Lihir gold turns green as it bubbles up

15 April 2007 | 12:37 Code : 13343 Geoscience events
Gold mines are found everywhere around the world, throwing up all sorts of....
Gold mines are found everywhere around the world, throwing up all sorts of operating challenges. Among them, Lihir Gold's world-class mine on Lihir Island in Papua New Guinea has had to overcome some of the most unusual challenges.Lihir's 830,000 ounces of annual gold production, located in an inactive volcanic crater that was in part breached by the ocean, comes from super-hot rocks – a legacy of residual geothermal energy.Safe mining practices – groundwater temperatures range from 60 to 200 degrees Celsius – require the ore body to undergo extensive cooling and depressurisation. And it has been that way since mining started in 1997.There is a cost to all that. But in recent years, the company has turned its namesake mine's volcanic legacy to its advantage by capturing the geothermal energy to generate its power needs.Steam released from the ore body by drilling is not simply vented. It is now tapped and used to drive steam turbines.With the recent commissioning of a 20-megawatt geothermal power plant at a cost of $US40 million, Lihir's geothermal power capacity now stands at 56 MW — 75 per cent of total power requirements.The company believes the availability of low-cost power gives it a significant advantage, reducing its costs and underpinning the long-term potential for annual gold production to grow to more than 1 million ounces.The development of geothermal power got going in 2003 with the construction of a six MW plant. That was followed by a 30 MW expansion in 2005.The development of the geothermal capacity means that the company's consumption of heavy fuel oil (HFO) has been slashed.Lihir estimates that geothermal power will save it $US40 million ($A49 million) in 2007.At US1¢ a kilowatt hour, geothermal power compares well with US12¢ a kilowatt hour for HFO-generated power.Once the new plant is fully commissioned, Lihir expects to generate as much as $US5 million a year from the sale of carbon credits on global markets, giving Lihir's gold a green tinge.

tags: QAZVIN

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