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Regulator launches Broken Hill mine fire investigation

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The New South Wales Resources Regulator has launched a causal investigation into the factors that led to an underground mine fire at Perilya’s Broken Hill mine in January.

The fire originally started on Sunday January 12 and was extinguished by the early hours of January 13, but restarted a short time later. It was extinguished for good later that week. All workers were safely removed from the mine with no injuries reported.

The fire started at level 23 underground at the Southern Operations, which is about 980m below the surface.

Workers were using chemical and mechanical ground support to remediate an area in the haulage shaft at the time, due to a wedge failure of rock intersecting the haulage shaft and the level 23 platform.

The chemical ground stabiliser is a two-part chemical classified as a polymeric or polyurethane chemical. When both reagents (typically an isocyanate and a polyol) are mixed, self-heating occurs.

Heating is usually managed through careful application in correct mixing ratios of the chemicals, or by using chemicals that do not significantly self-heat.

During the stabilisation process, workers reported fumes and vapour. All workers who were underground at the time retreated from work areas to fresh air bases and awaited rescue or clearance until the fumes subsided. But the fumes and vapour did not subside, and the area ignited.

Most workers were able to safely exit the mine unassisted, however, five workers stayed in a fresh air base for several hours until it was deemed safe by mine’s emergency team rescue for them to safely retreat.

A preliminary investigation of the incident undertaken by the Regulator did not identify any material breaches of the Work Health and Safety Act 2011, and the Regulator has no intention of conducting any further investigation into any potential non-compliance issues or taking any prosecutorial enforcement action.

A causal investigation team is being developed by the Regulator and will comprise representatives from the Regulator, Perilya, and other stakeholders where appropriate.

The purpose of the investigation is to enable the quick and full understanding of the causes of this incident, and publication of corresponding lessons to industry in a timely manner to reduce the likelihood of a recurrence.

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