Ansil copper mine up and running

The relatively rich massive sulphide copper deposit, which also hosts zinc, silver and gold mineralization, is the fourth mine in the division to be operated by Minnova, known formerly as Corp. Falconbridge Copper.

Capital investment costs, including pre-production, are listed by the company at $62 million. Current reserves mean a production life of about four-and-a-half years.

The opening attracted almost 600 people, including top officials of Noranda Inc. (TSE), which, through Kerr Addison Mines, controls Minnova. Also attending the ceremony, staged outdoors at the mine site under a hot, July morning sun, were federal and Quebec government officials.

Situated in Duprat Twp., the Ansil mine is 20 km northwest of Rouyn-Noranda and 5 km west of Minnova’s refurbished Norbec mill which is being used to process the mine’s ore.

The mill, built in the early 1960s, was not expected to be in operation past the end of that decade, let alone the late 1980s. The three area Minnova projects the mill has already served are the Norbec, Millenbach and Corbet mines. Until recently, the mill was treating ore from the area’s polymetallic Mobrun mining project, in which Minnova has a 30% interest.

According to Minnova geologists, the Ansil deposit lies at the contact of the northwest rhyolite and the Rusty Ridge andesite. The ground includes numerous series of andesitic and rhyolitic volcanic rocks of the Blake River group, with a general north-south strike and a dip of 35 degrees -50 degrees to the east.

The deepest of its kind to be discovered in the Rouyn-Noranda area, the deposit sits at a depth of between 1,200 m and 1,500 m. The mineralized zone has a strike length 100-400 m north-south and 350- 400 m along dip. The massive sulphide deposit consists of a core rich in copper (chalcopyrite) and an edge with a high zinc (sphalerite) content.

Current reserves are estimated to be 1.59 million tonnes averaging 7.22% copper. 0.94% zinc, 26.45 g silver per tonne (0.77 oz per ton) and 1.59 g gold per tonne (0.05 oz per ton).

The primary mining method employed is long-hole stoping and backfilling using a mixture of waste rock and cement. The secondary method is mechanized cut and fill and backfilling with waste rock. Minnova has been hauling ore from the mine to the Norbec mill since May. Mine manager Jean Desrosiers said more than 18,000 tonnes of material were treated at the mill in May, and more than 13,000 tonnes in June. Scheduled is mine production of 1,900 tonnes per day based on a 5-day week, and mill throughput of 1,350 tonnes per day based on a 7-day week.

Including maintenance and administration, the mine has a payroll of 200 employees.

The Northern Miner participated in an underground tour the day prior to the official opening, the inspection including a walk along a drift on a sub-level between the 9th (at 1,340 m) and 10th (at 1,400 m) levels. The drift was being driven into the orebody in preparation for production drilling and stope development.

The mine’s main shaft was sunk to below the 11th level, the deepest working level which sits at a depth of 1,460 m. A ramp serves the bottom half of the mine, from the 7th to the 11th level. A ventilation shaft, featuring three fans delivering 150 cu. m of air per second at low pressure, also acts as an emergency escape route.

All ore and waste material will be hoisted via the main shaft. The day of the tour, the crusher lay dormant at its 11th level resting place, the ore pass not yet fully open. Mine superintendent Roger Fortin said one small blast remained to free the passageway, a job expected to be completed not long after the official opening.

Speed of the hoist, which can carry a maximum load of 32,000 kg, is 700 m per minute.

A garage has been built on the 9th level for the maintenance of underground equipment. The heat is noticeable at that level, and on the day of the tour, the temperature in the garage was reported to be about 30 degrees C (86 degrees F). Surface temperature that day was 32 degrees C (90 degrees F).

Minnova continues to actively explore the area for a fifth copper project. The Ansil deposit was discovered in 1981. Minnova optioned the property from Ansil Resources, which retains a royalty interest.

Copper concentrate from the mill will provide an additional source of feed for Noranda’s Horne smelter at Rouyn-Noranda. Zinc concentrate will be shipped to Noranda’s zinc reduction plant at Valleyfield, Que., near Montreal.

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