When a spontaneous heating incident occurred in a Hunter Valley longwall coal mining operation earlier this year, the BOC Customer Engineering Services (CES) team was mobilised.
Within 29 hours BOC had liquid nitrogen on site ready for pumping into the mine. This included the laying of over 80,000m2 of road base to create the road and all weather hard stand.
The operation ran for 28 days, 24 hours a day with more than 1300 hours worked. During this time over 1000t of liquid nitrogen was delivered and tankers travelled more than 33,000km to get it there.
The coal mines in the Hunter Valley NSW have a long history of spontaneous combustion incidents.
BOC has a contract with NSW Mines Rescue to provide operators and liquid nitrogen when the Mine Shield Nitrogen Inertisation equipment is called to respond.
The BOC CES team works alongside Mines Rescue service personnel to ensure all fires or spontaneous heating are extinguished or quickly controlled.
While the mine usually manages spontaneous heating in an underground coal mine internally, sometimes mine personnel are evacuated from the mine or access to the heating is only via a borehole from surface. On these occasions control of the fire or heating can take from weeks to several months.
NSW/ACT regional coordinator BOC CES Greg Allen says during a mine emergency BOC has two skilled operators on site at all times working in 12-hour shifts.
“We place a very high priority on safety and never cut corners,” Allen says.
“Before we begin any operation there is a thorough risk assessment conducted. This stringent policy has meant that we have had no near misses, accidents or incidents in our work with NSW Mines Rescue,” he says.
Mines Rescue has a 50,000L road-transportable storage tanker and hot water vaporiser with control equipment. It also has about 5000m of 6" diameter hose and a 9t LPG road tanker that provides gas to heat the water.
During an incident the BOC operators work with a Mines Rescue service officer who acts as the coordinator between the mine and BOC.
The team operates the mine shield equipment, sets up the equipment and staffs it throughout the operation. BOC is also responsible for organising the fleet of road tankers.
Mobile lighting, site shed, toilet and diesel generators are the mine’s responsibility.
“This is a specialist area. In theory it may sound simple but the Mines Rescue and BOC team has to make decisions when they are setting up that require a high level of skill, determining the lay of the land and the best entry point into the mine,” Allen says.