Preliminary reports say that over an hour passed before the body of a mine worker killed at the Cadia Ridgeway gold mine was discovered.

The 28 year-old miner died on 6 September 2015.

The investigation has heard he was last seen by colleagues at 9pm, at which time he was working alone with a remote-controlled Jacon Maxijet shotcrete machine.

The machine was being used as an underground water cannon to blast material from a stope down into a draw point.

The report said that a “rapid movement of rock and material from the draw point into the extraction drive” occurred, striking the front of the Jacon and pushing it backwards.

The machine trapped the man against the side wall of the extraction drive.

The preliminary report recommends systems should be implemented to make sure people working alone are monitored more regularly.

It also found that while the risks of sudden movement of material from draw points that are choked or hung up are well known, there needs to be sufficient control measures including bunds to prevent movement of material, safe zones for mobile machine operators, and safe methods for egress in case of incident.

The investigation into the accident is ongoing, and has the full co-operation of mine owner Newcrest.

A full report from the secretary of NSW Department of Industry is underway.