Huckleberry

Overview

Huckleberry is a copper-molybdenum open pit mining operation located approximately 86 kilometres southwest of Houston in west central British Columbia, Canada. Imperial Metals corporation holds 50% in the Huckleberry Mines with the balance held by a Japanese group formed of Mitsubishi Materials Corporation, Marubeni Corporation, Furukawa Co. and Dowa Mining Co. Ltd.

The copper deposit was discovered during the nineteen fifties and nineteen sixties by following up on anomalous stream sediment samples collected from streams flowing into the Tahtsa Reach. From startup in 1997 to January 1, 2011 aggregate production has been approximately 870 million pounds of copper, 8 million pounds of molybdenum, 105,000 ounces of gold and 3.4 million ounces of silver.

Huckleberry is a conventional truck and shovel mining operation. Ore is processed in a 19,000 tonnes per day mill through crushing, grinding and flotation. Copper concentrate is trucked to a loadout facility located in the Port of Stewart some 540 kilometers by roaad from the mine. The copper concentrate is being bought by the Huckleberry mines' Japanese owners. Molybdenum concentrate is transported to Vancouver and sold to a broker. 

In 2011, the open pit mine produced 42.83 million pounds of copper and 6,929 pounds of molybdenum.

A Main Zone Optimization plan was approved in January 2012, thus extending the mine life to 2021. Therefore production from 2011 to 2021 was estimated to 424 million pounds copper, with copper production averaging 43.2 million pounds per year from 2011 to 2019.

Location

Huckleberry Mines is an open pit copper/molybdenum mine located approximately 86 kilometres southwest of Houston in west central British Columbia, Canada.

British Columbia is the westernmost of Canada's provinces. Its economy is largely resource-based - logging and mining. 

Houston is an important supply and industrial service centre for the mining and logging industry. It is linked by rail and highway to the rest of the country. Some 65 kilometeres west of Houston lies the town of Smithers which is a major regional service centre for the mineral exploration industry. 

Climate is characterized by short cool summers and long mild winters. Snowpack is usually 1 to 4 meters thick but could reach 10 meters in some of the winters.

Geology & Mineralization

 Huckleberry is a classic porphyry copper-molybdenum mineral deposit associated with multiple Late Cretaceous intrusive stocks that are characterized by concentric zones of copper, molybdenum and silver mineralization and hydrothermal alteration.

An important dextral shear zone subsequently dismembered the Main Zone Extension (MZX) deposit and East zone deposit in a few mieralized slices. The mineral deposit is 1,400 meters in length and 400 meters wide and extends to depths greater than 380 meters below surface.

Main copper mineralization at Huckleberry is chalcopyrite with minor bornite. Molybdenum occurs as molybdenite in quartz-gypsum veins and as disseminations in the host rock. 

The proven and probable reserves of the Main Zone were estimated at 39.7 million tonnes grading 0.343% copper.

Mining & Operation 

Huckleberry is a conventional open pit mining operation that began operating in 1997. From startup in 1997 to January 1, 2011 aggregate production has been approximately 870 million pounds of copper, 8 million pounds of molybdenum, 105,000 ounces of gold and 3.4 million ounces of silver.

The Huckleberry Mine comprises three open pits: the Main Zone pit (MZP), the East Zone pit (EZP), and the Main Zone Expansion (MZX) pit, which is the only pit currently being mined. The MZP and EZP were mined-out at an earlier stage of the mine life. The MZP was subsequently backfilled with waste rock and tailings.

In 2011 mining equipment consisted of Cable shovels: P & H 2100 (1) and 1900 (1); Excavator: Komatsu PC2000 (2); Front End Loader: Caterpillar 992d (1); Haul Trucks: Caterpillar 777C (5) and Caterpillar 785B (%); Blast Hole Drill: Bucyrus Erie 60R (2) and Atlas Copco PV275 (1).

New MZO development equipment that has to be acquired consists of Cat 785 120-t trucks (7); Komatsu PC3000 loader (1).

The strip ratio for the Main Zone Optimization plan,which includes the Main Zone extension pit, is 1.46 to 1.0.

Process 

The Huckleberry metallurgical process consists of crushing, grinding and flotation in a mill that has a 19,000 tonnes per day designated capacity.

Ore from the stockpile is fed to the SAG feed conveyor via two apron feeders. The grinding circuit integral equipment consists of a 32’ x 13’8” Svedala SAG Mill (driven by two GE 5500 HP motors), a 20’x 8’ Deister screen deck, a Metso HP500 pebble crusher, two 30’ x 16’ Svedala Ball Mills (each driven by one GE 5500 HP motor) and two clusters of six 26” technequip hydrocyclones. Cyclone overflow reports to the flotation circuit. 

The flotation circuit integral equipment consists of six 100 m3 Outotec tank cells (Rougher Circuit), two 10’ diameter columns (Cleaner Circuit) & six 16 m3 Outotec Ucells (Scavenger Cleaning Circuit). 

The dewatering circuit integral equipment consists of two thickeners (60’ diameter), and an Ingersoll-Rand 40/24 Automatic Filter Press.

Copper concentrates are transported by truck to the Port of Stewart, British Columbia and then by bulk carrier. The molybdenum concentrate is trucked to and sold in Vancouver. 

Tailings are transported to the tailings management facility (TMF) via slurry through 26 inch pipelines. 

Process water required for the mill is reclaimed from the TMF by a floating barge pump arrangement with fresh make-up water umped from Rio-Tinto/Alcan Nechako Reservoir. The mine is connected to the power grid at Houston through a 138 KVA power line.

The Potentially Acid Generating waste and tailings from the MZO pit require a new tailings management facility.  It would be an zoned eartfill, cyclone Non-Acid Generating sand and rockfill embankment 995 m high.

Environment & Community

All Potential Acid Generating waste rock and tailings are placed within storage facilities comprised of two tailing management facilities. 

At closure all buildings would be removed and top soil would be spread over the affected area and planted with native vegetation.