The five major projects within CSIRO’s exploration and mining division are:
- 3D aspects of longwall geomechanics
- mine gas control
- rapid roadway development
- top coal caving
- longwall automation
1. Longwall geomechanics
Site studies at 13 locations have highlighted aspects controlling longwall geomechanics, including stress controls, geometry, faulting, depth, longwall width and changes in lithology. Kelly said the outcome of the four current geomechanics research projects will deliver a commercial initiative that mines can use to improve their understanding of their particular conditions.
2. Mine gas control
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Controlling large goaf gas emissions is a critical issue for modern longwall mines, particularly in thick seams with low in-situ permeability. A research project at Dartbrook, ran from June 1997 to April this year, to gain a better understanding of gas flow mechanics in the goaf and the effect of various factors.
New strategies developed and implemented during the research project have improved gas drainage at the mine by 200% and have reduced spontaneous combustion risk. CSIRO has proposed continuing the research for two more years to widen the technology transfer.
3. Rapid roadway development (RRD)
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This project aims to design and build an automated coal conveying/bolting machine to improve development rates. A detailed design for the integrated platform has been completed this year. Specs include autonomous roof-bolt feed system using 2m self-drilling bolts; cassette system to hold 200 roof bolts, 100 rib bolts and chemical for their placement. Machine dimensions are length 12m, width 3.2m, tram height 2.26m, minimum transport height 1.45m, mass 50 t loaded, floor pressure 221 kPa.
Engineering design of the automated roofbolting system has been completed. The key consumable was originally BHP’s self-drilling bolt but this has become a problem recently with the spin-off of the division into a company called Onesteel. “Because of the tight tolerances required by the autonomous system, any changes in bolt specification may cause handling problems,” Kelly said.
The next year will be a crucial one for the project, with construction and field trials scheduled. A trial of the system over one pillar (240m driveage) is planned. Kelly said of 26 underground coal mines surveyed in Australia, 80% could be suitable for the RRD system.
4. Top coal caving
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Longwall top coal caving (LTCC) is a method developed by Chinese company Yankuang to extract up to 85% from 9m seams. At present a prefeasibility study is being undertaken with Yankuang, CSIRO and the University of NSW, to investigate the applicability of the method in Australia.
Initial cost models compared two methods for recovery of an 8m seam. Indicative results show higher production rates and lowered development rates for LTCC:
Block recovery was 94% using LTCC, versus 53% using conventional longwall methods. Rom tonnes were 7.9Mt, versus 6.7Mt. Weekly longwall production was 19,000t higher using LTCC. Annual development metres reduced by 6.5km for LTCC.
Kelly said it was likely that within three years LTCC would be operating in Australia.
5. Longwall automation
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The ACARP (Australian Coal Association Research Program) is funding this project as a landmark project. This means the project will receive greater funding with the aim of benefiting the industry as a whole.
The aim of this project is to develop longwall automation to the level of on face observation by the end of three years. Technologies that will be used include inertial navigation systems, sensor improvements, monitoring, and IT.
