Industry Safety Bulletin, News, Underground operations

Maintenance error behind continuous miner accident

Continuous miner

Continuous miners are critical assets in many mining operations, particularly in the coal sector, but they can also be dangerous.

An industry watchdog is calling for caution during maintenance of continuous miners after three high potential incidents on Queensland coal mines in the last 12 months.

Each incident involved the ejection of a cutter head stop pin from a continuous miner.

In one instance, the coal mine worker was struck directly in the chest. In the second, the worker was struck on the elbow. In the third incident, the ejected pin hit a rib pillar at the mine.

“In the incidents involving personal injury the coal mine workers were transported to hospital,” Resources Safety and Health Queensland said. “Medical examination indicated severe bruising but no long-term injury.

“These incidents are concerning because while there were no long-term injuries, there was the potential for a fatality.”

In each of the three incidents, the continuous miner was stopped for maintenance. This required resting the cutter on the head stops before works could be conducted. In each case, the safety pin had not been inserted all the way and the weight of the cutter head was acting on the tapered area of the pin, causing the pin to eject.

Looking at the incidents individually, the regulator found:

  • in some instances, both left and right-side head stop pins were not fitted before lowering the head, with only one pin fitted on one side
  • the head stop pins were not pushed fully into the correct position
  • in one case, the head stop pin was bent and would not go all the way through
  • in another case, the locking pin safety tabs were missing
  • excessive hydraulic force used to power the boom down onto the clevis pins resulted in bending of the head stop pins.

The regulator recommended developing a safety procedure in consultation with the original equipment manufacturer (OEM) for installing and using stop pins.

According to the regulator, sites should:

  • ensure procedures require both head stop pins be fitted
  • ensure risk management tools are used and exclusion zones have been considered
  • include recommendation and specific detail regarding the use, or non-use, of retaining plates
  • consider using longer pins with OEM consultation
  • ensure both pins are pushed all the way through when used
  • slowly lower the cutter boom onto the stops, do not shear down heavily
  • review existing OEM face equipment safety notices to ensure that any recommendations are included in safety & health management system and maintenance system
  • ensure suitable boom safety stop clevis inspections are included in plant inspections.

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