Teck/Corona mining to the max in Hemlo

It’s full steam ahead in 1987 for the Teck/Corona gold project here in the booming Hemlo camp. Though still in the development stage, the David Bell mine is already contributing to Teck’s and Corona’s earnings, according to mine manager Ruston (Rusty) Ford.

“Income from the mine is definitely improving as underground development contines” he told The Northern Miner. “In April we will be up to our rated capacity of 1,000 tonnes (1,100 tons) per day, grading 0.37 oz gold per tonne. We’re very close to it now, having been producing 936 tonnes per day (51 tonnes per hour) for the past four months.” By comparison, the average mill throughput for the previous fiscal year was 556 tonnes per day.

For the period October, 1986, to January, 1987, a total of 115,119 tonnes was milled, grading 0.327 oz gold per tonne. With a recovery of 94%, 35,483 oz of gold were produced during the period.

The joint venture is owned 50/50 by Teck Corp. and International Corona Resources, with Teck as operator.

Much of the underground development program has been financed from limited production on the upper levels (N.M., Jan 26/87). That development included shaft completion to a depth of more than 3,800 ft and drifting to the west on the 2,400 ft and 3,400 ft levels toward the main production area. Grade is highest on the west end of the property.

“The strategy has always been that ore could be developed on the first three levels far sooner than it could on the lower levels,” chief geologist Paul Bankes explained. Accordingly, ore began to be developed near surface shortly after the shaft passed the third level and while shaft-sinking was ongoing. The upper-level stopes were put into production to generate millfeed until the lower-level stopes could be developed.

Over the past three months about 30% of production has been coming from the No 7 (2,400 ft) level, which is the main production horizon, Mr. Banks said. “In January for example, we produced 7,000 tonnes off the No 7 level and 20,500 tonnes off the upper-level stopes.” Stoping in July

Development of the No 7 level is now complete and stoping is scheduled to begin in July, Mr. Ford said. He added that the No 10 level (the main haulage level should be completely developed by the end of May – about the same time the crusher station is expected to be installed. Also, development of the No 8 level, which has just passed through the diabase dike, is expected to have reached the ore zone within the next month.

Cut-and-fill stoping is used on the first three levels because of the dip and the narrowness of the orebody near surface, Mr. Bankes said. But he added that this method will eventually be discontinued, to be replaced by long-haul mining on the lower levels.

“We will be producing from the Lower A zone (the lower levels) starting in July and on for about another 10 years,” Mr. Ford said.

The current budget calls for an expenditure of $90 million to bring the mine into production. To date, however, the project is under budget with only $80 million having been spent.

Mineable reserves stand at 6.1 million tonnes grading 0.36 oz gold per tonne. That doesn’t include the West zone (see map), which Mr. Bankes said will not become a source of production in the immediate future.

In addition, Teck and Corona share a 50% net profits royalty interest in a quarter claim optioned to the Noranda group, which has developed an adjoining property (sse map). Mineable reserves here are 2.1 million tonnes grading 0.40 oz gold per tonne.