A global innovator in conveyor belt cleaning technology has helped a Detroit cement producer stop excessive carryback and equipment fouling by installing a revolutionary primary cleaner designed for punishing applications.
With a significant reduction in carryback, spillage, and labour for cleanup, the plant was able to improve workplace safety, lower the cost of operation and see a quick Return on Investment (ROI).
The St Marys Cement plant located along the Rogue River in Detroit, USA produces 200 to 250 tons per hour of Portland cement. Front loaders transfer limestone and gypsum aggregate onto the 30-inch-wide belt, which conveys cargo up to ground level. The conveyor discharge zone, with only enough room to fit one primary cleaning blade, offloads into a chute.
Roughly 30 000 tons (27 215 metric tons) of raw material and clinker arrive weekly by truck and ship. The aggregate is offloaded to an outdoor storage area, where the material tends to get saturated when the Michigan weather turns wet and cold. This causes large amounts of mud and sludge.
Operators found that polyurethane cleaner blades were unable to completely clean the belt. “The fines and mud take on a tacky consistency of toothpaste, causing it to cling to the belt along with smaller pieces of aggregate and shale,” says David Accomando, plant maintenance supervisor for St Marys Detroit. “This led to a lot of carryback spilled along the return path, where it fouled idlers and built up so high under the loading zone, it would encapsulate the tail pulley.”
Maintenance technicians periodically had to stop other essential duties and shut down the system to replace frozen return idlers and prevent further damage. The cleaner required regular tensioning and periodically needed to be removed, re-cut and shaped. In addition, two-to-three workers spent up to eight hours twice per month to clean the loading zone and the belt path, using shovels and a vacuum truck.
Solution in sight
Martin technicians concluded that the conveyor was an excellent candidate for the CleanScrape primary cleaner. It requires considerably less space than other primary cleaners, is effective enough to eliminate the need for a secondary blade, and is proven to deliver as much as four times the lifespan of competing urethane blades.
The flexible cleaner is installed diagonally across the discharge pulley, forming a three-dimensional curve beneath the discharge area that conforms to the pulley’s shape. The unique design incorporates a matrix of tungsten carbide teeth and is tensioned lightly against the belt to prevent damage to the belt or splices. Despite extremely low contact pressure, it has been shown to remove as much as 95% of potential carryback material.
Designed for belt speeds up to 780fpm (4m/s) for mechanically spliced belts, pulley diameters up to 50 inches (1 270mm), and belt widths up to 96 inches (2 438mm), the CleanScrape is engineered to perform under the punishing conditions of cement applications and other bulk handling industries.
After a full year of punishing 24/7 operation with little downtime through conditions that included cold slush and mud as well as hot and dry dusty material, the CleanScrape cleaner continues to perform consistently well, without a single adjustment. The patented design requires very little maintenance. The tensioners are tightened during initial installation, and typically no further adjustment is required over the life of the blade.