If you want to create a vision for the Australian coal industry in 2030, you can, with some confidence, base it on two elements: underground and high-capacity. The majority of current production comes from relatively low-cost surface operations, but that is changing. The number of open-cut reserves will diminish in the future and a greater percentage output will need to be sourced from more expensive underground mines.
Coal is still Australia’s most profitable resource but for the Australian industry to remain competitive these operations must become more efficient and productive.
Typical production from a single longwall operation in Australia averages about 3Mtpa, with a handful consistently achieving 5Mtpa and one close to 7Mtpa. The industry’s vision for 2030 is to more than double the current highest production by becoming high-capacity (15Mtpa) underground operations.
So far, 19 coal deposits have been identified as offering the potential to support a 15Mtpa operation. The Bowen Basin in Queensland and the Sydney Basin in New South Wales offer the best potential.
The world’s first high-capacity underground coal mine may not be fully operational at the dawning of 2030 but a good number of its essential elements could be. For example, the combined talents of science and industry will by then have identified the knowledge and technological gaps for such a mine. It may also have plugged many of these gaps with smart solutions.
Researchers should also have predicted the consequences of such a super mine accurately enough to develop a best practice system – or series of systems – that ensures present and future sustainability by then.
A recent Australian Coal Association Research Program (ACARP) report issued by CSIRO, the University of Queensland and the Sustainable Minerals Institute is the most comprehensive study to date on the possibilities for, and ramifications of, a 15 Mtpa operation from a single underground longwall system.
The report says the production target is 'more than double the current best, and quadruples the current Australian average' and that the 'feasibility of achieving such targets and the associated risks and consequences will be identified for the prevailing range of seam geometries and conditions found in Australia, in particular, those anticipated in the next 20 years'.
It stressed that the specific targets were to identify the following:
- Current best practice for high-capacity underground coal mining
- Knowledge and technological gaps for a 15Mtpa underground operation
- The existing published underground coal resource base available for mining in the next 20 years
- The consequences of a 15Mtpa production profile and any barriers this may generate through a mining environment/condition based analysis
- The viability of this production profile for current and future sustainability
- Common and strategic issues that may form the basis of research and development projects and post-graduate training.
The way forward
The report’s authors found that there is 'significant scope for improvement in longwall productivity in Australian coalmines, regardless of seam thickness or mining configuration as demonstrated by the respective research categories and projects'.
The top five recommended areas of R&D are:
- High-capacity gas drainage
- Integrated roadway development infrastructure
- Real-time maintenance management system
- Engineering design
- Management of adverse geotechnical and geological conditions.
A second group of research areas was identified that would reduce the potential critical threats to longwall productivity, including:
- Water use and recycling
- Aquifer disturbance
- Occupational Health and Safety (dust, heat and fatigue)
They said these areas show clearly the need for close collaboration between researchers and the industry.
ACARP’s vision for a high-capacity mine
A high-capacity mine of the kind envisioned by the ACARP report requires a re-think not just of obvious production elements such as equipment but all elements of an underground operation.
Well-designed and implemented management controls and processes will be needed to facilitate and engender a high-productivity environment. There will be increased demand for greater attention to detail and understanding of various processes and cross-discipline cooperation. Management will also need to oversee the integration of the sub-processes (coal haulage and ventilation, for example) into a truly continuous process.
Hazard management charts and predictions will have to be re-drawn mainly because significantly higher tonnages will exacerbate the issues of ventilation, gas and dust management. The ACARP report said one of the key limiting factors - effective gas drainage - will depend on technologies such as medium-radius drilling for greater drainage lead time and advances in gas flow stimulation.
There are serious structural issues because, regardless of the thickness of the seams, a mine of 15 Mtpa capacity is going to leave a much larger footprint, prompting a greater likelihood of intersecting geological structures - and risk.
A first step in this field is to significantly increase the amount of data available in the public domain to give science and industry more definitive detail of possible intersecting structures within potential 15Mtpa deposits.
A high-capacity mine will demand the optimisation of powered roof support density, operability and operating speed but while geophysical methods for structure location and characterisation have been successfully employed there continues to be a lack of skilled practitioners.
The report stated that longwall equipment is 'generally acknowledged (supported by international benchmarking) as capable of delivering higher production tonnages than are current industry norms' but still, mine equipment manufacturers will need to revisit and address designs.
Such a review should focus on essential elements including shearer speed and underbody clearance, cutting capacity, power requirements, rate of advance of hydraulic face supports and the capacity requirements of the hydraulic delivery system.
Automation and communication systems are essential components for the successful implementation of a high-capacity mine. The report noted: "There are significant opportunities to integrate real-time monitoring, sensing and automation technologies into roadway developments, cutting profiles while traversing faults, service extensions and strata monitoring and control.
"While there are technologies emerging to support components of modern communications networks, a comprehensive development of mine-wide ad-hoc wireless communication networks linked to comprehensive sensor nets, would provide the industry with the same advantages of Ethernet-based, real-time communications systems enjoyed by surface-based industries and urban communities for decades."
This article first appeared in CSIRO’s magazine earthmatters, issue 18.