View single post by Keith Pashina
 Posted: Mon Nov 19th, 2012 08:04 pm
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Keith Pashina

 

Joined: Sun Nov 4th, 2012
Location: Minneapolis, Minnesota USA
Posts: 753
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Bernd:

My understanding of the process is (spoken as a Civil Engineer, not a mining engineer, and not even living in Colorado) was mercury was spread over copper plates, call amalgamating pans, which were sloped sheets directly in front of the stamp mill. As the slurry ran across the amalgamating pan, free gold would stick to the mercury. The rest of the slurry, still containing some gold, would be concentrated further by other processes.

Periodically, the stamp mill would be shut down (a very interesting process in itself), and workers would use wood paddles to scrape off the amalgam - mercury, gold, and other metals, for separation in the mercury still.

A Gazette article by Hitzman about 1987 had very good article on this. I think the mercury still, as shown in Woodie's photo, basically heated a sealed metal pot with a tube coming out the top. As the vessel heated, the gold melted, and the mercury boiled off. The tube coming out of the vessel was submerged in water, and the mercury gas condensed into a separate vessel. The tube coming out the side of the still theoretically had only water vapor in it, but some residual mercury was lost, too.

It must have been a smelly, hazardous mess in some of those ore processing towns.

Keith

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