Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/531447
37 AGGREGATES MANAGER July 2015 EQUIPMENT MANAGEMENT water out of the fine aggregate," Schott says. "Another way to help build a material bed is to ensure at least 10 percent of your feed material is larger than the media opening. Features such as dams can also be integrated in the media panels to help improve the material flow and moisture content. "At the same time, you don't want to overload the screen to the point of dampening the stroke or damaging the deck," he adds. "You want to find that sweet spot between feed rate, the throw of the motors which controls rate of travel, and how much of the dam you have raised." The angle of operation can also be adjusted, though Schott says adjusting this is less common amongst producers. Typi- cally, dewatering screens function at an angle of 5 degrees, but can be lowered down to zero degrees if desired. The lower the angle of operation, the more water will carry with the material versus having the uphill slope to naturally hold it back. To find the optimal balance of settings, Schott encourages producers to only change one variable at a time. "If you need extra capacity, you can increase the throw of the motor to move material a little faster," Schott says. "Then analyze whether the dam needs to be raised or lowered to maintain an optimum bed depth or moisture content." "Just be aware that every adjustment affects one of the other variables in the process. For example, if you raise the discharge dam (weir) to increase the bed of material and improve the moisture content, you risk reducing capacity," he explains. "If you adjust the counterweights to reduce the rate of material travel on the screen, you also may risk reducing capac- ity. Larger media openings or more open area allows more water to pass through the deck, but you risk losing desired fine material." Replacing equipment When it comes time to replace your dewa- tering screen, several important elements must be considered, including product gradation, feed rate, and the percent solids of the slurry feed. Generally speaking, a finer product reduces the capacity of the unit. But just as important as the correct size and capabilities of a screen is the quality of the screen media and the manufac- turing involved in building the structure, Schott says. "Screens can receive a lot of abuse," he says. "Producers should ask themselves, 'Are they built to endure? Does the manufacturer offer a satisfactory warranty provision? Is there dealer support? Can you build a complete system customized to your needs?' By asking yourself these questions, you will be able to avoid incurring additional expenses associated with piecing together inferior commodity equipment or purchasing a system designed to do more than what you need." AM Michelle Cwach is the media relations manager for KPI-JCI and Astec Mobile Screens. YOUR UPTIME INSURANCE Your safety and productivity are in good hands with Atlas Copco CARE Agreements. Extended warranties, flexible ways to pay and various tailored plans are just some of the ways we CARE. 800-732-6762 www.atlascopco.us