Safer shaft lining

A ROBOTIC shotcrete shaft liner is helping to reduce the danger involved with shotcreting, keeping workers out of the firing line.
Safer shaft lining Safer shaft lining Safer shaft lining Safer shaft lining Safer shaft lining

The Coppabella coal mine in Queensland's Bowen Basin supplies 30% of the global pulverised coal injection market.

Staff Reporter

Macmahon Underground has developed the robotic shaft liner at its Western Australian workshop, to reduce the hazards associated with spraying shotcrete lining.

The robotic shaft liner has been designed to spray shotcrete linings in vertical or inclined shafts. It has an onboard scanning system to assess the thickness of the final shotcrete lining, while infrared cameras allow operators to monitor the spraying remotely.

Macmahon Mining Services operations manager Rory Burke said mining companies were increasingly being required to line their shafts, in order to increase the service life and safety of their mines, and to allow for raise boring in poorer rock conditions.

This has led to an increasing requirement for a better way to control the risks of working around open holes.

In developing the robotic shaft liner, Macmahon undertook an extensive review of the shotcrete shaft lining equipment available around the world, and conducted an analysis of the risks involved and how to mitigate them.

Macmahon’s robotic shaft liner consists of four main components – a robot that is lowered down the raise, a winch deck sitting at the collar of the hole, a dry shotcrete machine that enables pumping of dry material to the robot, and a control room.

The robot is lowered into the raise from the winch deck using a hiab crane and moveable boom, which allows the robot to be centralised in the raise correctly. Dry shotcrete mix and water are fed through separate hoses to the robot, where they combine at the nozzle before being sprayed onto the walls.

Because of the way the system is set up, there is no need for personnel to come within 1.5 metres of the hole collar, reducing the risk of people falling. All hoses are run through a fully enclosed channel on top of the boom. The water hose is on a reel at the rear of the winch deck, and the that runs through a set of rollers at the rear of the deck. This lowers the risk of injury to people working around the moving lines.

The robotic shaft liner was first put to work during the commissioning project at Barrick Gold’s Fairyland mine in Western Australia. It has since been used at the Carborough Downs Joint Venture coal mine in Queensland, Straits Resources’ Tritton copper project in New South Wales, Ramelius Resources’ Wattle Dam gold mine in WA and Newmont Mining’s Jundee gold operation in WA.

Jetcrete Australia is another company that deploys a remote control shaft lining system. Indeed, the Jetcrete offering has been around for several years.

One of the key problems with such shotcrete applicators is the nozzle jamming. Jetcrete beat that problem by putting dry shotcrete down one line and water down another – the same sort of approach Macmahon has taken with its applicator.

The Jetcrete robo-shotcreters also are fitted with cameras, which can survey the shaft before and after the shotcreting.

Published in the November 2009 Australia’s Mining Monthly

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