Speed production and cut costs
An independent contract crushing company is using its new KLEEMANN mobile jaw and cone crushers – flanking a new mobile screen – to boost aggregate processing productivity while saving money on fuel. “Our current business model is to do contract crushing,” said Duff Boyd, President, Riverbend Construction Services, Jefferson City, Tenn. “We focus on mining of construction aggregates and material recycling.”
At an established quarry in South Carolina, Riverbend was taking granite production to a new level that was unattainable by the quarry owner working with its own forces and equipment. There, a new MOBICAT MC 110 Zi EVO primary jaw crusher, a MOBISCREEN MS 15 Z screen, and a MOBICONE MCO 9i EVO secondary cone crusher – all from KLEEMANN – were working together to smooth production and lower costs. “Here we are making crusher run granite road base and a No. 4 material, which is 2 in. by 1 ½ in. with no fines,” Boyd said. The crusher run size is 100% passing 1 ½ in., all the way down to 200 mesh size. Riverbend does the drilling and blasting of the gray granite, and loads and hauls the raw stone to the processing site on the top of the pit.
The equipment is set up in a closed circuit. Material is primary-crushed at the MC 110 Zi EVO, and both crushed material and all fines go to the mobile screen. The MS 15 Z mobile screen has two decks, the top with 2-in. panels, and 1 ½-in. panels on the bottom deck. The top deck overs go to the MCO 9i EVO to be sized down (as the jaw is set to 65 mm, a 4- to 5-in. size rock goes to the cone). The cone crushes that material and sends it back to the screen for resizing. The bottom deck overs are a 2 x 1 ½-in. rock, and the bottom deck screen throughs is a 1 ½ in. size which is stacked as a product. Anything dropping through is crusher run which is stockpiled and loaded onto trucks.
Prescreening optimizes the crushing process
With the new equipment, Riverbend was averaging 305 to 335 tph, depending on the feed. “If the feed is a good, well-blasted material, with this closed-circuit arrangement I can easily put up to 340 tph through. “By well-blasted, I mean a rock that’s not chunky, that’s shot well throughout with some fines in it and a variety of sizes that go into the primary. The moving jaw on the jaw crusher is much longer than the fixed jaw,” said Duff Boyd, President, Riverbend Construction Services. “That longer crusher jaw not only protects the pitman on the jaw crusher, which is great, but secondarily, it eliminates the edge or lip found on competing crushers, with their shorter crusher jaws – a place that bigger rocks tend to catch and hang on to. KLEEMANN’s taller crusher jaw all but eliminates stoppage due to big rocks. If you are doing 330 tph, and you have to stop for a half hour to dig the rock out, you’ve lost 165 tons of productivity.” Instead of a grizzly, Boyd’s new MC 110 Zi EVO primary jaw crusher utilizes an independent prescreen that speeds productivity. “The prescreen pulls all the fines out, and that’s where the tons per hour really pick up,” Boyd said. “But if it’s a coarse material, it all has to go through the jaw and my tons per hour will go down. The prescreen is the ticket. It cuts down on the wear on the crusher jaws and the wear plates. It prevents wear and tear, and increases throughput.”
Fines do not get into the crushing process
“Currently we don’t drop any fines through the prescreen that kick out the side; instead they drop right underneath and bypass the jaw, and we blend and mix them at the MS 15 Z scalping screen. When we crush through the MCO 9i EVO, those fines return and we blend the pit fines with the crusher fines to make a more consistent crusher run product, with stable gradation,” Boyd said. If we kicked them out at the jaw, and made crusher run at the screen, we’d have two separate products. The feeder itself sets the feed rate for the tons per hour coming into the plant.
Boosting efficiency with a diesel direct drive
“One great benefit of the KLEEMANN plants is its diesel direct drives,” Boyd said. “The MC 110 Zi EVO and the MCO 9i EVO are diesel over electric,” he said. “The crushers are run off fluid couplings but the rest of the plant is electric. The advantage is that the electrical systems are much easier to work on; any electrician who knows about three-phase electricity can troubleshoot or repair it. That’s unlike competing makes, in which all of the products are hydraulically driven. And when you have hydraulic problems, they are very difficult to troubleshoot.
Optimized material flow increases productivity
The other great benefit Boyd found was how the EVO plants optimize their material flow. Both crushers are equipped with the Continuous Feed System (CFS) which controls the speed at which the material is conveyed in relation to the crusher fill level. This clever system results in high output. With the continuous crusher loading, a high final product quality is also achieved and wear is reduced. “As the day progresses, and we start to see a little manganese wear on the cone or die wear on the jaw, and factors change throughout the day, the plants can be easily adapted,” Boyd said. If he sees the recirculating load is rising out of the MCO 9i EVO in the closed-circuit loop, Boyd can “tighten” the cone via adjustment of its closed-side setting.
Automatic gap setting and zero-point detection
“We can go in on a daily basis and do a zero-point set on the MCO 9i EVO,” Boyd said. “The cone will screw itself down until it touches, and then back itself off. It’s a super-accurate way of checking your closed-side setting. If you just go in and set it, unless you know where the zero point is, it’s not an accurate measurement. By being able to automatically zero out your cone, you don’t have to use lead weights or crush slugs to measure the lead, in order to see what the setting should be. The automatic setting is fantastic; you push a couple of buttons and it’s set within five minutes. The MOBICAT jaw crusher design also aids maintenance,” Boyd found. Like the MOBICONE, it features fully automatic hydraulic crushing gap adjustment, which guarantees quick setup times and on-the-fly adjustments.
A partnership that pays
While Riverbend has two other mobile aggregate processing plants of other makes, Boyd chose KLEEMANN after doing research that included visiting KLEEMANN’s plant in Göppingen, Germany. “I visited KLEEMANN’s factory about two years ago, and was fascinated by the design, engineering and fabrication of KLEEMANN equipment,” Boyd said. “The engineering is fantastic. As a result I had to give them a try.” At the same time, he found support for his existing equipment was getting weak. “The support I get from KLEEMANN and Linder Industrial Machinery Co. has been fabulous,” he said. “It’s of excellent quality.”