McFinley wrestles with temperamental ball mill

The McFinley Red Lake Mines (TSE) project near here, looks like a safe bet to become the first new gold producer in the Red Lake camp for at least 25 years.

After spending about $25 million, the company has outlined a geologically inferred reserve inventory of 890,000 tons of grade 0.21 oz gold per ton. The company is also putting the finishing touches to a 200-ton-per-day milling facility before bringing hydro electric power lines from nearby McMarmac.

But behind McFinley’s blue panelled headframe and milling complex, the company is struggling to cope with severe tune up problems which have brought underground development to a halt.

When The Northern Miner visited the project recently it was left with the impression that success will depend very much on the faith of European investors who are being asked to put up an additional $4 million in working capital.

In a bid to determine what the project’s operating grades will be, McFinley had planned to complete a 15,000-ton bulk sample by late September. The test is vital to a project which has already tested the patience of The Coniagas Mines (TSE) and Phoenix Gold Mines (COATS). They sold their 50% interest last year for $5 million and McFinley is now acting as operator in a joint venture with New York- based junior mines finance house DRX Inc.

“It is difficult for us to assign a sensible figure to the ore grade when the gold is so erratic,” said geologist Steven Ball. “So we decided to build a mill and see what sort of grades we could get.”

However, an over-rotating ball mill has forced project manager John Whitton to shut the mill down and lay off the McFinley underground staff. Impor ted from Sweden at a cost of $75,000, the mill was achieving recovery rates as low as 60% before the decision was taken to press the stop button. Based on metallurgical tests at a Lakefield, Ont., assaying office, McFinley should be able to achieve 93% recovery levels using gravity separation and cyanidation methods.

“When we sent the motor out to be rewound, the guys in Toronto gave us a motor speed of 1,100 rpm when it should have been 1,200 rpm,” said Whitton.

“Since the larger balls were spinning too fast, the grinding circuit wasn’t performing adequately. It was producing too much slime and rejecting all of the oversized ore fragments every time we tried to increase our throughput above 140 tons per day,” said Whitton who is giving himself until next February to get the teething problems sorted out and complete the bulk sample.

If everything goes according to plan, he will use 4,000 tons of development muck to retune the mill following what he called fundamental changes to the grinding circuit.

“I think we could do fine at a grade of 0.25 oz,” said President Bill Cummins who is attempting to arrange terms for a $4-million rights offering through British investment house Kleinwort Grieveson and Co. “A grade of 0.3 oz would throw off a really nice profit and give us enough money to go further underground,” he said.

When The Northern Miner toured McFinley’s underground workings, all development work in six stopes had come to a halt. “There is no point in breaking any more ground until we get the mill up and running,” explained Ball who pointed to some of the cross cutting quartz fractures which are typical of the local geology.

The McFinley orebody is currently accessed via a 400-ft 2-compartment shaft and workings on the 150-ft, 275-ft and 400-ft levels and about 4,000-ft of infill diamond drilling is being completed on the 400-ft level.

But contract miners in the area say that current reserves will only allow the company to operate for a maximum two years and shaft deepening is essential.

If grades prove high enough, Ball said the company would like to mine further north on the 400-level and explore a talc-chlorite- carbonate schist which runs 300 ft east of current mine workings. It is believed to host a number of high grade pods.

Future plans also include refurbishing about 2 miles of powerline and building 2 miles of new lines to connect what is still very much an exploration project to the outside world.

A production decision could mean at least 100 new jobs for a community which badly needs the financial and psychological boost which a new mining operation would bring. But as both Whitton and Cummins readily admit, the value of this project to the local area rests on the results of the bulk test.