Gold mining in PNG – when geothermal heat is a challenge
Lihir Gold Mine, Papua New Guinea - geothermal plant to the left side (source: Newcrest Mining)
Alexander Richter
22 May 2021
Dealing with high temperature ground at the gold mininig operations on Lihir Island in PNG is a challenge, as described by German company Bauer, yet it also provides electricity to the 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 open-cast mines for almost 25 years – now from a depth of up to around 300 m below sea level, so an article by German company Bauer on its work for the mining operations.
In the geothermal context, this mine has seen a lot of attention and is often perceived as a role model for renewable energy utilization for mining activities. The Lihir geothermal plant set up for the mining operations of Newcrest Mining on Lihir Island has been producing electricity for a long time.
For a planned expansion of the mine, due to the close proximity to the Pacific Ocean, a waterproof protective wall is required around the new mining area. For this purpose, the planning envisages a 1.8 km long sealing structure with a cut-off wall, which will be integrated into the geothermally active subsoil at temperatures of around 150 degrees C to a depth of 60 m. The two main functions of the cut-off wall: The sealing of the new mining area or the opencast mine against the ingress of sea and groundwater through the cut-off wall and the protection of the mine from the direct inflow of water into the open-cast mine in the event of an extreme earthquake – which leads to the liquefaction of the foundation sediments and thus lead to the failure 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 the client 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 with 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-off wall elements are being produced in geothermally active subsoil conditions with soil temperatures between 120 and 150 degrees C,” explains Gebhard Dausch, project manager at BAUER Engineering PNG Ltd.
The article by Bauer goes into further detail on the concrete work and technology being used, but the key element of a 120-150 degrees Celsius temperature so close to the surface being a nuisance and challenge is incredible.
The work of BAUER Engineering PNG Ltd. started in September 2020 and were successfully completed in April 2021.
Check out the full article below.
Source: Bauer, company release
