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Full-Text Articles in Engineering
Laboratory Testing Of Rock Bolt Stress Corrosion Cracking, E. Gamboa, A. Atrens
Laboratory Testing Of Rock Bolt Stress Corrosion Cracking, E. Gamboa, A. Atrens
Resource Operators Conference
The incidence of Stress Corrosion Cracking (SCC) in rock bolts has not been quantified and its magnitude has not been addressed. A laboratory test has been achieved that causes a tensile sample to fail in a manner similar to the failure mode observed from service failures, namely slow SCC followed by fast brittle fracture. The laboratory tests involve subjecting a tensile sample to a linearly increasing stress at a slowly applied stress rate whilst the specimen in exposed to a dilute sulphate solution of pH 2.1. Detailed fractography of SCC fracture features from the LT has shown that these fracture …
High Risk Management In Two Long Wall Operations, R. Kahler, M. Slater
High Risk Management In Two Long Wall Operations, R. Kahler, M. Slater
Resource Operators Conference
Within the mining industry, there is recorded data which describes damage to people. The damage can be classified in a hierarchy ranging from incidents which produce multiple fatalities, single fatalities, nonfatal permanent disabilities, temporary damage and inconvenience. There is also a body of unreported collective knowledge in the workforce associated with the tasks which do not produce damage, which are not perceived as high risk; are seldom, if ever, reported and are consistent with that which produce non-fatal permanent damage. The key to successful high risk management is the collection of this unreported knowledge. The vast majority of personal damage …
Update On Outbursts And In-Seam Drilling In 2002, J. Hanes
Update On Outbursts And In-Seam Drilling In 2002, J. Hanes
Resource Operators Conference
There have been some developments in understanding the outburst mechanism and improving the control of in seam drilling. Experience with techniques for draining from the surface has shown promise. There is a need for operators to provide facilities for more research so that the outburst phenomenon can bet better understood.
Respirable Dust Results From Nsw Longwall Mines, K. Cram
Respirable Dust Results From Nsw Longwall Mines, K. Cram
Resource Operators Conference
An outline of airborne dust sampling methodology, instrumentation and exposure standards in the New South Wales coalmining industry are presented combined with the results of dust monitoring of the mining industry workforce with particular emphasis on longwalls. The overall improvements to workforce exposure levels and the systems and techniques which led to these improvements are dealt with, as are respirable quartz levels, together with sources and difficulties of compliance with the Coal Mines Regulation Act (CMRA) 1982 requirements. The non-punitive nature of the regulations combined with the mutual co-operation between management and unions in the interpretation and use of monitoring …
The Measurement Of Airflow Through Regulators, H. W. Wu, S. Gillies, T. Mayes
The Measurement Of Airflow Through Regulators, H. W. Wu, S. Gillies, T. Mayes
Resource Operators Conference
One very reliable approach to establishing air quantity through a ventilation branch is through measurement of differential pressure across an opening or regulator. Mathematical relationships are available to relate (with some qualifications) pressure drop and quantity through an orifice placed symmetrically in a round flow conduit. However these can only be used to approximate mine regulator behaviour due to variability in construction, questions of symmetry and leakage Efforts to characterize and/or mathematically model a number of types of operating mine regulators are described. Results can be used in the development of a computerized monitoring and simulation system to provide immediate …
Controlling And Reducing Heat On Longwall Faces, P. Mitchell
Controlling And Reducing Heat On Longwall Faces, P. Mitchell
Resource Operators Conference
In recent years uncomfortably high ventilation temperatures have become more common on longwall faces in Australian coal mines. Increasing strata temperatures at relatively shallow depths in combination with high surface ambient temperatures, particularly in Queensland, have led to high intake temperatures. These have approached trigger levels that introduce reduced face operator exposure times. With the addition of heat from coal breakage and goaf caving on high production longwall faces the working environment has become uncomfortable and continuous exposure over a shift is potentially injurious to health. Typical strata temperatures at 200m depth are 35ºC increasing to 38ºC at 350m depth. …
Southern Districts Emergency Escape System, P. Baker
Southern Districts Emergency Escape System, P. Baker
Resource Operators Conference
A new emergency escape system has been implemented into the coal industry in the Southern Districts of New South Wales. It has eventuated from a long process of trials and risk assessments and has involved every facet of the mining industry. A team of over 20 people had direct input into the development of this system, as well as the countless others who have helped refine initial ideas and avail themselves of a series of tests and trials. This paper The culmination of their combined efforts is presented.
Hazard Management In Longwall Installations, B. Lyne
Hazard Management In Longwall Installations, B. Lyne
Resource Operators Conference
From its beginnings in the mid 1960’s, longwall mining has become the mainstay of the current underground coal mining industry in Australia. In addition and contrary to the variances in legislation applying to mines operating in Queensland and New South Wales, the underground coal reserves in both states exhibit the same hazards. Words in mining legislation may differ from state to state, however the intent has a common theme - management of the safety and health hazards in the workplace. All longwall mines share three basic features, they all involve the employment of people, they use similar types of machinery …
The Coal Mine Roof Rating In Mining Engineering Practice, C. Mark, G. M. Molinda
The Coal Mine Roof Rating In Mining Engineering Practice, C. Mark, G. M. Molinda
Resource Operators Conference
The Coal Mine Roof Rating (CMRR) system was developed ten years ago to fill the gap between geologic characterization and engineering design. It combines many years of geologic studies in underground coal mines and worldwide experience with rock mass classification systems. Like other classification systems, the CMRR begins with the premise that the structural competence of mine roof rock is determined primarily by the discontinuities that weaken the rock fabric. Since its introduction, CMRR has been incorporated into many aspects of mine planning, including longwall pillar design, roof support selection, feasibility studies, and extended cut evaluation. It has also become …
Longwall "Pore Pressure" Gas Emission Model, D. Ashelford
Longwall "Pore Pressure" Gas Emission Model, D. Ashelford
Resource Operators Conference
Extraction of coal by longwall mining methods has improved greatly over recent years with tonnage rates per week now surpassing yearly tonnes of a few years ago. As mines go deeper and tonnage rates increase then gas emission also increases. For the purposes of understanding gas emission and planning strategies short and long term, modelling of gas emission using the “Pore Pressure” longwall gas emission technique, illustrated is an attempt to model this phenomenon. The input data to the model includes the gas reservoir properties relevant to underground coal seams and extraction of coal using the longwall technique to evaluate …
The Use Of Sonic Velocity Logs To Define Potential Goaf Delamination Horizons, B. Ward
The Use Of Sonic Velocity Logs To Define Potential Goaf Delamination Horizons, B. Ward
Resource Operators Conference
This paper presents the findings of part of ACARP Project C9003 (Green & Ward, 2002) which examined the possibility of deriving quantitative guidelines for the use of sonic velocity logs in the identification of potential goaf delamination planes, with a view to improving predictive capability for the delineation of heavy roof conditions. The downhole sonic velocity log is widely used for the interpretation of overburden strata into geomechanical units and for identifying thick or strong sandstone layers in the main overburden. It can also depict discrete weaker horizons that can act as goaf delamination planes within such layers as high …
Study Of Load Transfer Capacity Of Bolts Using Short Encapsulation Push Test, N. Aziz, B. Webb
Study Of Load Transfer Capacity Of Bolts Using Short Encapsulation Push Test, N. Aziz, B. Webb
Resource Operators Conference
A series of laboratory experiments were conducted on a variety of bolt types to examine the load transfer capacities of different profiled bolts in short encapsulation push testing. A 70 mm section of 150 mm long bolt specimen was anchored in a 70 mm long stainless steel tube using full resin encapsulation. Six types of different profiled bolts and two non - profiled bolts were tested. Bolts with higher profile were in general found to have greater shearing resistance and higher stiffness than low profile bolts. Widely spaced profiles allow greater displacement at peak shear strength, and bolts with no …
Investigations Into Premature Rock Bolt Failures In The Australian Coal Mining Industry, B. Hebblewhite, M. Fabjanczyk, P. Gray
Investigations Into Premature Rock Bolt Failures In The Australian Coal Mining Industry, B. Hebblewhite, M. Fabjanczyk, P. Gray
Resource Operators Conference
An ACARP project was initiated in 1999 to address the observed phenomenon of premature failure of rock bolts in a number of Australian coal mines, and with a particular focus on the problem of Stress Corrosion Cracking (SCC) in rock bolts. This paper briefly outlines the findings of this study.
The Challenge To Improve The Prediction Of Subsidence Impacts, C. Harvey
The Challenge To Improve The Prediction Of Subsidence Impacts, C. Harvey
Resource Operators Conference
Over the last twenty-five years, due largely to direct monitoring and industry funded research the understanding of mining induced subsidence has been greatly enhanced. A high level of correlation between predicted subsidence and actual ground movement has been achieved, especially where the terrain is fairly uniform. The more critical component is determining the nature of impacts specific levels of subsidence will have on surface features, both natural (cliffs, gorges and rivers) and man made structures (roads, pipelines, houses and commercial buildings). With proposed changes to the approval mechanism for longwall mining operations there will be a greater need to improve …
Potential Management And Rehabilitation Requirements Of Environmental Effects From Longwall Subsidence On Streams, Lakes And Groundwater Systems, A. Dawkins
Resource Operators Conference
Following a series of highly publicised environmental issues relating to subsidence of rivers, streams, lakes and other surface water bodies, as well as groundwater systems, the longwall coal mining approval and environmental management process in NSW now has a significant focus on predicting, monitoring, managing and rehabilitating adverse effects on surface water and groundwater systems. Due to the recent public and regulatory focus on the issue, future longwall layouts and approvals may be required to demonstrate that unacceptable effects will not be imposed on rivers and streams. This may result in significant changes to panel layouts, or if no acceptable …
Tailgate Support Design - An Empirical And Analytical Approach, G. Tarrant
Tailgate Support Design - An Empirical And Analytical Approach, G. Tarrant
Resource Operators Conference
There are currently no methods that provide mine operators with reliable tailgate support design. The reliance on experience or at worst, trial and error for tailgate support design is a major contributing factor responsible for longwall downtime and has potentially catastrophic consequences. An ongoing approach to tailgate support design seeks to better understand tailgate strata mechanics and the interaction between the strata, installed support and longwall powered support. The approach combining empirical and analytical methods for roadway layout and detailed gateroad support design is an alternative to statistically based assessments. It is also expected to provide greater rigour for pillar …
Longwall Roof Control By Calculation Of The Shield Support Requirements, U. Langosch, U. Ruppel, U. Wyink
Longwall Roof Control By Calculation Of The Shield Support Requirements, U. Langosch, U. Ruppel, U. Wyink
Resource Operators Conference
In the 1990s the German mining industry introduced a new generation of shield supports. The new design of support has a maximum load capacity of 10,000 kN, making these units as strong as the shields used in Australia and in the USA. Deutsche Montan technologie (DMT) took more than 3,100 underground observations in order to verify the roof fall frequency by statistical analysis. The results of this work have led to practical recommendations for roof control and the required shield support system on longwall faces.
The Impacts Of Mine Subsidence On Creeks, River Valleys And Gorges Due To Underground Coal Mining Operations, A. Waddington, D. Kay
The Impacts Of Mine Subsidence On Creeks, River Valleys And Gorges Due To Underground Coal Mining Operations, A. Waddington, D. Kay
Resource Operators Conference
Measured subsidence profiles above coal mining operations regularly show less than expected subsidence at creeks, river valleys and gorges. Horizontal measurements across such surface notches indicate that they reduce in width as mining occurs. The reduction in subsidence is referred to as ‘upsidence’ and the reduction in width is referred to as valley closure. The upsidence and closure movements tend to increase in amplitude as the size of the valley increases, and as the magnitude of subsidence increases. The movements are greatest when the insitu horizontal stresses are high and when the valleys are fully undermined. The upsidence is a …
New Regulation For Health, Safety And Subsidence, R. Regan
New Regulation For Health, Safety And Subsidence, R. Regan
Resource Operators Conference
As you may be aware, the Occupational Health and Safety Act 2000 applies to every industry in New South Wales, including the coalmining industry. However, despite this, the Government has determined that in addition, specific coalmine health and safety laws should remain in force in this State. The Coal Mine Health and Safety Act 2002 (The Act) replaces the 20-year-old Coal Mines Regulation Act 1987 (CMRA) with modern legislation that aims to better protect the health, safety and welfare of people who work in the New South Wales coal industry. The Act is complementary to the more general Occupational Health …
Case Studies In The Application Of Influence Functions To Visualising Surface Subsidence, R. Byrnes
Case Studies In The Application Of Influence Functions To Visualising Surface Subsidence, R. Byrnes
Resource Operators Conference
The influence function method assumes that a subsidence surface can be represented as a mathematical function. In the case studies presented a gaussian function is used. Examples are given of how the influence function is calibrated to local mine performance, and also in greenfields applications. In the latter cases, geotechnical analysis of likely performance of pillars and roof and floor strata were incorporated into the analysis. The major application of the influence function method is in visualising subsidence – as the method models surfaces and surface deformations. Detailed post mining topography and deformation histories can be produced.
Application Of Bulk Coal Self-Heating Tests To Longwall Operations, B. Beamish, J. Phillips, M. Brown, D. Millers
Application Of Bulk Coal Self-Heating Tests To Longwall Operations, B. Beamish, J. Phillips, M. Brown, D. Millers
Resource Operators Conference
A new laboratory has been established in the Division of Mining and Minerals Process Engineering, which has refurbished and recommissioned a 2-metre self-heating column built at The University of Queensland (UQ). This equipment overcomes the limitations associated with previous large-scale testing. Repeatable test results are achievable within days instead of months and are far more advanced than any previous work at this scale. The column is ideal for simulating goaf behaviour and for teaching the fundamentals of heating development, including gas detection and analysis. Seventeen test runs have now been completed since the initial recommissioning test in late 2001, with …