Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr
Issue link: https://emj.epubxp.com/i/142836
O P E R AT I N G S T R AT E G I E S Atlas Copco Goes 'Green' for Improved Underground Air Quality Mining equipment supplier Atlas Copco recently noted that energy supply is one of the biggest challenges currently facing the underground mining industry as mines all over the world step up their efforts to cut costs and increase efficiency. The spiraling price of diesel to fuel underground equipment is the biggest "villain," closely followed by the soaring cost of energy to power largescale ventilation systems which commonly represent as much as 30% of a mine's total running costs. LHD vehicles and mine trucks traditionally account for the greatest proportion of these energy needs, but the future is looking decidedly greener with the availability of electric powered vehicles, slashing costs and improving the environment, both below and above ground. Underground miners are dependent on a constant supply of clean air in order to breathe and carry out their duties underground without risking their health. This means the toxic emissions from diesel powered equipment have to be constantly evacuated by ventilation systems, which require significant amounts of energy, irrespective of the size and complexity of the mine structure. By replacing diesel powered equipment with electric powered equivalents, mines can realize huge potential savings at the same time as they improve the environment, not to mention the spin-off effect of increased job satisfaction and reduced personnel turnover. Atlas Copco is the first, and so far only supplier, to introduce a complete family of electric powered underground loaders and trucks, according to the company. Known as the Green Line, the new family was launched in April 2013 and includes seven products: two trucks, four LHDs and a trailer-mounted generator. The LHDs were designed and produced by the company's division for Underground Rock Excavation in Örebro, Sweden, while the trucks are based on the Kiruna electric truck, developed by GIA, an Atlas Copco subsidiary since 2012. According to David Shellhammer, president of the division, the Green Line represents a major step toward a significantly better environment for all underground miners. "At present, the underground mining industry is facing numerous challenges regarding energy efficiency, carbon emissions and environmental footprints," he said. "We are the only supplier of underground electric trucks in the world and together with our range of electric loaders we have compiled a family of green alternatives that will change the future of underground mining." He emphasized that field tests, as well as products in operation in Canada, the U.S., China and Sweden, conclusively prove Atlas Copco's Green Line of electrically powered underground vehicles includes two truck models: the Electric Minetruck EMT35 and EMT50, with 35- and 50-ton payload capacities, respectively. 72 E&MJ; • JULY 2013 the use of electricity instead of diesel to power loading and haulage equipment substantially increases productivity and lowers overall running costs. Trucking with Trolleys The two trucks in the Green Line family are Electric Minetruck EMT35 and EMT50, with payload capacity of 35 and 50 tons, respectively. During normal operations the trucks are powered up and down the ramp by an overhead, electrified trolley rail. Where there is no access to an overhead trolley rail, for example at the loading and dumping station, the truck disengages itself from the trolley and automatically activates a small, onboard diesel engine. This unit, with an output of just 80 kW (107 hp), uses only 10% of the fuel used by a large diesel engine but is powerful enough to move the truck into the correct position for loading or dumping and then move it to be re-engaged with the trolley rail. This system results in a minimum of diesel emissions and exhaust fumes in the mine. In addition, a clever contribution to the overall green result is that empty trucks traveling down the ramp regenerate electric power, replenishing the mine's electricity grid. This is accomplished by the truck's high efficiency electric motors, which drive the axles directly, thereby minimizing transmission losses, together with a regenerative braking system. In this way, approximately 30% of the energy that is consumed by fully loaded trucks driving up the ramp is regenerated by the empty trucks driving down. In terms of ventilation, Atlas Copco said the extremely low level of emissions in an electrically mobile mine reduces the energy cost for ventilation by up to 90% while still keeping ventilation rates at the mining standards. Apart from these environmental improvements and the cost savings associated with an all-electric haulage fleet, there is also another major advantage that will appeal to all efficiency conscious mines. Due to the trucks' impressive speed on ramps—fully loaded on a 15% gradient they are twice as fast as any diesel powered equivalent—it means that fewer trucks are required to transport the same volume of material, according to the company. This translates into an opportunity for significant productivity gains, typically 20% or higher. Great Depth? Great Benefits Electrically powered haulage vehicles such as Atlas Copco's Electric Minetruck EMT35 and EMT50 are ideally suited for deep mines with steep ramps, multiple ore bodies and production operations located below the bottom of the main shaft, a point which Erik Svedlund, Atlas Copco's product manager–electric vehicles, sees as a significant economic factor. "Mines are continuously looking for new orebodies and this often means that they have to go deeper. When that happens, they have to decide how to solve their haulage needs. They can either choose to extend the main shaft, which is a big undertaking and an enormous expense for any mine, or they can decide to extend the ramp and prepare it for electric trucks. The latter is much less costly," Svedlund said. www.e-mj.com