Gold mining in PNG – when geothermal heat is a challenge
Treating the high temperature soil in gold mining operations on Lihir Island in PNG is a challenge, as described by the German company Bauer, but it also supplies electricity to local mining operations.
One of the largest gold deposits in the world is located on the volcanic island of Niolam, the main island of the Lihir archipelago in Papua New Guinea. Discovered in 1982, the coveted precious metal has been mined here in surface mines for almost 25 years – now to a depth of up to about 300m below sea level, so an article from the German company Bauer on his work for mining operations.
In the geothermal context, this mine has received a lot of attention and is often seen as a model for the use of renewable energies for mining activities. The Lihir geothermal power plant set up for Newcrest Mining’s mining operations on Lihir Island has been producing electricity for a long time.
For a planned mine expansion, due to the proximity to the Pacific Ocean, a waterproof protective wall is required around the new mining area. To this end, the planning foresees a 1.8 km long waterproofing structure with a cut-off wall, which will be integrated into the geothermally active basement at temperatures of about 150 degrees C at a depth of 60 m. . The two main functions of the cut-off wall: Sealing of the new mining area or open-pit mine against the penetration of sea and groundwater through the cut-off wall and protection of the mine against influx direct water to the open air – lead in the event of an extreme earthquake – which leads to liquefaction of the foundation sediments and thus leads to the rupture of the cut-off wall.
Due to the special location of the mine on the geothermally active island of Lihir in Papua New Guinea, BAUER Engineering PNG Ltd., a subsidiary of BAUER Spezialtiefbau GmbH, was commissioned by customer Lihir Gold Limited, a member of the Newcrest Mining Group in cooperation with Klohn Crippen Berger (KCB) – Newcrest’s consultant for the construction of the sealing structure and the cut-off wall – commissioned the execution of two test cut-off wall elements, each with three diaphragm wall slats to a depth of 55 m below the top of the ground. “For the first time in the history of diaphragm wall technology, cut wall elements are produced under geothermally active basement conditions with soil temperatures between 120 and 150 degrees Celsius”, explains Gebhard Dausch, project manager at BAUER Engineering PNG Ltd.
Bauer’s article goes into more detail on the concrete work and the technology used, but the key element of a temperature of 120 to 150 degrees Celsius so close to the surface being a nuisance and a challenge is incredible.
The work of BAUER Engineering PNG Ltd. started in September 2020 and ended successfully in April 2021.
Check out the full article below.
Source: Bauer, liberation from society