The company said a mechanical inspection at the Dendrobium mine project in February had identified a fault on a shuttle car (SC) isolation point when the lockable isolation point was used to enable routine maintenance to be performed.

“A check on the isolation point showed that there was sufficient movement in the isolation device whilst locked to allow power to be inadvertently restored,” the company said.

“It is believed that accidental contact with the isolation point may result in a restoration of power due to the movement of the switch mechanism.”

The operation was stopped immediately and the machine isolated by removing supply plugs. A subsequent investigation found the equipment inspection system did not identify the need to test isolation points in the lockout position for inadvertent operation. It also found that the design of the isolation lock out point as a hard barrier was inadequate.

According to the newsletter, another similar incident at a Queensland mine was not formally communicated to the industry.

Following the investigation, Dendrobium took corrective actions by altering the inspection system to test isolation points for inadvertent operation with locks in place. The information was also communicated to the manufacturer.

“A key learning was that design flaws are occasionally evident in hard barriers,” the company said.

In sharing the incident report with other sites, a similar fault was found at the Crinum mine in Queensland, underlining the importance of near miss reporting and distribution.