New technique halves ventilation costs

A new twin-shaft ventilation system, developed by Craigs Mining Services, has reportedly halved the cost of upgrades at Forrestania's Flying Fox Mine in Western Australia.

A new twin-shaft ventilation system, developed by Craigs Mining Services (CMS), has reportedly halved the cost of upgrades at Forrestania’s Flying Fox Mine in Western Australia.

The miner was looking to increase the primary ventilation in the tunnels from 140 to 220 m3 per second.

Normally, this would require a single 4.5 m diameter vertical concrete shaft, sunk 50 m into the ground.

However, CMS consultants determined that two 2.7 m diameter parallel shafts would instead provide the required volume of air, as well as additional cost, maintenance and safety benefits.

Each shaft would effectively operate independently, with one offering a similar flow to the original system.

Furthermore, the company said its innovative steel shaft sinking technique made it possible to install the shafts at around half the cost of conventional systems.

The system comprises a series of telescoping steel cylinders, which are progressively lowered into the shaft and welded into place to provide a continuous lining.

According to Flying Fox Mine underground manager Duncan Sutherland, sinking two shafts did not take any longer than sinking one large shaft by conventional methods.

“Because there is no exposure to the rock wall, it’s probably inherently safer as well,” he said

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