Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/485104
AGGREGATES MANAGER April 2015 32 stinger conveyor has the ability to move linearly along the length of the outer conveyor, thereby varying the location of the discharge pulley. The height of the discharge pulley is variable, as well as the radial position of the conveyor. The undercarriage design also delivers support and rigid lateral stability. "We adhere to some very rigorous steel structure codes; and the load sharing hydraulic cylinders add even greater structural support and stability," Grimm says. He adds that the cylinders used to raise and lower the stacker are specially de- signed for safety, as a counterbalance valve keeps the "raise" cylinders from lowering should there be a hydraulic failure. Also, he explains that, in extreme weather situations (such as hurricane winds), safety and loss prevention are aided by the ability to quickly and easily adjust the stacker by retracting the stinger conveyor and bringing the unit into a low profile. Performance points According to Grimm, some mast-type stacker manufacturers describe the wire rope suspension system as allowing the dis- charge point of the stacker to remain slightly above the top of the pile, thereby decreasing material segregation and degrada- tion. "In truth, mast-type stackers are not known for precise control and increased range of movement. As such, they are prone to deliver higher material segregation within the finished stockpile," he says. To mitigate this situation, some operations have added spray systems or specialized chutes to reduce seg- regation issues and minimize particulate matter in the air. "An automated telescoping radial stacker is the only solu- tion to creating a fully desegregated stockpile," Grimm says. "It stockpiles in very thin lifts or layers, with each layer consisting of a series of windrows of material. To accomplish this, the conveyor is in motion continuously, and the three-axis varia- tion of the discharge pulley is essential in making the layered pile that overcomes segregation." Telescoping conveyors can also be programmed to create higher-volume stockpiles of many different shapes, sizes, and configurations. Grimm points to the fact that some site foot- prints are more suited to a rectangular or pie-shaped pile; or a producer may want to stockpile inline over a reclaim tunnel for more live storage. This stockpiling flexibility can result in high- er production capacity at a lower cost, he says, adding that these advantages are particularly important to the portable op- erator who wants to build the largest stockpile possible before relocating or to the producer who wishes to maximize stockpile volume on a site with limited space. Portability is another consideration, he says. The telescop- ing radial stacker has three styles of road or radial travel axles from mobile, to in-pit portable, to fixed radial stacking. "Mast- type stackers require a lot of clearance and are very expensive to move," Grimm says. Ease of maintenance The wire rope used on mast-type stackers requires frequent and meticulous inspections by a designated competent per- son. Guidance on these inspections can be obtained from the American National Standard for Wire Rope for Mines; the Oc- cupational Safety and Health Administration; and from the wire rope manufacturer's specifications, which indicate the number of allowable wire strand breaks per equipment type. The number of broken wires on the outside of the wire rope is an indication of its condition and whether it must be considered for replacement. An automated telescoping radial stacker can create high-volume, fully desegregated stockpiles in an assortment of configurations.