Engineering & Mining Journal

JUN 2018

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

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Page 51 of 115

VENTILATION 50 E&MJ • JUNE 2018 "Free as the air we breathe" is a notion that's only valid on the surface of this planet. Underground, it's a different story. Maintaining the air flow and quality need- ed to keep workers in deep mines safe and comfortable is a costly endeavor, account- ing for anywhere from 30% to 40% or even more of a mine's total energy bill. In fact, mine air is so expensive that Epiroc, a leading producer of underground mining equipment, currently features on one of its webpages a mock ad picturing a 400- ml aerosol can of "mine air" and inviting customers to "Take a deep breath…this is some of the most expensive air in the world." The can is priced at $39.95. With a capacity of just eight breaths worth of air, the imaginary can is no bar- gain — and when it comes to mine ven- tilation in general, bargains are hard to find. For instance, the huge fans most mines use for primary ventilation purpos- es aren't cheap to buy and install, but their purchase price might be considered a bargain compared with the cumulative power costs they accrue over the course of their service lives. And as mines extend to greater depths, the costs and chal- lenges of maintaining proper ventilation and cooling of underground work spaces grow in lockstep with development. It's an ongoing struggle for underground mine operators — one that regularly demands solutions to thorny technical issues, and involves decisions made from the top of the organization down to the lowest level of the mine regarding everything from the multimillion-dollar funding of a new ven- tilation shaft to the selection and place- ment of helper fans in the stopes and workrooms. Unexpected problems in mine ventilation performance and quality can cause a sudden and complete work stop- page lasting for weeks or more, as expe- rienced by Vale's Coleman operation near Sudbury, Ontario, last November when the company determined that repairs were needed in the mine's ventilation shaft. Fortunately, mine ventilation is also an area in which many potentially use- ful solutions are available, ranging from basic products such as mine doors and ducting to high-tech, mine-wide ventila- tion-on-demand (VOD) systems that in- clude extensive sensor arrays, asset track- ing and energy management capabilities. A Swing Toward Safety Until quite recently, mine doors installed to control air flow in underground mines weren't regarded as sophisticated devic- es, but increased emphasis on worker safety and efficiency, along with a rising interest in ventilation automation, has re- sulted in a new generation of door designs that cater to these concerns. For exam- ple, American Mine Door's EcoVent door, introduced to the industry at MINExpo 2016, addresses safety issues encoun- tered when workers open and close doors in zones where the pressure drop from one side of the door to the other is high. EcoVent doors are distributed in the U.S. by Jennmar, which offers a variety of door types, stoppings and other ventilation ac- cessories, and is available through other sales agents in the international market. Traditional mine doors require miners to open one panel at a time. The EcoVent doors use a patented opposing-wing de- sign in which the wings are connected. When one wing is opening, the other wing also opens simultaneously in the oppo- site direction. This design, according to the company, uses equalized air pressure to assist the door in opening and closing with little effort. The air pressure does the work instead of the miner, creating a safer work environment for miners as doors will not slam closed, significantly reducing the potential for injuries. Apart from their safety features, these "swing type doors," which are also avail- able from other suppliers such as Zacon Focusing the Flow Tight control of underground mine ventilation system performance can be an ongoing challenge, but software, hardware and service options for drafting better ventilation plans keep expanding. By Russell A. Carter, Contributing Editor The main ventilation system at this large European copper mine comprises four fans, each with an outer diameter of 3.8 m (12.5 ft) and total installed power of 4,000 kW. (Photo: TLT-Turbo)

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