Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/789750
Managing Water Use and Recovery OPERATIONS Effective A water management program needs to not only focus on recovery, but also on conservation, environmental impact, and plan- ning. Water is integral to aggregate operations. As the need for aggre- gates continues, the need for water is necessary. "All water should be recycled from tailings ponds, runoffs, and wheel washes whenever possible," says Lance Griffi n, director of aggregate operations for Cemex in Texas and New Mexico. "You should always look for ways to better manage and conserve this limited natural resource within your operation." Follow solid engineering practices by keeping a plant's fl ow, design, and operation simple. "Prepare for break- downs by making the plant as simple to repair as possible and look at cur- rent and future water needs," Griffi n says. "Many water recovery plants are undersized and don't perform to expectations. A complete water audit is a great place to start when consid- ering a water management system." At LafargeHolcim, water manage- ment plans in place are reviewed every fi ve years to get a better under- standing of consumption. Water fl ow diagrams are put together, indicating all points of consumption. "Plants change, operations change, and things move around," says Joel Nickel, head of land and environment in the United States for LafargeHol- cim. Reviewing the plans and water fl ow provides an accurate snapshot of water consumption. "It has provided good learning," Nickel says. "We have found leaks in water lines. Repairing those has made a big difference." Nickels points out that, at one op- eration, nearly 1 million gallons were saved by repairing water leaks. "We recognized through metering of water that we were consuming more water than we were putting through the plant," he says. "By doing a diagram, we found water was going some- where we didn't know." Now, the level of awareness about water management and its importance is quickly being raised as an industry, especially because it is quantifi able, explains Tom O'Brien, engineer and consultant for Paschal Associates LLC. "Fifteen years ago, it was just dirty water," he says. "Now, it has become a cost center and a point of focus. We can now evaluate a plant's waste ef- fl uent (stream) and create a model for necessary fi nes recovery equipment, including capital and operating costs." Ultimately, good water manage- ment can contribute to a producer's bottom line. Although there may be an initial investment in the equipment necessary for fi nes recovery, there is a return on invest because there is a lower operating cost in handling all the water, O'Brien says. "Some of the larger operations I ser- vice will use up to 35,000 gallons per minute," O'Brien says. "If you are not using some kind of recirculating sys- tem, that is a lot of water. The amount of waste or mud washed off can be as high as 500 tons per hour. When you get into those volumes, it just makes sense to recirculate it." AGGREGATES MANAGER Water is integral to aggregate operations. As the need for aggregates grows and the area and community around an operation develops, there will be a greater need for water. Adequately plan so the water recovery plant meets expectations. To help improve effi ciencies and meet the demands of a booming Texas economy, Cemex's Balcones Quarry installed a base stone circuit, a state-of-the-art tertiary washing and crushing plant, a new mobile repair shop, and an environmentally sensitive oil storage area, along with overall quarry and plant improvements. The new water recycling plant uses 90 percent less water annually than previously used by the aggregate operation's wash plant. Regularly conduct a water audit to determine how and where water is used at your operation. Look for areas where the most consumption is taking place and deter- mine if there are any opportunities to optimize use and effi ciency. Use opportunities such as harvesting rainwa- ter or using stormwater or recycled water for haul road dust suppression or to wash lightweight aggregates. Recycling water minimizes the risk that an operation might have to curtail operations as a result of drought conditions or increasing water costs. Be sure to inspect equipment and waterlines for leaks or worn-out parts that may be contributing to excess use. Conduct a water audit Plan for current and future needs 1 4