It was also agreed that the first colloquium would be a tribute to an important founder of geotechnical practice, Dr Alan Hargraves.
The first Australian geotechnical colloquium was held at the University of Wollongong on February 15. Close to a hundred industry participants attended the colloquium which covered a range of subjects such as gas management, new legislative frameworks and case studies from various operations.
ILN reviews the subjects covered.
Conference overview
Retired senior inspector of coal mines, Wollongong, Bob Kininmonth, opened the conference by reflecting on the contributions of Alan Hargraves.
Jim Enever, principle scientist CSIRO Petroleum, spoke of the many initiatives implemented by Dr Hargraves from the late 1960s onwards as part of a BHP/AIS research group. The research that grew out of this group continues to define and influence modern advances in coal mine geomechanics. The sphere of activities the group were involved with included gas related issues, mining subsidence, roadway support, longwall mechanics, chain pillar design, slope stability and underlying basic rock mechanics. Perhaps one of the most important contributions was the group’s focus on numerical modeling and instrumentation, such as the finite element method (FEM) of stress analysis, previously not applied to coal mining geomechanics.
John Hanes, co-ordinator of ACARP in-seam drainage and gas research, provided a comprehensive overview of the current understanding of outburst in Australia.
“Outburst research and investigations have been conducted in three main fields - prediction, prevention and control,” Hanes said. “Considerable progress was made during the last 20 years in the fields of prediction and prevention with lesser progress in control, mainly because of the relative success of preventative measures adopted by industry.”
See an edited version of Hanes paper.
Ian Anderson, senior inspector of coal mines, NSW Department of Mineral Resources, discussed the new legislative framework and the role of geotechnical and gas drainage professionals.
“In recent times legislators have moved away from prescriptive legislation to duty of care models. Such a move places employers and consultants under a need to demonstrate due diligence in the exercise of their functions. The pricinple legislation under which the coal industry operates is the NSW Occupational Health and Safety Act. This Act has substantial punitive measures including fines and imprisonment.”
Anderson discussed three case studies in which consultants and internal company managers had been imprisoned after the occurrence of fatalities. The response to the warning sounded in Anderson’s paper generated a sense of alarm and anxiety among the many consultants present at the colloquium. Some participants suggested that the burden being imposed on mine managers would strip the industry of experienced professionals.
See article on Anderson's paper.
Brian Nicholls, managing director of consultancy Brian Nicholls Mining, looked at differences related to rock strengths, stress regimes, location and operational approaches between New South Wales and Queensland coalfields.
Nicholls draws from substantial experience of working at open-cut and underground mines in NSW and Queensland, which most recently included stints at longwall operations North Goonyella and Oaky Creek in Queensland’s Bowen Basin.
ILN will publish Nicholls’ paper in March.
Les Lunarzewski, managing director of gas drainage company Lunagas, examined current gas drainage practices. Lunarzewski looked at pre-drainage, post drainage and in-seam goaf drainage practices.
Lunagas has also just released new software Floorgas and Roofgas which allows for the design of optimum parameters for various gas recovery and methane utilization systems, as well as accurate prediction of gas emission from roof and floor strata gas sources.
See overview of Lunagas software.
Ray Williams, managing director of GeoGAS Systems, spoke about gas emission modelling during gate road development mining. GeoGAS has developed software called the SIMED II gas reservoir simulator which is presented as an EXCEL speadsheet. The model takes account of a range of gas reservoir and mining parameters which need to be considered in designing gate roads.
Williams said the strengths of the approach like in its ability to quickly convey a message that facilitates action toward improved ventilation and/or gas drainage design and implementation. In addition, it contains all the important gas reservoir and mining parameters within a manageable package.
Naj Aziz, University of Wollongong, described the university’s newly launched website for Australian longwall practices. Primarily a site designed for students, various industry groups have considered using the website for general industry training. www.uow.edu.au/eng/current/longwall
Mitch Jakeman, general manager Capricorn Coal Management, discussed geotechnology engineering at German Creek.
Jakeman’s paper presented the geotechnical experiences at German Creek over 21 years of operation after four draglines were bought in 1979.
“Today the operation sustains one dragline, two underground longwall operations and another underground in the project phase. Lifelong experiences and the need to understand what is happening has sharpened our focus about our mines and operational business risks. The task of digging out a longwall, whilst good for experience and character building, should only ever be done once or twice.”
Peter Hayes, general manager Wallarah Coal joint venture, looked at mining the Great Northern Seam under a claystone roof.
“All three mines (Chain Valley, Wallarah and Moonee) have attempted at various stages in their history to find an economic mining method under these claystone roof conditions, with varying degrees of success at each operation. Moonee currently operates a longwall under claystone roof while Chain Valley and Wallarah are place-changing operations which have operated under claystone with some success … The most critical roof support issues in achieving high productivity under a claystone roof are the setting and maintenance of very high support installation standards and the development of a robust support management plan responsive to changes in strata conditions.”
Phil Eade, manager engineering and technical support, and Jeff Wood, geological services manager, both of BHP Coal Illawarra, covered longwalling and its impacts in the Southern Coalfield.
BHP’s five longwall mines in the area – Appin, Tower, West Cliff, Cordeaux and Elouera – each use a retreating longwall extraction system. The two speakers examined the following challenges facing longwall mining in the Southern Coalfield: safety and legislation, economic viability, environment and community, technical issues, and surface effects.
