The pressure on recovery

As one of the largest coal rich regions in Australia, the main focus within the Bowen basin is to extract the most resources possible.
However, despite the high tonnages of coal being mined, a sizeable amount ends up being lost in tailings dam as refuse.
While there are a number of methods used to extract the value from tailings and run off, such as employing mobile machinery or dredging equipment, both have serious limitations Superior
Coal managing director Ross Garling told Australian Mining.
Another method that is used extensively overseas but not widely in Australia is hydraulic mining.
“This method opens up new opportunities for the recovery and re-process­ing of coal and other commodities,” Garling said.
Currently, Superior Coal is working with South African based Fraser Alexander in joint venture Hydraulic Mining Solutions (HMS) to provide hydraulic
mining and tailings dam management,in particular the recovery of coal tailings.
There is currently about 1 billon tonnes of coal residing in tailings around Australia and hydraulic mining is a way to gain access to this, with the average tailings dam offering around a 50% yield, Garling said.
Hydraulic mining involves cutting dry material with a high pressure water jet of 30 bar within a small area to break up and convert material into slurry which is then allowed to flow along pre-established channel and over a screen to remove debris.
A major aspect of hydraulic tail­ings recovery is safety, with the oper­ator using the machinery from the banks of the dam without dealing with large pools of water.
On top of this, the hydraulic mining process also creates less dust and suppresses that which may be thrown into the air via process.
Typically, the process uses water from minerals processing or salt water which results in a water neutral process.
The recovery system is mounted on caterpillar-type tracks which allows for high mobility and low ground pressure and can be powered by diesel or via an electric system and is remotely controlled by an operator.
While dredging is an effective system, hydraulic recovery overcomes some of the inherent problems faced such as visibility, where operators can not see the face, fluctuating density and transporting the material recovered.
Using hydraulic mining over mobile machinery overcomes the problems that mobile equipment faces such as limited reach from the bank, transport concerns and the fact it is labour intensive, Garling said.
Another factor that hydraulic mining has over the other traditional tailings recovery methods is its ability to be used around existing infrastructure without the risk of damage due to the precision of the jets.
While this method is not widely used in Australia, Garling expects it to increase in visibility as more companies look to extract the maximum value of their tailings.

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