Published in March 2007 Australian Longwall Magazine

Unique to Australia and only seen before at a few international coal mines, the 400m wide longwall face at Ulan has been a mammoth project for managers and equipment operators at the mine, who have found there aren’t too many case studies to refer to when a problem needs solving.

The longwall operation, nestled in the Western coal fields near Mudgee in New South Wales, produces about 3 million tonnes of coal each year, but with the new gear now installed and cutting coal, the mine is now well on its way to achieving 7Mtpa by 2009. Since ramping up, production has steadily increased in line with the plan and has achieved a maximum daily production of 33,000 ROMt.

It has long been known that mining conditions at Ulan are conducive to a wider face, but moving from a 250m wide face to 400m was always going to present logistical, financial and technical challenges. In late 2004, with the potential end of opencut mining in the current area at Ulan in 2007, the management team got serious about the idea and began feasibility studies into the fat face.

Fast forward one year and the complete longwall at Ulan, with the exception of an Eickhoff shearer, was supplied by Joy Mining Machinery, boasting a number of Australian firsts, including 198 by 2m wide roof supports, operated by a revamped RS20s Roof Support Control System. The RS20s is the latest of its kind from Joy and is arguably the most advanced automation system available today.

Training the longwall crew to operate the new system was a major focus for both Ulan and Joy, which devised an intensive RS20s training package for a small group of operators, who then went to work on the longwall and taught other miners at the coal face.

A number of other innovations were needed to effectively support the wider face, including the world-first 50mm Joy Broadband Low Profile chain on the armoured face conveyor, and a higher power 3750kW AFC/beam stage loader/crusher combination to maintain enough drive over the 400m long face.

The Ampcontrol electrical package includes two 6.25MVA, 11kV/3.3kV/1050kV substations which includes another Australian first – a water-cooling manifold which dissipates the heat from the surface temperature of the transformer to prevent it from heating the surrounding air to unacceptable levels.

Two Inoxihp pump stations rated at 1360 litres per minute were chosen so that the mine could pre-install the longwall face ahead of moves, leapfrogging equipment from one panel to the next and preventing any disruption to production. A Macquarie Manufacturing-supplied monorail, capable of 205m of retraction, manages the larger cables and hoses required to maintain the water and fluid pressure along the 400m longwall face.

When the $90 million, 400m longwall package began arriving at the site in late 2005, an 80m wide mini-build was constructed to test the compatibility of the shearer, stageloader and monorail and give the longwall crew a preview of what they would soon be working with.

Not willing to risk any big surprises once the longwall was moved underground, the team at Ulan and the Joy support crew then set up a 400m longwall trial site, minus roof supports, which was loaded with coal and operated to test the AFC chain.

Joy’s Ulan longwall site coordinator, Dennis Cutajar, said because of the extra power from the AFC drives, the chain was under more pressure than normal and the trial run discovered that the tensioning needed to be adjusted accordingly. “The whole idea of having the 400m trial was to see what the Broadband Low Profile broadband chain was going to do and then create a procedure on chain management. We wanted to see what was going to happen underground and make any necessary changes while it was on the surface,” he said.

The AFC has definitely been tested as production steadily increases, and will be pushed to its 3500tph capacity over the next couple of months.

The major drawcard of the wider face, long term, will be reduced mining costs stemming from a decrease in roadway development metres and improved productivity as the shearer spends more time cutting coal at the face.

Longwall coordinator Jerry Bailey said the long-term financial savings of moving to a wider face were definitely a key factor in the decision. “We did a lot of research on ways of maximising the resource at Ulan over the life of the mine and the main justification to go to the wider face was saving money on development, not having to do development driveage.”

Joining the “fat face” project as it was on the verge of production in August 2006, longwall superintendent Ian Williams said the cost benefits from Ulan would be seen over the life of mine.

“Obviously it [the wider face] reduces gate and turnaround times – we only turn around every 400m compared to 250m on a standard longwall. So that’s increasing our efficiency and we will see the production figures of the longwall ramp up as the life of this longwall continues.”

Williams said a particularly daunting aspect of the project was finding there wasn’t a whole lot of support information on how to run a 400m longwall face, particularly regarding the known challenge of creep control. “We did a lot of research looking at the horizon control and creep control of a 400m longwall and there is actually zero out there in the mining world, so we took a shot at creep leads and lags and the guys are now managing it really well,” he said.

Williams said gas issues were almost non-existent at Ulan, describing the conditions as “one of the least gaseous mines in Australia”. The main advantages of this are obvious, as it eliminates the need for expensive and continual gas drainage.

Meanwhile, Ulan’s strata engineers have found “beating the bulge” at Ulan a continual challenge, as they race to keep secondary support ahead of the fat face. “We are relying on standard roof bolting technologies and monitoring regimes and we are finding we have to get the support in earlier and further ahead of the face,” they said.

Being such a wide face, the longwall spans across both sides of the main headings, which means Ulan engineers have to monitor the increase in horizontal stress across the gateroads. “Roof control is an ongoing challenge so we have to put the secondary support in on the back of continuous miners,” they said. “It’s basically a sequence issue – you don’t normally expect your development gateroads to be affected by the longwall, 400m away.”

Ulan longwall maintenance coordinator Clinton Maynard said the mine ran a midweek and weekend maintenance schedule of between 20 and 32 hours depending on production requirements.

Maynard said a relatively large team of 24 people work to balance production against maintenance while further OEM support is provided through a five-year, cost per tonne maintenance contract with Joy. The OEM’s onsite support service includes a full-time service engineer for three years as well as Cutajar’s coordinator role, which will end next year. “Our objective is to support the equipment over its life cycle at the lowest cost per tonne and ensure that our machinery works to full design capacity,” Cutajar said.

Being a pioneer in any area is usually associated with hardship and struggle, but as the fat face project approaches full circle, most workers at the mine contend that the biggest challenge has simply been walking up and down the 400m face.

“I have been getting a lot of feedback about the 400m face, a lot of mines are sitting on the fence waiting to see how Ulan goes, and if it’s successful they’ll be going the same way,” Cutajar said.