Bio-heap leaching idea to get test in California

Coastech Research Inc. of Vancouver has teamed up with Chester Millar, president of heap-leaching experts Glamis Gold to form a new public company, Biomet Technology Inc.

Together, they have raised $550,000 in an initial public underwriting early last month. They want to use that money to try out the idea of bio-heap leaching.

Unlike more conventional heap leaching with cyanide, the idea of bio-heap leaching involves charging a heap of gold ore with a common micro-organism known as thiobacillus fero-oxidans.

Under the right conditions, this sulphur-loving organism will liberate gold entrapped in pyrite and arsenopyrite by oxidizing the sulphur. Then, by washing the heap to make it alkaline and amenable to cyanide leaching, a mine operator can recover gold using conventional, proven techniques.

Without the pretreatment with micro-organisms, such so-called refractory ores would yield uneconomic gold recoveries of about 30%. Biomet hopes to get recoveries of about 80%.

Biomet wants to try the idea out on some 50,000 tons of old gold mine tailings near Jackson, Calif. Coastech has designed a pilot plant to demonstrate the commercial viability of bio-heap leaching. It would cost $186,000 to build and a further $18,000 to run for 90 days.

To fund the project, Biomet has issued 500,000 units at $1.25 per unit. Each unit consists of one share and one warrant exercisable at $1.50 within six months of listing.

The pilot plant could be running as early as June, 1988.