Senior inspector of electrical engineering, Mine Safety Operations, with the New South Wales Department of Primary Industries (DPI), John Waudby said plant-related hazards were a growing priority.
“Plant in the workplace is involved in too many fatalities and injuries - it is of such concern that a national strategy is being developed for designing safety into plant," Mr Waudby said.
"Plant is used in mines in such a way that there are usually high concentrations of plant in relatively small areas. The situation is compounded in underground mines where the strata puts considerable constraints on the amount of room. Combine this with people in close proximity and the risks increase significantly.
"Plant is getting bigger and more complex. Risks are often transferred from one group of workers to another - an example is remote control and automatic equipment. Operators are generally well clear of plant during production, however, the maintainer and repairer are in close proximity with an increased risk due to the increased complexity of automatic and remote control plant."
Unplanned movements of plant not unusual
Among the dangers are unplanned movements (UMOs) of plant – put simply, the machine starts up unexpectedly. The NSW DPI issued at least three safety alerts dealing with UMOs in 2006, including one investigating the UMOs of a shuttle car and two continuous miners when power was restored to circuit breakers.
There had been problems with the shuttle car's tramming function and the tramming circuit breaker for some time. When the tramming circuit breaker tripped off, the driver left his seat and went to the panel to reset the breaker. The car immediately began tramming and travelled about 10 metres before crashing into the rib. The shuttle car foot switch had jammed in the full “on” position.
The first continuous miner was parked in a Safe Zone for a planned shutdown. When the operator restored power and selected conveyor start, the cutter/conveyor circuit breaker was open but closed suddenly, starting the conveyor, because the control interlock on the circuit breaker failed.
The second continuous miner had tripped off at the distribution control box. When power was restored, the cutting heads operated because the cutting head contactor failed in the “on” position.
Issuing the safety alert, John Waudby said all three incidents "…had the potential to seriously injure or kill mineworkers.".
None of the incidents would have happened if the machinery and control systems met Australian Standards for safe design.
For information on Australian standards relating to this issue, see part two of this article.
