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.
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.
Daniel Grundy
General Manager, GRT
GRT provides engineered solutions for dust control, process optimisation, erosion control, road stabilisation and water management in the Resources, Roads and Rural sectors.
Our company is wholly Australian owned, based in Queensland, but with staff based in each state, who service mining, quarrying, civil, and rural clients both nationally and internationally.
GRT products and site solutions are developed by our own technical staff in conjunction with key industry partners – we provide the total site management options from pit to port!
Mathew Haddrick
Site Safety and Health Representative
Brent McKay
BMA Saraji Mine
The mining industry has historically managed fatigue in an ad hoc fashion. A majority of leaders simply told their employees to “toughen up and deal with it” this is all part of the job. The slightly better leaders would encourage their employees to focus on sleep and preparing for work when they were away from the job. Most employees accepted that they were paid well and “being tired is simply part of the job and why they get the big bucks”.
This presentation will focus on the journey Saraji mine travelled to develop our current fatigue culture, procedures and education materials. Currently the site has a solid process, a good education program, and strong tools for managing fatigue. The current culture has improved but it is a long journey and many employees still haven’t embraced the fatigue policy fully.
The journey was initiated by the site SSHR, through bipartisan support of Management, incorporating key work force participation. Site was able to learn and understand that our miners were struggling throughout the shift and were exposing themselves and other road user to an increased risk of a fatigue related accident. This presentation will share some details on the journey Saraji has embarked on to achieve a common objective of reducing fatigue related events.
Chris Hall
Superintendent Geotechnical, Cannington Mine, South32
Cannington mine is a silver lead zinc operation located in north west Queensland. The operation has been in production since 1997. Ore is primarily moved through an underground material handling system comprising of a crusher, conveyor and hoist. The underground crusher and conveyor system were sited in lower grade ore when the mine was first commissioned and a mine design exclusion zone was established around them. As the mine matured, stopping fronts advanced towards the crusher, resulting in an increase in damage of rock mass and ground support within infrastructure areas in the lower parts of the mine.
In response to preliminary observations of crusher chamber deformation, additional ground support was designed and installed. As the rate of damage began to exceed the rate of rehabilitation, monitoring of rock mass became the predominant control to ensure that exposure to personnel working in the crusher chamber was appropriately safe. The intensity of the monitoring regime continued to increase as the rockmass deformed to the point that new laser scanning technology was implemented to provide short interval monitoring. Ultimately, the monitoring system enabled a safe and controlled closure of the chamber.
James Hall
Partner, Ashurst
Brett Elgar
Counsel, Ashurst
In November 2018, the Coal Mining Safety and Health Act 1999 was amended to introduce a number of significant reforms.
A number of the changes were aimed at improving the focus on contractor management and safety. We discuss these important changes and their practical implications for the industry.
Clive Hanrahan
Operations Manager – Mine Inertisation, Queensland Mines Rescue Service
Due to the mining environments in some underground operations, particularly longwalls, where the void space in the goaf becomes wider and longer, the potential for spontaneous combustion and fire events is possible and, in some cases, has happened.
The nitrogen foam table is relatively quick to deploy, set up and become operational delivering the gas mixture to the required area. The water in-foam cools the heating whilst the nitrogen gas displaces the oxygen.
Using the nitrogen foam table supplies a medium of water foam and nitrogen gas. The water in-foam cools the heating – one leg of the fire triangle whilst the nitrogen gas displaces the oxygen – second leg of the fire triangle.
The nitrogen foam table allows for the distribution of the gas/foam mixture to either one borehole or by opening secondary valving, an additional borehole can be treated at the same time. Where a spontaneous combustion/fire event has been identified mid pillar, the utilisation of the table to treat two boreholes at the same time will greatly assist in the reduction or elimination of that event.
When drilling boreholes from the surface into underground voids the nitrogen foam table allows the gas/foam mixture to be utilised to create an inert shield whereby the foam acts as a wetting agent to prevent any incendive sparking during the drilling process & the gas displaces any potential oxygen present.
In mining areas: Such as the maingates of longwalls where there is oxygen contained within the airwash zone the gas foam mixture could be utilised to create a “plug” behind the maingate face end shields which would reduce / eliminate any airwash issues. The table can be readily located adjacent to a seal site either prior to or after the seal installation. The gas/foam mixture can be distributed from the nitrogen foam table via piping through the erected seal or hosing through the proposed seal site.
Ian Hawkins
Seam Gas Manager, Anglo American – Moranbah North Mine
Minimising risk to our people is Anglo American’s number one priority. Anglo American has implemented a system to improve the control of works being conducted on the surface to support the underground operations.
Recognising that unplanned work can often be the most unsafe, Moranbah North operation has taken advantage of the existing, proven underground planning tool and processes (Fewzion) and aligned the surface operations to these processes.
The surface area of the mining lease has been split into geographical zones with a zone controller responsible for each zone.
All activities in each zone are planned within a shared database (Fewzion) and managed and scheduled through planning meetings and agreed processes.
Any break-in or unplanned work is assessed independently by the activity owner and zone controller prior to approval to proceed is granted.
Zoning of surface works provides confidence that:
- All surface work activities are planned and scheduled, minimising the need for break-in and unplanned work
- Permits to Work are in place, with associated risk assessment and hazard identification completed
- Simultaneous works are identified – minimising conflicting work areas
- All work is communicated to all surface workers – maximising awareness
- Break-in work is effectively managed, as it is planned through the scheduling process.
Bill Haylock
Director, Green Ticket
All mine sites have two things in common—workers and risks. Their workforce, the company’s biggest asset, need to be trained efficiently and effectively on hazards’, risks’ and incidents’ management. Mine site workers handle highstakes machinery and dangerous substances in high-risk settings. The success of risk procedures for a company depends on how well workers understand, accept, and implement these procedures. Without appropriate knowledge and specific tools workers are at high risk of impacting their safety and health, while also undoing corporate compliance measures implemented by management. To mitigate this, we need cost-effective and time-efficient tools. We need targeted, pertinent, specialised training.
This raises questions about what tools contractors need to do the job and how these tools can effectively and efficiently be created and delivered.
Questions to address:
- What is the decision-making process undertaken to create a targeted, pertinent, specialised training program?
- What is the problem?
- Who is at risk?
- What are the regulations?
- Who is the target?
- What are the methods of delivery and desirable frequency?
- What locations?
- What are the workers’ levels of literacy?
- And most importantly, what decision-making processes help to answer these questions and get cut-through to the workers?
