HudBay tackles challenges at Namew Lake nickel mine

The country’s newest nickel mine will produce 12.5 million lb of nickel this year compared with the 15 million lb originally planned.

The reason is a delay in reaching full capacity, now set for some time during the second quarter, mine operator and 60%-owner Hudson Bay Mining & Smelting (TSE) says. The mine and mill, which is located on the south shore of Namew Lake in northern Manitoba, was originally scheduled to be running at a rate of 2,100 tonnes per day in the first quarter. But a number of factors has slowed development rates in the underground mine.

The mill, designed by 40%-partner Outokompu Oy of Finland, was commissioned in November (N.M. Nov. 21/88) and is now running at about 400 tonnes per day. Concentrates are being shipped to refineries in Thompson, Man., and Fort Saskatchewan, Alta.

But production from the underground stopes is not yet up to capacity. As a result, the ore being hoisted from underground is not enough to meet target milling rates.

The delay could mean lower than anticipated pretax profits this year for HudBay, depending on which way the price of nickel goes in 1989. HudBay is a wholly-owned subsidiary of Inspiration Resources (TSE) of New York.

HudBay expects pretax profits from the mine to be about $13(US) million this year. The prediction is based on a rather conservative nickel price of $3.32(US) per lb (nickel traded in London recently at $8.46 per lb) and mining costs of $1.60(US) per lb. HudBay’s share of nickel production is expected to total 7.5 million lbs in 1989.

Factors contributing to the delay include:

A short delay, early in the project during underground development work. Contract miners encountered a water-bearing fault structure in the shaft, but successfully grouted through the zone. What appears to be the same structure, was again intersected in a development drift on the 320-m level at about 100 m from the orebody. Crews have since drifted through the zone but the project was delayed so that a pumping test could be performed on the structure to determine the long-term pumping capacity required to depressurize the system. The mine workings are located below the waters of Namew Lake.

A number of holes were drilled into the structure, piped into a 12-inch manifold and pumped back to the shaft at a rate of about 3,000 gal per min. As a result of the test, HudBay expects to be able to control the flow of water into the workings by pumping at a slightly higher rate. Additional pumps will have to be purchased.

The method of mining at Namew has also slowed development rates as well. Because of the low (45 ) dip of the orebody, HudBay plans to use a mining method called longhole raise mining in the majority of the orebody. Unique to Canada, the method was pioneered at the Vasaria mine in Sweden in the early 1980s. Namew is the only active mine currently using the method.

It requires driving circular raises, 3 m in diameter and about 110 m long, along the hangingwall contact of the ore body, then lowering an electric-hydraulic drill rig down the raise to drill 2-inch diameter longholes through the orebody to the footwall, at right angles to the dip. These rings of holes are then blasted into the draw point below and mucked out using 5-cu-yd scoops.

The first raise has been reamed part way up and no major problems have been encountered. The risks associated with using raise bore machines include the long periods of time required to repair a damaged reaming head and delays in finding a dropped head and re- attaching a repaired head to the drill string.

The electric-hydraulic drill rig, which was custom-designed and manufactured by Tamrock in Finland, has been delivered to the site and is being transported underground.

Additional ore is coming from a drift and fill stope in the narrower, higher-grade portion of the orebody. About 70% of the strike length of this stope has been silled out with some dilution. But higher- grade ore will be shipped from the stope in subsequent lifts as the width of the ore mined narrows.