and needless to say that its handling is very nasty; however, the gold content of 1500 ppm or 48 Oz/ton is equivalent to approximately 60,000 UD$/ton which could make, depending in the size of the deposit, the economic of the process very attractive. I am more inclined in following the route of retorting to recover the mercury, that also have a commercial value, and then conventional cyanidation and Merrill Crowe to finally produce Dore. Obviously taking in consideration all the safety required that already have been discussed.


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