High potential incident | IncNot 0036237
Summary: A significant gas push from an active longwall goaf tripped power and forced the evacuation of an underground coal mine (under trigger action response plans [TARP] conditions). The gas appeared to come from a roof break in the goaf. Peak gas readings were 3.7% in the tailgate and 1.9% in the bleeder return heading. The longwall had pre- and post-drainage and the mine increased its post drainage suction after the event to manage the gas levels. The mine followed all withdrawal TARPs at the time of the event.
Recommendations to industry: Effective gas drainage and main ventilation systems are essential for the control of gas and the safe operation of coal mines.
Withdrawal TARPs must be enacted immediately after alarms have been activated. Mines should identify, through a risk assessment, all events that would require withdrawal of workers from the mine.
High potential incident| IncNot 0036250
Summary: A substantial amount of rock fell from a low wall in an open cut mine, hitting an excavator. The excavator was not being operated at the time of the incident and no workers were in the vicinity at the time the incident occurred.
Recommendations to industry: Operators and supervisors should be trained in geological hazard identification and must implement effective controls including, but not limited to, installing catch berms, water management and set-back distances for parking up machines. The minimum controls implemented must be defined in the principal hazard management plan (PHMP) taking into account the level of risk.
Dangerous incident | IncNot 0036275
Summary: Operators were fault finding on an Airtrack hydraulic circuit. Upon repressurisation of the load sense circuit (about 25 Bar standby pressure), an operator was hit in the neck by a quarter inch hydraulic hose and was covered in hydraulic oil. The operator was cleared of any fluid injection injuries.
Recommendations to industry: Mine operators are reminded that when equipment is being tested after maintenance and repairs, effective no standing zones are to be put in place that remove workers from the line of fire should a failure occur. Review our safety alerts, bulletins and guides on this topic:
SB13-01 Fluid injections result in surgery
SB12-03 Fluid power isolation failures
SA06-16 Fatal high-pressure hydraulic injection
SA09-04 Hydraulic injection near miss
MDG-41-Fluid-power-systems
MDG-40 Guideline for hazardous energy control
Dangerous incident | IncNot 0036300
Summary: While installing a roof support on the longwall installation face, a fitting failed on the power take off (PTO) manifold block resulting in the fitter being sprayed with Solcenic oil. The fitter was standing about 50 centimetres away at the time of the fluid release. The procedure identified controls that would remove people from the area, however these were not implemented.
Recommendations to industry: When tasks cannot be completed in line with the procedures provided, workers must stop the task and, in consultation with their supervisor, implement addition controls to maintain an equivalent level of safety. The recommendations from IncNot0036275 (above) must also be considered.
Dangerous incident | IncNot 0036240
Summary: A PTO supply hose failed during a longwall installation. The hose was installed and pressurised for about five minutes before it failed. The failure occurred at the ferrule and was a clean break. No-one was hit by the release of fluid. The hose was sent for testing to determine the cause of failure.
Recommendations to industry: With any equipment failure, the mine has an obligation to determine the cause to ensure a reoccurrence does not happen. The use of metallurgical specialist to assist mine personnel to determine causes is one method mines have of ensuring this is done thoroughly.
Dangerous incident | IncNot 0036277
Summary: An electrician was about to start investigating a fault on a magnet within a coal handling and preparation plant. He touched the magnet control panel located in a switch room and felt a shock across his chest. His other hand was touching earth.
The investigation identified the fault to be in an adjacent braking resistor panel that was connected to a variable speed drive (VSD). Following consultation with the original equipment manufacturer (OEM) it was identified that resistance between the braking resistors and earth was low and the cable earthing was incorrect for the installation. The resistors were replaced, and the cable earthing was corrected.
Recommendations to industry: Workers should not experience electric shocks when conducting any form of work. AS/NZS 3000 requires all exposed metallic parts and panel lids to be earthed. Mines should ensure maintenance practices are suitable for the application and ensure cable earthing associated with VSDs meet the manufacturer’s specifications. Read our Safety Bulletin SB11-04 Electrical hazards associated with variable speed drives and earth fault current limited systems.
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