Rock Products

MAR 2017

Rock Products is the aggregates industry's leading source for market analysis and technology solutions, delivering critical content focusing on aggregates-processing equipment; operational efficiencies; management best practices; comprehensive market

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54 • ROCK products • March 2017 SUSPENDED SOLIDS T he discharge of dirty water from wet screens, sand screws or classifiers has always presented numerous challenges to sand-washing operations. While the use of settling ponds is typical, the method unleashes a host of disadvantages. Pond maintenance is costly, time consuming, and hazard- ous to equipment and personnel. Water resources are not adequately recycled and production is potentially stalled if dirty water gets back to the plant – pushing sustainability further from reach. Importantly, amidst today's restrictive permitting envi- ronment, wash plants are commonly locked into limited footprints that simply cannot accommodate a series of ponds. Additionally, water may be scarce for some oper- ations; while others may not have a significant budget for high-dollar dewatering devices such as hydrocyclones, belt presses, and plate and frame presses. Consequently, companies must innovate to create sustain- able, affordable and efficient wash water management solutions. The latter is illustrated by a recent collaboration between Wendling Quarries Inc. and Clearwater Industries, two companies that employed "a teamwork approach" to engineer a clarifying and sludge-thickening system that delivers highly cost-effective wash water clarification. Wendling Quarries operates nearly 100 quarries in its 14-county region throughout eastern Iowa and western Illinois. "Our Cedar Rapids South Quarry faces a footprint constraint that requires proper clarification to pump out clear water on one end, and a high percentage of solids on the other," said Wendling General Superintendent Steve Yerington. He said that the plant was operating an older, existing clarifier and even after some experimentation with floc- culants, results remained inconsistent. "We could not get a consistent mud discharge from the old clarifier; and we were seeing a low percentage of solids. The system was not operator-friendly. It needed to be monitored constantly as it would either flow too rapidly, or would solidify and plug up," Yerington said, stressing that the situation would take his operator away from the wash plant for far too much time. Settling Suspended Solids An Innovative Sludge-Thickening System Delivers Cost-Effective Wash Water Clarification. By Carol Wasson Wendling operates a single 13,000-gal. clarification tank where flocculant is added via an automated system.

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