The Gibraltar mine is a large calcalkaline copper-molybdenum porphyry deposit located about 10 km north of McLeese Lake, British Columbia, and hosted by tonalite of the Late Triassic Granite Mountain batholith.

The Gibraltar Mine is a bulk tonnage, low-grade copper-molybdenum deposit concentrated along hydrothermally altered shear zones within the Granite Mountain Batholith along the west slope of Granite Mountain. It is one of the lowest grade base metal deposits ever mined in British Columbia. It is also the first in the province to have the majority of its initial production from supergene ore.

Copper-molybdenum mineralized rocks at Gibraltar have been mined from four open pits, the Gibraltar East (093B 012), Gibraltar West (093B 007), Granite Lake (093B 013) and Pollyanna (093B 006) (Figure 4). The ore bodies mined form part of a semi-continuous, anastomosing mineralized shear zone up to 100 metres or more in thickness, that parallels the strike of the regional foliation. The shear zone and associated mineralization are affected by broad open folding and display a geometry similar to that described previously for the regional foliation. Sulphide mineralization develops within or marginal to the more schistose zones, and fades out into the more massive, less foliated quartz diorite, with mineralization confined largely to the foliation surfaces and narrow mineralized veinlets (Simpson, 1970). The best mineralization is found towards the center of the mineralized belt of schistose rocks. The main ore minerals are chalcopyrite, chalcocite (supergene) and molybdenite. Pyrite is common in both ore and peripheral alteration zones and also forms an extensive halo with a few percent pyrite that envelopes the mineralized shear.

The Gibraltar deposits have been developed using open pit mining methods since the commencement of mining on site in 1971.

Current and future mining operations will be carried out utilizing conventional open pit mining equipment. The waste and ore are mined utilizing five electric blast hole drills, five electric rope shovels, one large front end loader and 26 haul trucks. The main mining fleet is supported by a fleet of ancillary equipment including track and rubber tired dozers, motor graders as well as sand and water trucks. The reserve mine plan does not require the purchase of any additional mine production equipment.

Bulk Concentrator #1
Gibraltar sulphide ore is processed through a single stage of crushing using a 60x89 gyratory crusher. This crusher produces a 6 inch minus product which is conveyed to a coarse ore stockpile. Material is drawn from the coarse ore stockpile using apron feeders and a conveyor belt to feed a 34 foot diameter, 13,000 Hp Semi-Autogeneous Grinding (SAG) mill. SAG mill discharge is screened with the oversize returning via conveyor belt to the feed of the mill. Undersize material, consisting of 0.5 inch minus, is then pumped to a distributor where six 13.5 foot diameter, 2500 Hp ball mills are operated in closed circuit with hydrocyclones to produce a minus 350 micron product used to feed the flotation circuit. Design mill throughput is 55,000 t/day.

Bulk Concentrator #2
Gibraltar sulphide ore is processed through a single stage of crushing using a 54x74 gyratory crusher. This crusher produces a 6 inch minus product which is conveyed to a coarse ore stockpile. Material is drawn from the coarse ore stockpile using apron feeders and a conveyor belt to feed a 34 foot diameter, 13,000 Hp Semi-Autogeneous Grinding (SAG) mill. SAG mill discharge is screened with the oversize returning via conveyor belt to the feed of the mill. Undersize material, consisting of 0.5 inch minus, is then pumped to a distributor where a single 20 foot diameter 8,500 Hp ball mill is operated in closed circuit with hydrocyclones to produce a minus 350 micron product used to feed the flotation circuit. Design mill throughput is 30,000 t/day.

Sulphide ore is processed at a design rate of 85,000 t/day through two bulk concentrators to produce a concentrate which contains copper, silver and molybdenum values. The bulk concentrate from both facilities is combined and processed through a single molybdenum flotation plant. The molybdenum concentrate from this plant is dewatered and bagged, and subsequently shipped to market. The underflow from this plant is the final copper concentrate which includes silver as a by- product. The copper concentrate is dewatered and shipped in bulk to market.

A solvent extraction and electrowinning plant processes leachate from oxide waste dumps to produce a copper cathode product. This system is operated intermittently as conditions allow.

Bulk Concentrator #1
Flotation feed is pumped to two parallel rougher flotation circuits, each consisting of five 160m3 flotation vessels. Flotation tailings are then pumped to a storage facility. Rougher concentrate from the parallel ........