Tri-State Workhorse

An Ohio-based contract crusher puts its crew and crushing plant through a hectic schedule.

It has been said that a rolling stone gathers no moss. If that’s the case, then it doesn’t have a chance with American Excavating, a contract crusher based in Enon, Ohio. Through the first quarter of 2002, the company has crushed nearly 200,000 tons of recycled asphalt, concrete and aggregate with its single portable closed circuit impact crushing and screening plant, moving the operation seven times in the process to keep up with customers’ demands.

"We will go just about anywhere and crush just about anything our customers need," comments Orville Lykins, plant manager for American Excavating. The company provides custom crushing services primarily to customers in the Indiana, Ohio, and Kentucky Tri-State market area.

Although the company processes a wide variety of feed material, nearly 80% consists of recycled asphalt pavement (RAP), with recycled concrete and aggregate equally accounting for the other 20%. Its primary finished product is a spec 9/16-of-an-inch-minus sold to asphalt producers such as Shelly Stone, Barret Paving and S.E. Johnson. In order to keep up with demand, Lykins sets an aggressive crushing schedule for the plant.

The quarterly production target for the company is a minimum of 150,000 crushed tons. This averages to an impressive 600,000 tons or more of saleable product each year produced by the company’s single portable crushing and screening plant. These numbers rival the annual production of some medium-size quarries, in which these quarries will typically use a multiple crusher circuit to produce their final product. Since purchasing an RDS-20 model crusher made by IROCK, Wooster, Ohio, American Excavating has produced nearly 900,000 tons of finished product in approximately 14 months.

To achieve production goals, Lykins employs crews working two, 11-hour shifts with one hour in between for maintenance. Each three-man crew consists of one plant operator, one loader operator and a clean-up/maintenance person. With a majority of the company’s crushing contracts ranging from 15,000 to 25,000 tons each—with only an occasional 50,000+ tons job—the crews do not stay at one location for long. Averaging 225 TPH production, American Excavating moves in, quickly crushes the stockpile and moves on to the next job.

Moving from location to location approximately 2.5 times per month, American Excavating’s crushing plant and entire operation must be extremely portable to stay on schedule. However, a previous plant the company owned took nearly two days to tear down, severely cutting into the production schedule. A plant requiring nearly a week to complete a move cycle would make sticking to the company’s current production schedule nearly impossible. So choosing the right plant was a critical step for the crushing operation.

When selecting a plant, Lykins recommends companies take a close look at the plant to make sure it fits the overall operational needs. "The first thing is to make sure the plant will be able to handle the feed sizes and material to be crushed and give you the hourly production you need," Lykins suggests. Then, if it’s an operation that will move from site to site, the company needs to look at the little things that affect portability. How many loads will it take to move? What components need to be disassembled? Does the plant require additional, costly equipment like a crane for disassembly? All these items need to be reviewed before buying a plant, says Lykins.

With its current set up, American Excavator’s entire operation—including the IROCK RDS-20, a Caterpillar 980G loader, Cat 330 track hoe, Bobcat 753 skid steer, job trailer that includes a Cat 3412 generator, an 80-foot stacker, other conveyors and miscellaneous equipment—is moved in seven loads and takes approximately six hours to prep for transport. The entire tear down/set up cycle is 12 hours plus transportation time. The RDS-20 requires only two loads to move, with only the feed hopper requiring removal, and IROCK Crushers have devised a unique feature to assist operators with this task.

The specially-designed hopper on the RDS-20 uses hydraulic legs and a power unit to raise and lower the hopper in place. After transport, the legs raise the unit off the trailer and allow the crushing plant to back in underneath the hopper. Once in place, the hopper is lowered onto the plant and bolted into place. The entire process takes less than an hour and eliminates the cost and time associated with using a crane.

Although establishing lofty production goals, American Excavating realizes it will not be in business long unless it delivers a quality, in-spec product. Lykins crew keeps a close eye on the amount of returns going back through the crusher and adjusts the impactor’s upper and lower apron settings to compensate for liner wear. Additionally, the company works with the customer to conduct gradation tests, ensuring the final product meets specs.

With the company’s primary saleable product, 9/16-inch-minus RAP, it is critical to send the recycled asphalt feed material through the plant as few times as possible. The more the feed re-circulates through the impactor before being properly sized, the greater the chance to separate the asphalt from the aggregate. The end result is white rock that requires more liquid AC at the asphalt plant, defeating the purpose of using RAP in the first place.

American Excavator’s portable plant uses an impactor with a rotor that is 40 inches in diameter and that features a "two active blow bar" rotor design. This enables the impactor to generate a rotor speed up to 700 rpm, nearly twice as fast as some three and four-bar rotor designs. As rotor rotation speed increases, the amount of kinetic energy increases exponentially. Thus the IROCK 4056 impactor develops up to 800,000 pounds of crushing force.

The end result is more properly sized product exiting the crushing chamber and less re-circulating load. "The impactor on our plant breaks up and sizes the rock better," comments Lykins. "The more sized product you put through the first time, the more money you make. And that is the name of the game," he continued.

Most crushing plants are equipped with their own power source to operate all plant functions. Most will be either a plant-mounted diesel engine or diesel engine/generator combination to power the crusher, plant conveyors, screen deck, auxiliary conveyors and belt magnet. However, Lykins’ 20+ years of crushing experience told him to buck tradition and run the plant with a separate off-plant generator. This required the plant to be customized.

Lykins and IROCK worked together to modify the plant’s configuration. With the modified design, Lykins runs cables from his enclosed Cat 3412, 750 hp generator and plugs them into the electrical panels located on the plant. Although the initial costs of these modifications and separate power unit are higher, Lykins defends his position by looking at the long-term benefits.

"With a separate enclosed generator, you keep your power source away from plant vibration, any dust generated and the overall environment close to the plant. It helps significantly reduce maintenance to the engine and radiator and lowers your overall long term costs," claims Lykins. With the available 750 hp, the crew has plenty of surplus power to run ancillary equipment, and according to Lykins, the fuel costs are about the same as with an on-board power unit.

With the onset of a new asphalt production season, American Excavating is looking ahead to another busy year. Last year, the company exceeded every quarterly production target, with the exception of the fourth quarter.

"The tragedies of 9/11 hit everyone hard, and many businesses were very conservative the last quarter of 2001," says Lykins. However, as the country moves forward from this horrific event, he sees companies getting on with business and expects to beat each quarterly goal this year.