The Labrador Trough consists of Paleoproterozoic sedimentary and volcanic rocks, which extend along the eastern margin of the Archean Superior Craton to Ungava Bay. It forms the western part of a larger orogenic belt called the New Québec Orogen. In southwestern Labrador, the Labrador Trough extends into the younger Grenville Province, where the sedimentary rocks were deformed and metamorphosed.

The western boundary of the Labrador Trough is the basal unconformity between Paleoproterozoic sedimentary rocks and the Archean basement. To the east, it is bounded by allochthonous deep-water sedimentary and volcanic rocks, possibly derived from an oceanic realm. The sedimentary sequence of the Labrador Trough, termed the Kaniapiskau Supergroup, is interpreted to include a lower rift-related sequence and an upper transgressive sequence that progresses from shelf sediments at the base through deepwater turbidites and into shallow marine and terrestrial rocks at the top.

Several large metataconite deposits are located in the Labrador City–Wabush area and adjacent Québec, and have been mined continuously since the 1960s. These deposits are all thought to represent a single stratigraphic horizon, and the economic deposits are largely developed by hinge-thickening and fold repetition.

The Carol Lake deposits consist of 13 separate ore bodies, of which two are currently active. Individual deposits are associated with thickening of the magnetite–hematite schist on the closures of synforms and its repetition by complex isoclinal folds, which increase the aggregate thickness of deposits to approximately 400 m, in places.

Mining is carried out using open pit techniques, which involve the drilling, blasting and hauling of waste rock and ore. Broken ore is loaded by electric shovels and transported by truck to either the Automatic Train Operation (ATO) or the Parallel Ore Delivery System (PODS). The ATO system consists of four underground loading pockets where the as-mined ore is transferred from mine haul trucks to unmanned automatic trains. The automatic trains carry broken ore from the loading pockets to a crusher located adjacent to IOC’s processing facilities, a distance of between 8 and 12 kilometres from the loading pockets. The PODS consists of a gyratory crusher located adjacent to the Luce Pit and an overland conveyor. The conveyor carries crushed ore a distance of 6 kilometres to the concentrator. Currently the mine and the automatic train and conveyor have a nominal capacity to deliver up to 55 million tonnes per annum of ore to the concentrator.

The company’s existing mining operations in Labrador City consist of four active open pit mining areas (Luce, Humphrey Main/West/Sherwood, Humphrey South and Lorraine South), one existing pit to be reactivated (Spooks), and a new open pit Wabush 3.

Concentrator
IOC employs an entirely mechanical process to separate the ore from the waste rock. In order to extract the iron ore from the associated rock and silica gangue, the crushed ore is ground to a size of approximately one millimetre at which point it is liberated from the associated undesirable minerals. The grinding is currently done in four wet mills.

Ground ore is then concentrated in the spiral plant using gravity spirals to increase the iron content from 38% to approximately 65%. The spirals utilize the forces of gravity, centrifugal action and friction to separate the heavier iron ore grains from the lighter waste rock particles. The ground ore slurry must pass through three successive stages of spiralling (including rougher, cleaner and recleaner) before the concentrate is of sufficient grade and can be conveyed to a stockpile for direct shipping or used as feed for the pelletizing plant. A magnetic separation plant extracts magnetite from the spiral pla ........