Whitehaven Coal’s Narrabri North mine set new production records last year and subsequently ordered a second Cat® EL3000 Longwall Shearer and a second Cat BSLPF6 Stage Loader for delivery in August this year. The mine, located in the Gunnedah Basin of New South Wales, Australia, set a weekly production record of 257,000 tonnes in June and a new quarterly production record in the final quarter of the year. The mine produced a total of 5.659 million tonnes in the year.
A Whitehaven production report summarized the longwall performance: “The longwall has been consistently producing coal at above the original design levels since production commenced in the second panel.”
Full commercial production from the longwall started in October 2012, and production has increased steadily from that time. The EL3000 Shearer features a unique one-piece mainframe engineered to optimize productivity while ensuring reliability and durability. Ranging arms feature cast hinge points designed to handle higher cutting and haulage forces, such as 860-kW (1,380-hp) cutting forces with haulage capable of 32 m/min (105 ft/min) while cutting.
The new shearer and stage loader are scheduled to go into operation in Narrabri’s longwall block number 5, which is about 300 meters wide and will have an extraction height of 4.2 meters. Seam height is 8 to 10 meters, but Whitehaven determined that extending the longwall face – to as wide as 400 meters – will be more cost effective than would mining shorter face widths with longwall top coal caving techniques.
Both the first EL3000 Shearer and the new one are equipped with the Cat PMC Evo-S control system and advanced automation package. In 2014, Narrabri implemented full shearer automation, which boosted longwall productivity and horizon control. Utilization of full shearer automation – with no input from operators – is now exceeding 94 percent on average and is 95 to 100 percent except near gate ends.
Cat Advanced Automation Control uses state-based automation, which enables the shearer to operate precisely to the mining company’s defined production process, including direction of travel, speeds, arm height and ranging arm control modes. As many as 200 states are defined, and specific actions and conditions must be met before the system enters the next state. The system is available as shearer automation only or as integrated longwall automation. The latter offers improved face alignment and horizon control, as experienced at Narrabri.
The greatest benefit to operators on the longwall face is the ability to stand clear of moving machinery and away from dust generation sources. The cutting process is consistent in speed and distance the shearer travels in and out of snakes—with no need to slow down to straighten or align the face as personnel control shields manually. Also, automatic horizon control delivers coal with less dilution from roof and floor material.
The new stage loader features Cat PF6 line pans, 42 mm power chain and a tensionable drive frame. Cat Slacktronic, the electronic chain slack sensor and control system, helps ensure reliable operation and long chain life.
WesTrac, the Cat dealer in the region, provides sales and product support services for Narrabri’s longwall operations.