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12-05-2012, 03:22 PM
Do any of you folks have any detailed knowledge of "bioleaching" of ore...more specifically black shale? I'm just getting into researching the subject as I have ore that I want to subject to the process. Bit by bit I'm learning, so every tip helps.

12-05-2012, 07:29 PM
Bacteria can be cultured for specific applications.

Reno Chris
12-05-2012, 09:22 PM
You'll see in reading the Wiki that bioleaching does not leach gold and silver - it converts pyrite to iron salts and sulfuric acid (basically a toxic waste)
and Chalcopyrite into copper, iron and sulfuric acid - also toxic waste you'll need to deal with.

Some high sulfide ores are bioleached rather than treated with an autoclave. After treatment to oxidize the sulfides in either process, they are neutralized and then leached with cyanide to extract the precious metal values. Have you had your black shale assayed by a reputable company? Is it full of sulfides?


12-06-2012, 07:12 AM
Years ago I was working with this same shale using non traditional wet chemical extraction processes. I had an electron microprobe analysis done at the Colorado School of Mines on a precipitate I came up with and I had very high readings in gold, platinum and several other metals. I have contacted Actlabs in Canada to inquire about getting an analysis done.
My understanding is that I will have to add sulfur in some form. The black shales of Alberta will be processed with the sulfur that is a byproduct of the tar sands oil extraction. Also my understanding is that dilute sulfuric acid can be added to the leach. Have you ever visited a bioleaching project? I sure would like to see one in operation.

12-06-2012, 09:15 AM
I mentioned that sulfuric acid can be added to the leach. That is not for the purpose of adding sufur but to maintain pH.
The bacteria derive their energy from the consumption of sulfur, carbon and oxygen. Then in turn they produce enzymes which attack the iron compounds, oxydizing them and releasing the metal salts. The leachants are collected, stripped and removed by electrowinning [copper], cyanidation, and probably other types of chemical precipitation.