Rock Products

APR 2018

Rock Products is the aggregates industry's leading source for market analysis and technology solutions, delivering critical content focusing on aggregates-processing equipment; operational efficiencies; management best practices; comprehensive market

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36 • ROCK products • April 2018 G iven the number of conveyor-related injuries that occur during routine maintenance and cleanup, every bulk material handler has a vested interest in technologies to help reduce hazards and prevent injuries. Seemingly mundane tasks such as adjusting belt cleaners and removing spillage often require employees to work in close proximity to the moving conveyor, where even incidental contact can result in serious injury in a split second. Further, spillage can contribute to the risk of fire by interfer- ing with pulleys and idlers and by providing potential fuel. Even worse, in confined spaces, airborne particles can create the right ingredients for an explosion. The buildup of fugitive material can occur with surprising speed. As the table below illustrates, spillage in an amount equal to just one sugar packet (about 4 grams) per hour will result in an accumulation of about 700 grams (1.5 lb.) at the end of a week. If the rate of escape is 4 grams per minute, the accumulation will be more than 45 kg (nearly 100 lb.) per week, or more than two tons per year. If the spillage amounts to just one shovelful per hour (not an uncommon occurrence in some operations), personnel can expect to have to deal with more than 225 kg (nearly 500 lb.) of fugitive material every day. Table 1: Material loss from conveyors. Belt Cleaning to Reduce Carryback Although there are a number of belt cleaning technologies available to conveyor operators, most designs in use today are blade-type units of some kind, using a urethane or met- al-tipped scraper to remove material from the belt's surface. These devices typically require an energy source – such as a spring, a compressed air reservoir or a twisted elasto- meric element – to hold the cleaning edge against the belt. Because the blade directly contacts the belt, it is subject to abrasive wear and must be regularly adjusted and periodi- cally replaced to maintain effective cleaning performance. Typically, the blades of a cleaner do not cover the full width of the belt, because the full belt surface is not generally used to carry material. CEMA specifies the minimum blade coverage based on belt width, as shown in Table 2. Keeping Up the Pressure Keeping Up the Pressure Optimizing Conveyor Belt Cleaner Tension to Maximize Performance and Service Life. By Alan Highton and Todd Swinderman Table 2: CEMA minimum blade coverage based on belt width.

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