Pit & Quarry, February 2017
SAND PROCESSING Aggregate supplier focuses on sustainability efforts with sand washing technology EDITED BY DARREN CONSTANTINO 56 PIT QUARRY February 2017 pitandquarry com PHOTOS COURTESY OF SUPERIOR INDUSTRIES ur greatest resource is our water says Christopher Larson president of Wissota Sand Gravel a Milwaukee based aggregate supplier As its third generation owner Larson is keenly focused on sustainability initiatives the latest being the installation of new sand washing technology that allows cost efficient fines recovery and the conservation of valuable water resources The operation is utilizing an innovative new system that combines a fine material washer and a dewatering screen in a single machine Its advantages are far reaching Were realizing these benefits at a fraction of the typical costs per ton in this application Larson says WATER CONSERVATION When using its prior sand screws Larson says the sand was coming out at about 25 percent moisture content Per my calculations we were losing about 400 gallons of water per minute and the water was going to a part of the operation where it could not be recovered he says Replacing that water would require pumping it from a deep well or finding some surface water within the operation that could be recovered It was the latter costly challenge he stresses that led to the acquisition of the Aggredry dewatering washer which is designed and manufactured by Superior Industries Larson describes the new system as making a lot of sense in its unique combination of two triedand true technologies sand screws and high frequency screens The Aggredry system at Wissota features twin 60 in fine material screws 600 tph combined with twin high frequency dewatering screens Our sand is coming off the two screens at 8 percent moisture content and requires no drying time Plus were saving about 350 gallons of water per minute Larson says The washed material is conveyed to finished product stockpiles and is immediately saleable With our prior sand screws the 25 percent moisture content would cause material to stick to conveyor components or to slough off into the wheels of the radial stacker With the new system we have eliminated that problem The dry material is easy to convey even when the stacker is elevated to its full height allowing us to manage our stockpiling far more effectively Larson says WATER WISE Overhead view of the Aggredry dewatering washer As of the latest season we cut that water use in half Ongoing sustainability is the mission CHRISTOPHER LARSON WISSOTA SAND GRAVEL O
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