The Gibraltar Copper-Molybdenum Mine is an open pit mine located in the Cariboo Mining Division in south-central British Columbia, Canada.
It is the second largest open pit copper mine in the country as well as the largest employer in the Cariboo region.
Recommended White Papers
The project is operated by a joint venture (JV) of Taseko Mines and Cariboo Copper Corporation. Taseko holds an effective 87.5% interest in the Gibraltar Mine.
Gibraltar was reopened in 2004 and since then Taseko has expanded and modernised operations at the mine.
A mineral reserve update of the Gibraltar mine was reported in March 2022. The Total Proven and Probable reserve of 706 million tonnes grading 0.26% CuEq is expected to support mining operations until 2044.
This will support Life of Mine (LOM) average production of approximately 129 million lbs of copper and 2.3 million lbs of molybdenum annually for 23 years.
Gibraltar Mine location details
The Gibraltar mine and associated facilities are located 65km north of Williams Lake in Cariboo. Williams Lake is around 590km north of Vancouver.
The property includes 32 mining leases covering 2,275 hectares (ha), 215 mineral claims spread across 21,425ha, and five optioned claims encompassing an area of more than 2,888ha.
Ownership History
In 1964, Gibraltar Mines acquired a group of claims in the McLeese Lake area.
Canadian Exploration, which was a wholly-owned subsidiary of Placer Development, and Duval Corporation were exploring area adjacent to Gibraltar’s claims.
The two companies optioned the property in 1969 and Canex acquired Duval’s remaining interest in 1970.
In October 1970, Placer commenced construction of the mine. The concentrator became fully operational by March 1972.
Westmin Resources acquired 100% control of the property in October 1996. In December 1997, the company was acquired by Boliden Resources.
In 1998, mining operations ceased at Gibraltar due to low copper prices.
Taseko Mines acquired interest in assets of Gibraltar project in July 2022, and after a period of care and maintenance mining operations resumed in May 2004.
In March 2010, a joint venture (JV) was established to operate the Gibraltar mine. Taseko owned 75% stake in the JV, while Cariboo Copper held the remaining 25% interest.
In March 2023, Taseko acquired an additional 12.5% interest in the Gibraltar Mine raising its stake to 87.5%.
Expansion of Gibraltar Mine
Originally, Gibraltar Mine was designed to process 36,000 tonnes of ore per day. However, after restarting the mine, Taseko initiated a programme to increase the copper reserves and expand the mining and processing capacity of the mine.
The first modernisation phase commenced in 2007. It included the construction of a 34ft semi-autogenous grinding (SAG) mill, conversion of rod mills to ball mills and the complete replacement of the flotation recovery system with 160m3 float cells.
New mining equipment was also procured in this phase.
The C$76m expansion was completed in 2008 and it increased the processing rate of the concentrator to 46,000 tonnes per day.
The Phase II modifications increased the capacity in other circuits of the concentrator, enabling the new SAG mill to process up to 55,000 tonnes per day.
The second phase cost C$224m and was completed in mid-2011.
The Gibraltar Development Plan 3 (GDP3) construction started in spring 2011. It included the construction of a standalone 30,000 tonne per day concentrator beside the 55,000 tonne per day facility, a new molybdenum recovery facility and upgrading mining fleet with a new mining shovel, production drill and ten haul trucks.
This further increased the design capacity of Gibraltar to 85,000 tonnes per day.
GDP3 entailed an investment of C$235m. It was completed on time in the fourth quarter of 2012 and produced the first concentrate in early 2013.
Geology and Mineralisation
The Gibraltar Mine is a calc-alkalic porphyry copper and molybdenum deposit hosted by the Late Triassic Granite Mountain batholith of the Quesnel volcanic arc terrane.
The Mountain batholith consists of Border Phase diorite, Mine Phase tonalite, and Granite Mountain trondhjemite phases with mineralisation predominantly occurring in the Mine Phase tonalite.
There are five defined mineralised zones on the property- Granite, Pollyanna, Gibraltar, Connector, and Extension zones.
The copper ore at the property basically occurs in potassic and ankeritic hydrothermal mineral assemblages in the form of disseminated and vein-hosted chalcopyrite mineralisation.
The main sulphide minerals present are pyrite and chalcopyrite. Other sulphides are also present with molybdenite as an economically important associate of chalcopyrite in the Pollyanna, Granite, and Connector deposits.
Reserves
Taseko Mines filed an updated mineral reserve estimate for Gibraltar Mine in March 2022.
As of 31 December 2021, the mine holds 706 million tonnes (mt) of proven and probable reserves graded at 0.25% Cu and 0.008% Mo.
Gibraltar’s measured and indicated resources stand at 1,215mt graded at 0.24% Cu and 0.004% Mo, as of 31 December 2021.
Mining and Ore processing
Since 1971, the deposits of the property have been developed by open pit mining methods.
Mining is carried out using conventional open pit mining equipment. Waste and ore are mined using five electric blast hole drills, four electric rope shovels, two large front-end loaders, and 24 haul trucks.
Along with these, a fleet of track dozers, motor graders, wheel loaders, and sand and water trucks support the operations.
Four additional haul trucks and one additional drill will be added to the fleet in 2036 and 2037.
The Gibraltar Mine’s processing facilities have two separate bulk sulphide concentrators, a dedicated molybdenum flotation plant, and multiple oxide leach dumps to feed a solvent extraction and electrowinning (SX/EW) facility.
The ROM ore is fed into the two sulphide concentrators, which have a combined design rate of 85,000 tonnes per day.
The ore is fed to primary crushing and transported to a closed circuit SAG/Ball comminution stage. The ground ore is processed through a rougher flotation stage.
Tailings separated from the rougher flotation stage are transported to a Tailings Storage Facility and the concentrate is reground and upgraded through two additional cleaner flotation stages. The final bulk concentrate includes copper and molybdenum values.
The bulk concentrate is then processed through a single molybdenum flotation plant. The process depresses the copper minerals and selectively recovers molybdenum. The underflow is the final copper concentrate.
Subsequently, the final concentrates of copper and molybdenum are dewatered before shipping.
Project infrastructure
The Gibraltar project’s facilities include processing facilities, waste storage facilities, utilities for natural gas, electric power, and domestic use water, maintenance support and administrative facilities among others.
The mine is connected to the provincial electrical grid by a 69kV power line with electricity supplied by the British Columbia Hydro and Power Authority.
In 2031 and 2032, the final 6km of access road with 69kv powerline, a 2inch natural gas pipeline, and water discharge pipeline will be relocated to enable mining in western areas of Gibraltar pit and in the Extension pit.
Contractors involved
Ausenco secured the Engineering, Procurement, and Construction Management (EPCM) contract for Gibraltar Development Plan 3 (GDP3) project.
Durability solutions provider Kryton was associated with the development of flooring for Gibraltar Mine.
Construction company Ledcor relocated 27 million metric tonnes of waste material from the Gibraltar Mine. The company mobilised in late 2013 for the 20-month contract.
The company was contracted again in May 2014 for mine development and pioneering activities to move an additional 11 million tonnes of waste rock.
