Two GA110 variable speed screw compressors replaced several diesel-powered units.

The decision to replace the existing diesel-driven compressors with Atlas Copco electrically powered screw compressors at the Unity mine in Neath Valley, South Wales, has resulted in significant benefits in terms of process efficiency, energy use and reduced environmental impact. The Australian mine, which re-opened in 2008, is now in the process of moving to full production of approximately 1 million tons per year or more.

After the mine’s re-opening, management focused on the reliability and efficiency of production equipment. Duncan Kilbride, director of projects and procurement at the Unity mine, said, “The initial plan for the mine’s workings were based on the [room-and-pillar] extraction methods that employ a continuous miner and secure the work with roof bolting, as opposed to arched roadways. This process requires air-driven equipment fed by a reliable continuous supply of compressed air. We also operate pumps on a permanent basis to remove water.”

Air for these operations was supplied originally from a number of small, rented diesel-driven compressors, but there was growing concern with their mechanical reliability and the risks of any break in the regular supply of diesel fuel. This dependency issue, coupled with increasing rental and fuel costs, made it evident that replacement with more energy and cost-efficient compressors was essential.

The new compressor installation will lower energy costs for the mine dramatically. “We invited tenders for the system and Atlas Copco came up trumps as a one-stop shop solution for the compressors, filtration units, controller and compressor house installation. They scored as a world-leading specialist offering long-term options on a range of packages best suited to our needs within the required timescale plus an ongoing support organization,” Kilbride said.

Two oil-lubricated, air-cooled, full-feature GA110 variable speed drive screw compressors were installed together with a companion fixed-speed version machine. It has been calculated that energy savings in the region of $22,000 per year are achievable, in addition to substantial savings in equipment rental costs. These Atlas Copco compressors provide base load and back-up peak 7-bar air to the drilling and roof bolting equipment, and the water pumps.