Published in June 2005 Australian Longwall Magazine
When an underground fire ignited at the Southland Colliery on Christmas Day 2003, Gympie Gold’s worst nightmare came true. The fire went on to devastate the mine and its owner. Gympie entered voluntary administration and its gold and coal assets were sold off.
While its Eldorado gold mine was sold to Australian investors, the Southland coal operation (now named Austar) near Cessnock in New South Wales’ Hunter Valley went to Chinese outfit Yanzhou Coal Mining for $US23 million in December 2004.
With the sale came a litany of rumours through the Australian longwall sector. Yanzhou was experienced with longwall top coal caving (LTCC) at home, so would the Chinese operator introduce the technology to Australian shores? The answer, in short, was yes.
Austar’s geology, with a thick seam of 4.5-7.5m, was conducive to LTCC, and the mine had been already nominated as likely to respond well to the method. LTCC technology, successfully developed in China, incorporates a conventional longwall shearer typically mining at a height of about three metres.
Special shields have an elongated gob shield with a retractable flipper at the back that allows the coal in the roof to come in behind the shields. This coal is collected by a second chain-driven conveyor located behind the shields. Both chain conveyors dump coal onto a third chain-driven conveyor, the stageloader.
Yancoal Australia and Austar deputy managing director Boyun Xu told Australian Longwall Magazine Austar’s conditions were ideal for LTCC. “We believe depth of the cover, cleats in the Greta Seam and strength of the seam are suitable for LTCC mining, based on our feasibility study,” he said.
Xu said the first two panels had a full seam thickness of 6-6.5m in the North West area and the seam thickness over the current mining lease area varied from 4.5-7.5 m. Xu expects to achieve 80% recovery of the full coal seam at Austar.
Beside the fact the mine’s original longwall equipment was lost when the longwall was sealed off at the time of the fire, LTCC mining requires new equipment.
Yanzhou selected DBT to manufacture the LTCC shields in Germany. Significantly, this will be the first time LTCC technology will be designed, manufactured and used outside China.
DBT and Yankuang Group, the technology owner and Yanzhou’s parent company, recently signed an agreement for an exclusive licence for the original equipment manufacturer to develop the LTCC technology for western markets, with Austar placing the first order.
Yankuang owns the intellectual property over LTCC, with DBT and Yankuang are developing a joint system design in Germany. Yankuang indicated it hoped to have Austar back in production by the middle of next year.
If successful, LTCC technology is likely to become more widespread, particularly in some of Australia's thicker seams like the Goonyella Seam, where only partial recovery of the resource is possible at present.
Start-up development at Austar has been scheduled to begin in June this year. Initial production will be 2.5 million tonnes per annum, but according to Xu, there will be a significant capacity potential at the face.
The first two LTCC panels are near the previous Southland longwall but there is a coal pillar barrier to isolate the previous fire area.
Yanzhou has elected to keep a mainly local management team supported by a core LTCC team bought over from China. Greg Duncan has been appointed senior site executive by Lai Cunliang, managing director of Yancoal Australia and Austar, and deputy general manager of Yanzhou. Mine manager Phil McNamara will join the company in June.
