Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/420189
EQUIPMENT MANAGEMENT 19 AGGREGATES MANAGER December 2014 and dredging operations. Excess water causes more materials to report to the underflow of the screen. Bucket-wheels, dewatering screws, and the like still have their place, but nothing dewaters like a dewatering screen — let's get real — 1G for the older technology versus 5G or more cannot compete for stockpiling and inventory avail- ability. Inventory space availability is a big fo- cus, as it can take three days on the stockpile to dry from 25-percent moisture, and at 600 tons per hour, that is a lot of stockpile; not to mention that with the water go the fines, so a cleaner product is the result. Safety and housekeeping are other issues important to consider when looking at dewatering equipment. At 10-percent points drier than a bucket-wheel or screw washer, the material goes up a conveyor and does not create a dangerous mess at the tail pulley of a conveyor that someone would need to clean before material eats the belt or bearings. Ad- ditionally, there is less carry back on the belt, trucks and loaders are not mired in constant water drainage, and when the Department of Natural Resources or an inspector comes to visit or an open house is planned, the stock- pile area looks great. In the configuration shown on this page, the separator controls the cut, and the dewatering screen controls the final product moisture. Most producers would trade a lile extra horsepower for a drier and cleaner product with fewer fines lost to the pond, which is exactly what this system does. Summary Dewatering screens are available for capaci- ties up to 400 tons per hour per machine depending on application and product grading, and while they are just one piece of the puzzle, they have evolved in the industry to be a key part of aggregates processing sys- tems. W hen properly applied, units provide a consistent, drip-free product; a safer, cleaner work environment; and a very low main- tenance cost. Used for decades in the minerals industry, these machines are now standard equipment for aggregates, too. AM John Best is general manager-process engineering for Hollidaysburg , Pa.-based McLanahan Corp.