Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/214806
OPERAT 1 For safety's sake Keep Your Operations Arteries Flowing Freely I t's often said that conveyors are the arteries of a mine. And because they carry the operation's lifeblood to each processing stage, certainly for productivity's sake, conveyors should be designed, constructed, and maintained with as much care as any other piece of equipment in the plant. But conveyors don't only affect an operation's productivity. They also can affect product quality — and they can present safety challenges if they aren't properly guarded and maintained. According to Dana Boyd, vice president of operations for North American Limestone Corp. (NALC), the issue of spillage affects employee safety because of the manual labor required to clean it up. "Every time a job requires excessive manual labor, it exposes workers to higher risk for accidents and injury," he says. Larry Goldbeck, manager of conveyor technology for Martin Engineering agrees. "Cleaning up spillage from conveyors definitely puts employees at risk," he says. "They can suffer anything from back injuries to getting caught in conveyors." Additionally, spillage on catwalks adjacent to conveyors can cause slips, trips, and falls — and for this reason, such spillage is often cited by the Mine Safety and Health Administration under housekeeping issues. Boyd and Goldbeck both say that mixing shovels with conveyors creates especially high risks. Employees are prone to taking shortcuts. And it is so AGGREGATES MANAGER easy for a shovel to become caught in a moving conveyor during a cleanup. "There's an incentive for employees to not have to work around the belt," adds Goldbeck. But how do you reduce spillage? Belt cleaners help to prevent carryback and buildup, and receiving boxes at transfer points help ensure the scrapings don't end up on the ground. Making sure belts are aligned and are tracking properly is also helpful. Troughing idlers create a trough in the belt and work to funnel the material so that it will settle into the belt quickly, rather than spilling or bouncing out. Impact and slider beds are even more effective in helping material to settle at transfer points. "Truth is, spillage happens, no matter what you do to eliminate it. The key is to clean it up immediately and safely," Boyd says. An additional safety issue related to conveyors is dust. State environmental departments and the Environmental Protection Agency regulate opacity in the air because, on the safety side of things, it can affect visibility and breathing. Transfer chutes, skirting, and sealing the entry and exit at transfer points also help to funnel the material onto the belt, while helping to reduce dust. "And, to put it simply, a clean conveyor system contributes to the overall appearance of the plant, which creates a better work environment for employees," Boyd says. "It helps them to feel better about their jobs, which leads to better work practices." Without proper care and attention, conveyors can quickly create problems at any aggregates facility. Fugitive dust from conveyors can impair visibility. Spillage on catwalks adjacent to conveyors can lead to slips, trips, and falls. Any time employees are exposed to cleaning up conveyor spillage, they also face greater exposure to accidents and injuries. Shovels, especially, can be deadly if used around a moving conveyor. 4 Belt cleaners reduce carryback Without belt cleaners, carryback can affect up to 3 percent of an operation's overall production. This doesn't sound like much, but even at 100 tons per hour, this amounts to 3 tons per hour lost or gained. Just one belt cleaner per conveyor is likely not enough. A primary belt cleaner will catch up to 85 percent of carryback. A secondary cleaner, behind the primary, will catch another 12 to 13 percent of carryback. A tertiary cleaner will catch another 1 to 1.5 percent of carryback.