The chameleon colliery

WHEN Indian coke giant Gujarat NRE Coke floated its Australian subsidiary India NRE Minerals in May this year, it also announced plans to return the historic NRE No.1 colliery into a 4 million tonne per annum, multi-seam longwall operation by 2012.
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The NRE No. 1 colliery.

Staff Reporter

Published in September 2007 Australian Longwall Magazine

The New South Wales mine has been no stranger to change - since it began producing 120 years ago it has used bord and pillar, pillar extraction and longwall mining techniques, and has been renamed numerous times. When Gujarat bought the mine for $A10 million in late 2004 it was known as Bellpac No. 1 Colliery, previously Bellambi West Colliery, South Bulli Colliery and originally Russell Vale.

The bord and pillar operations are in a consolidated coal lease, which covers more than 6421 hectares of land in the southern coalfields near Wollongong. Since reopening in September 2005, the mine has produced and sold 652,000 tonnes of ROM coal, which is exported to the mine's parent company in India.

Before listing on the Australian Stock Exchange in July, India NRE outlined its intention to undertake a $1.5m feasibility study into longwall mining at the site - with results due in 12-18 months. The plan is to develop a new set of access roadways in the lower Wongawilli seam and expand operations by developing longwall panels in the mine's western area. Pillar extraction will continue in remnant blocks bound by workings.

India NRE chairman Arun Kumar Jagatramka told Australian Longwall Magazine the company has invested more than $A90 million in the mine. The money has gone towards refurbishing continuous miners, shuttle cars, feeder breakers, mobile diesels and rail mounted vehicles, as well as towards outbye roadways and upgrades to surface infrastructure. New equipment has also been purchased, including three Joy shuttle cars and several rebuilt items for development panels.

"If the company is unable to proceed with the development of longwall mining operations, the company will assess alternative options and mining techniques, which at a minimum include the expansion of bord and pillar mining operations at NRE No. 1," Jagatramka said.

Of the four continuous miner units at the mine, one unit is extracting remnant blocks in the Western area of the Bulli seam, which will continue through to 2010. Two other units are developing roadways in remnant blocks in the central part of the mine, with some potential for future pillar extraction and the formation of a medium term conveyor road. The fourth unit is developing roadways relating to future longwall activities.

India NRE Minerals technical services manager Chris Harvey told AL that while development rates are around 700 tonnes per unit, per day, there are plans to double or triple advance rates by introducing a bolter miner together with a continuous haulage system.

"We have high expectations for the Magatar Mining system for roadway development that is proposed for our mains and gate road development … the rapid development unit has the attraction of reducing the number of continuous miners needed to support longwall development.

"With the introduction of this system, we would expect a positive development float for future longwalls panels," Harvey said.

The three main seams targeted for mining at the colliery are the Bulli coal seam, and the largely untapped Balgownie and Wongawilli seams. With a resource in excess of 300Mt, the proposed 4Mtpa multi seam operation has potential for more than 30 years of mine life.

The conceptual mine plan for NRE No.1's upgrade involves ten 300m-wide longwall blocks, ranging in lengths from 2km to over 3km following the development of the new access corridor. Harvey said if plans progress, a longwall operation in the Bulli seam would begin in 2012, with potential for a longwall in the Wongawilli seam possibly ramping up ahead of that date.

"Thin seam development techniques in the Balgownie Seam will be used to block out under the already extracted Bulli longwalls. This method will use continuous haulage techniques forming small pillars (approximately 15m) that will result in a high percentage recovery of the resource on the advance," Harvey said.

"Once in virgin areas, sequential mining is planned for all three seams, with a top-down approach [from Bulli down to Wongawilli]."

Harvey said specific thin-seam development equipment will be required to mine the 1.2-1.3m Balgownie seam, which has limited longwall mining potential because of the overlying Bulli goaves and possible subsidence constraints.

The proposed longwall mine plan also includes a new set of main entries ('J mains') from the Russell Vale side of the operation in the Wongawilli seam, which will link up with underground headings approximately 8 km in-bye. These roadways will allow for the installation of a high capacity conveyor belt and a parallel track road to replace the roads.

A new coal handling and preparation plant will also be needed to accommodate increased coal production.

The mine employs 164 permanent and 49 contract employees, but with the proposed multi seam operations, more than 250 employees could be required.