Porgera ships first gold, raises production target

International mining company Placer Dome (TSE) recently made the first shipment of gold bullion to refiners from the newly commissioned 1,650- ton-per-day first-stage plant at the Porgera mine in Papua New Guinea. The company has a 22.7% interest in the mega-mine project which it operates through its 75.8% owned subsidiary, Placer Pacific of Australia. Porgera, in mountainous terrain in the Western Highlands some 370 miles northwest of Port Moresby, represents one of Placer’s most ambitious and challenging projects undertaken anywhere in the world.

The plant was completed and commissioned on schedule, and construction of the next stage of the plant is scheduled for completion in the third quarter of 1991. The final stage of the US$1-billion project is scheduled for completion by the end of 1993.

Currently, ore from the underground mine is being treated in the plant to produce both a gravity concentrate from which bullion is produced by direct smelting, and a flotation concentrate which is further treated by a conventional carbon-in-pulp process. In the later stages, a pressure oxidation plant will be added to process sulphide concentrates.

A revised production schedule was recently announced for the project which is expected to take its place eventually as one of the top six gold producers in the world.

The mine is now targeted to produce more than 900,000 oz. gold per year, up from 800,000 oz. previously estimated, over the first six years of the mine life at an average cash cost of about US$105 per oz. (in 1990 terms).

The cash cost of production over the estimated 18-year life of the mine is projected to be about US$150 per oz. in 1990 terms, and the mine is targeted to produce over 11 million oz. of gold based on current reserves.

A revised minable reserve was also announced (subject to further revision for the open pit) of 56 million tons at an average grade of 0.22 oz. gold per ton, compared with 66.2 million tons grading 0.19 oz. reported earlier. Underground reserves are estimated to be 7.3 million tons grading 0.71 oz. and open pit reserves are reported as 48.7 million tons grading 0.15 oz.