The Independent reported that Bangladesh could examine the option of Longwall Top Coal Caving an alternative mining method beyond the conventional board and pillar or standard longwall systems as it could enable miners to extract up to 75% to 80% of seams, it has been observed.
B K Hebblewhite & Y J Cai of UNSW Mining Research Centre, School of Mining Engineering of the University of New South Wales, Sydney claimed in a paper titled Evaluation of the application of the Longwall Top Coal Caving Method in Australia that through using this method the Australian coal mine industry could achieve maximum benefits.
The LTCC method offers a viable means of extracting up to 75% to 80% of seams in the 5 meter to 9 meters thickness range. Single pass longwall is considered to be limited to an upper height of 6 meters and is currently only operating at or below 5 meters.
Dr M Tamim special assistant to the former Chief Adviser said that "We could examine the method at Barapukuria as we failed to utilize its maximum output through the present conventional method." He said that however, the recovery rate of Barapukuria would be only 15% to 20%.
Following a world wide opposition to the open pit mining and obstacles from the Green Movement, the Australian mine experts focused on it following significant production improvements achieved in the Chinese coal mining industry over the last decade, as a result of development and application of the LTCC method.
The Australian coal industry is an export oriented one, where high productivity, sustainable financial viability and the highest safety standards are paramount. As such, the Australian requirement is for appropriate methods that meet the Australian safety and productivity/financial performance criteria, or preferably improve on them, at the same time achieving improved resource recovery.
The researchers focused on three areas:
(i) Continual updating of a thick seam minable reserves database, relative to potential mining methods
(ii) Investigation of the geomechanical factors that affect the safe and efficient performance of LTCC, relative to Australian mining conditions, and optimization of the LTCC configuration, performance and management with respect to caving and coal handling capacities.
A paper on the alternative mining device presents the key issues and the latest findings from each of these three areas of research. Under the geomechanical research, factors such as coal strength and rock mass characteristics are considered with respect to caving potential and face support performance. The caving and coal clearance simulation/optimizations research includes evaluation of a range of front and rear conveyor capacities relative to different caving strategies, as well as alternate panel conveying options.
The study said that the Chinese industry has reported averages of 15,000 tonnes per day to 20,000 tonnes per day from an LTCC face; up to 75% recovery of 8 meters thick seams using a 3 meters operating height longwall; and +5 MTPA face production. There are now well over 70 LTCC faces in China. A new semi-automated 300 meters long LTCC face was installed at the Xinglongzhuang Colliery of the Yankuang Group, in Shandong Province, in August, 2001 with production capacities of at least 7MTPA.
The study claims that the major perceived benefits of the LTCC method for Australia includes operating cost reductions: The LTCC method enables potentially double the longwall recoverable tonnes, per meters of gateroad development, thereby reducing the development cost per tonne significantly and reducing the potential for development rate shortfalls leading to longwall production disruption.
Regarding mine safety, it said lower face heights result in improved face control, smaller and less expensive equipment and improved spontaneous combustion control 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 operations of Yankuang and other companies over the past five years. All groups have returned with very favorable impressions and views about prospects for the method in Aust
(Sourced from Theindependent.com)
