THE DAILY Independent Bangladesh has published an article which suggests the country could begin utilising an unconventional mining technique which has improved China’s mining industry and could improve Australia’s.
The University of New South Wales (UNSW) Mining Research Centre, Sydney claims an alternative mining method could help the Australian coal mine industry achieve maximum safety benefits, among others.
The University released a paper titled "Evaluation of the application of the Longwall Top Coal Caving (LTCC) Method in Australia".
The technique could enable miners to extract up to 75 to 80% of seams in the 5m - 9m thickness range. These seams cannot be fully extracted by conventional methods of coal mining.
The method is essentially an extension of the original soutirage concept, but with significant equipment and face operational changes related to the use of the second rear AFC behind the face for handling the caved coal.
In terms of equipment innovation, the more recent Chinese developments have relocated the top coal draw points to the rear of the longwall supports, rather than bringing coal through the roof canopy of the shield onto a conveyor within the shield structure.
The equipment has a pivoting supplementary goaf or tail canopy behind the support. Beneath this is a retractable second AFC. With the rear AFC extended and the rear canopy lowered/retracted, caved top coal can be loaded onto the rear AFC, whilst production continues conventionally in front of the supports. In the retracted rear AFC position with the rear canopy raised, the supports and face operation can function conventionally.
Regarding mine safety, lower face heights (relative to high reach single pass longwall) result in improved face control. Furthermore, spontaneous combustion control is improved in thick seams through removal of the majority of top coal.
The technique could enable miners to extract up to 75 to 80% of seams in the 5m - 9m thickness range. Single pass longwall is considered to be limited to an upper height of 6m, and is currently only operating at or below 5m.
The study looked at China’s use of LTCC and the following significant production improvements achieved in its coal mining industry. The researchers then applied the knowledge Australia’s export-oriented industry where high productivity/ financial viability, sustainable development and the highest safety standards are paramount.
In terms of operating costs, the technique enables potentially double (or greater) the longwall recoverable tonnes per metre of gateroad development. Similarly, smaller and less expensive equipment needed.
The method eliminates the need for open-pit mining which has faced world-wide opposition from the 'Green Movement'.
Regarding mine safety, lower face heights (relative to high reach single pass longwall) result in improved face control. Furthermore, spontaneous combustion control is improved in thick seams through removal of the majority of top coal.
Various study visits by UNSW, CSIRO, CMTE and industry representatives from Australia visited China to inspect the LTCC. All groups have returned with very favourable impressions and views about prospects for the method in Australia.
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