The idea behind the operating excellence (OE) program, as it is known, is to identify ongoing production problems that then become the focus of three-to-six month projects. These projects draw on the skills and expertise of people in different functions and roles, across a range of mine sites. Various techniques are used including process mapping, statistical analysis and change management.

Scott Lowe, manager operating excellence for BHP Coal, said, “OE is vital for our business, it will involve our people in solving problems and improving business performance in a way which better serves our customers, and enhances our competitive position”

BHP’s initial analysis of four Illawarra longwall mines in New South Wales – Elouera, Appin, Westcliff and Tower – identified six main project areas. These are longwall; development; coal clearance; gas drainage; logistics/yield; and disabling injuries. ILN will examine each of these issues over the next few months. This week’s overview looks at the work being done around the longwall.

Longwall face roof control has been identified as the major cause of production downtime in the face area. This has translated into a goal to get the maximum available tonnes into the roof for maximum possible roof support. Other identified issues were water and stone related blockages, water management, CH4 and belt delays, and shearer availability.

According to longwall coach Dick King, longwall availability has been significantly impacted by roof control related delays.

“This has had a significant impact on the business and has been one of the chief contributing factors to production problems,” King said in a company newsletter.

King said it was the team’s intention to draw and expand on the lessons gained at the Elouera longwall where the introduction of a high pressure chock pump and monitoring system has provided a substantial improvement in face roof control. The current OE project at Elouera aims to introduce shearer initiation/face automation to improve overall production and roof control efficiency.

At Appin, the first project has been to improve longwall face roof control by introducing a high pressure set pump for better roof strata management. The pump was installed as part of the longwall changeout. Tenders for the hose work and valve gear are yet to be installed, with the system expected to be completed and installed around mid-March.

“The system is planned to be run at approximately 390–400 bar, which would give an improvement in set pressure of approximately 25% [with the high pressure pump in operation],” King said. “The increased set pressure is expected to reduce delays related to coal/stone blockages by between 33% and 50%. This will result in approximately 80 to 120 hours more up time per annum.”

At Tower a high set pressure system has been installed but because the supports are older, the high set pressure can only be increased from 310 to 340 Bar.

King said the work on roof support had grown out of earlier work carried out at Elouera by longwall consultant Nick Wills.

“Nick emphasised the critical importance of longwall roof support density and we took his comments on board and adopted them.”

An important part of the OE longwall project has been and will continue to be conducting safety, isolation, operator training and risk assessments. Training workshops, run by King, Elouera longwall deputy Clyde Johnston and longwall consultant Chris Taylor have focused on strata management and other issues such as isolation of the high-set system. When roof cavities occur individual supports need to be isolated from the high set system. King said the key was to keep the canopies of all the supports level.

An interesting by-product of the current project had been a focus on "hydraulic health" King said. Extensive surveys have been conducted on the hydraulics of the roof supports which showed in some instances, up to 40% of the supports were not functioning as well as they could.

In conjunction with Joy Mining Machinery, the OE team devised a fortnightly auditing schedule for the supports. This has essentially taken existing information and converted it into a more visual format. Under-managers have been made responsible for various aspects of hydraulic health.

“The aim of the longwall OE team is to increase production from our five mines from 170,000 to 228,000 tonnes per week by February 2001,” King said.