Published in March 2005 Australian Longwall Magazine
Located 40km south of Newcastle, the Mandalong longwall mine will produce 3.5 million tonnes in its first full year of production, ramping up to in excess of 4Mt per annum at full capacity.
Longwall mining on the lease last took place at the adjacent Cooranbong mine from 1990-95. Place change mining and pillar stripping was then introduced, allowing the mine to continue supplying about 1.5Mtpa to the Eraring power station.
Original owner, Powercoal, intended to extend mining at Cooranbong using the existing workings to gain initial access to the mining area and put product onto the conveyor link to Eraring power station.
By the time Centennial took over Powercoal’s mines and lease holdings, Mandalong was an established development project.
Centennial management said they had aimed to have the new longwall operational by January 2005, and it was a real achievement that this had been realised. Mandalong general manager Mark Levey praised the commitment of the workforce and the focus of suppliers in getting the mine running on schedule.
Mandalong will be filling long-term contracts of 3.3Mtpa for local power generators, Eraring and Vales Point. Excess production will likely be channelled to export markets.
Mining is targeting the West Wallarah seam, ranging in height from 3.4-7m. The shearer is currently cutting at 3.8m, but the mine plans to cut as high as 4.8m once approvals are granted and horizon control commissioning completed.
Joy Mining Machinery was awarded the contract to supply a complete longwall package, consisting of shearer, roof supports, armoured face conveyor and beam stage loader.
The roof supports are 68 Joy two leg 1053t shields, 1.75m wide, each weighing 33t.
The face control system is the RS20, Joy's latest generation of control technology, and, significantly, the first full-face installation of the system in the world.
The shearer is Joy’s newest, the 7LS6, believed to be one of the most powerful shearers in Australia. Rated at 1760kW, the machine incorporates 750kW ranging arms, twin 110kW AC haulage and Ultratrac 2000 face haulage.
Because the block width is relatively short at 115m wide, the AFC’s power demand can be satisfied with a single 1000kW TTT drive. The AFC, BSL and crusher are fitted with Reliance Electric water-cooled motors. The 1000kW flame-proof AFC motor is the first to be supplied on an AFC in Australia by manufacturer Rockwell. The 42mm by 146 face and 38mm by 126 BSL chains were supplied by Parsons Chain.
The shearer speed is currently limited at 6m per minute on the tailgate to maingate run, and 12m/m on the clean-up run.
The mine is currently running at a target of around 1200-1400t per hour, but could peak at 2300tph.
The conveyors had only just been installed at the time of going to press and had been commissioned in a very tight timeframe as part of a major outbye conveyor upgrade and extension.
The conveyor system is a Continental Conveyor structure. The equipment includes two trunk conveyors rated at 2000tph, 1200mm wide, driven by two primary 450kW TPKL drives and a 450kW tripper drive. A third trunk conveyor is rated at 3750tph, at a width of 1600mm, with the same drive power. Two maingate belts were also supplied at 2700tph at 1400mm wide.
One of the trunk conveyors will feed through to the Delta power station, but the roadway for this system is still being laid. When that opens, the mine will have substantially more clearance capacity than it has at the moment.
To assist with overflow, an underground surge bin with a 1500t capacity was installed by Cementation Skanska.
Ampcontrol supplied the $8 million electrical package, including a 33kV/11kV surface switchyard with dual supply 10MVA transformers, and eight conveyor substations with integral starters.
Also included is Ampcontrol's VoiceCom and iMAC monitoring systems to allow remote data gathering and fault diagnosis.
The Mandalong pump stations were supplied by UK company Repower Mining International (RMI), the second longwall order RMI received from the local market.
The roof supports will be supplied with hydraulic fluid at 400 litres per minute at 350bar from three S350 main system pumps rated at 262kW. One S350 high set pump, rated at 262kW, supplies 163 litres per minute at up to 420bar. The emulsion tank capacity is 9000 litres.
The shearer water boost pump station includes two S200 pumps rated at 150kW, each supplying 423 litres per minute at up to 100bar. The water tank capacity is 2000 litres.
A 3x105m pillar monorail with material handling system was supplied by Macquarie Manufacturing and is still undergoing minor commissioning.
Access to the mine is gained through a 1.3km men and materials drift completed in October 2004. The drift is 4.8m wide and about 5m high and has been concreted to facilitate travel.
The first longwall panel is 2.1km long and due to be completed by June 2005. Future panels will be 2.6-3.5km long. There is a little uncertainty concerning the position of longwall 5 as a dyke is believed to be present with in-seam exploration drilling being carried out to further delineate the structure.
The relatively short width of the panels at 125m has been imposed by the subsidence constraints under which the mine operates (see related article).
Geotech consultant Ross Seedsman, who assisted with subsidence planning, said this was one of a few mines designed against subsidence constraints.
The narrowness of the panels will put pressure on roadway development and the mine has a big focus on getting ahead with development.
Three ABM25s are in service at the mine – two operating in a super-panel configuration in the maingate at an average of 230m per week of driveage, while a third machine is working mains development. The machines are working solidly around the clock. Since going into service last year, the new ABM25s have performed well, achieving availability rates in excess of 99% within the first months of commissioning.
Roadway support is...click here to read on.