At the McCreedy West Mine, mineralization occurs as Contact and Footwall Deposits. Historic and current operations exploit both Contact Ni-Cu mineralization along the base of SIC within Sublayer Norite and granite breccia-filled embayments, and Footwall Cu-Ni- PGM mineralization in the footwall Sudbury Breccia environment.

The Contact Deposits on the property (Inter Main, Upper Main, and East Main), are related to a suite of sulphide and inclusion-rich sublayer norites and leucocratic granitic breccias. The orebodies occupy embayment structures and traps that often penetrate into the footwall of the SIC. These embayment structures are characterized by significant thickening of the mafic norite and sublayer units accompanied by thicker zones of granite breccia. Hanging-wall rocks composed of basal mafic norite and felsic norite of the main SIC overlie the contact mineralized zones. Brecciated rocks of the Levack Complex consisting of granodiorite, granodiorite gneiss and migmatites form the footwall to the deposits.

The Footwall Type Cu-Ni-PGM vein deposits are represented by the 700 Vein Complex; 950 Vein Complex; and the PM Deposit. These are now regarded as one deposit with a progression from sharpwalled massive chalcopyrite veins in the 700 Deposit passing down through the 950 (now referred to as the Upper PM) to the PM Deposit where mineralization occurs both within veins and as matrix fill within the Sudbury.

Contact-Type Ni-Cu Depos ........

Extraction is through mining methods which are dependent on the geometry of the deposit – mainly a mechanised method of selective extraction using undercutting of successive levels from bottom to top at various mine levels.

In order to decrease depletion and increase the amount of ore in areas with thin veins, conventional back stoping of ore is applied.

All of the ore extracted from the mine, containing copper, nickel and precious metals, is processed in the Clarabelle plant in Sudbury owned by Vale.

Clarabelle plant
At the concentrator, the ore is crushed and ground and fed to the froth-flotation cells. The multistaged froth flotation separates the sulphide minerals into a nickel concentrate and a copper concentrate. The tailings are disposed of in tailings ponds. The nickel concentrate typically averages 11% Ni and 4% Cu . The copper concentrate typically averages 31.5% Cu and 0.4% Ni. The plant is operated in such a way to place as much copper into the saleable copper concentrate as possible, then recover remaining copper and maximum possible nickel into a high-grade nickel– copper bulk concentrate to maximize the product NSR values.

The copper concentrate is filtered and shipped to market buyers. The nickel–copper bulk concentrate is dewatered at the smelter, and upgraded to Bessemer matte by processin ........