Mont-Wright Mining Complex
There are some 1,000 employees at the Mont-Wright Mining Complex, which comprises an open-pit mine, an ore crusher and a concentrator, huge maintenance workshops, a large parts storage facility and a train loading system.
The facilities are complemented by an extensive fleet of mining equipment, including drilling machines, electric shovels and large-capacity loaders, as well as some thirty 200-250 short-tonne production trucks.
The mine, extending over 24 square kilometres, has reserves and resources of one billion tonnes of crude ore with an iron content of approximately 30%. Generally, every 2.6 tonnes of crude ore yield 1 tonne of concentrate.
According to an established plan, drilling machine operators carve deep holes (15.8 metres) in the ore-bearing rock, into which an explosive mixture is poured and blasted to split the rock. Blasting operations, each requiring about sixty holes, are carried out four to five times a week.
Power shovels and – less frequently – large-capacity loaders stack the fragmented rock onto production trucks. The bucket of our biggest electric shovels can carry 35 cubic metres of rock (as much as it would take to fill two minivans), while three or four bucketfuls are enough to fill a 250-tonne truck.
Each day, production truck drivers make about 1,000 runs to the mine, most of them to the unloading point: the ore crusher. Truck boxes are unloaded into one of two gyratory crushers, which break up the ore into pieces some 20 centimetres in diameter. The crushed ore is moved by conveyor to one of the six storage silos in the concentrator.
The first step in the concentration process is to grind the ore finely in one of the six autogenous mills. The ground ore is then screened by vibration, and particles too large to pass through the screen are returned to the grinder. The remainder is routed to the concentrator’s 8,640 spirals, divided into three separate circuits, to increase the iron content of the crude ore.
The concentrator works on the same principle as a centrifuge: when water is added to the mix, iron particles can be separated from residue particles because the iron particles are heavier. The process yields a concentrated ore with an iron content boosted to over 66%, while the residue – primarily silica, or sand – is routed to the tailing pond, which will be rehabilitated when the mine is worked out.
The concentrate is processed through filter tables to remove the water, and routed to the loading silo to be put on trains bound for Port-Cartier.