Aggregates Manager

April 2015

Aggregates Manager Digital Magazine

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31 AGGREGATES MANAGER April 2015 EQUIPMENT MANAGEMENT Trinity Materials' Indian Village Plant keeps dredges and processes sand from a small lake in southwest Louisiana where the recent oil and gas boom has brought new life to the construction industry. A Stronger Side of Material Handling by Carol Wasson The outer truss section of the mast-type stacker is solely supported by a wire rope suspension system. C onveyor systems vary widely in overall quality and efficiency. Con- sider that operations may obtain conveyors from a variety of sources — from in-house or local fabrication operations, to used equipment outlets, to opting for the lat- est technologies from major manufacturers. No matter the source, producers should ultimately evaluate each material handling system and component — not just on price or immediate availability — but based upon performance, safety, and ease of maintenance. Examining the latter criteria is the basis of a long-term and forward-thinking approach to choosing any piece of equipment. Case in point: A recent industry water-cooler discussion focused on evaluating the differen- tiating factors between mast-type stackers and telescoping radial stackers. Is one type more ad- vantageous than the other? How does each rate based upon the key criteria? Arguably, there are a number of varying opinions as to using either stacker type. Lafe Grimm, chief engineer for por- table projects at Superior Industries, shares his take on how the two systems stack up. Safety first Designed with an outer truss section that's hinged to an inner section, the mast-type stacker assembly is supported by a massive mast or tower structure that extends well beyond the hinged interconnection. This mass and height is required to support a wire rope suspension system that raises and lowers the outer section during conveying and stockpiling. The wire ropes are the sole support of the outer section. "Wire ropes can deteriorate over time. If left in service long enough, they will break – causing the potential of serious injuries, and costly equip- ment damage and downtime," Grimm says. He explains that the fiber strands in the wire ropes are susceptible to deterioration due to overload- ing, extreme heat, and damage due to bending, flexing, and kinking. These effects are acceler- ated in a system that involves sheaves and a moving cable. "Also, with the higher profile of the mast-type stacker's tower, the unit is more sus- ceptible to wind load pressure," he adds. Alternatively, the telescoping radial stacking conveyor consists of a stinger conveyor mounted inside an outer conveyor of similar length. The When evaluating stacking conveyor systems, consider their impact on material specifications, safety, and ease of maintenance.

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