With the installation of Martin Engineering’s CleanScrape Primary Cleaner on its #14 conveyor, St. Marys Cement’s Detroit plant was able to improve workplace safety, lower the cost of operation and see a quick return on investment.
The 30-in.-wide belt is loaded with material that contains a moisture level of 10 to 15 percent, which causes dust and fines to build up into a thick paste.
“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. The polyurethane cleaner required regular tensioning and periodically needed to be removed, re-cut and shaped. In addition, two to three workers would spend up to eight hours twice a month cleaning the loading zone and the belt path using shovels and a vacuum truck.
Martin technicians concluded that the #14 conveyor was an excellent candidate for the CleanScrape Primary Cleaner. It requires considerably less space than other primary cleaners, can be effective enough to eliminate the need for a secondary blade, and is proven to deliver as much as 4x the lifespan of competing urethane blades, according to the manufacturer.
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 percent of potential carryback material.
Designed for belt speeds up to 780 fpm (4 m/s) for mechanically spliced belts, pulley diameters up to 50 in. and belt widths up to 96 in., the CleanScrape Primary Cleaner is engineered to perform under punishing conditions. In addition, 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.
After a full year of 24/7 operation with little downtime, the original CleanScrape Primary Cleaner installed at the St. Marys Detroit plant continues to perform consistently well, without a single adjustment. Additionally, the cleaning schedule has been reduced to a single worker hosing down critical areas for an hour or so, once a month.
Martin Engineering, www.martin-eng.com