Vertical crater retreat mining at the Centennial Mine of Hudson Bay Mining & Smelting Co., Limited

CIM Bulletin, Vol. 72, No. 801, 1979

C.S. CROCKER, Chief Engineer of Mines, Hudson Bay Mining & Smelting Co., Limited, Flin Flon, Manitoba

The Centennial orebody was discovered and named in 1970, Manitoba's centennial year. It is relatively small, about 2 million tons. Strike length varies from 400 to 600 feet and widths from 10 to 60 feet; dip is 75 degrees.Low grade and metal prices demanded low-cost mining, and the mine was developed for conventional sublevel sloping. As the ore lay entirely under a large lake, ground movement had to be avoided and the slopes were to be filled hydraulically.Late in 1973, vertical crater retreat mining was introduced at Inco Limited, Sudbury, to recover pillars between filled stapes. It proved satisfactory and the results were publicized by CIL, who developed the technique. The method seemed to offer some advantages and one slope at Centennial Mine was selected to be mined by VCR while production was maintained from bias thole stapes.The trial slope was safe and showed lower development costs, reduced drilling time, a favourable powder factor and good fragmentation.VCR mining is now an accepted method at HBM&S Co., Ltd., and its use is being extended.
Keywords: Underground mining, Vertical reater retreat mining, Cnetennial mine, Stoping, Pillar recovery, Cratering, Backfillings, Blasting, Drilling