Published in June 2007 Australian Longwall Magazine

Working under unsupported roof is one of the biggest physical hazards to underground coal miners, but a team from Centennial Coal’s Myuna bord and pillar mine and engineering firm Macquarie Manufacturing devised the Hydraulic Advancing Temporary Support (HATS) system to make the process safer.

In a bord and pillar mine, the hazard arises when a continuous miner becomes disabled and timber props are installed to allow miners to carry out the repairs under the unsupported roof.

In New South Wales alone, in the last 10 years there have been seven fatalities due to roof or rib falls.

Myuna mine manager Terry O’Brien told Australian Longwall Magazine the HATS system is a revolutionary solution to a fundamental problem that has existed since mining began.

The system is inexpensive, quickly assembled and also reduces the time taken to access a disabled continuous miner, reducing the recovery time and the machine down time.

“It allows a series of commercially available and lightweight hydraulic [water] roof props to be remotely installed from a safe location, permitting temporary roof support to be installed while eliminating the requirement for mine workers to be exposed to unsupported roof,” O’Brien said.

Myuna mine deputy Steve Screen and mine operator Bill Grundy presented the innovation at the recent NSW Minerals Council Mine Safety Conference. They were part of a team who devised the original idea for the system; the team then engaged Macquarie Manufacturing to design and manufacture a full-size working model which was trialled, reviewed and successfully implemented.

The system has been operational at Myuna Colliery since late 2006, and recently took out the prestigious NSW Minerals Council Mine Safety Innovation of the Year Award.

“The award is a testament to Centennial’s safety commitment, from the management to the coal face. We would like to thank Centennial for their support and ongoing commitment to their workforce,” Grundy said when accepting the award.

“The HATS system won because it is a simple solution to one of the greatest physical hazards associated with underground mining … it has the potential to save lives and is transferable across mining and other industries.”

A prototype of the HATS system has been developed for use on a longwall face and is already being trialled at Centennial’s longwall mines.

“The first hydraulic prop is set to the roof under a supported roof environment and the HATS advancing mechanism is attached to a bracket on the first prop. A second prop is attached to the extension arm part of the advancing mechanism. The second prop is then pushed out under unsupported roof the required distance (eg 1–1.5m) and set against the roof using mine water pressure. The advancing mechanism is then detached,” O’Brien said.

“The process can then be replicated for as many props required for the distance of the unsupported roof to be temporarily supported (eg to set the third prop the advancing mechanism is attached to the second already installed prop).”

The main safety advantages of HATS address the three key areas of manual handling, behavioural safety and risk management principles.

“Firstly the design includes lightweight components to ensure the risk of manual handling was not introduced as a result of this innovation … significant effort and research was put into the lightweight design of the advancing mechanism and the physical constraints of the hydraulic props,” O’Brien said.

“Secondly the process of setting timber props can be slow and heavy work – there may be a chance a mine worker may venture out under unsupported roof to deal with the problem rather than go to the effort to set the timber. The quick and lightweight HATS system reduces the probability that this will occur.

“Thirdly the HATS system introduces a system that positions a mine worker under supported roof while they are remotely installing temporary support, reducing the probability that they will be exposed to unsupported roof and the consequence if there is some failure of the roof.”

O’Brien said the system is transferable across all mining and other industries such as tunnelling, civil, building and rescue where there is a requirement to make an unsupported structure safe.

The HATS system was also the winner of the Safety Award at the 2006 Centennial Coal HSEC Conference, and as the 2007 state winner, the innovation is now entered in the 2008 Minerals Council of Australia National Safety and Health Innovation Awards.