Researchers from CSIRO Minerals have developed a new process to decrease copper levels downstream from BHP's Ok Tedi mine in Papua New Guinea.

The process will also increase profitability, by increasing the amount of copper recovered.

The process raises copper recovery by about four per cent, and significantly reduces the amount of heavy metals and sludge released into the Fly River system at the minesite. It should also lower energy consumption and maintenance--and all for a relatively small cost.

Trials at Ok Tedi have gone so well that a processing line which underwent pilot conversion several months ago has been kept operating while full scale conversion of the other parallel line takes place.

The CSIRO Minerals solution is to convert copper hydroxide back to copper sulphide. This is achieved by adding particular chemicals under controlled conditions. "The important trick in getting the process to work is not to overdose the system" says the CSIRO Minerals research team leader, Dr Geoff Senior.

The CSIRO team was able to determine exactly the right amounts by simulating the conditions at Ok Tedi in a small version of an industrial flotation cell set up in the laboratory. They measured precisely the impact of changing the chemistry of the cell mixture. Recovering more copper and gold from ore means less copper and particularly less copper hydroxide finding its way into the river.

OTML Managing Director John Grubb said the outcome of this research was a good example of how a positive environmental outcome could go hand in hand with increased productivity. "We undertook this research initially to look at how we could reduce the level of copper going into the river and ended up with a result that had quite strong economic benefits for the project as a whole", Mr Grubb said.

More information from: Dr Geoff Senior CSIRO Minerals 03 9545 8500, 0419 376 641 or Michael Spencer BHP 03 9609 3137.