Gravity concentration cheaper, better for gold

I enjoyed reading your commentary, “Gold industry should address critics,” by Greg Barnes (T.N.M. Nov. 18-24/05). In my opinion, two gold industry problems were not mentioned in that piece: the large-scale uses of water and cyanide in the recovery of gold.

Water is something we all use everyday and, in many cases, take for granted. But a June 16, 2004, article in The Vancouver Sun titled “Deserts could soon claim a third of Earth’s surface” showed how our supply of water could rapidly diminish. The article cited a United Nations study which found that from the mid-1990s to 2000, 3,558 sq. km of land had turned into desert — driven by “slash-and-burn agriculture, sloppy conservation, overtaxed water supplies and soaring populations.” Then Maclean’s magazine recently featured an article titled “America is thirsty.”

In future, the large-scale use of water will become problematic for the mining industry.

Gravity concentration is a process with which mill personnel are familiar. But in the gold industry, it is only used at the beginning or end of a circuit — with recoveries generally in the 20% range.

Gold gravity concentration is not used as a complete concentration system to the extent that it is for the recovery of coal or iron ore. And coal and iron are sold at much lower prices than gold or base metals.

Gravity concentration for coal and iron has low capital and operating costs. Thus, perhaps a complete and efficient gravity concentration process is something that has the potential to generate a big payback in the gold industry.

Taking that a step further, a dry gravity concentration system would be a solution in place of the large-scale use of water and cyanide.

George Rodger

Coquitlam, B.C.