The hunt is on for the brazen thieves who used a sewage truck to suck up gold-rich liquid from a Kalgoorlie mine site.



The ABC understands the liquid waste truck, which was reported stolen last week, was backed up to a dam and filled with gold-bearing concentrate at the Kanowna Belle mine, 630km east of Perth.



The value of the haul is unknown, and police are still searching for the truck which belongs to waste collection contractor Suez.

The case is in the hands of detectives from the Kalgoorlie-based Gold Stealing Detection Unit, which has handled gold theft cases across WA for more than a century.

A Suez truck similar to this one was reported stolen from a South Boulder yard on July 24. ( Supplied: WA Police )

Bizarre gold heist baffles locals



Life-long resident Doug Daws, who managed the Kalgoorlie Gold Refinery in the 1980s, said it was one of the strangest gold heists he had heard of.



"I've never heard of anything like it in my life," he said.



"It shows a certain level of inventiveness and it just goes to show gold has an allure that transcends all classes of society.



"Everyone wants a piece ... even if it doesn't belong to them.

"I remember even with all the checks we did at the mint, we still had one fellow who was stealing gold."



The stolen Suez truck should be easy to spot with markings similar to this truck. ( Supplied: WA Police )

Not such a simple getaway for gold thieves

The Kanowna Belle thieves were not driving a typical getaway car, given the bright blue exterior and Suez markings hardly making the truck low-profile.

The thieves would also need sophisticated smelting equipment to transform the concentrate — crushed rock which had been ground down into a sand-like substance — into gold bars.



Smelting is the process of applying heat to ore in order to extract out a base metal.



A freshly-minted gold bar in Kalgoorlie-Boulder. ( ABC Goldfields-Esperance: Jarrod Lucas )

Mr Daws suspected the bandits must have some knowledge of the gold mining process.

"This product from all accounts, if the story is correct, is in a sulphide form and that has another level of difficulty," he said.



"You would have to think the scoundrels who have perpetrated this crime have had some thoughts, knowledge or believe they have some way of processing when people in the industry find it quite a difficult task.



"It would be interesting to see whether they have those sorts of skills or whether it's something they have dreamt up over a beer."



Third time in a year

The latest incident is the third time Kanowna Belle, 18 kilometres north-east of Kalgoorlie-Boulder, had been targeted by thieves in the past year.



A Kalgoorlie man is due to be sentenced in the District Court in October over the theft of an estimated $33,000 worth of gold concentrate.



The 51-year-old has already been convicted of trespassing on the mine site twice and cutting a hole in the security fence.



Thieves have targeted the Kanowna Belle gold mine on other occasions. ( ABC Goldfields-Esperance: Jarrod Lucas )

Another gold thief was jailed for eight months in July after pleading guilty to trespassing on six separate occasions and stealing an estimated $1,600 worth of gold concentrate from Kanowna Belle.



During the 32-year-old's sentencing, Magistrate Adam Hills-Wright suggested it would be almost impossible to prevent thefts from WA gold mines.



"Because of their remote locations, mine sites can never be protected with 100 per cent success," he said.



Northern Star Resources, which owns Kanowna Belle and is Australia's third-biggest gold producer, declined to comment.

The ABC has sought comment from the Gold Stealing Detection Unit, but they were unable to comment at the time of publication.