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Review Of Oxygen Deficiency Requirements For Graham’S Ratio, Sean Muller, Larry Ryan, Jeremy Hollyer, Snezana Bajic
Review Of Oxygen Deficiency Requirements For Graham’S Ratio, Sean Muller, Larry Ryan, Jeremy Hollyer, Snezana Bajic
Resource Operators Conference
Graham’s ratio is a commonly used indicator for measuring the intensity of the oxidation of coal in underground mine atmospheres. Successful measurement of oxygen deficiency is critical in order to generate relevant results, as well as meaningful data trends. Graham’s ratio is often used as a trigger for Trigger Action Response Plans (TARP) for the management of spontaneous combustion. If a Graham’s ratio is calculated where there is an insufficient oxygen deficiency the result can be overestimated and trigger a TARP level. Mitchell (1996) and the NSW Mines Rescue gas detection and emergency preparedness book (2014) has previously identified issues …
Variation In Anchorage Performance Of A High Capacity Modified Bulb Cable Bolt Under Differing Conditions In A Weak Confining Medium, Dishabjit Singh, Paul Hagan, Danqi Li
Variation In Anchorage Performance Of A High Capacity Modified Bulb Cable Bolt Under Differing Conditions In A Weak Confining Medium, Dishabjit Singh, Paul Hagan, Danqi Li
Resource Operators Conference
Cable bolts are increasingly being used for ground reinforcement due to their high load carrying capacity, tendon length and flexibility that affords easy installation. There are a variety of cable bolt designs on the market and while many have been tested, few studies have examined anchorage performance in a weak confining medium that approximates behaviour in coal. This paper presents the results of testing a high capacity cable bolt, the MW9 indented cable bolt, in weak material of differing borehole diameters and grout strengths. Both the standard recommended borehole diameter of 42 mm and an oversize borehole of 52 mm …
A Comparison Between Resin And A Cementitious Material In The Grouting Of Cable Bolts, Prabhdeep Singh Bajwa, Paul Hagan, Danqi Li
A Comparison Between Resin And A Cementitious Material In The Grouting Of Cable Bolts, Prabhdeep Singh Bajwa, Paul Hagan, Danqi Li
Resource Operators Conference
The mining and civil underground construction industries have increasingly become reliant over recent decades on the use of grouted cable bolts for ground support especially in difficult ground conditions. Despite this there are still some key areas of cable bolt performance that are poorly understood. This paper details an investigation that compared the anchorage performance of a plain strand cable bolt that was grouted in a confining medium using in one case a resin grout and in a second case a cementitious grout. The impact of borehole diameter on the performance of the two grout types was also studied. The …
Quantifying The Creep Behaviour Of Polyester Resin And Grout, Jacobus Johan Van Der Schyff
Quantifying The Creep Behaviour Of Polyester Resin And Grout, Jacobus Johan Van Der Schyff
Resource Operators Conference
Creep of in-situ rock bolts has been apparent and problematic since their introduction in the mining environment. If enough creep is experienced, the bolt has the possibility of failure leaving the opportunity for roof instability. In an attempt to quantifying the creep behaviour in polyester resin and cement grout, laboratory-testing procedures were developed. It wasdecided that two separate tests would provide the data needed to fulfil the scope and objectives. The tests chosen were UCS machine deformation testing and Laboratory Short Encapsulation Pull Test (LSEPT). Based on past research in the scope of the project, a methodology was developed along …
Mechanical Direct Shear Tests Of Cables – Combined Stress Relationships, Kent Mctyer, David William Evans
Mechanical Direct Shear Tests Of Cables – Combined Stress Relationships, Kent Mctyer, David William Evans
Resource Operators Conference
Cables have remained an integral part of underground mining in Australia since the 1970s and many of their properties are well-researched. However, no standardised test is generally accepted for shear - an important failure mechanism for cables; therefore, this fundamental property is not fully defined. Further, the uncertainty means the relationship between shear load capacity and axial tensile load (pre-tension) is not completely understood. This paper begins to fill the information gap by reporting the results from a new test method. A simple, replicable and valid mechanical direct (90°) shear test method has been developed, that intentionally departs from existing …
Fundamental Principles Of An Effective Reinforcing Roof Bolting Strategy In Horizontally Layered Roof Strata And Three Areas Of Potential Improvement, Russell Firth, Guy Reed, Martin Mckinnon
Fundamental Principles Of An Effective Reinforcing Roof Bolting Strategy In Horizontally Layered Roof Strata And Three Areas Of Potential Improvement, Russell Firth, Guy Reed, Martin Mckinnon
Resource Operators Conference
It is arguable that the development of reinforcing roof bolting systems has largely stagnated in recent times primarily due to the prevailing industry view that few, if any further improvements can be made to the current state of the art. On the contrary, this paper will contend that reinforcing roof bolting systems can be further refined by considering both the specific manner by which horizontally bedded roof strata loses its natural self-supporting ability and the specific means by which reinforcing roof bolts act to promote or retain this natural self-supporting ability. The Australian coal industry’s seeming insistence on minimising bolt-hole …
Development Of The Anzi Strain Cell For Three Dimensional In Situ Stress Determinations In Deep Exploration Boreholes, Ken Mills, Jesse Puller
Development Of The Anzi Strain Cell For Three Dimensional In Situ Stress Determinations In Deep Exploration Boreholes, Ken Mills, Jesse Puller
Resource Operators Conference
The Australia, New Zealand Inflatable (ANZI) strain cell is an instrument used to determine the three dimensional in situ stresses with a high level of confidence, through the overcoring method of stress relief. The ANZI cell has been used for over three decades at numerous sites around the world, typically in short inclined boreholes drilled from underground mines. Technical advances during the last decade have seen the ANZI cell deployed and overcored in increasingly deeper surface exploration boreholes. Recent development of a downhole electronic data logger, a wireline enabled drilling system and an instrument deployment system has greatly simplified the …
Finite Difference Modelling In Underground Coal Mine Roadway, Ali Akbar Sahebi, Hossein Jalalifar
Finite Difference Modelling In Underground Coal Mine Roadway, Ali Akbar Sahebi, Hossein Jalalifar
Resource Operators Conference
This paper presents stability analysis of roadways of the Tabas coal mine in Iran. Tabas Coal Mine is the first fully mechanised coal mine in Iran, producing 1.5 million tons of coal per year. The mine extracts coal by both longwall and room and pillar methods. The results gathered from field investigations and the geomechanical properties of rocks, were determined in the laboratory and indicate that the rock masses of this area are weak. So, the excavated roadways need to have suitable support. For this purpose, the roadways were modeled with FLAC-2D software. The Finite Difference Method (FDM) models were …
A Case Study Illustration Of The Layout And Support In An Indian Coal Mine With Difficult Roof Condition Where Continuous Miner Is In Operation, Sudipta Mukhopadhyay, Satish Sharma
A Case Study Illustration Of The Layout And Support In An Indian Coal Mine With Difficult Roof Condition Where Continuous Miner Is In Operation, Sudipta Mukhopadhyay, Satish Sharma
Resource Operators Conference
Coal is the most important source of energy. Coal India Limited (CIL), a public sector coal company of the Ministry of coal, has reported the highest ever production of 538.75 MT of coal during 2015-16. This performance was made possible through better planning and monitoring of mining projects, increase in productivity, and better utilization of machinery and commissioning of new projects. In near future CIL will be concentrating on underground mining. In 2013-2014, 34.357 MT of coal was produced by CIL from underground mines. Continuous miners are being used for enhancing production in Tandsi underground coal mine of Kanhan Area …
Hume Coal – An Overview, Rod Doyle, Ben Fitzsimmons
Hume Coal – An Overview, Rod Doyle, Ben Fitzsimmons
Resource Operators Conference
Hume Coal is a subsidiary of POSCO, the South Korean steelmaker. It maintains a 100% interest in the Coal Exploration Authorisation 349 (A349) in New South Wales near Sutton Forest. This paper describes the exploration activities undertaken to date both historic and more recent as well as how the results of those activities have assisted in developing the proposed mine plan. Land Access has proved to be difficult in places. Located near the south western edge of the Sydney Basin the stratigraphy is different to the normal sequence towards the centre of the basin. Mining Lease Applications have been submitted …
An Assessment Of Coal Pillar System Stability Criteria Based On A Mechanistic Evaluation Of The Interaction Between Coal Pillars And The Overburden, Guy Reed, Russell Frith
An Assessment Of Coal Pillar System Stability Criteria Based On A Mechanistic Evaluation Of The Interaction Between Coal Pillars And The Overburden, Guy Reed, Russell Frith
Resource Operators Conference
Coal pillar design has historically been based on assigning a design Factor of Safety (FoS) or Stability Factor (SF) to coal pillars according to their estimated strength and the assumed overburden load acting upon them. Acceptable FoS values have been assigned based on past mining experience and at least one methodology includes the determination of a statistical link between FoS and Probability of Failure (PoF). The role of pillar width: height (w/h) ratio has long been established as having a material influence on both the strength of a coal pillar and also its potential mode of failure. However, there has …
Experimental And Numerical Investigation Of Injection Of Coal Washery Waste Into Longwall Goaf, Zongyi Qin, Baotang Shen
Experimental And Numerical Investigation Of Injection Of Coal Washery Waste Into Longwall Goaf, Zongyi Qin, Baotang Shen
Resource Operators Conference
Mining, preparation and consumption of coal produce large amounts of waste, of which the coal washery rejects account for a major part. Currently emplacement of coal washery waste not only requires large land, but also pollutes the air, soils and underground water. A number of methods have been developed to make use of coal wastes to fill the voids and strata gaps formed from coal extraction, including dry material backfill, paste backfill and overburden slurry injection. Without the need of underground transport system and interference with coal production, the overburden injection technology is considered a cost-effective method in which the …
Insights Into The Mechanics Of Multi-Seam Subsidence From Ashton Underground Mine, Ken Mills, Stephen Wilson
Insights Into The Mechanics Of Multi-Seam Subsidence From Ashton Underground Mine, Ken Mills, Stephen Wilson
Resource Operators Conference
Examples of subsidence monitoring of multi-seam mining in Australian conditions are relatively limited compared to the extensive database of monitoring from single seam mining. The subsidence monitoring data now available from the mining of longwall panels in two seams at the Ashton Underground Mine (Ashton) provides an opportunity to significantly advance the understanding of subsidence behaviour in response to multi-seam mining in a regular offset geometry. This paper presents an analysis and interpretation of the multi-seam subsidence monitoring data from the first five panels in the second seam at the Ashton Underground Mine. The methods used to estimate subsidence effects …
Connectivity Of Mining Induced Fractures Below Longwall Panels: A Modelling Approach, Yvette Heritage, Winton Gale, Adrian Rippon
Connectivity Of Mining Induced Fractures Below Longwall Panels: A Modelling Approach, Yvette Heritage, Winton Gale, Adrian Rippon
Resource Operators Conference
Gas make into active longwall panels is an important issue in ventilation and gas drainage design. A method of simulating the mining induced fracture network and associated increase in hydraulic conductivity is a necessity for improved mine design, hazard management planning and gas drainage efficiency. This paper identifies and illustrates the key components in determining the connectivity of lower gas sources to an active goaf. Computer modelling identifies the formation of cyclic fractures that form below the longwall face and extend down back below the goaf. These cyclic fractures form when the stress conditions are high enough and the strata …
Impact Of Bedding Plane And Laminations On Softening Zone Around The Roadways – 3d Numerical Assessment, Mahdi Zoorabadi, Marzieh Rajabi
Impact Of Bedding Plane And Laminations On Softening Zone Around The Roadways – 3d Numerical Assessment, Mahdi Zoorabadi, Marzieh Rajabi
Resource Operators Conference
When the distributed rock stress around the roadways exceeds the strength of the rock, the rock is failed and a softening zone is formed. Roof deformation developed in the roof and ribs of the roadways are highly controlled by the depth of softening zones. The rock failure process starts from a point ahead of the face and grows into the roof, floor and ribs by advancing roadway. The maximum stress that can be transferred through the failed rocks would be equal to its residual confined strength. Therefore, rock stress is moved above failed zone and will create new failure zone …
Roof Support And Roadway Serviceability Assessment Using Beam-Column Principles, Terry Medhurst, Peter De Roma
Roof Support And Roadway Serviceability Assessment Using Beam-Column Principles, Terry Medhurst, Peter De Roma
Resource Operators Conference
This paper outlines the development of a roof support assessment method that takes account of differing roof conditions, effect of support type and stiffness that can be used in the strata management (TARPS) process. The proposed model is based on beam-column principles and incorporates bending, horizontal loading and shear. Estimates of roof convergence for various heights of softening (or surcharge loading) above a roadway can be obtained for a given support pressure. The model relies upon inputs from the Geophysical Strata Rating (GSR), roof bolt pull-out stiffness/load, H:V stress ratio and UCS.
Single Shear Testing Of Various Cable Bolts Used In Australian Mines, Naj Aziz, Owen Rink, Haleh Rasekh, Ellie Hawkins, Ali Mirzaghorbanali, Guanyu Yang, Saman Khaleghparast, Kenneth Mills, Jan Nemcik, Xuwei Li
Single Shear Testing Of Various Cable Bolts Used In Australian Mines, Naj Aziz, Owen Rink, Haleh Rasekh, Ellie Hawkins, Ali Mirzaghorbanali, Guanyu Yang, Saman Khaleghparast, Kenneth Mills, Jan Nemcik, Xuwei Li
Resource Operators Conference
Sixteen single shear tests were carried out on eight geometric cable variations provided for testing from Australian suppliers – Jennmar, Megabolt and Minova. Each test was subjected to varying pre-tension values of zero and 15 tonnes, exploring the effect of plain, spiral, bulbed, indented and a combination of plain and indented wire strands. The results obtained demonstrated that the shear strength of plain strand cable was higher than the spiral and/or indented profiled cables with direct correlation to the strands ultimate tensile strength. All the plain profiled cables experienced an element of partial debonding suggesting that their application at embedment …
The Extent Of Shearing And The Integrity Of Protective Sleeve Coating Of Cable Bolts, Naj Aziz, Ali Mirzaghorbanali, Matthew Holden
The Extent Of Shearing And The Integrity Of Protective Sleeve Coating Of Cable Bolts, Naj Aziz, Ali Mirzaghorbanali, Matthew Holden
Resource Operators Conference
Long term integrity of cables installed around tunnels for ground reinforcement can be influenced by ground movement. This paper reports on the laboratory study of the influence of shearing on damaging the encapsulated plastic sleeves leading to exposure of the cable surface to a hostile environment. Two experimental studies were carried out to assess the extent of shearing displacement and damage to the sleeves. Various shear displacement tests were carried out. In the first test a sleeved cable was encapsulated in a plastic tube and single sheared up to 43 mm vertical displacement and the same procedure was repeated with …
A New Indirect Method For Evaluation Of The Swelling Potential Of Argillaceous Rocks, Mahdi Moosavi, Hasan Samani
A New Indirect Method For Evaluation Of The Swelling Potential Of Argillaceous Rocks, Mahdi Moosavi, Hasan Samani
Resource Operators Conference
One of the most important characteristics of argillaceous rocks is their swelling potential. This can be determined either by direct or indirect methods. Conventional tests are performed in which one of the properties/indices of rock is associated with the swelling potential. Since the direct tests are usually costly and time consuming, this article is focused on introducing a new method for evaluation of the swelling potential of argillaceous rocks. This is a quicker and less expensive test. The present study shows that there is a good correlation between “Contact Angle” of a drop of water on a flat rock surface …
The Effect Of Water Saturation In Sandstone And Limestone Samples On Disc Cutting Performance, Samarth Yadav, Paul Hagan
The Effect Of Water Saturation In Sandstone And Limestone Samples On Disc Cutting Performance, Samarth Yadav, Paul Hagan
Resource Operators Conference
A study was undertaken to quantify the changes in disc cutter performance between dry and saturated rock. The tests were conducted using samples of limestone and sandstone to determine whether changes in performance are consistent across rock types. A linear rock cutting machine was used to conduct the tests with a rolling disc cutter. The tests were performed at varying depths with fixed disc spacing. Cutting forces were measured in the different rocks and cutting depths with rock yield determined and specific energy calculated. Comparing the results between cutting in dry and saturated rock showed reductions in cutting forces of …
A Preliminary Study Of Dynamic Failures In Laboratory Tests, Qiyu Wang, Chengguo Zhang, Ismet Canbulat
A Preliminary Study Of Dynamic Failures In Laboratory Tests, Qiyu Wang, Chengguo Zhang, Ismet Canbulat
Resource Operators Conference
Sudden and dynamic failure of rock/coal mass during mining is a serious threat to safety in underground mines. This failure is often referred to as ‘rockbursts’ or ‘coal bursts’, mainly attributable to high level of stress. In order to investigate the coal burst phenomenon, a series of laboratory tests were conducted to examine the failure patterns associated with a burst event. Optical glass cube samples were drilled under varying stress conditions, to investigate the influence of stress environment on the dynamic failure. The outcomes of these laboratory tests will improve the understanding of the loading mechanisms leading to coal burst, …
New Advances In Mine Site Gas Analysis Using Gas Chromatographs, Lauren Forrester, Yet-Hong Lim, Inga Usher
New Advances In Mine Site Gas Analysis Using Gas Chromatographs, Lauren Forrester, Yet-Hong Lim, Inga Usher
Resource Operators Conference
Gas analysis using mine site gas chromatographs has traditionally been restricted generally to permanent gases (i.e. helium, hydrogen, oxygen, nitrogen, methane, carbon monoxide, carbon dioxide, ethylene and ethane). Improvements in the technology now allow for additional gases such as aliphatic hydrocarbons and BTEX to be analysed. Aliphatic hydrocarbons and BTEX have implications for the detection of spontaneous combustion, currently under investigation by ACARP project C25072. This paper will detail the modifications needed to enable analysis of these gases existing mine site equipment. The analysis capabilities of the modified equipment will be determined and examples of the chromatography produced by the …
Underground Coal Mine Gas Monitoring Emergency Preparation, Larry Ryan, Martin Watkinson
Underground Coal Mine Gas Monitoring Emergency Preparation, Larry Ryan, Martin Watkinson
Resource Operators Conference
An emergency situation in an underground coal mine site is an unexpected and often dangerous event that can quickly escalate if immediate action is not undertaken. Emergency situations often occur at the worst possible time and have the potential for multiple loss of life, loss of equipment, loss of coal assets and major damage to a company’s reputation. In an underground coal mine, an emergency situation involving a coal heating or small fire can quickly deteriorate into a large fire or worse a gas explosion. As the emergency situation unfolds, various activities will need to be undertaken that are not …
How To Plan A Safe And Successful Permeability Test Program In Coal Seams, Alberto Kamenar, Gelber Taco, Jeff Edgoose
How To Plan A Safe And Successful Permeability Test Program In Coal Seams, Alberto Kamenar, Gelber Taco, Jeff Edgoose
Resource Operators Conference
While discussing coal permeability testing, it is often asked what constitutes a successful test and why. An understanding of these concepts will assist the development of an optimum test program that uses appropriate test equipment and procedures. This approach will provide reliable results, which in turn will improve the design, exploitation and economic recovery of gas and coal resources.
The Case For Developing An Australian Technical Specification For Structural Design Of Ventilation Control Devices, Michael Salu, Verne Mutton
The Case For Developing An Australian Technical Specification For Structural Design Of Ventilation Control Devices, Michael Salu, Verne Mutton
Resource Operators Conference
Ventilation management and control plays an essential part in underground coal mining. Failure of the ventilation system or failure of underground seals can lead to multiple fatalities and closure of a mine. Examples include: Moura No.2 (Qld, 1994); Sago (USA, 2006) and Pike River (NZ, 2010). Following the Moura No.2 disaster, the Qld Dept. of Mines put new regulations in place specifying pressure ratings for various classes of Ventilation Control Devices (VCDs). They also initially specified that only VCD’s that had been subject to “full scale testing” would be accepted for use in Qld mines. No guidance was provided on …
Assessing The Reactivity Of Pyrite, Basil Beamish, Jan Theiler
Assessing The Reactivity Of Pyrite, Basil Beamish, Jan Theiler
Resource Operators Conference
The presence of pyrite in coal has often been attributed to being a factor in spontaneous combustion, but quantifying the effect has been problematical from a hazard assessment viewpoint. A simplistic approach of correlating high sulphur content with the presence of reactive pyrite is unreliable and can be misleading. Pyrite needs to be present in an appropriate form (size and morphology) to enhance its oxidation potential. Consequently, it is important to be able to identify and quantify any reactive pyrite contribution to coal mine heatings in a systematic and scientific manner. In 1992, the US Bureau of Mines recognised there …
Estimate Of The Optimum Horizontal Well Depth For Gas Drainage Using A Numerical Method In The Tabas Coal Mine, Adel Taheri, Farhang Sereshki
Estimate Of The Optimum Horizontal Well Depth For Gas Drainage Using A Numerical Method In The Tabas Coal Mine, Adel Taheri, Farhang Sereshki
Resource Operators Conference
One of the hazards in underground coal mining operations is the sudden coal gas emission leading to coal outburst. To reduce the risk of gas emissions to enable safer mining, it is necessary to pre-drain coal seams and surrounding strata. According to the experimental data, there exists a relationship between the gas flow from the coal seam and the stress changes in the upper layers above the coal seam. This is achieved by drilling horizontal drainage holes in the coal seam. Phase2 commercial software was used to investigate induced stresses caused by methane drainage operations during mining. The optimum depth …
A Study Of Potential Occurrence Of Biogenic Methane In Coal Seams, Abouna Saghafi, Kaydy Pinetown, David Midgley
A Study Of Potential Occurrence Of Biogenic Methane In Coal Seams, Abouna Saghafi, Kaydy Pinetown, David Midgley
Resource Operators Conference
A significant proportion of the total gas emitted from coal mining, particularly for shallow seams (depth), is believed to have been generated from microbial activities within the coal seams and water filling the pores and fractures in coal. To investigate the potential and extent of gas generation in coal due to microbial activities, we developed a method to culture and monitor the production of biogenic methane in coal. We then applied the method to study the process of biogenic methane generation in coals from a mining region in New South Wales. Fresh coal core samples were collected from an exploration …
Control And Management Of Gas Emissions To Reduce Production Delays And Fugitive Emissions, Dennis J. Black
Control And Management Of Gas Emissions To Reduce Production Delays And Fugitive Emissions, Dennis J. Black
Resource Operators Conference
The process of longwall coal extraction coal causes fractures in the overlying and underlying strata and these fractures become pathways for gas released from adjacent coal seams to flow into the mine workings and contaminate the ventilation air. If the rate of gas emission exceeds the diluting capacity of the ventilation air, the gas concentration will increase and exceed the statutory limit resulting in production delays. All potential gas sources within the planned mining area, including coal seams located above and below the working seam, should be identified and sufficient gas data collected and used to determine the specific gas …