Doug Ashbury
Northern News Services

Yellowknife ( Mar 01/00) - For Miramar Mining, the Giant mine's gold tailings could literally be a golden opportunity to up production and lower costs.

Miramar, which acquired Giant mine last December, says Giant's tailings hold a "significant" resource.

Ore, especially from the early years of the mine, was rich in gold and produced higher-grade tailings than in more recent years. Miramar plans a tailings feasibility study this summer with extraction and processing of the tailings, possibly starting in spring 2001.

"If we can make a buck, we'll do it," said Miramar spokesperson Brian Labadie.

Asked if processing the tailings would mean more jobs, Labadie said, "potentially," but added the number would be small. There may be no net gain as workers at the mine move from existing work to work with the tailings, he adds.

The resource is contained in four separate tailings ponds and is estimated at 11.6 million tons grading .055 ounces per ton. That's 640,000 ounces of gold.

The grades vary though. The oldest tailings ponds hold as much as .097 ounces per ton while the lowest levels in the newer ponds is about .033 ounces per ton. Miramar is currently getting about .3 ounces of gold per ton of ore.

But the tailings have already been mined and milled and that makes them more attractive, despite the lower grade. Miramar estimates cash operating costs for the tailings reprocessing at about $200 US per ounce of gold recovered.

Previous attempts to reprocess the tailings, through what is known as whole-ore leaching, failed due to the refractory nature of the gold. Refractory gold is gold that is tied up in additional ores, in this case it's encapsulated in arsenopyrite. However, test work with magnetic separation using iron indicates about half the gold could be recovered at the Giant site then reprocessed in Con's autoclave, a vessel which heats and compresses materials.

Besides adding to gold production, putting Giant's tailings through Con's autoclave has environmental benefits, the company said. Adding a high-iron concentrate to the autoclave could speed up Miramar's surface-stored arsenic waste.

Con has 85,000 tons grading .47 ounces per ton in arsenic wastes. This concentrate could also provide iron to help stabilize the 270,000 tons of arsenic waste stored underground at Giant.