Underground mine refuge chambers have proved to be a safety haven after an ammonia leak in an underground mine in New South Wales last week.
The leak occurred when a maintenance contractor was conducting commissioning checks on an ammonia plant for the mine’s bulk air cooler that feeds cool air into the mine shaft.
The bulk air cooler was being recommissioned in preparation for the summer season. During the commissioning, a leak occurred between the ammonia system and the water-cooling system, allowing ammonia to bleed across a failed gasket.
Some ammonia passed into the mine air cooling water and ammonia was smelt in the ventilation underground.
The intake airway sensor recorded no detection of ammonia, and the underground workers were sent to refuge chambers.
“When maintenance commissioning activities can have inadvertent or unintentional safety or health ramifications it is recommend a specific risk assessment be carried out to identify what can go wrong and implement relevant controls prior to the commissioning activities,” the NSW Resources Regulator said in response to the incident.
“Where plant has been decommissioned for a period of time, consideration should also be given to potential degradation of components from age and being idle.”
Safety pods and refuge chambers are common in underground mines in Australia, with their critical function being to shelter workers in an emergency.
These chambers are either externally supported (wired to infrastructure on the surface) or self-sufficient. In the latter case, these chambers can support themselves for up to 36 hours – well within the timeframe typical for an underground mine rescue.
Refuge chambers are critical components of safe underground mining practice. In March, 28 workers made it so safety thanks to refuge chambers after a mine collapse in Ballarat.
Refuge chambers are typically equipped to provide clean air, water, humidity control, power, a communications link to a control centre, gas-monitoring equipment to measure air quality within chamber, first-aid equipment, a toilet, and food.
In the case of the NSW mine’s ammonia leak, all workers were able to take cover in the chamber until it was established there was no safety risk.
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