Underground » Ventilation, Gas Drainage and Monitoring
In Australia there are over 17 Billion tonnes of resources of thick coal seams applicable to extraction by underground methods. There have been a number of research investigations over the past twenty years to investigate safe and efficient means of extracting these resources. However the maximum underground mining height used in a high production operation in Australia remains approximately 5m.
The most recent of these research investigations was the pre-cursor to this current project. The original project C6038 Underground thick seam mining: Old problems, new technologies conducted by the School of Mining Engineering, UNSW and CMTE, under the same collaborative arrangements as this current project. Four priority mining methods were identified as having the maximum potential application in Australia's thick seam resources:
- single pass longwall (SPL),
- caving longwall (CL),
- multi-pass longwall (MPL) and
- hydraulic mining (HM).
The objectives of this current research project were to conduct a detailed investigation into the overall mining system and technology components of the systems listed above, with emphasis on three methods - SPL, MSL, HM. The investigations were to include:
- Ability to up-scale production levels, productivity and hence the economic viability above current best practice for each method.
- Identification of the detailed equipment requirements necessary to achieve the above objective.
- Geotechnical design studies on critical issues identified from previous ACARP project.
- Critical review, economic evaluation and risk assessment of methods under review.
As the project investigations proceeded, several critical factors became clear. Firstly, the previous project had left the generic 'caving longwall' method, essentially the original European style 'soutirage' mining system, out of the top three priority methods. This was based on poor operational experiences in Europe and China, and also a high level of perceived risk with issues such as spontaneous combustion and dust management.
Longwall Top Coal Caving Method
However, during this project, the project team became aware of the significant advances being made in China with a modified version of the soutirage method, known as Longwall Top Coal Caving (LTCC). This method was identified as having not only the potential to be an alternative to soutirage, but as a top priority thick seam method, in comparison with all other options.
It has been concluded that if this method to be considered in this country, there are still a number of issues that must be resolved. The problem of coal/goaf interface detection is of particular importance, if levels of dilution are to be reduced. In addition, environmental issues such as dust suppression and spontaneous combustion still need to be further examined.