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26 www.coalage.com May 2017 moving overburden Uncovering Coal on the Surface New ideas and equipment may provide a more effective way of moving overburden by steve fiscor, editor-in-chief The coal production figures that some surface operations post are impressive, especially in the western U.S. What is more incredible is the amount of overbur- den they must move to mine that coal. If the stripping ratio is 7:1 or greater, then the mine needs to move seven times as many bank cubic meters (bcm) of rock to access the coal seam. Traditionally, coal operators have relied on draglines as the primary load- ing tool to move overburden. Over time, draglines have proven to be the most cost-effective means for the job at hand. These machines, which are some of the largest machines to walk the Earth, consume as much electricity as a small town. Obviously, technological advanc- es in control systems could improve op- erating efficiency and reduce electrical demand and the stress induced into the machine's structure. The digging end of the dragline deals with some of the most arduous conditions. Inconsistency in blast fragmentation leaves various shapes of oversize material in the muck pile. The impact on the drag- line buckets and the connection points take their toll. Likewise, improved design and metallurgy for these high wear points is extending tool life. Truck-shovel loading is another meth- od of stripping overburden. While it is not as cost effective as a dragline per bcm of material moved, the technique presents other opportunities, such as high mobili- ty or pre-stripping in advance of dragline mining. Recently, a new system was intro- duced that could dramatically improve the efficiency of loading haul trucks. New Dragline Control Systems During dragline mining operations, bank penetration exerts tremendous stress on the machine's major mechanical systems. Until recently, fixed machine limits and operator judgment were the only means of assessing whether the demands placed on draglines structural members were nearing or exceeding original equipment manufacturer (OEM) specifications. This reality has led to premature mechanical damage in the past, resulting in machine downtime, lost production and even safe- ty issues. Real-time, objective, structural stress monitoring can be achieved with the new FREEDOM control system for drag- lines, which combines the FREEDOM open-architecture platform with its most recent shovel innovation, Optimized Bank Performance (OBP). The OBP sys- tem offers real-time boom and gantry structural feedback to the FREEDOM platform. This real-time monitoring en- ables enhanced performance and in- creased productivity while staying within the machine's existing OEM limits. Using FREEDOM, structural abuse to the ma- chine is reduced while hoist and crowd FLANDERS recently introduced the FREEDOM control system for draglines, which is based on a similar system used for shovels (above).