Friday, February 21, 2014

SA-manufactured safety system installed at Mongolian copper mine

An emergency fall-arresting system (EFAS) developed and manufactured in South Africa by conveyance safety solutions provider Horne Group was commissioned this month at a large copper mine in Mongolia.

Horne Group engineers have been on site at Number One shaft at the Mongolian copper mine since early January testing and calibrating the EFAS to ensure that commissioning proceeds on schedule and on time for the Mongolian mining inspectorate.

Commercial production at the mine will begin immediately afterwards.

The EFAS, which is a dual-purpose pro-duct that delivers a safe-stop to a mine cage in free fall and the standard chairing function needed at mine shaft stations, is a radical departure from safety dogs and other devices traditionally used to arrest mine cages under emergency conditions.

The EFAS offers mines the advantage of controlled cage deceleration, and works equally well on wooden and steel shaft guides, as opposed to safety dogs, which do not offer controlled deceleration, and can only be installed in mines with wooden guides.

The EFAS system uses a hydraulic accumulator that operates in combination with Levelok guide clamps – which is also a Horne Group product – running along the shaft guides.

Under failed rope conditions, a valve on the EFAS hydraulic accumulator auto-matically opens to force hydraulic fluid, under regulated pressure, to the system clamps, activating them and bringing the cage to a safe halt.

The accumulator recharges to full pressure each time the cage is stopped at a shaft station.

Mining electronics company Guduza System Technologies, previously known as Grintek Mining Electronics, is also on site at the mine working alongside Horne Group as the South African company responsible for EFAS communications with the winder room.

This communications line must effectively circumvent the accidental earthing to which a mining installation is prone, owing to damp.

Horne Group explains that other cage safety systems have a reputation for accidental earthing and the transmission of false signals that trip the system. Safety dog communication systems in particular have caused transient signals and tripping on so many occasions that many mines have disabled them, electing to use manual communications instead.

To prevent transients in Mongolia, where ambient temperatures can drop to
–30 °C, the EFAS has been fitted with special printed circuit boards. Special oils have also been used in the system power pack and on all lubrication points.

Horne Group GM Rob Allman says the possibility of transient signals on the EFAS has been completely eliminated.

“We have experienced no problems at all during commissioning,” he says.

Concurrent with the commissioning in Mongolia, Horne Group is proceeding with the manufacture of its second EFAS system, ordered by global engineering company FLSmidth subsidiary FL Smidth Peru, on behalf of mining group Minera Aurifera Retamas SA (MARSA), for the San Andres gold mine.

The EFAS for MARSA has been modified to reduce the weight of the externally fitted power pack and to align it with the smaller size of the shaft cage.

Manufacture of the EFAS will be com-plete by the middle of next month, said Horne Group, adding that it will then be shipped and installed on the cage in Peru.

Commissioning is scheduled for May.

“We expect orders for our EFAS to accel-erate rapidly after these installations are commissioned,” says Allman, adding that mines in Canada have shown particular interest in the system.

“We expect a shorter and easier instal- lation process in Peru, and we are confident that orders will begin to flow soon after successful commissioning there,” he says.

Edited by: Martin Zhuwakinyu

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