Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/141834
OPERATIO 1 2 Old school efficiency Driving Efficiency in Dredging I n dredging, efficiency drives production, and production drives profits. But what drives efficiency? Experts pinpoint several factors. According to Charlie Johnson, director of sales for Reserve, La.based Dredging Supply Co., the single greatest effect he has found on dredge efficiency is bank height. "Do you have a 20-foot layer of material, or a 10-foot layer of material?" he says. "I ask this because with a higher bank, you can set the water jet above the cutter to create an angle of repose and dredge a thicker layer of material, staying in one spot for a longer period of time — and raising your efficiency." Rick Parton, director of mining for Sahara Sand, a division of Fairless Hills, Pa.-based Silvi Group, says his company has recently been looking at the faces of its dredging mines, pointing to face width as a factor of efficiency. "We typically mine a 300-foot-wide cut at one of our mines," he says. "Now, with the dredge in a new spot, we're in a cove-like location, and we're cutting a 200-foot face. We've raised our production by 50 tons per hour in this location. We've realized that when the material falls off of the face, the cutter doesn't have to move as much. The smaller cut is working to our advantage." Parton says he believes part of the equation with this increase in production is the fact that this site has a lot of clay in the deposit, and the cutter must "work" the walls to make the material fall. With a narrower face, the cutter is not working as hard, and the material is falling more freely. That said, because no mine is created equal, there are other factors that also affect dredge efficiency. For instance, as a navigational dredge moves farther away from the plant, the cost per ton rises, while production declines. Also, preventive maintenance is often ignored, leading to costly downtime later. And in striving for consistency, which is the basis for steady production, a manual dredge often struggles, when compared to an automated dredge. Joe Sharf, owner of Carri Scharf Materials, based in Bloomington, Ill., is a believer in the benefits of dredging automation. In fact, he has automated all of his company's dredges at this point. "If it's pumping in automatic mode, you can hold your tonnage consistently all day long," he notes. "Otherwise you're fighting it all day long." Scharf says with a manual dredge, even with an experienced operator, "All might be well and fine until you have a cave-in, then you have to fight to recover." An automated dredge, however, can sense the cave-in, and automatically speed up the flow to recover. "It's just not worth it not to have it," he says. Most producers define dredge efficiency using an old-school formula: "If the dredge is capable of producing 1,000 tons per hour, and I'm producing 800 tons per hour, then I'm 80-percent efficient." The flaw in this formula is ignoring variables such as bank height, distance from the plant, and preventive maintenance. Additionally, automation allows for consistent production, which improves dredging efficiency. 4 5 Preventive maintenance a must A dedicated maintenance program that tracks the hours on each component and follows regular servicing will eventually pay for itself by reducing downtime and increasing wear part life. By tracking when production begins to fall off within the lifecycle of pump casings or impellers, the producer can proactively begin to replace these parts before their wear causes production to sharply decline. AGGREGATES MANAGER OperationsIllustrated_AGRM0713.indd 20 6/17/13 12:41 PM