Published in June 2007 Australian Longwall Magazine

The most popular method of coal haulage in Australia and overseas is by electrically driven shuttle cars or battery haulers that collect coal from the continuous miner, dump it on the section conveyor and return to the continuous miner – resulting in wasted time as the CM frequently waits for shuttle cars to return or change out.

Although various continuous haulage methods have been tried in Australian coal mines in the past, Gary Gibson and Associates principal consultant Gary Gibson told Australian Longwall Magazine there are currently no continuous haulage systems in use in Australia.

“Some coal mines trialled various continuous haulage systems in the mid-1980s and 1990s, but ultimately I think Australians had a lot of trouble taking on the new technology,” he said.

The linear continuous mining system developed by South African company Magatar Mining and now en route to the bord and pillar Cook mine, consists of around 90% proven, standard mining equipment. It revolves around a flexible belt haulage system, the Flexiveyor, which is a series of cascading conveyor belts mounted on wheels, providing a permanent link between the CM and the section conveyor belt, which moves coal out of the mining section.

Produced by Canadian company, Prairie Machine & Parts, the Flexiveyor has been proven in Canada’s potash mines for over 14 years and is not in itself new technology, but the model being delivered to Cook has been adapted to suit the conditions and requirements of its new environment. As a result, all electrical equipment has been made to Australian Standards and carries Australian certification.

The Magatar system incorporates a continuous miner with onboard bolters, a continuous haulage system (Flexiveyor), straddle frame on the section conveyor boot-end, self-deploying conveyor belt structure and loop take-up, as well as a totally integrated support system to maximise equipment utilisation.

The Flexiveyor bound for Cook is 96m long (individual cars are 6m), which means it can perform at least 90m of mining in any direction before a belt advance is needed.

The rapidly advancing belt system is a key feature of the Magatar system and means a belt advance becomes possible in as little as 20 minutes, as opposed to two to three hours using conventional methods.

The system also offers continuous mining in a single roadway for extensive distances at a time, without the need for relocation. This approach minimises tramming damage to the floor by eliminating heavy equipment driving over the same piece of floor multiple times.

Magatar Mining’s Phillip Venter told AL that the system has the inherent capacity to bridge the gap between traditional bord and pillar mining and longwall mining by rapidly increasing CM production rates.

“In typical Australian conditions, strata support remains a huge challenge, hence the incorporation of six semi-automatic roof and rib bolters onto the CM. All six bolters will be operated simultaneously, four in the roof and two in the ribs,” he said.

“Longwall gives a very high output but is dependant on large undisturbed blocks of coal and on development sections to develop roads to service the longwall panels.

“The Magatar system is capable of carrying out mains development (four or five road) at production rates significantly higher than batching systems.”

Venter said the method is based on the maximum advance rate, maximum safety factor in terms of strata control, minimum number of intersections, with minimum roadways during the development phase.

The production phase is characterised by parallel single roadways, advanced without interruption, for at least the length of the system, with only one punch required through adjacent roadways to establish ventilation before the system is required to retreat from a heading. “The system also offers the possibility of extracting the pillars between adjacent parallel roadways but this will not be attempted as yet, as the mine will take a conservative approach at the first implementation,” Venter said.

While most CM sections struggle to achieve utilisation factors above 35%, the Magatar system can increase this utilisation figure to over 60%, which would allow production figures of over 200,000 tonnes per month to become a reality in good mining conditions.

“In typical Australian mining conditions, the strata control issues prevent this kind of output, hence the 100,000t per month forecast at Cook,” Venter said.

“Once Cook personnel have come to terms with the new system and grasped all of its advantages, the production rates could potentially increase even further.”

Gibson said considering that on average, Australian longwall mines are now achieving about 15,000-20,000t a month in development, the performance they’re expecting at Cook is a pretty significant step up from where the industry is today in Australia.

“The Flexiveyor is making some pretty significant production advances in the Potash mines and I think it has a very good application for gateroad development in longwall mines, so I’m waiting to see how it performs,” he said.

Caledon Resources chief operating officer Peter Seear said the system was chosen not just to improve productivity, but to address many of the safety issues of underground mining.

“It means we won’t have as much traffic underground as a shuttle car operation and it will improve dust levels because the system moves slowly behind the continuous miner at all times, so you don’t have fast-moving vehicles kicking up dust in the roadways.”

Seear said the continuous haulage unit can also carry ventilation ducting and the water and electrical power supply to the continuous miner, which reduces the manual work people have to do underground.

“We will have cleaner coal because we don’t have traffic breaking up the surface of the roadways – resulting in a cleaner product,” he said.

“You put all of its attributes together, and we will mine safer, in a better working environment for our people, better dust levels, less manual work, less traffic and therefore less potential for collisions, while also raising productivity.”

The Flexiveyor continuous haulage system has already started arriving at Cook Colliery, and will be assembled onsite and taken underground in time for August first coal.

“A crew of PMP engineers will be helping with the assembly of the Flexiveyor, they also have a training routine – it’s a combination of electrical, hydraulics and mechanical commissioning so that the Cook crew can maintain, then operate and maintain the unit effectively,” Seear said.

Magatar engineers will also be onsite for an extended period during the introduction phase to ensure that all parts of the system function as planned and are used in accordance with the design specifications of the system.

Seear said because they were trying something new with obvious safety benefits, the mine was in the unusual position of having people approach them to apply for jobs.

“We have been able to employ a full crew complement because people have heard about what we have planned for Cook, which has helped us enormously with our employment program.”

The mine currently employs about 90 people, which will increase slightly once the mine is in full production.

For the first of its kind to be put to work in an underground coal mine, the system will surely be operating under the watchful eye of an industry keen to see new technology tried and proven.

“Other people have tried – there are several concepts of continuous haulage out there – but what’s attractive with the Magatar system is that its building blocks are proven equipment although in a different environment, so that to us was a worthwhile, calculated commercial risk to take,” Seear said.

“There’s been a lot of interest from most of the big coal companies, but not surprisingly everybody wants to be second, they don’t want to be first.”