Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/85639
OPERAT 1 it comes to crusher selection. "Due to the economy and the environment we're in, producers are looking for ways to maintain their current pro- duction levels, but be more effi cient," says Kelly Graves, technical sales manager for Kleemann. This is driving changes to the C track-mounted crusher market, he says. By addressing issues such as energy efficiency through the introduction of diesel-over-electric machines and offering machines with higher tonnage capacity, track-mounted plants are increas- ingly competitive in areas that have long been dominated by stationary crushers. "I see the track market moving toward being able to crush at the face, eliminate the load/haul aspect of a quarry, and be as pro- ductive, as well as being more fuel efficient, which, in turn, is a lower cost per ton," Graves elaborates. In the past, these plants had production limits of around 300 tons per hour. For operations that needed greater throughput, track-mounted plants simply weren't a viable option. By building machines with larger inlet openings and optimizing material fl ow throughout the crushing circuit, some units now produce upwards of 1,000 tons per hour. At the same time, diesel-over- electric allows crushers to use less horsepower than their diesel-over-hy- draulic counterparts. Th e diesel-over- AGGREGATES MANAGER Get the Most from Your Crushing Circuit ost per ton is the driving force behind many operator decisions in today's market, and the same holds true when electric option works well in cold environments where the ambient temperature might prohibit opera- tion of a diesel-over-hydraulic unit because of the cold temperatures and the fluids. Dual power capabilities also increase producer options. The machine's diesel power pack can be used to move the machine between locations, while it can plug into land power when available. Another widely embraced track- plant design change is the ability to pre-screen material before it enters the primary. Jessie Hoskins, owner of Longdale, Okla.-based Hoskins Gypsum, says the ability to pre-screen material before it enters the crusher helps maximize his production capabilities and was a key driver to his decision-making. His plant runs at rates of approximately 500 tons per hour, with relative ease. "We plugged the crusher up one time," he says. "That was due to several marginally oversized pieces of rock going into the crusher at the same time. We're producing 1.5 million tons per year, and we've only had one overload." Pre-screening offers a number of benefits, Graves adds. It lowers wear costs because material that doesn't need to be sized never enters the crusher. In addition to allowing the crusher to be more productive, pre-screening also helps remove mud and contaminants from the product on the discharge end. "You're more productive and creating less wear on your wear components inside the crusher," he says. Pre-screening material ensures more consistent and even material flow to the primary crusher. Undersize material is pulled out and sent to the discharge belt, while oversize material is sent to the crusher. By reducing the material go- ing into the crusher, operators can reduce wear costs while increasing production levels. And, some of the mud and con- taminants are removed from the material during screening. To get the most from your crushing circuit, it should be designed based on the deposit's mineralogy. Conduct tests for density, L.A. abrasion, psi levels, and silica content to determine the best crusher confi gurations for your site. Also keep in mind the desired product mix. For example, if fi nes are desired, impact crushing makes sense. Conversely, compression crushing can help operators avoid fi nes production. 4 Screen fi rst Know your rock