The workers observed roof strata dribbling after scaling the area. 

They waited to assess the area before moving in to bolt the location.

The Queensland Mines Inspectorate said no injuries were sustained by the workers in the fall of ground.

"The fall blocked the primary means of egress leaving only one escapeway from the mine available for use," it said.

"The fall dimensions were approximately 3m long, 3m high and the full width of the roadway.

"All personnel inbye of the fall were withdrawn from the mine via the man winding shaft."

Immediately following the fall, the underground part of the coal mine was placed under a directive to suspend operations for an unacceptable level of risk.

Limited access was permitted to the inbye side of the fall via the man winding shaft to allow for statutory inspections to continue.

Limited access was also permitted in the drift to allow for a specialist crew to recover the fall.

An independent geotechnical engineer provided advice to the site senior executive and underground mine manager to determine the cause of the support failure and the subsequent strata fall as well as develop an appropriate staged plan for the recovery of the fall.

The area where the fall occurred had been heavily reinforced at the time the drift was driven, some 50 years prior. Over time, in this case several decades, the reinforcing steel liner and steel set had rusted to the point of failure.

"The mine operator should ensure that the SSE and UMM at their underground coal mines review their Strata Control Principal Hazard Management Plan to ensure this is effective to prevent any potential for a similar incident," the inspectorate said.