Distinguishing ore types at the Lac des Iles PGE-gold-copper-nickel mine, Ontario: Implications for resource modelling, mining and processing

CIM Bulletin, Vol. 96, No. 1068, 2003

M.J. Michaud and M.J. Lavigne

A cornerstone of any successful mining project is an understanding of the mineral assemblage and metal distribution comprising the deposit. Knowledge of the precise mineral/metal zoning enables an operation to utilize different mining and processing methods optimized for different parts of the deposit. The Lac des Iles mine, located in northwestern Ontario, is one operation that depends on a good understanding of these issues. Current resources for the Roby Zone total 94.1 Mt grading 1.66 g/t Pd, 0.18 g/t Pt, 0.14 g/t Au, 0.062% Cu, and 0.053% Ni. The Roby Zone occurs within the gabbroic portion of the Lac des Iles intrusive complex and consists of three compositionally and texturally different ore types with variable PGE, base and precious metal contents. PGE occur as sulphides and bismuthotellurides in net-textured sulphides, coarse sulphide blebs and as finegrained inclusions within secondary silicates. Knowledge of the precise mineral/metal zoning has directly and indirectly improved several operational aspects, including resource modelling, mining, and processing. For example, metallurgical recoveries have been increased by up to 3% to 5% and concentrate grades have increased by up to 100%.

Keywords: Ore types, Lac des Iles, Mineralization, Resource estimation, Mining, Metallurgy, Geology.