Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/339575
25 AGGREGATES MANAGER July 2014 PLANT PROFILE yardbucket. It scoops out the sand to a depth of about 50 to 60 feet and stock- piles it. After the sand has been allowed to drain for a couple of days, a loader operator comes in, scoops it up, and places it into a second feeder. The sand is then run up to the processing plant on the same conveyor system that the rock is transported on. The products are washed, screened, crushed, and sepa- rated when they reach the processing plant. "When the ma- terial comes into the plant, we scalp off 10-inch and larger cobbles with sidekicks and put them into a separate stockpile," Stauffer explains. "The rest of the material goes into a primary wash screen. Everything 1-inch and smaller goes to a coarse material washer and a fine material washer. It then goes to a secondary wash plant where we make high-quality concrete sand, pea gravel, and 1-inch natural concrete aggregate. Anything 1-inch and larger goes to a crusher that reduces everything to 4-inch and smaller, which then goes to an HP500 and HP400. Everything gets reduced down to 1-inch minus and goes out to final sizing and to the different stockpiles." The control room in the processing plant is fully automated with all the latest in high-tech computer equipment and programs, allowing the operator to start and stop everything. He can also monitor all activities and machines to keep track of everything going on in the plant. Customer trucks are loaded from stockpiles, as well as from silos. Yard loaders are equipped with bucket scales so the loader operator can load the trucks to 80,000 gross pounds, which is the Cal- ifornia maximum allowable weight. If, at the scale, the truck is a bit underweight, two bins with conveyors top off the load before the driver receives his ticket. Hallwood Plant makes approximately 15 different products ranging in size from 12-inch cobbles to crusher dust. Five of the crushed stone products are used in the asphalt plant on site. "The asphalt plant is a portable plant, but it has been in one location for 12 years," Stauffer says. "We made it station- ary as far as the permits go, but it's all on wheels, so we can move it if we need to. We have three 300-ton silos to store the asphalt for our customers. Teichert Con- struction is one of our customers, but it isn't our biggest customer. We supply asphalt for many of our biggest competi- tors, as well as for small local companies." In addition, used asphalt, or RAP, is recycled at the plant. Asphalt grindings from road construction jobs are brought in and stockpiled. The grindings are then crushed down and added to the asphalt mix. Caltrans (California Department of Transportation) currently allows 15 Wheel loaders simply scoop material from the large windrows of tailings left behind by gold dredges that mined the area in the early 1900s. High-grade sand below the water table is mined to a depth of 50 to 60 feet by a dragline with a 6 1/2-cubic-yard bucket.