David Kelly 1991

07/02/1991 - Isa Mine, Mount Mount Isa Mines Limited - Crush Injury / Collapsed steelwork

On the morning of the accident, the sinter plant and blast furnace were shut down and a clean out of accumulated dust accretion in the gas cooler tower was commenced. Three men employed by the contracting firm of Gardner Perrott Pty Ltd and using specialised water jet tank cleaning equipment were engaged on this task. The crew consisted of the deceased, David Anthony Kelly acting as nozzle operator, John Peter Currie, radio communications officer, and Graeme James Knudson, water jet pump operator.

Kelly and Currie were on the platform at hopper level near the bottom of the tower. Kelly was directing the nozzle of a waterjet through an access hatch on the south-west side of the hopper washing accumulated dust from the crash bars above the buhler conveyor. Knudson was operating the water jet pump mounted on a truck parked at ground level in the north-east corner of the tower. Currie was acting as contact between Kelly and Knudson.

As Kelly continued to operate the water jet, the sub-structure supporting the tower began to collapse allowing the tower shell to drop vertically. The hopper at the base of the tower shell struck a concrete wall forming part of the old spray chambers above which the tower had been built. The shell then fell over to the north-east taking the downcomer duct with it and pushing over the steelwork on the north side. On striking the east wall of the old spray chambers and the
ground, the shell of the tower split around its circumference into two parts. 

When the tower began its initial vertical drop, Currie was moving away from Kelly towards the east side of the platform to communicate with Knudson below. He managed to scramble through the handrails and down steps to the ground escaping with little more than shock. Knudson was struck by loose falling steel and knocked to the ground receiving cuts and bruises. Kelly did not get clear. His body was found among collapsed steelwork in the old spray chambers.

This accident claimed the life of David Anthony Kelly


  • Where communications of a serious import are received, a mechanism should be put in place for ensuring that positive action is implemented without delay.
  • For vessels and ducts in which accretion or attrition occurs, records of the rate of accretion or attrition should be kept and used to determine adequate and regular cleaning or rebuilding intervals. Suitable monitoring instruments should be used.
  • Vessels of this type should be prominently marked with a safe working load capacity. 
  • Consideration should be given by operating companies that the design, construction and modification of major structures be signed off by a qualified structural engineer.