The Casino project is a copper-gold-molybdenum-silver mining development located in Yukon, Canada. It is considered to be one of the biggest underdeveloped copper-gold deposits in the world.
The open-pit project is proposed to be developed by Western Copper and Gold through its wholly-owned subsidiary, Casino Mining Corporation.
A feasibility study for the project was released in January 2013, while additional exploration and drilling activities were carried out subsequently. An updated resource report based on the 2019 drilling campaign was published in July 2020.
The project is currently in the process of obtaining the environmental impact assessment (EIA) approval.
The mine life of the Casino project is estimated to be 22 years while the total pre-production capital investment is estimated to be approximately £1.86bn ($2.5bn).
Project location and geology
The Casino copper-gold project covers a mining tenement of approximately 13,124ha on the north-westerly trending Dawson Range Mountains in the Yukon Territory of Canada, approximately 300km north-west of Whitehorse and 150km away from Carmacks.
The deposit lies on the Patton Porphyry, an east-west elongated tonalite porphyry stock of the Upper Cretaceous-age, which intrudes Mesozoic granitoids of the Dawson Range Batholith and the Paleozoic schists and gneisses of the Yukon Crystalline Complex.
The northern, southern, and eastern contact of the stock is brecciated due to the intrusion of the tonalite stock into the older rocks. Younger, non-mineralised dykes intrude the tonalite stock and surrounding granitods and metamorphic rocks forming a pipe-like body to the west and a dyke-like body to the east.
The Casino Project is a porphyry deposit with four primary mineralisation types of copper, gold, and molybdenum occurring in breccias, granitoids, and schists. Higher mineralisation grade occurs in breccias and gradually decrease outwards to the granitoids and schists.
The leached cap mineralisation (CAP) is a gold-rich zone with depleted copper while the supergene oxide mineralisation (SOX) zone that occurs as a thin layer overlaying the supergene sulphide zone is copper-enriched, with traces of molybdenite.
The copper mineralisation at the supergene sulphide mineralisation zone has an average thickness of up to 60m and a depth of up to 200m below the leached cap. The hypogene mineralisation occurs as stock-work veins and breccias in alteration zones throughout the project area.
The proven and probable mill-ore reserves at the Casino project were estimated to be 965.2 million tonnes (Mt) grading 0.204% copper, 0.240g/t gold, 0.0227% molybdenum, and 1.74 g/t silver, as of January 2013.
The measured and indicated mill resources for the project were estimated to be 2,173.3Mt grading 0.16% copper, 0.18g/t gold, 0.017% molybdenum, and 1.42g/t silver as of July 2020.
The Casino Project will feature a conventional open-pit, truck and shovel operation with drill and blast.
The final pit design is based on a floating cone shell with proposed 45° inter-ramp angles for the majority of the slope sectors with up to a maximum vertical wall of 200m at the inter-ramp angle.
The haul roads are designed with a width of 36m to accommodate the 360t haul trucks.
The Casino process plant will house separate processing facilities to treat sulphide and oxide ore. The project is estimated to process approximately 120,000 dry tonnes of ore-material per day or 43.8 million dry tonnes a year.
The run-of-mine (ROM) ore at both facilities will undergo crushing in a primary gyratory crusher to reduce the ore size to less than 200mm. Sulphide ore will undergo secondary crushing in a semi-autogenous (SAG) mill while secondary crushing for the oxide ores will be carried out in a cone crusher.
The crushed ore material at the sulphide processing facility will be introduced into a froth flotation circuit to concentrate and separate copper and molybdenum sulphide minerals and produce a concentrate of copper and molybdenum. The bulk concentrate will be separated into copper and molybdenum concentrates.
The crushed ore at the oxide ore processing facility will undergo leaching with cyanide solution to produce a pregnant leach solution from which gold and silver will be recovered with the use of activated carbon in carbon in column (CIC) tanks. Copper will be recovered from the pregnant leach solution by the sulphidisation, acidification, recycling, and thickening (SART) process.
The final products of the mine will be packaged and trucked to the Alaskan port of Skagway, located approximately 560km away from the site for export.
The project site is currently accessible by small aircraft via an existing 760m airstrip. A 132 km-long unpaved road from Freegold Road, approximately 70 km northwest of the village of Carmacks, as well as a new airstrip are proposed to be constructed as part of the project.
The process and potable water requirement for the project are expected to be received from the nearby Yukon River.
The project will require self-generation of electrical power which will be developed in two phases. A 20MW initial supplementary power plant comprising three internal combustion engines (ICE) and dual fuel-driven generators will be constructed before the construction of a main 125MW gas-fired combined-cycle main power plant.
The liquefied natural gas (LNG) required for the power plant will be trucked from Fort Nelson, British Columbia, and stored on-site in a large 10,000 m3 LNG storage tank.
The Casino project technical report with updated mineral resource estimate was prepared by Arizona based M3 Engineering & Technology Corporation (M3), while the open-pit design for the mine was provided by Knight-Piésold.