Unintended movement of conveyor boot end unit

September 25, 2017 Tara

Event: Dangerous incident.

Location: Ulan West Operations, near Mudgee, NSW

The NSW Resources Regulator is coordinating a causal investigation into an incident on 29 August 2017 in which seven workers sustained minor injuries during a conveyor extension in maingate 5 development panel at the Ulan West Operations underground coal mine. The purpose of the causal investigation is to enable the full understanding of the causes of this incident.

While the investigation is ongoing, inquiries to date have identified that:

• a software parameter of the dynamic move up (DMU) was disabled on installation, which allowed the DMU to advance while the panel belt loop take-up winch was not powered and this was not identified during the commissioning process

• during the conveyor belt extension on 29 August 2017, and due to an unrelated incident, power was lost to the conveyor drive head, winch and the DMU and the subsequent restoration of power did not restore power to the conveyor winch

• as a result, as the DMU was advancing inbye, an over-tensioning of the belt occurred, causing a failure of a linkage point between the DMU and the conveyor boot end, breaking large steel components. This preliminary report is being issued at this early stage of the investigation in accordance with the regulator’s causal investigation policy. A full investigation report will be published on the completion of the investigation. The mine Ulan West Operations is near Mudgee, NSW.

Ulan West Operations operates one longwall panel (400 m wide) and three development units, of which one has a flexible conveyor train (FCT)/DMU to convey coal from the miner to the section conveyor. The incident At 12.36 pm on 29 August 2017, seven workers were conducting a planned conveyor belt extension in maingate development panel MG5. This process involved advancing the DMU that forms part of a system known as the 4 FCT. This system is used to transfer coal from a continuous miner to the panel conveyor. The DMU advancing process (part of a panel belt extension) includes reducing tension in the panel conveyor belt from its normal operating set-point, and isolating certain parts of the conveyor drive systems. The DMU is then advanced using hydraulic rams, which pulls the boot end inbye and pulls the belt from the conveyor storage unit (commonly known as a loop take-up) located at the conveyor drive head.
Unintended movement of conveyor boot end unit

During the conveyor belt extension and due to an unrelated incident, power was lost to the conveyor drive head, winch and the DMU. The subsequent restoration of power did not restore power to the conveyor winch. As the DMU was advancing inbye, an over-tensioning of the belt occurred, causing a failure of a linkage point between the DMU and the conveyor boot end, breaking large steel components. The release of stored energy resulted in the boot end unit being dragged about 16 m by the belt, impacting on the installed conveyor structure and also the workers who were standing in the area. No-one was seriously injured, however, one worker suffered suspected head injuries and was taken to Mudgee Hospital for treatment. He was released later that evening.

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