Prairie Creek Zinc-Lead-Silver Project

Prairie Creek zinc-lead-silver project is located in the Dene territory in north-west Canada. NorZinc (formerly Canadian Zinc), is developing the $279m project.

Feasibility study of the project was completed in September 2017, while construction and development are expected to be started in 2020. The project is expected to commence production in 2022 and is expected to have a mine life of 15 years.

The construction phase of the project is expected to create 211 jobs, while 330 direct jobs will be created in the operational phase.

Prairie Creek zinc mine is expected to produce approximately 65,000t (tonnes) of zinc concentrate and 72,000t of lead concentrate over the first ten years of production.

Prairie Creek zinc-lead-silver project location, geology, and mineralization

The project site is hosted within the South Mackenzie Mountains, which are located approximately 500km from Yellowknife in the Northwest Territories of Canada.

Prairie Creek hosts the Siluro-Devonian stratigraphy, which is formed in a paleo-basin near to ancient North American platformal sediments. It is located within a wedge of sedimentary carbonate rocks belonging to mid-Proterozoic to mid-Jurassic age.

Prairie Creek hosts four styles of base metal mineralization namely quartz vein, stratabound massive sulphide (SMS), stockwork (STK), and Mississippi Valley-type (MVT).

Main quartz vein (MQV) is the most significant mineralization and consists of massive to disseminated galena, low-pyrite sphalerite, and tennantite-tetrahedrite in a quartz-carbonate-dolomite sheared matrix.

Prairie Creek zinc-lead-silver project reserves

As of August 2017, the proven and probable mineral reserves of the Prairie Creek zinc mine were estimated to be 8.1 million tonnes (Mt) of ore grading 124.22g/t silver, 8.10% lead, and 8.64% zinc.

Mining at Prairie Creek zinc-lead-silver project

Longhole open stoping (LHOS) and mechanized drift-and-fill (DAF) mining methods will be applied at the underground project. The former will be applied to extract the MQV and STK ore, while the latter will be used to extract ore from the SMS zone.

Major mining fleet will comprise four type-2 boom jumbos, two Muckmaster 600EB LHD loaders, two Sandvik LH410 LHD loaders, four Sandvik TH430 haulage trucks, and three Maclean type scissor lifts.

Ore processing at Prairie Creek project

Ore will be crushed in a primary and secondary crushing unit equipped with a vibrating screen and conveyed to the dense media separation (DMS) plant for further processing.

The crushed ore will be deslimed in the DMS plant followed by dense media (ferrosilicon) cyclone separation process. The deslimed ore will undergo two-stages of ball mill grinding, following which polymetallic, sequential flotation will be employed to separate lead and zinc sulphide, and lead oxide.

Three separate flotation circuits will be installed to produce sulphide lead, sulphide zinc, and oxide lead flotation concentrate. The resultant concentrate will be dewatered by thickening and pressure filtration.

The lead oxide and lead sulphide concentrates will be combined in the lead thickener to produce a blended lead concentrate. The filtered lead and zinc concentrates will be stored separately in temporary stockpile before being loaded onto 20t purpose-built concentrate containers.

The final concentrates will be transported to the CN railhead at Fort Nelson through a 184km road between the mine site and Liard Highway. It will then be forwarded to the Port of Vancouver for shipment to smelters overseas.

Off-take agreements

NorZinc signed a five-year off-take agreement with Korea Zinc for the sale of concentrates produced at Prairie Creek, in March 2016. The scope of supply includes between 20,000Mt and 30,000Mt of wet zinc sulphide concentrate, 15,000Mt-20,000Mt of wet lead sulphide concentrate, and 5,000t of lead oxide concentrates a year.

NorZinc also signed an agreement with Boliden for the sale of 20,000Mt dry and up to 40,000Mt of dry zinc sulphide concentrates a year for a minimum period of five years.

Infrastructure facilities at Prairie Creek zinc project

The project can be accessed through a 1,000m gravel airstrip located near the camp, and by a 180km winter road from Liard Highway 7.

Power supply for the project will be sourced from four new 2.77MW dual-fuel low-speed power generator units. The generator units will be powered by a combination of liquefied natural gas (LNG) and diesel fuel.

Water will be collected from on-site wells from the Prairie Creek aquifer. Workers are currently accommodated at an existing 50-person accommodation camp, while a new 170-person camp will also be constructed.

Contractors involved

AMC Mining Consultants prepared the updated feasibility study of the project, with contributions from consultants such as Ausenco Engineering, Global Mineral Resource Services, F. Wright Consulting, and Allnorth Consultants.