Published in March 2007 Australian Longwall Magazine
The report, put together by Gary Gibson and Associates, is part of the larger Australian Roadway Development Improvement Project. During this phase of the project, Gibson and his team reviewed other sectors and technologies, including drill and blast and tunnel boring machines (TBMs), to see if they could be applied to underground coal to improve roadway rates.
Of the many applications Gibson found, automation was a significant one. “Integration of current state-of-the-art machine guidance and control systems to enable continuous miner operating functions to be automated during the break-away process to ensure consistency, repeatability and reliability of breakaways without the need for highly skilled operators,” he outlined in the report.
Similarly, integration of current machine guidance, sensing and control systems to enable continuous miners to be operated remotely from a non-hazardous environment – and/or to be operated free of delays due to the operator’s inability to sight the position of the cutter head and machine body relative to the roof, floor and sides, or other persons – also has great potential.
The application of drill control systems for remote, semi-automated operation of miner mounted drill rigs could be applied, along with the use of remote control technology to enable shuttle cars and continuous haulage systems to be operated remotely from a non-hazardous environment.
The issue of continuous haulage to improve roadway rates raised its head again, this time under the guise of utilising extensible conveyor systems to facilitate the continuous operation of continuous miners, TBMs and roadheaders.
For roof and rib control, Gibson identified the incorporation of carousel bolting systems to continuous miner mounted drill rigs (as is reportedly being progressed by Joy Mining Machinery), as a precursor to the potential development of other automated bolting systems.
The carousel drilling systems could also be adapted to the continuous miner mounted cable bolting systems, potentially including cable storage and insertion systems.
On the training side, immersion technologies could be used to train operators in the safe and productive operation of roadway development equipment.
Gibson also assessed the option of driving larger dimension roadways in all phases of mine development. By doing this, lower ventilation pressures and hence lower mine ventilation costs and reduced risk of spontaneous combustion in prone mines could be achieved. Also, larger diameter and less resistant ventilation ducting could be used.
Larger roadways would avoid the development of a third entry in longwall gateroads and subsequent formation of a second row of chain pillars.
With larger roadways continuous miners could be restructured to fit automated bolting and material handling systems and allow higher capacity coal haulage and material distribution systems.
When looking at TBMs, Gibson found the machines could provide an integrated roadway development system, particularly in punch longwall applications. “However, indicative costs of $21-22 million may limit their immediate and widespread application in the underground coal sector unless it can be demonstrated that significantly improved development rates can be achieved,” Gibson said.
The application of TBMs in gateroad development will pose a number of regulatory challenges, particularly in relation to equipment certification and approvals of flameproof and intrinsically safe apparatus, the use of high voltage substations and motors in the hazardous/explosion risk zone, single entry drivage and the provision of emergency escape.
Gibson said Ishikawajima-Harima Heavy Industries (IHI) and Pacific Tunnelling have both developed engineering concept designs for application of TBM tunnelling technology to underground coal mines, while other OEMs (Herrenknecht, Lovat, Robbins and Wirth) are also likely to pursue any such initiative. Experienced civil and mining contractors also expressed interest in participating in any such initiative (John Holland, Leighton, McConnell Dowell and Walter Mining).
Application of TBMs (and other integrated high capacity development systems) will require a major reconsideration of how the roadway development process is managed, with the current level of management resources being applied at most mines being insufficient to ensure the technology is both utilised at and performs to a level that could sustain the high capital cost, Gibson said.
“Utilisation of TBM-experienced mining and/or tunnelling contractors will be necessary to ensure that the technology, equipment, systems, expertise and skills that are available can be transferred to and developed within the coal sector in an effective, efficient and sustainable manner,” he said.
Existing borer miners and continuous haulage/extensible conveyor systems as utilised in Canadian potash mines could – with integration of onboard bolting and support systems – be utilised as the basis of an integrated, high capacity roadway development system in Australian coal mines, according to the report.
Also, conventional widehead continuous miners could, with further enhancement, similarly be utilised as the basis of an integrated, high capacity roadway development system.
The report recommended a work group be set up to further see how the technologies could be applied in the underground coal sector.
Gibson recommended an economic and technical evaluation of various entry configurations, including two entry/high (partially out-of-seam) roadways and three entry/low (in-seam) roadways, be conducted to determine which configuration of roadways is likely to address ventilation and gas management issues associated with future high capacity longwalls producing more than 10 million tonnes per annum.
He also said a feasibility study should be undertaken on the potential application of TBMs for punch longwall gateroad development. The study should also assess the performance capability of TBMs utilising “temporary” support systems such as rock bolts and mesh as typically utilised in coal mines.
