A practical approach to vertical crater retreat mining in soft ground at Whitehorse Copper

CIM Bulletin, Vol. 74, No. 830, 1981

J.J. JANSSENS Mine Superintendent, and P.W. PERCIVAL, Senior Mine Engineer, Whitehorse Copper Mines Ltd., Whitehorse, Yukon

Whitehorse Copper is a 2600-ton-per-day underground copper mine located within the city limits of Whitehorse, Yukon. In early 1978, due to increasingly difficult ground conditions, it was decided to investigate the conversion from longhole open sloping to vertical crater retreat mining. On-site crater testing by C-I-L demonstrated the feasibility of V.C.R. mining at Whitehorse Copper.After some investigation, a down-the-hole drilling rig was chosen and drilling began in November 1978. Blasting began in June 1979, and to September 1980 approximately one million tons of ore had been blasted. In-field changes to both drilling and blasting techniques have been implemented. Some of these changes were dictated by problems encountered; others were made to improve efficiencies.To date, V.C.R. mining has proven successful from a drilling and blasting aspect.
Keywords: Underground mining, Vertical crater retreat mining, Soft ground, Whitehorse Copper Mines Ltd., Drilling, Blasting, Loading.