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Building a better sluice box

Mom-and-pop placer mines in the Yukon will soon receive some tips to improve the efficiency of their operations. Research that aims to boost gold production at such outfits by one to five per cent.

Mom-and-pop placer mines in the Yukon will soon receive some tips to improve the efficiency of their operations.

Research that aims to boost gold production at such outfits by one to five per cent will be posted online, presented at the Yukon Geoscience Forum and printed in a book within two years, courtesy of the Klondike Placer Miners’ Association.

Project engineer and consultant Randy Clarkson will be conducting the research. He’s already helped bring in one advance for the Yukon’s placer gold industry, through his breakthrough research on sluice boxes in 1987 to 1990.

Sluice boxes help separate gold from dirt using barriers called riffles. Clarkson’s previous research helped miners design better sluice boxes, boosting production from 60 per cent to 95 per cent, he said.

A total of around $500,000 has been allocated to the research. The Canadian Economic Development Agency, the territory’s Department of Economic Development and the Yukon Research Centre together invested $444,000 to the project.

Around 100 mines associated with the Klondike Placer Miners’ Association also donated approximately $50,000 in kind by allowing Clarkson to use their equipment and facilities to run tests for the research.

“I have a special place in the industry because I worked with them since 1987. So everybody knows me, everybody trusts me. They wouldn’t give info to other people,” Clarkson said.

Because the mines are sharing their industry secrets with Clarkson, they cannot be named in the research, he said.

Yukon’s placer miners are often unusually forthcoming with Clarkson, he said. “They’re usually quite happy to show you their gold recovery system. You don’t get that in Alaska.”

Building on his research from 1990, Clarkson will illustrate the best methods to extract gold from a mixture of other minerals and gravel.

He will test whether the use of gravity, magnetic fields or flotation methods is most efficient for reducing the mixture, or concentrate, to gold.

As it stands, many mines use gravity to retrieve the gold, Clarkson said. Sluice boxes, mineral jigs and tables with a thin film of water all aim to separate gold from lighter minerals.

To evaluate other methods, Clarkson said he would run lab tests in mines both inside the territory and Outside.

For example, a mine in Fairbanks, Alaska, uses the flotation method, which involves putting the concentrates in a cell with air bubbles, allowing gold to float to the top of the water. A miner would then skim off the surface of the cell, which would yield powder-like gold, Clarkson said.

He reckons his complete report will allow miners to identify which method best suits their needs. This, in turn, would save miners time and boost production. That’s important, as miners only have 100 to 120 days a season to find gold, Clarkson said.

Smaller operations have to work especially hard to make a profit. Clarkson sees some placer miners who start searching for gold as early as May and end as late as October, he said.

“When someone is out there working in sub-zero weather freezing their buns off ... they’re not there because of the fun of it, because they’re rolling in cash. They’re there to get enough money till the next spring,” he said.

Clarkson’s research from 1990 has taken him around the world. He showed miners in Guyana how to build efficient sluice boxes and saved the country from using mercury, which has toxic environmental effects, Clarkson said.

But he still chooses to base himself in the Yukon, having come to the territory in 1974.

“When I go to Dawson, it’s like me going home ... the great thing about working for mom and dad is that when you suggest that they do this, they do it, because (the expense) came out of their back pocket.”