JOLU JEWEL Corona has opened La Ronge’s second gold mine.

Hemlo’s David Bell mine it’s not. But like its much larger cousin, the Jolu gold mine, operated by Corona Corp., is expected to make money — and that’s reason enough to celebrate. Located 130 km north of La Ronge, Sask., the $34- million Jolu project is in the tune-up phase, having poured its first gold bar in November. Although Corona owns only 30%, almost every facet of the project bears the corporation’s stamp — first evident when one drives into the staff camp known as Royexville. (Royex Corp was the original parent of International Corona before the two companies merged to become Corona earlier this year). International Mahogany Corp holds the remaining 70% interest in the mine. When The Northern Miner Magazine toured the facility, 2,412 tons of rock had been processed by the mill with only a few start-up hitches, according to Mine Manager Garry Biles. These included a loosened bolt on the main jaw crusher, which was quickly tightened, and a broken shaft on the thickener, which required replacing.

Although still not quite out of the tune-up woods, the mine and mill appear to be meeting original operating parameters. Rated at 400 tons per day, the mill is expected to produce about 50,000 oz of gold per year. Proven and probable reserves of 627,000 tons grading 0.386 oz gold per ton give the mine a 4-year life.

“Our initial recoveries are exceeding our target recoveries of 95%,” John Kazakoff, Jolu’s mill superintendent, said during a mill tour. “To date, we have not experienced any metallurgical problems.” He added, however, that considerably more tonnage will have to be processed before he is confident of the ore’s metallurgical attributes.

A conventional crushing and grinding operation, the mill utilizes carbon- in-pulp (cip) technology and a gravity circuit in the liberation of gold. At the time of the visit, the cip circuits were still being loaded. Feed from the mine is first introduced to a grizzly with a 50-tonne capacity hopper and a 30×42-ft used jaw crusher. The final crushed ore is belt-conveyed to a 400-tonne- capacity fine ore bin which in turn feeds limed rock to the ball mill via belt conveyor. A cyclone pump box feeds five used cyclones, which separate the rock into two streams. The coarse fraction is sent to the jig feed pump, which is part of the gravity- mineral jig circuit.

The jig produces a high-grade gold concentrate in a secured area. About 50% of Jolu’s gold is recovered by this circuit, Kazakoff explained. A peek inside the mill vault revealed four full trays of gold concentrate averaging 60% gold; total contained gold from the jig concentrate is 100 oz, said Biles. Appearing on the low side, the amount of gold recovered by both the jig and cip will dramatically increase as higher-grade feed is introduced to the mill. Currently, the mill is processing development muck averaging 0.15 oz gold per ton, Biles explained.

A thickener tank feeds four leach tanks which, in turn, overflow to six cip tanks. A pregnant solution tank loads the steel wool in the electrowinning cell. When fully loaded, the cathodes, sludge and gravity concentrate are placed in the mill’s bullion furnace for the final pour. Straightforward and simple, the mill was designed by Kilborn Engineering. Considerable used equipment is evident throughout the plant, which saved both partners a tidy sum.

“Construction of the mill began on June 6,” Biles said, noting the relatively short construction time leading to the first gold pour on Nov 15. Other key mill contractors who aided in the quick startup were Linnvale Construction (steel fabrication) and Graham Construction on the concrete work.

Underground, the scene is typical La Ronge-style gold geology. The La Ronge camp has been revitalized following the discovery of the 21 deposit by the Saskatchewan Mining Development Corp. (now known as Cameco) in 1983. Located immediately next door to Jolu, the 21 deposit blossomed into the Star Lake gold mine in January, 1987. At Star Lake, gold is hosted in a vertically dipping pyritic quartz lense within a northeast- striking shear structure.

Jolu’s Rod main and Rod south zones display similar geology. Both are hosted within northeast-striking shears cutting felsic intrusives of a regional pluton. In fact, much of the exploration in this busy area has focused on identifying structures displaying the same orientation, followed by prospecting and surface sampling.

“Gold is mainly associated with pyrrhotite and pyrite, but we do find some VG (visible gold) also,” Richard Kilpatrick, a Corona geologist explained. A ramp driven to the 275-m level provides access. Eight working levels have been developed, Biles explained during a tour of the underground workings. When completed, the ramp will reach the 400-m level.

Following a test mining program on the 95-m level, which removed 29,000 tons of rock, Corona selected a shrinkage stope mining method. “The mineralization in this deposit is erratic and we test-mined across a 1.5-m width,” Biles said. Shrinkage stoping is the best way to effectively handle both deposit constraints. To date, three stopes have been mined out and three are currently being mined. Broken rock underground totals 60,000 tons.

Tonto Mining, which collared the portal, is the underground contractor and is expected to sign a 3-year deal to mine out the deposit. Tonto has been active in the camp, mining at Star Lake and supervising the underground program at the nearby Fork Lakes discovery. All-in costs are estimated at $98.54 per ton, which translates into about $260 per oz of gold. Actual mining costs are approximately $60 per ton. However, final average costs are expected to decline to $218 per oz, Biles said. “Our overall costs are expected to decline over time because we’re mining well ahead of milling. After the mining ends, the mill will still be processing. That’s where the costs really drop.”

Although zone definition is easily done by sight, the geology staff is still kept on their toes as a result of erratic grades and variable widths. In the 110 stope, for example, which displays some of the widest sections in the mine, the quartz vein ranges up to 20 ft in width. In places, additional slashing had been ordered to take out sections of vein left on the stope walls. In one small section of the stope, several tons of excessive waste had been blasted out. Ground conditions appear good with little rock-bolting evident. Biles also noted that few ground problems have been encountered.

The company uses jackleg drills for mining and jumbos for mine development work. In addition, one 5-yd scoop tram and two 2-yd trams are employed to haul rock to surface. A pair of Jarvis-Clark 426 trucks are used on-site.

With the deposit remaining open at depth below 400 m, a shaft may possibly be required for the future. Biles noted that the current reserves will be accessible by decline but did concede that “we’re getting a bit deep for a decline, there’s no question.”

A simple solution will be the upgrading of the current ventilation shaft to one with hoisting capabilities, Biles explained. “If the reserves justify spending the money, we would put a skip in the shaft.” Workers and equipment would still be transported to work stations via the decline ramp. If the need becomes real, a 2-compartment, metal-lined shaft for hoisting and air would be commissioned by late 1990.

By then, of course, Jolu’s mine geologists would have added considerably to the mine’s reserves and to its life. Although the engineering appears geared to a 3- to 5-year life, there remains a chance that Jolu just might be around for a few years longer.