LTCC potential now under investigation

MAJOR Chinese coal producer Yankuang has signed an agreement with Australian research providers to progress the introduction of longwall top coal caving (LTCC) in Australia.

Staff Reporter

Yankuang is China’s biggest coal producer and subsidiary, Yanzhou Coal Mining Company, is listed on the Shanghai, Hong Kong and New York Stock Exchanges. Vice general manager, Xu Jianhua, who is in charge of technology development and overseas business, said the main objective for coming to Australia was to progress LTCC technology and expand Yankuang’s coal production abroad.

The group holds the intellectual property over LTCC, a proven technology for high production coal mining that it believes can be introduced in Australian conditions. In 1999 the company produced 26 million tonnes from six Chinese mines with eight longwall faces all using the LTCC method.

A 1999 visit to Australian mines by Yankuang officials concluded that the method could be introduced into certain Australian mine sites working in thick seam conditions. Since then, researchers from the CSIRO and the University of New South Wales have conducted initial investigations that included visits to Chinese mines to evaluate the LTCC method.

“We want to collaborate with an existing mine and possibly take equity in an operation,” Xu said. “We have found there are many mines which could use the technology. We have worked together with CSIRO since last December because CSIRO show the most interest in the technology we use in China.”

According to Xu, the main reason for involving the Australian researchers is to progress LTCC and to reduce risk. In addition, he said geological structures, management and environmental protection regulations were very different between the two countries.

Signing of the formal agreement between CSIRO, the UNSW and Yankuang will progress the introduction of the technology into Australia, beginning with a pre﷓feasibility study starting on April 1 this year.

“The first stage is a feasibility study to establish how we can develop the top caving technology developed in China for Australia,” Xu said.

Michael Kelly, coal mining co-ordinator, CSIRO exploration and mining, said during the first phase of the project the research team would assess similarities and differences between Australian and Chinese conditions. A nine﷓person technical team is due to visit the Chinese operations to further investigate the technology in detail in May 2001. Later stages of the project will target regions in Australia that have high potential for the method and will provide an economic comparison between LTCC and current high-reach longwalls. Issues under close scrutiny will include mining systems (people deployment, coal clearance, equipment used, etc), geomechanics and geology subsidence, ventilation, spontaneous combustion and gas control.

One example of these differences is in how the Chinese mines clear the coal once it has caved. Roof supports are designed with rear flippers, used to control coal flow. These are typically manually activated but differing dust legislation and conditions in Australia may require remote or automated control. These and numerous other related issues would be under investigation. Kelly said a range of R&D projects was likely to grow out of the initial pre-feasibility project.

While there was undoubtedly some remaining scepticism among Australian operators about the level of advancement of Chinese technology, those who had visited Chinese mines and seen the LTCC method in operation had come away impressed and convinced of its applicability in Australia, Kelly said.

“Here we have a method that has produced 6Mt from a single face in a year while achieving 85% recovery from a 9m-thick seam,” he said. “It may reduce initial capital costs due to the smaller face and greatly reduce operating costs by reducing gateroad development metres per tonne of product coal. It will also improve capital utilisation because of the higher recovery from thick seams.

“In an environment that is now so cost driven and with the thick seam assets that Australia possesses, it is a method with great potential.”

Kelly was also optimistic about using the method in areas of mines that required geotechnical control. “Operators have known the advantages of fault traversing at a reduced height for some time,” he said. “Current high faces of 4.5m have difficulty with face control during these traverses. Here is a method that can operate at up to 12m extraction during good conditions, but can be reduced to, say 2.5m, in difficult ground conditions by just turning off the rear coal flow.”

There are various ways in which the method could be introduced into an Australian mine, according to Kelly. LTCC could potentially be tailor-made for a new greenfields site; it could be introduced into a brownfields site where a mine was developing a new area; or it could be introduced into an existing longwall operation. Another option was for a contractor to partner in the implementation of the LTCC method.

It will probably be about two years before a pilot or demonstration mine can be introduced, but Xu said Yankuang was eager to start a project as quickly as possible. He said during the initial phases of the project it was likely equipment would be imported into Australia from China.

“After that we’d like to collaborate with an international company to produce the LTCC. As for management, we must obey Australian law and regulations. We may send a small number of technicians here but also we are happy to train Australian technicians in China,” he said.

Originally published in the March 2001 edition of Australia's Longwalls.