Eastern Newfoundland welcomes new antimony-mining operation

It may not be gold, or even nickel, but the large deposit of antimony discovered near this air traffic centre could soon be worth $15 million a year to Roycefield Resources (ASE).

Antimony is a brittle, silvery-white, relatively rare metal used in lead-antimony products such as batteries and solder, as well as in plastics manufacturing (in the form of white antimony oxide powder). In Canada, it is produced as a byproduct at Cominco’s smelter in Trail, B.C., and Brunswick Mining & Smelting’s plant in Belladune, N.B. The only primary producer of the metal has been Consolidated Durham Mines & Resources, which operated the Lake George mine in southern New Brunswick. That project was shut down in 1989, however, and the company has since ceased to exist.

That same year, Noranda was searching for gold in the Beaver Brook area near Gander, using antimony and arsenic as indicators of gold mineralization. While gold was not found in economic quantities at the time, antimony was found to be plentiful. Roycefield became involved in Beaver Brook in 1994, gaining a 50% stake in the property before buying it outright.

The antimony found at Beaver Brook is in Silurian greywacke that has been folded and faulted, creating brecciated zones filled with silica and stibnite (antimony sulphide), most likely leached from the nearby granite formation. Commercial-grade antimony has been found over a strike length of 900 metres in the property’s East zone, and a lesser amount has been delineated in the Central zone.

Roycefield has drilled 116 holes for a total of 16,000 metres at Beaver Brook. Drill-indicated reserves in the East zone now stand at more than 1 million tonnes grading 4.62% antimony, bringing total reserves for the East and Central zones up to 1.2 million tonnes grading 4.71% antimony.

Significant drill intersections from 1995 include: 4.67% antimony over 10.6 metres at a depth of 135 metres; 3.32% antimony over 7.7 metres at a depth of 150 metres; 5.84% antimony over 1.2 metres at a depth of 160 metres; and 4.15% antimony over 1.2 metres at a depth of 210 metres.

The deepest intersection to date is 5.42% antimony over 1.2 metres at a depth of 210 metres, which Roycefield geologists believe could represent the top of a new, deeper zone.

Much of the drilling to date has been shallow, although one hole hit mineralization as deep as 600 ft.

“Whether the whole zone, a kilometre long, will go down that deep, we don’t know,” Roycefield President Albert Bourgoin told The Northern Miner on a recent site visit. “But there’s no indication that it does not.” The size and apparent continuity of the East zone have left Bourgoin unconcerned that reserves at Beaver Brook are only drill-indicated (that is, that there are no reserves in the proven category). Although banks normally give chief consideration to proven reserves when judging the merit of a project, Bourgoin is remaining optimistic.

“We believe this ore is very continuous, and the structure it is in is very strong. We hope our prefeasibility study will satisfy the banks, but, if not, we may have to come and do some more work.”

Roycefield has picked up gold values of 1-5 grams per tonne within the zone of antimony mineralization. Core samples from the hangingwall, which is away from the high-antimony zone, returned values of 5-8 grams per tonne. “There is no tonnage tied up with the gold,” noted mine geologist Charles Morrissy. “But we hope to recover, in concentrate, any gold that occurs [in the ore mined]. If not, we will construct some sort of a circuit for gold.” He added that the property’s potential for containing a gold zone will be explored.

In addition to last year’s drilling, Roycefield advanced a ramp by 350 metres and opened up 50 metres of drift to expose the antimony zone on two levels.

“The ore is pretty continuous, and not displaced by a fault or a fold,” said Bourgoin, adding that “we think the mining is going to be relatively simple.” The company plans to build a mill on site, which will employ flotation to produce a concentrate of 70% antimony. The mill will be designed for 500 tonnes per day, which would supply close to 10% of the world’s current antimony needs, though Roycefield plans to produce only 400 tonnes per day for now.

The company also intends to construct a hydrometallurgical plant to produce antimony oxide, a value-added compound used in the manufacture of plastics.

Tentative plans call for the plant to be built on site, so that administration of the concentrator and the hydrometallurgical plant can be shared.

Roycefield’s proprietary process employs a combination of widely used hydrometallurgical systems. Antimony oxide plants in other parts of the world employ roasting, which releases large amounts of sulphurous gases into the air, something Canadian authorities will not tolerate.

Bourgoin said Roycefield’s process is designed to protect the environment.

“It’s a full circuit, where nothing is discarded. The only thing we do is remove the sulphur in the form of elemental sulphur, and that can be either sold, given away or put into the tailings.”

While pure antimony metal is selling for US$3,200 to US$3,500 per tonne, an equal amount of oxide will fetch 20% more. As a result, pre-tax cash flow from Beaver Brook could amount to $15 million a year.

Roycefield can either sell its antimony oxide directly to plastic manufacturers, or accept the offer of a major antimony oxide manufacturer to act as a middleman.

“We have been talking to a couple of large end-users who are willing to buy our product,” Bourgoin said. “One has said it will take 100% of production, one said 50%, but we have not committed.”

He said manufacturers’ business deals with China, the source of most of the world’s antimony, have not always been honored. Consequently, many customers are willing to pay a premium for antimony from other sources.

Roycefield is aiming for a late-1996 startup at Beaver Brook, after which time the mine is expected to last 12 years. The capital cost of constructing the mine, mill and hydrometallurgical plant is estimated at $15 million.

Beaverbrook now employs about 20 miners and seven Roycefield personnel, although Bourgoin says the total will rise to 125 once production is reached.

A wide, all-weather road connects the minesite with the Trans-Canada Highway at Glenwood. Roycefield has asked the provincial government to replace three bridges on the road, the cost of which is estimated at $400,000. The cost of running a new hydro line the length of the road will be about $1.4 million.

A second, inferior road connects the mine site with Grand Falls, and while Roycefield will not maintain the two roads to the mine, Bourgoin said the province might consider doing so, which would give Grand Falls residents the opportunity to benefit from the mine.

The company is now working on its prefeasibility study and applying for environmental permits for its mill and tailings disposal site. Bourgoin does not expect any delays in the permit process.

“This is not an acid-generating project. As a matter of fact, the pH [measure of hydrogen ion concentration] is above 7,” he explained, noting that waste materials will be less acidic than pure water. Referring to the fact that the nearby Gander River is slightly acidic as a result of acid rain, he quipped: “We could argue that we’ll improve the river.”

Roycefield is prepared, however, to install a water treatment plant for the mine’s waste water, if required.