The Premier gold project is a high-grade gold and silver mining project located in British Columbia, Canada. The project is fully owned and will be developed by Ascot Resources.
The project comprises three brownfield underground deposits namely, Premier, Silver Coin, and Big Missouri that witnessed historical mining activities.
The Premier underground mine was one of the biggest gold mines in North America that remained in operation under multiple companies from 1918 to 1952.
Ascot Resources acquired the asset from the Swedish mining company Boliden through an agreement signed in June 2009.
Ascot plans to assimilate the Premier gold operations with its Red Mountain gold project which is located in a separate valley, approximately 23km to the southeast. Feasibility study for the Premier and Red Mountain gold project was released in April 2020.
The combined project is expected to produce 1.1 million ounces (Moz) of gold and 3Moz of silver over an estimated mine life eight years with an estimated initial investment of £118m ($147m).
Project location and geology
The Premier gold project is located approximately 19km northwest of the town of Stewart in the prolific Golden Triangle in the Skeena Mining Division of British Columbia, Canada. Terrace is the nearest major city located approximately 327km to the south of the project site.
The Premier gold project covers an area of 8,133ha comprising three key deposits Premier, Silver Coin, and Big Missouri, as well as two smaller deposits namely, Martha Ellen and Dilworth to the north.
The property is underlain by Jurassic-aged Hazelton Group rocks in an Island Arc setting and the most dominant rock types in the area are intrusive dykes and sills of the Premier porphyry.
Mineralisation and reserves
The gold-silver mineralisation in the Premier property is hosted within structural zones of quartz breccias and veins including stockworks that measure from a few centimetres to many metres in thickness. The strike lengths vary from several hundred metres to kilometres. Gold is found in the form of electrum while Silver occurs in electrum, argentite, and freibergite.
The proven and probable reserves of the Premier gold project were estimated to be 3.63 million tonnes (Mt) grading 5.45g/t gold and 19.11g/t silver as of April 2020.
The combined reserves estimate for the Premier and the Red Mountain gold projects stand at 6.17Mt grading 5.89g/t gold and 19.72g/t silver.
The underground mining operations at the Premier gold project will be based on different variants of long-hole mining methods.
The Silver Coin deposit is planned to be mined through longitudinal long-hole method (78%) and inclined undercut long-hole method for the flatter zones (19%).
Approximately 81% of the ore at Big Missouri will be mined by room and pillar method, while the remaining 14% will be extracted through the cut and fill methods.
The Premier deposit is planned to deployed with long-hole stopes (70%) and inclined undercut long-hole stopes (19%), while a minor portion of the ore body will be extracted through room and pillar, and cut and fill methods.
Mining operations will be initially carried out at Silver Coin from existing historical portals. A new portal and ramp will be developed for Big Missouri from a bench in the existing S1 pit. A connector ramp will join the Silver Coin and Big Missouri areas to allow sharing of services and ore haulage via a single portal.
Mine access at the Premier deposit will be via slash and development of an existing access stub at the 4.5 level horizon.
The average ore production rate of the Premier gold project will ramp-up from pre-production to reach 1700t/d in the first year of operation. It will increase to 2500t/ in the second year. From the third year onwards, the ore production will be reduced to a steady rate of 1,250t/d with the commencement of the Red Mountain project operations.
The run-of-the-mine (ROM) ore will be sent to a nearby processing facility where it will undergo crushing double toggle primary jaw crusher and two-stage grinding in a semi-autogenous grinding mill (SAG) and a closed-circuit ball mill.
A portion of ore material will be fed into the centrifugal gravity concentrator and the resultant gravity concentrate will be sent to an intensive leach reactor (ILR) for the recovery of gold followed by electrowinning, while the remainder ore material will be cyanide leached in a conventional carbon-in-leach (CIL) circuit for the recovery of gold and silver.
The recovered gold and silver will be eluted in a pressure Zadra-style elution circuit before undergoing electrowinning to produce a sludge gold and silver.
The gold/silver mixture will be dried and smelted in a refining furnace for the production of dore bars.
The detoxified tailings produced in the process will be thickened and pumped to a tailings storage facility (TSF).
The Premier gold project area is accessible via gravel-surfaced Granduc Mining Road from Stewart connecting Highway 37A.
The electricity for the project will be supplied through a 138kV line connecting the Long Lake Independent Power Producer (IPP) line.
The freshwater will be pumped from the nearby Cascade Creek diversion channel which will be treated at an on-site water treatment plant.
The feasibility study for the project was prepared by Sacre-Davey Engineering, a consulting engineering firm based in Vancouver.
The other consultants engaged during the feasibility study phase of the project were Bird Resource Consulting Company (BRCC), Arseneau Consulting Services (ACS), Mine Paste (MPL), Sedgman Canada, Knight Piésold (KP), SRK Consulting Canada (SRK), McElhanney (MEL), and Marsland Environmental Associates (MEA).