The New South Wales Resources Regulator has published its findings from an investigation into a fire at Newmont’s Cadia gold mine.
On October 5 2021, a worker was operating a loader in the mine underground when he noticed a fire break out near the front left tyre.
The worker activated the fire suppression system, exited the cabin and observed flames around the rear of the loader. While running past the loader’s engine bay to escape the fire, the worker suffered serious burns.
Despite a thorough investigation at the time, the Regulator was unable to establish the source of the fire.
But in 2023 new information surfaced revealing nearly half a tonne of an explosive mix was disposed of by workers in the area a month before the fire broke out.
The disposal process involved cutting open the explosive’s cartridges, emptying the product onto the ground, and the product then immersing in water on the roadway using a water cannon.
The explosive dissolved contained, among other things, ammonium nitrate and cellulose nitrate. Significantly, ammonium nitrate is soluble in water, but cellulose nitrate is not.
Ammonium nitrate will not ordinarily combust when exposed to heat without the presence of another fuel source. However, cellulose nitrate can combust when exposed to heat greater than 150º, which the Regulator investigation revealed was likely reached by the loader through friction.
It’s a timely reminder that explosive control plans are key for Australian mines and must be enforced, with training essential for workers handling or disposing of explosives.
The state Regulator is also currently investigating another explosion at Cadia that took place on July 22 2024 involving polyethylene pipe electrofusion welding.
HDPE electrofusion is a continuing safety concern for industry bodies, and the Resources Regulator’s investigation will aim to canvass the effectiveness of controls to eliminate or minimise the risks to health and safety of workers arising from the practice.
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