Overview
The New Afton copper-gold project is located 350 km northeast of Vancouver and 10 km west of Kamloops, British Columbia, Canada. It is located in the semiarid south Thompson Valley.
In 1858, news of rich goldfields in the Thompson area of the Fraser River arrived in San Francisco. Within a month 30,000 of American prospectors rushed into the new land of promise. Frightened by this American 'invasion' Britain rushed to declare the territory the Colony of British Columbia. Mining started on the Afton property in the last years of the 19th century and lasted until 1927.
The property was explored and then open pit mined by Teck from 1977 to 1987. New Gold acquired an option on the New Afton property in 1999 and began exploration work in 2000.
A 2007 Feasibility Study contemplated a block cave mine and conventional grinding and flotation mill operation with a daily throughput of 11,000 tonnes. Mineral Reserves comprised 44.4 million tonnes in the Probable category grading 0.98% Cu, 0.72 g/t Au, and 2.27 g/t Ag. Mine life was estimated to be 12 years.
The New Afton deposit is being developed as a block cave mining operation to produce 4 Mtpa of copper-gold ore for processing in a flotation plant for the recovery of copper in and gold in concentrates. Development commenced in 2007; it was halted in 2008 but re-commenced in 2009.
A Participation Agreement had been reached with two of the First Nations that have asserted Aboriginal rights over the area comprising the Afton project.
Location
Canada is a large North American country that stretches from one ocean to another ? i.e. from Atlantic to Pacific according to its motto: 'A Mari Usque Ad Mare' (From Sea to Sea). British Columbia is the westernmost of the Canadian provinces and it is renowned for its natural beauty.
The city of Kamloops ('the meeting of waters; in local Shushwap language) is located at the confluence of two branches of the Thompson River.
The city was first visited by a European in 1811 and subsequently a fort was established by fur traders at that location. The city benefited from the 1860s gold rushes and from the construction of the railway some 20 years later. Nowadays it boasts a population of 80,000 people mostly involved in forestry, ranching, mining and tourism.
The Kamloops area is in the rain shadow of the Coast Mountains. Precipitation is minor, averaging about 257 mm annually (of which 175 mm is rainfall), with light winter snow and infrequent rain in the spring and fall. The area has warm summers where temperatures can reach 38°C and cool winters where temperatures hover around the freezing mark. During the winter, short periods of cold weather can occur where temperatures drop to as low as -29°C.
The general area of the project is undulating grasslands formed on till covered drumlinoid terrain and interspersed by numerous small, alkaline water bodies.
Geology
The New Afton deposit is hosted within the Cherry Creek member of the Iron Mask batholith complex. The Iron Mask complex is a multi-phase plutonic body exposed in a southeast-trending belt measuring 34 km long by 5 km wide. The Cherry Creek phase is the principal host unit for the New Afton deposit.
At Afton, the Cherry Creek intrusive is a variably and multiply brecciated assemblage of porphyritic and equigranular monzonite-monzodiorite.
The principal host phase of the Cherry Creek forms a wedge of intrusive breccia between the Nicola and Pothook rocks.
Two faults, termed the Hanging Wall (east) and Footwall (west) faults, constrain the New Afton deposit to a relatively narrow steeply dipping corridor.
The Afton deposits are copper-gold silica-saturated, alkalic porphyry style deposits. Mineralization results from late stage hydrothermal activity driven by remnant heat within an alkalic intrusive complex.
Hypogene mineralization comprises fine-grained disseminated chalcopyrite and relatively minor bornite or chalcocite.
Very late epithermal processes have overprinted the porphyry system and introduced mercury, antimony, and arsenic in geochemically significant concentrations.
Mining & Operations
The New Afton deposit is being developed as a block cave mining operation to produce 4 Mtpa of copper-gold ore.
Underground mining by caving methods will result in surface subsidence. A Geotechnical Monitoring Program will be an essential component of the project's rock mechanics program.
During the initial development of the mine, all ore and waste will be trucked to the surface using a fleet of 50 tonne capacity articulated haul trucks. Following commissioning of the underground crushing and conveying system, truck haulage in the conveyor decline will be limited to delivery of bulk materials to the mining areas and possibly some waste transfer to surface. The decline will be driven at 5.5m x 5.5m at a gradient of 1:6 (16.7%). Movement of material would peak at 11,900 tpd when production would reach full capacity.
LHDs operating on the extraction level will feed ore to short ore passes leading to the ore transfer level located approximately 17 m below. Two 17-tonne capacity LHDs will load ore from the base of the ore passes and tram it to a 150 t to 600 t capacity crusher dump pocket.
The primary ventilation circuit will be a push-pull system with six main surface fans installed on three intake shafts and three exhaust shafts.
Automatically activated water sprays will be fitted to production drawpoints on the extraction level to minimize dust. Dust extraction systems will be installed on orepasses, at conveyor transfer points and in the crusher station.
To avoid the problems associated with air intake temperatures consistently below freezing, it is proposed to install natural gas, direct fired heating plants on each of the intakes.
Total groundwater inflow to the pit/block cave is predicted to reach 8 L/s during mining operations.
Shops for fleet maintenance, a fuel bay and explosives magazine would be built underground.
A BC Hydro transmission lines and a Terasen natural gas pipeline traverse the mining lease north of the Afton pit. A water pipeline approximately four km in length can deliver fresh water from Kamloops Lake to the mine site.
The proposed mine communications system includes telephone communications (voice over internet), a leaky feeder radio network, an asset tracking system, video monitoring systems and programmable logic control systems for pumps, fans and ventilation control systems, ore pass level monitoring, crushing and conveying systems.
Current underground mobile equipment include: One Atlas Copco ST-6C LHD; three Atlas Copco ST-1520 LHDs; three Atlas Copco MT-5010 trucks; one Atlas Copco MT-444 truck; two Atlas Copco Jumbo Boomer M2C; one Atlas Copco Jumbo Boomer 322; one Atlas Copco MC Bolter;one 7110 Sprayer; one 6050W sprayer; one 6050EW sprayer; one M40 boom truck; one D65EX-15 Komatsu dozer; two 930G Caterpillar loaders; one 140M Caterpillar grader; one T100 Kubota tractor.
Planed additions to mine equipment fleet include: three development Jumbos; three development bolters; one cable bolter; three transmixers; two shotcrete sprayers; one boom truck; three long hole drill; one cubex drill; six small development LHDs; two large production LHDs; six small production LHDs; one cassette truck.
The mine is expected top produce 47.4 Mt ore over a 12 years mine life.
Processing
The New Afton processing facilities have been designed to process 4 Mtpa of ore and recover copper, gold, and silver. A conventional crushing, grinding, gravity concentration and flotation process has been proposed for the Project, utilizing standard processes and equipment.
The New Afton mill has been designed to process a blend of primary, transition, and supergene ores. The process will utilize conventional crushing, grinding, and concentration processes to separate valuable minerals from gangue into concentrates at marketable grades. Mineral separation will be achieved by gravity concentration and differential flotation. A regrinding stage will be included in the flotation circuit.
Equipment include an 8.3 m x 3.96 m SAG mill (7,000 HP) and a 5.5 m x 9.75 m ball mill (7,000 HP); 5m3, 20 m3 and 100 m3 flotation cells; thickener and pressure filtration equipment;
The New Afton mill has been designed to process 11,000 tpd of ore at full capacity and will operate 24 hours per day, 365 days per year.
The Tailings Storage Facility includes the Pothook pit, the tailings dam, and the impoundment zone.
