Official reopening of Youanmi's underground mine

11/11/94

A world first for the gold mining industry will occur in the Murchison region today as Youanmi's underground mine officially reopens using a revolutionary new processing operation.

Resources Development Minister Colin Barnett said the opening marked the world's first commercial use of a special bacterial leaching process.

This process was developed in Western Australia to extract a maximum amount of gold from the $23 million Youanmi Deeps underground mine, 100km south-east of Mt Magnet.

"This innovative technology looks set to revolutionise the mining industry," Mr Barnett said.

"Not only is this process environmentally sound but it has been adapted by a Western Australian company especially for Australia's harsh conditions.

"The development of this technology and the move to underground mining looks set to breathe new life into the project."

The official reopening of the Gold Mines of Australia mine is the fourth for Youanmi over the past century.  Underground operations at Youanmi ceased in 1942 and the open-cut operations were exhausted in 1992.  The BacTech (Australia) Ltd system has now provided a cost-effective way to treat Youanmi's sulphide ore.

"Youanmi is not only leading the way in resourceful mining practices but underscores the growing confidence for the future of the State's underground gold mining operations," Mr Barnett said.

The Minister said testing of the process indicated that gold recoveries of more than 90 per cent could be achieved.  He said this landmark process could be adapted in the future for such other resources as silver, nickel and copper.

Bacterial oxidation is a process where sulphur ore is treated with special bacteria to separate the gold from the sulphur.  After crushing, grinding and flotation of the ore, the gold concentrate is pumped into bacteria-filled tanks.  Once the bacteria have separated off the sulphur, the gold concentrate is then put through the standard process to extract the final gold bullion.

Mr Barnett said the new system was used instead of the traditional roasting process and eliminated the release of sulphur dioxide into the air.

BacTech is similar to a bacterial leaching system used at such mines as Wiluna but is based on the use of higher temperatures and saline instead of fresh water, which the company believes is a far more cost-effective system for Australia's harsh conditions. Gold Mines of Australia employs more than 95 people at Youanmi and is confident that increased mining operations due to the efficiency of the BacTech process will allow the operations to expand in the future.

The Minister said that last year Australia was the world's third largest producer of gold after South Africa and the USA, producing more than 240 tonnes.  Three quarters of this was mined in WA.

For only the second time in the past 20 years, gold surpassed iron ore as the State's most valuable mineral commodity with the value increasing by more than 20 per cent to $3.14 billion.

Media contact: Carolyn Vicars 222 9699