Engineering & Mining Journal

JUN 2019

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FANS AND VENTILATION 56 E&MJ • JUNE 2019 www.e-mj.com the mine is cooled down to acceptable working conditions. Here, electric vehi- cles have another advantage to offer, as they produce much less waste heat than a diesel vehicle due to the much higher overall efficiency of the drive train. "When driving downhill on ramps with an electric vehicle, the braking energy is electrically fed back into the battery in- stead of being converted into heat by the brakes or the engine, as is the case with a diesel vehicle. This results in a further relief of the mine ventilation system." Steinberg expects that, in the future, we will see a combination of different al- ternative powertrains used underground. "It will very much depend on the local conditions of the mine and on the require- ments of the machine as to which type of propulsion achieves the best performance with minimum emissions," he said. "Our various battery-electric LHDs up to 11-mt payload and matching haul trucks operate very efficiently — sever- al units already for eight years. If more power is required for larger payloads, a diesel-electric hybrid variant, or electric drives with a cable or overhead conductor will probably be used initially. As soon as new battery technologies enable higher en- ergy content and shorter charging times, battery-electric drives will be able to suc- ceed, even with high power requirements." Reducing Energy Intensity There is no avoiding the fact that the en- ergy intensity of mines is increasing due to several factors: firstly, mines are get- ting deeper and, as a result, require more energy to circulate the air (increased pressure drop, and increased air density requires more power to circulate the air). Secondly, as mines increase their depth, the rock temperature increases the tem- perature of the ventilation air. As a result, many deep mines now require the pre-chilling of air, which is a significant drain on energy costs. In colder climates, the air may also need to be heat- ed in winter months to allow miners to work in a comfortable temperature range. "There will be some relief in the ener- gy intensity of mines when full electrifica- tion takes place," Gribbons said. "Elec- tric motors are far more efficient than internal combustion motors so the heat that is given off is less and there are no noxious gas emissions to deal with. As a result, less ventilation will be required in these types of mines. At the moment, we are at the start of this cycle since electric mobile vehicles are much more expensive than diesel vehicles. "It may take another 20 years to ful- ly change the current fleet of equipment, but for those that can afford this technol- ogy, it will reduce their demand on venti- lation and energy." Ensuring adequate ventilation at the mine face is another omnipresent challenge. "By appropriately designing and main- taining the auxiliary ventilation system, this could be mitigated," Trapani said. She add- ed that an exhausting ventilation system, with the air being exhausted from the face rather then pushed toward it is one way of tackling high temperatures as this limits ex- posure of the air to heat sources. However, when the heat is too high, such a preventive measure would not be sufficient and some type of cooling would be required. Gribbons hits the nail on the head when it comes to implementing mine ven- tilation solutions. COMPANY PROFILE-PAID ADVERTISEMENT At Stantec, we help mining companies recover natural resources in a safe and environmentally sustainable way. From front-end studies to mine closure and reclamation, we keep clients at the forefront of a rapidly changing industry. Here's just a few of the services we offer: exploration and resource assess- ment, feasibility studies and project management, environmental baseline and permitting, mine development and closure planning, civil infrastructure, mine facilities, operations support, tail- ings and waste, and legacy remediation. With over 30 years of creative solu- tions for clients and communities around the world, our approach is defined by a commitment to communities, creativi- ty, and client relationships. Balancing these priorities results in projects that advance the quality of life in communi- ties across the globe. Among our notable projects is the expansion of an existing hoisting plant at a mine in Saskatchewan, Canada. Our innovative approach included construct- ing the new stand-alone, four-leg steel headframe over the existing headframe. This allowed the team to successfully complete the entire expansion while minimizing production downtime at the mine. At 95.7 meters, the headframe was the tallest in the world at the time of its construction. The Stantec team is comprised of specialists in mining engineering, mine water and waste management, hydro- geological studies, material handling, mine ventilation, mine power and more. With more than 800 global staff mem- bers dedicated to mining and 22,000 employees across multiple industries, we offer the flexibility and responsive- ness of a small firm with the expertise and resources of a large company to execute some of the largest and most challenging mining projects. We take advantage of innovations in diverse industries worldwide and apply them to even the most complex mining projects. One example is our work at the Cerro Corona Gold Mine in Peru. Our team was recruited to design and super- vise the construction of a tailings dam, waste dumps, and other associated infra- structure. 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