March 1, 2014
A new portable impact crusher allows an Arizona operator to streamline crushing operations; all while boosting production and lowering fuel costs.
By Ken Kuennon
A new mobile impact crusher with self-contained screen is enabling an Arizona operator to leverage his demolition concrete and reclaimed asphalt pavement into a saleable product. In addition to crushing his own demolition concrete, he’s able to generate tipping fees from other contractors as they bring recycle material to his Phoenix-area plant. And he’s doing it all with a single, new Kleemann Mobirex MR 130 ZS mobile impact crusher with secondary screen, which became operational in summer 2013.
“Recycling is something we’ve worked with for decades,” says Jerry Buesing, president and CEO, Buesing Corp. “We respected and bought products such as recycled concrete aggregate [RCA] and reclaimed asphalt pavement [RAP] principally because of the cost, but also the difference in the weight of the materials compared to virgin aggregate — and the ability to lay down and pave on it — is much better than a lot of natural aggregates.”
That, he says, is because the percent of fractured faces of crushed, recycled products is higher than for many virgin aggregates, depending on the availability.
“Many local governments and agencies specify a certain percentage of fracture,” Buesing adds. “Most of the aggregate sources here can meet that fracture spec, but not all, and barely meeting the fracture spec results in an unstable base material; you will have to keep it very wet to get on and pave it, but when you put down crushed concrete and grade it, it’s there to stay.”
Concrete recycling operations
The company operates its concrete recycling facility on an unincorporated 10-acre site within Chandler, convenient to major freeways. While it principally recycles demolition concrete, it also accepts RAP for processing.
Buesing estimates he will process 100,000 tons of RAP each year, and more than 300,000 tons of RCA in a banner year. Trucks haul material to large stockpiles, which are reshaped by front-end loaders and excavators as they provide raw feed for the impactor.
While the operator crushes its own demolition concrete, the majority of the concrete recycle feed comes from other sources, he says. “We reuse the material in our own construction when feasible; otherwise we sell it,” Buesing adds. “We have many customers, from the mom-and-pops to major contractors. We quote the materials delivered out of there to other contractors, and will deliver them F.O.B. to the job site. The smaller contractors will come in with pickup trucks or trailers and haul the material away.”
The RCA is used for driveways, parking lots, pipe bedding, and bases of all kinds. From RAP, the operation typically will produce a half-inch rock that can be incorporated into asphalt mix that it sells.
“RAP has not been as well accepted in the Phoenix area as it is elsewhere in the country,” Buesing says. “It’s used primarily as base aggregate, but also as an inexpensive surfacing for parking lots. If it’s treated, it will portray the same properties as hot-mix asphalt pavement. It won’t be as smooth and will be more easily eroded, but it does a pretty good job at it while being fairly dust-free.”
RCA base material that meets spec typically will be 1.25-inch minus size, and that’s been Buesing’s mainstay. “We can do upgrading of the plant to produce even concrete aggregate, as it’s normally clean enough if screened,” Buesing says.
And he’s looking forward to producing additional sizes of aggregate. “With this machine, we are planning on getting more aggressive in producing other products, and see if we can’t up-market those, so rather than getting $5 or $6 a ton, we could get $8, $9, or $10,” Buesing says.
Fighting deleterious material
The operation rarely encounters alkali-silica reactivity compromised concrete, he says. “One way of fighting that is in the way you handle your input into the plant,” Buesing explains. “All of our loads are inspected when they come in. Garbage in, garbage out. We do our best to inspect loads; we’ve sent trucks out to landfills so that it stays out of our plant. We also use a belt picker when we have any problems, but tightening up on dumping helps the most. Our guys have done a great job on this.”
The impact crusher replaced a dual impact crusher set-up with 14 x 13 and 13 x 13 crushers. The assembly of the machines particularly impressed Buesing, he says. “I’ve been around equipment long enough to tell what it’s going to give you by how it’s built,” he notes. “Kleemann does an excellent job in the build, right on through the paint process.”
That being said, versatility was of paramount importance. “The plant that we had was a stationary plant on wheels, and it took 12 loads to move it somewhere,” Buesing says. “The MR 130 gives us portability and mobility. We probably can produce as much or more with this one machine than we could with our two previous machines, with a fuel savings as well.”
Small footprint, big impact
Mobirex impact crushers with integrated secondary screens such as Buesing’s are designed to produce large volumes of screened or “fractionated” RAP or RCA on a relatively small footprint and with an eye toward fuel economy.
Mobirex impactors are said to be especially suited for RAP because they break up chunks of asphalt pavement or agglomerations of RAP, rather than downsize the aggregate gradation, while compression-type crushers such as jaws and cones can clog due to packing (caking) of RAP when the RAP is warm or wet.
Contaminants such as soil are part of processing demolition concrete so the crusher’s integrated, independent prescreens remove dirt and fines before they ever enter the crushing circuit. This reduces equipment wear, saves fuel, and with some customers, creates a saleable fill byproduct.
Also important for recycling, the lined, heavy-duty vibrating feeder below the crusher eliminates belt wear from rebar or dowel or tie bar damage. By having the feeder below the crusher, it — not the belt — absorbs the impact of rebar dropping through the crusher.
An efficient rebar magnet with maximum discharge capacity can be hydraulically lifted or lowered by means of remote control, providing more clearance for larger sizes of rebar if present.
The flow concept of the EVO models is said to eliminate restriction to the flow of the material throughout the entire plant. With this Continuous Feed System (CFS), each step the material goes through in the plant is wider than the diameter of the one before it, eliminating choke or wear points. The CFS also keeps a choke feed to the crusher, eliminating stops/starts of the feed system, which improves production, material shape, and wear.
Kleemann’s Contractor Line diesel-electric drive option has the crusher directly diesel-driven, with the conveyor troughs, belts, and prescreen electric-driven. This concept not only reduces diesel fuel consumption, but also results in significantly reduced exhaust emissions and noise levels.
And mobile tracked crushers permit recycled material producers to relocate piles while staying open, selling from existing piles while creating new ones, and improving traffic flow, while eliminating the need to move a stockpile with loaders or other equipment.
Diverse business interests
Buesing Corp. is a major excavating and shoring contractor in the Southwest and is positioned in the energy industry, among others. “We’re involved in creating and grading solar energy sites and providing aggregates for road bases in the interior of these sites,” Buesing says. “We’ve driven well over a million piles at solar energy sites from northern California to San Antonio, Texas.”
Buesing originally began as an excavating contractor, and migrated into highway and heavy construction in the 1970s. At that time, Buesing was involved in precast bridges and foundations, roadway grading and paving, and even concrete curb and gutter work.
In addition to its other capabilities, Buesing now is active in deep excavations and shoring in the Phoenix area and building basement walls in these structures.
This article courtesy of Kleemann.