New ground for Newlands

A development float which would make most longwall mines green with envy, a history of groundbreaking use of three-dimensional seismic technology and a ranking as number one longwall producer in 2003 have all the hallmarks of a mine with a bright future – results Xstrata Coal’s Newlands operation plans to repeat at its new Northern longwall mine.
New ground for Newlands New ground for Newlands New ground for Newlands New ground for Newlands New ground for Newlands

Newlands mine manager Dave Stone

Angie Tomlinson

Published in Australian Longwall Magazine

Located 130km west of Mackay, the underground operation is currently mining thermal coal from the Upper Newlands 3.4-5.2m thick seam, in the Southern underground.

Production-wise Newlands has consistently climbed the rankings; placing third in 2001 with 4.26 million tonnes and fourth in 2002 with 4.472Mt, before achieving highest Australian longwall coal producer in 2003 with 4.50Mt.

At the start of 2006 full production will begin in the Northern underground with a near new DBT shearer, additional DBT roof supports and a mine plan based on extensive exploration. The new area is expected to produce 7Mt per annum, considerably more than the current mine, due to wider and longer blocks.

Extensive exploration of the Northern underground using 3D seismic technology stemmed from the landmark use of the technology almost seven years ago. In 1997 then-owner MIM Holdings began a panel in Southern after running the accepted exploration techniques of the day, surface to seam boreholes, which indicated no major faults. Just a week before starting the face, amid a lot of publicity surrounding the mine as Australia’s (then) biggest longwall, Newlands found an undetected fault running the full length of block S4, subsequently sterilising the panel.

In a move that eliminated much business risk, Newlands appointed Brisbane-based seismic survey specialist Velseis to undertake the acquisition, processing and interpretation of 3.6 square kilometres of 3D seismic data over panels N1-N5 of Southern.

The 3D seismic survey was a success, with a number of new faults located within the mine design, and the character of previously identified faults better defined. Seismic imaging of the target coal seam enabled more focused drilling efforts to assess faulting within the mine area, and helped with the design of grouting programs and identifying roof support needs.

In 1999 a further of 3D seismic data from the Southern underground mine was acquired, processed and interpreted by Velseis. Again, seismic imaging improved understanding of faults previously located by drilling, as well as delineating many new structures that would have otherwise hindered mining operations. As a result of the second survey, the mine design was significantly altered to avoid mining through a number of severe structures.

Following these experiences with 3D seismic, Newlands quickly recognised the benefit of undertaking 3D seismic exploration much earlier in the mine planning and development process. As a result, the Northern underground mine area was imaged with a total of of 3D seismic data before the mine plan was finalised.

Velseis conducted this work in a number of stages, from December 1999 to August 2002. The 3D seismic results helped locate the final mine design so as to optimise extraction of coal away from significant structures and likely seam intrusions and allowed Newlands to realign the gateroads to bypass major faults. In addition, the Northern underground drilling program became much more focused, enabling robust assessment of risks associated with zones of structural and stratigraphic anomalies identified in the seismic data.

Northern’s coal quality and geology is consistent with Southern and with the extensive exploration completed the mine planning looks solid – however the new area is not without its challenges. The shortest block in Northern is longer than the longest block in Southern.

Long blocks, while having numerous advantages, raise issues of availability and equipment life. The first and largest block holds 8Mt and is 4,800m long.

The first panel at Northern involves a particularly complex belt installation where the gradient heads down, flattens out and then goes back up a steep incline. Newlands have opted for two belts to cope with the length, with the intention of using the existing equipment from the Southern Underground.

Equipment will be modified and overhauled in the move from South to North and 38 roof supports are currently under tender to accommodate the wider face.

The new DBT EL3000 longwall shearer was delivered to the mine in August and started mining the 6.2m thick seam in block S7a in the Southern mine. The shearer is capable of a 5m cutting height and features a new 2 x 100kW AC haulage system.

The EL3000 shearer is equipped with the new COMPACT shearer control system which incorporates significant improvements and capabilities. The EL3000 shearer at Newlands also features the new EL43 ranging arms, with 2 x 600kW of cutting power. It has been fitted with the Jumbotrack 2000 haulage system, replacing the original Rhinoride chain haulage system.

The major components of the shearer are incorporated into a new heavy duty mainframe designed specifically to accommodate the increased levels of installed power capable with this shearer.

Mine manager David Stone said there would be a proposal to tender for another shearer for the P2 panel at the Northern Underground, to commence operating in January 2007.

He said Northern would have wider and higher roadways for increased ventilation and greater ability to steer the longwall in and out of gateroads. To date the first gateroad and tailgate will be driven by August 2005 with about 30,000m of roadway to be driven before the first panel can be installed.

One advantage of the longer blocks is the reduction of downtime through less longwall relocations. In the past three years Newlands Southern has performed nine moves, three of them in the last year alone. In 2006, in the new area, only one move will need to be performed.

Newlands also boast what could possibly be one of the best development floats in the country. The operation here to read on.