Covering old ground

The development of an underground mine in a historical mining region created a number of hurdles.

 Ever since the suspension of operations at Xstrata’s Ulan coal mine’s open cut around four years ago, the miner has been considering possible ways to get the mine running at its full potential again.

But Ulan was on the backburner as Xstrata focused more on the growth of its Hunter Valley and Queensland operations.

However an increasing global demand for coal and a strong market price has impelled it to capitalise on Ulan’s existing infrastructure and an established local workforce.

But it was unsure of how to do this effectively, as nearly a century of work in the region had created a number of significant hurdles.

So Xstrata brought in GW Engineers to examine its options for continuing mining at its Ulan operation and the development of Ulan West.

Ulan’s age was a major factor, as mining has been carried out in the area for close to 90 years, so it had to deal with an exacting brownfields construction.

GW also had to optimise Ulan’s longevity while ensuring that operations could be carried out in compliance with Xstrata’s environmental management strategy – in particular noise containment.

It developed a number of different concepts, considering the viability of each and the individual approvals processes, before coming to an eventual decision – move further underground.

Going deeper

Preparation is now underway for the new Ulan West underground mine, which will begin production this year, longwall production in 2014, and will have an extended mine life that will see it run until nearly 2030.

Not bad for one of the most established coal mining operations in the western coalfields of New South Wales.

To achieve GW Engineers’ optimal site design of around 5 500 tonnes per hour of run of mill coal it faced a serious challenge due to the mine’s previous activities.

The clearance system from the one kilometer box cut to the 600 000 tonne hub stockpile needed to run over areas of the previous open cut mine which was now filled with around sixty metres of uncompacted, loose soil.

The engineers were forced to develop a design which minimised the rate of predicted long term mine spoil settlement.

They also had to create a means of structural adjustment for the clearance system’s 2.7 kilometre conveyor to compensate as settlement occurred.

According to GW, actually designing the movement and processing of coal between the hub and the stockpile "entailed some exacting analysis.

"The conveyor configuration comprises of a hub stockpile reclaim conveyor with 2000 tonnes per hour draw down points and a curved 2000 metre radius downhill conveyor falling 30 metres over a distance of about 1500 metres, and crossing the Goulburn River," the engineering firm explained.

Ulan West’s hub to product stockpile yard configuration will feed a sizing station with one secondary and two tertiary sizers, as well as two trash screens.

GW state that it can feed a stacker at up to 2000 tonnes per hour, which in turn will generate a 200 000 tonne stockpile with additional capacity via dozer push out.

A system of three conveyors reporting to an already existing rail load out bin will complete Ulan’s new surface infrastructure requirements, GW Engineers saying that each conveyor will service the stockpile reclaim and product outloading conveyor system’s seven draw points.

While the design of the facilities was difficult, the associated challenges that came with it – such as noise levels – presented a serious issue.

GW Engineers’ Keith Clegg said "beyond the more significant challenges posed by the curved downhill conveyor dynamics, Ulan’s environmental necessities required the company’s particular attention.

"Effectively suppressing the unavoidable noise from the operations was a significant concern, as approval conditions mandated that the mechanical and acoustic designs comply with the Ulan’s Environmental Management Strategy’s sound control parameters."

The specifications required all conveyor transfer points and elevated gantries to be fully enclosed to contain the noise and dust as well as any light emissions after dark.

GW stated that low noise idlers and conveyor drives units will all be certified before delivery to ensure compliance.

The actual coal handling system will be integrated into the mine’s existing control technology, with scope to expand.

Regarding the entire process from first approach to design, Clegg said that "although this is a brownfield site, Ulan’s state of the art and largely discrete monitoring and control technology will include provisions to create a planned environment where predictive, and importantly preventative, maintenance will enhance operations and save energy".

Workforce issues

Following the construction of infrastructure at the site, Ulan will also look to increase its workforce.

Its initial steps in doing so have already seen the miner accused of attempting to "poach" skilled workers from Queensland, in particular the Mackay region.

Ulan had representatives at the Mackay Show in June last year, who were looking for miners, tradespeople, mine under-managers, and also cleanskins to work at the new underground mine.

According to Ulan general manager Dan Clifford the mine was simply looking to source workers with varying skills at the ‘state-of-the-art’ operation.

"The strength of the mining industry across Australia has made it extremely difficult for other mines to attract new employees in recent years, but we believe Ulan has more to offer," Clifford said.

He went on to say that "Mudgee is a great place to live".

However the head of Mackay’s Regional Economic Development Corporation, Narelle Pearse, said mining regions should work together to build skills bases, rather than compete with one another, stating that Ulan was drawing away its region’s coal miners.

Pearse added "where would you want to live: the Whitsundays or rural New South Wales?"

In November 2010, Ulan was granted project approval from the NSW Department of Planning for the continuation of its existing and new underground longwall mining and open cut activities to generate around 20 million tonnes annually for another 21 years.

It has a measured resource of around 126 million tonnes of run of mill coal, and is targeting a production average of about 6.86 million tonnes of ROM coal annually once the longwall is operational.

The mine is a 24 hour, seven days a week mining operation, employing more than 900 people onsite.

Its site includes a coal handling and preparation plant, surface conveyors, stockpiles, rail loadout facility and various other infrastructure.

The mine, located near Mudgee and Gulgong, is a joint venture between Xstrata and Mitsubishi.

It will consist of two underground operations – Ulan No.3 and Ulan West.

Ulan West grew out of the expansion of Ulan No.3 underground works.

 

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