Ravindu Goonawardene
Geology Geotechnical Superintendent
Chris Crosby
Surrey Superintendent, Anglo American Grosvenor Mine
The risk of fatalities due to roof and rib failures is still prevalent in underground coal mines which highlights the fundamental importance of monitoring roof and ribs in underground roadways.
Monitoring strata deformation and convergence in underground roadways is a key metric for measuring instability of excavations. Visual inspections, tell tales, extensometers and instrumented bolts are some of the methods used to quantify strata deformation.
The significant limitations of the current methods only provide a point-measurement along the roadway. Using laser technology allows the mine to scan and measure large regions of roof and ribs across continuous regions with millimetre accuracy.
The Maptek SR3 laser scanner has been used as a control during the rib optimisation trial at Grosvenor. This technology provides a baseline scan and subsequent scans to ascertain the extent of deformation throughout the active development mining areas. Thus, allowing geotechnical engineers to assess the adequacy of the trialled support system. Moreover, this technology allows geotechnical engineers to better analyse geological anomalies (fault orientations, dips, throw), bolting tolerances and excavation dimensions in an effective manner.
Ravindu Goonawardene
Geology and Geotechnical Superintendent, Anglo American – Grosvenor Mine
Chris Crosby
Surveying Superintendent, Anglo American – Grosvenor Mine
The risk of fatalities due to roof and rib failures is still prevalent in underground coal mines which highlights the fundamental importance of monitoring roof and ribs in underground roadways. Monitoring strata deformation and convergence in underground roadways is a key metric for measuring instability of excavations. Visual inspections, telltales, extensometers and instrumented bolts are some of the methods used to quantify strata deformation.
The significant limitations of the current methods only provide a point-measurement along the roadway. Using laser technology allows the mine to scan and measure large regions of roof and ribs across continuous regions with millimetre accuracy.
The Maptek SR3 laser scanner has been used as a control during the rib optimisation trial at Grosvenor. This technology provides a baseline scan and subsequent scans to ascertain the extent of deformation throughout the active development mining areas. Thus, allowing geotechnical engineers to assess the adequacy of the trialled support system. Moreover, this technology allows geotechnical engineers to better analyse geological anomalies (fault orientations, dips, throw), bolting tolerances and excavation dimensions in an effective manner.
Rav Goonawardene
Geology and Geotechnical Superintendent, Anglo American – Grosvenor Mine
Ben Elliot
Trainee ERZ Controller, Anglo American – Grosvenor Mine
A series of floor heave and gas inrush events have occurred during the development mining process in MG103 and MG104 at Grosvenor Underground Coal Mine. These events have exposed coal mine workers to elevated levels of methane preventing safe mining operations.
The presence of an undrained source of gas in the immediate floor, geotechnical floor characteristics, loading environment and various other factors have contributed to the dynamic floor failure. Methane released during these events are originating from the underlaying thin Goonyella Middle Lower (GML) seam which is a thin carbonaceous layer with high ash content. The 1m – 5m interburden thickness between the GM seam and the GML has an increased likelihood of the floor gas release events.
Based on the analysis of these gas events, creating a conduit in the interburden between the GM seam and GML will allow the gas to freely release to the development roadway during development drivage. This will prevent the build up of gas within the interburden creating a floor gas release event.
The proactive interburden fracturing was initiated using water pressure generated from a longwall salvage pump. The current UIS drilling equipment was retrofitted with a series of subs, packers and a fracturing tool to initiate a hydro fracture within the drilled UIS borehole. Once the packers are fully inflated and in position, a diversion valve is then activated to allow the fracturing tool to inject high water pressure to the desired location. Thus, given the complexity of predicting verticality of the hydro fracture in the interburden, a UIS borehole was drilled in the lower section of the GM seam as proving hole to check the effectiveness of hydro fracture.
The main benefit of the proactive interburden fracturing process is having the ability to reduce the likelihood of exposing development coal mine workers at the face to high methane levels.
Garry Gosling
Joint Action Solutions
Scott Graham
Mineplex
Dr Eryn Grant
Anglo American
Joel Gray
Senior Mining Engineer – Operations, Cannington Mine, South32
Several paste backfill bulkhead failures over the space of 12 months demanded that paste inrush risk at Cannington be re-evaluated. The resulting risk assessment led to the introduction of a set of new operating rules for high risk filling conditions to ensure safer use of the popular backfill method at the mine.
This paper will talk operators through the high potential incidents which occurred, the primary causes and the risk assessment which followed. Implementable actions utilised at Cannington are shared, while challenging other operations to consider their own current level of risk with regards to the use of paste backfill.
Nicole Gray
The Keil Centre
Daniel Grech, Port Production Manager, Crispian Mallise, Engineering Projects Superintendent and Shaun Phelan, Project Lead, Mechanical, BHP Mitsubishi Alliance (BMA)
Evan Greenaway – Superintendent CHPP, Anglo American Capcoal
Anthony Duck – Operations Manager, Dust-A-Side Australia Pty Ltd
ABSTRACT
No matter the industry, whether it’s mining, rail, shipping or agriculture, dealing with dust is unavoidable.
Massive sites with high yields across any industry will have multiple dust generation points. Controlling dust generated during the transport of materials via conveyors and trucks on haul roads presents a unique set of challenges to mining operations.
In situations where there are multiple dust generation points, it’s rarely enough for a site to just wet all material and expect the dust to be controlled throughout each stage of processing.
In this Anglo open cut site and coal handling and processing plant a two-pronged approach incorporating both Dust Prevention and Dust Suppression is being used to control not only the dust you see, but the microscopic dust that you can’t see – the dust that creates health and environmental concerns, and regulatory issues.
While we continue to test its success, we believe this “smart”, flexible, integrated system, combining technology and well-developed products with attention-to-detail management can ultimately reduce dust exposure to people, equipment and environments.
The expertise exists to implement total dust control solutions in any situation. The key is to find the right type of solution for each specific dust generation point.