In a low-price environment, when second-quartile producers just aren’t good enough, many mining companies are forced to persuade bankers that their mines can still make money. The process is doubly hard for exploration companies trying to promote properties for development.
One such company is
The copper-molybdenum project, which is envisaged as an open-pit/heap-leach operation, suffered a blow earlier this year when
At that time, the property had undergone only a preliminary prefeasibility study, which concluded that a mining operation could break even at US73 cents per lb. of copper — not an easy sell considering that prices have been hovering in that range for several months now.
The study forecast a cash operating cost of US60 cents per lb. However, William Lane, General Minerals’ vice-president of engineering, says the company wants to prove it is capable of reducing costs to below that level before committing to a final feasibility study. And on a recent visit to the property, The Northern Miner learned of the company’s plan to spend US$250,000 on metallurgical tests to reducing operating costs to as low as US43 cents per lb.
The tests are partly aimed at increasing the copper recovery by 15%, which is expected to knock 4 cents off the cash costs. The prefeasibility study used a 50% recovery based on preliminary leach test (using sequential analysis) on the oxide and secondary enrichment ores. Typical recoveries varied from 26% to 62%, though the higher percentage recoveries were obtained from samples collected near the surface.
Vizcachitas is nestled in the valley of Rio Rocin, where the walls of the canyon have just enough room to accommodate an open pit. Lane expects that much of the mineralization on the flanks of the pit, though of lower-grade chalcocite ore, could be mined early. “Including this material in the mine plan would bring the stripping ratio to 0.5-to-1,” he said.
Within the core of the deposit, near a river, the company has outlined a higher-grade blanket of secondary enrichment grading up to 1% copper.
General Minerals is evaluating the partial leaching of sulphide concentrates as a way of lowering cash costs by as much as 6 cents per lb. Partial leaching would allow a greater proportion of copper cathode to be produced on site and thereby avoid costly smelter charges. The company is also investigating technologies that would allow the concentrate to be completely leached; if this can be achieved, cash costs could be dropped another 6 cents per lb.
Meanwhile, General Minerals is looking at ways to improve the grade of the concentrate to 35% from the 29.6% outlined in the prefeasibility study. Such an improvement could reduce costs by a further 3 cents.
Electrical power was originally budgeted at 5 cents per kilowatt-hour, though the company is confident this can be reduced to 4 cents, which would push down cash costs by an estimated 2 cents per lb. (Other mining projects in the region pay 4 cents per kilowatt-hour.)
General Minerals is considering increasing throughput as another way of trimming cash costs. The prefeasibility study considered only half of the resource when it established a throughput rate of 60,000 tonnes per day (30,000 tonnes for the mill and 30,000 tonnes for the leach pads). Subsequent drilling later expanded the resource to 1.1 billion tonnes grading 0.42% copper and 0.014% molydenum, up 58% from the previous estimate. With a larger resource, Lane says, the mine could operate at 90,000 tonnes per day (45,000 tonnes for the mill and 45,000 tonnes for the leach pads) without reducing the proposed mine life of more than 20 years.
To date, the company has drilled 67 holes totalling 18,300 metres. Further definition drilling is planned, as is large-diameter drilling for metallurgical testing, all of which will be incorporated into a final feasibility study that will begin in earnest next year.
Capital costs at Vizcachitas are pegged at US$276 million.
Be the first to comment on "Vizcachitas gets closer look"