In July 2018, a worker was cleaning a decanter when he stepped back through an open grate into an operating screw conveyor, which amputated his foot just above his ankle.
Also in July, a worker’s arm was crushed when it became entangled in the chute of a ribbon mixer. Initial inquiries indicate that the machine guarding was inadequate to prevent a person coming into contact with the mixing blades.
Both investigations are continuing.
Preventing a similar incident
Plant guarding, which may be a shield, cover, or physical barrier, is essential to prevent workers coming into contact with moving parts. Guarding increases safety for operators and others involved in the normal operation, servicing and maintenance of machines.
Conveyors (including screw and belt type conveyors) and augers pose significant risk to workers when moving parts are exposed. Hazards likely to cause injury include:
rotating shafts, gearing, cables, sprockets, chains, clutches, couplings, cams or fan blades
the run-on points of belts, chains or cables
crushing or shearing points e.g. augers and slide blocks, roller feeds, conveyor feeds
machine components which move, cut, grind, pulp, crush, break or pulverise materials.
There are four types of machine guarding:
Permanently fixed guard: used if access to the area of plant requiring guarding is not necessary during operation, maintenance or cleaning.
Interlock guard: used if access to the areas requiring guarding is necessary during operation, maintenance or cleaning.
Fixed guard: used if it is not reasonably practicable to use a permanently fixed or interlocked physical guard or barrier. Fixed guards can only be altered or removed using a tool.
Presence-sensing system/guard: used if it is not reasonably practicable to use a permanently fixed, interlocked or fixed guard.
If any type of guarding is removed for maintenance or cleaning, it must be replaced before the machine is put back into normal operation. Before removing or opening any type of guarding, workplaces should adhere to a strict isolation, lockout and tag-out process. The plant should not be able to restart unless the guarding is in place.
Each year there are about 55 accepted workers’ compensation claims involving a worker being caught in or hit by some sort of conveyor, mincer or auger. Of these claims, 42 per cent involve a serious injury with five days or more off work. This rate is much higher compared to the rate for all workers’ compensation claims, where only around 30 per cent involve serious injuries.
This type of machinery has been associated with 29 amputations over the last six years, mostly hands or fingers, and one in which a worker’s toes were cut off when they were caught in an auger.
Since July 2012, there have been 278 incidents where a worker or bystander was crushed, hit or entrapped by a conveyor, auger, mincer or mixer. Of these, 173 resulted in a serious injury. During the same period, 105 improvement notices, 56 prohibition notices and one electrical safety protection notice were issued relating to conveyors, augers, mincers or mixers.
Prosecutions and compliance
In 2015, a local government was fined $32,500 after a worker’s finger was amputated. A screw auger at a sewerage treatment plant had become blocked and two workers were directed to unblock the waste caught around the shaft of the auger. The auger was stopped and the guard removed to allow the blockage to be removed, but it was restarted while the worker still had his hand in it.
In 2014, a company was fined $35,000 after a worker’s hand was amputated when it was drawn into a nut harvesting auger. He was operating a combined tractor harvester using rotating augers which harvested macadamia nuts from the ground. An accumulation of earth and debris blocked the machinery so he used a piece of fallen tree to try to free the blockage, while leaving the motor of the tractor and the augers in operation. The stick caught and was pulled with the worker’s left hand into the auger.