Sigma mine concentrator (Val-d’Or)

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The Sigma mill has been operated since 1937. Milling initially started at 300 t/d and, by the end of that year, was at 500 t/d. In 1938, the mill was stepped up to 650 t/d and in 1939 to 750 t/d. The mill was again expanded to 1,000 t/d in 1940 and to 1,100 t/d in 1942. During the 1970‟s it operated at 1,420 t/d. In 1995, the mill was further expanded to 2,200 t/d. In 1996 to 1997, the Merrill-Crowe system was abandoned and the plant converted to carbon-in-pulp (CIP).

In 1999, McWatters expanded the operation to 5,000 t/d. The expansion was completed and the start-up of the “new” mill took place on the November 21, 2002 with the processing of stockpiled ore mined during the open pit pre-production phase. The mill was scheduled to produce at a rate of 3,000 t/d in January, 2003 and to increase production to 5,000 t/d by November, 2003. The McWatters operation never reached commercial production. Operations were shut down in October, 2003 and McWatters was placed into bankruptcy.