The Baker Mine operation

CIM Bulletin, Vol. 79, No. 893, 1986


This paper reviews the complete cycle of a small mining operation in a remote section of northern British Columbia, including discovery, exploration, development and production. The discovery of high-grade epithermal gold-silver mineralization occurred in 1969 following a regional geochemical reconnaissance program designed to search for porphyry copper mineralization in the Cassiar-Omineca Mountains. Exploration and development from 1971 to 1979 included geological, geochemical and geophysical surveys; trenching, almost 30 000 feet of surface and underground drilling in about 100 holes and cross-cutting, drifting and raising on the principal gold-silver-bearing vein. This led to the delineation of 100 000 tons at an estimated grade ofO. 9 oz gold per ton and 18 oz silver per ton to an average depth of 120 feet below surface. A production decision in early 1980 led to the establishment of a 100-ton per day mining operation employing about 50 personnel with all supporting infrastructure transported to the site by a Hercules aircraft. The operation was subsequently supported by its own Twin Otter aircraft with periodic Hercules campaigns supplying major items including fuel. The mining operation included both open-pit and cut-and-fill methods. The milling operation employed conventional cyanide-leach process with cyanide destruction initially by alkali chlorination and subsequently by the Inco SO2/Air process. The fly-in operation, initially structured on a 21-day-in and 7-day-out basis was modified to a 14-day-in and 7-day-out basis with no loss in efficiency and with a significant increase in employee satisfaction. The operation, which earned the B. C. Small Mines Safety A ward in two consecutive years in its 31-month operating history, emphasized safety and process hazard awareness. Wildlife studies in the environmentally sensitive mine area also showed that industry and wildlife can coexist in harmony. Most importantly, the paper compares the feasibility assumptions with actual operating experience.
Keywords: Mine operation, Mill operation, Open-pit mining, Cut-and-fill method, Exploration, Mine development, Geology, Capital costs, Baker Mine.