How to achieve a clean Conveyor Path

Innovative Belt Cleaning Technology eliminates Carryback at Cement Plant

How to achieve a clean Conveyor Path

After installing an innovative primary cleaner designed for punishing applications a Detroit cement producer could stop excessive carryback and equipment fouling. With a significant reduction in carryback, spillage, and labor for cleanup, the plant was able to improve work­place safety, lower the cost of operation and see a quick return on investment.
(ed. wgeisler - 26/3/2018)
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The St Marys Cement plant – located along the Rogue River in Detroit, Michigan – produces 200 to 250 tons per hour (180 to 225 metric t/h) of Portland cement. To achieve that figure, roughly 30 000 tons (27 200 metric tons) of raw material and clinker are supplied every
week by truck as well as by 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.

Front-end loaders transfer the fine grained, dust containing 1.5 to 2 inch (38 to 50 mm) minus limestone and gypsum aggregate onto the 30 inch (750 mm) wide No. 14 belt. Inclined approximately 20 degrees at the point of loading, the belt conveys cargo for 20 feet (6 m) up to ground level, moves horizontally for 200 feet (60 m), then begins another long 30-degree incline into the top of a 50-foot-tall transfer tower. In the conveyor discharge zone, with only enough room to fit one primary cleaning blade, material is off­loaded into a chute.

Limestone and other raw material taken from trucks and barges is stored in outdoor piles.                        

Operators found that polyurethane cleaner blades were unable to completely clean the belt. “The fines and mud take on the tacky consistency of toothpaste, causing it to cling to the belt along with smaller pieces of aggregate and shale,” said 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 that 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. After digging out the tail pulley, workers needed to clean the face, which often had abrasive buildup that could reduce the belt life. The cleaner required regular tensioning and periodically needed to be removed, re-cut and shaped. In addition, 2 to 3 workers spent up to 8 hours twice per month to clean the loading zone and the belt path using shovels and a vacuum truck.

The previous blade heaped up and encrusted material, degrading cleaning performance.                         

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