Like all operators James Elder Duff, co-owner of Duff Quarry, wanted an operation that would produce more high-quality material, in less time and for less money.

With this in mind, Duff Quarry set out to build a new limestone crushing operation in the spring of 2005. But it was going to be a big leap from its previous plant, which had been running since 1956. Duff Quarry operates in Huntsville, Ohio; outside of Columbus.

Duff hired Innovative Processing Solutions. This company is an affiliate of Stedman, which designed and fabricated the quarry's automated material-handling equipment.

Duff Quarry now has a 5460 Mega Slam and 6460 Grand Slam crushers from Stedman at its new plant, along with a complete automated plant system from Innovative Processing Solutions. The design and fabrication for this new plant took nearly two and a half years to complete as each idea was considered and wish lists were sorted out.

“When we were designing the plant I didn't want to come back and say we should have done this or done that,” Duff says, “I wanted the very best of everything that we could get into the plant for longevity. I'm concerned about longevity, not just today.”

The Duff Quarry team of 12 employees kept the old plant running as the new plant was designed and later installed. The previous quarry was able to produce 600,000 tons of limestone annually, but the original crushers required a lot of maintenance.

“These Stedman crushers will save 50% of the maintenance that we had in the other plant,” Duff says. “I say that because the nature of this plant is so much different than the old one because of the welding needed on the crushers. At the old crushing plant we had to weld the crushers every 10 to 15 days.” The welding on this old plant took about two days to complete, which cost the company production and high maintenance costs.

With the new plant and crushers the quarry can produce up to 1.5 million tons of limestone a year running at full capacity. The plant also has the capability to stockpile large amounts of finished product. “We have the capabilities of stockpiling 155,000 tons of rock underneath this plant.”

The flexibility to produce a multitude of products also was achieved. “Markets change and we wanted to go into something where we had the flexibility to do different things and different sizing,” Duff says.

But they didn't stop with the crushers. This new plant also required numerous conveyors, stackers, sensors, controls, vibrating screens, feeders and other equipment. The quarry also received Apex electronics and control systems to create and design a programmable logic controller. Each conveyor at the crushing plant is equipped with terminal strips that are wired to send information to one main processor. This greatly reduces operator confusion.

“There are too many conveyors for one guy to stand there and say he knows what's going on. So this brings all of this information together in one place,” says Bill Page, maintenance supervisor at Duff Quarry. Page worked with Apex in designing the control and information system.

All of the feeders and conveyors are monitored to give the company all of the information needed about the plant.

“Every electric motor here tells the amp reading on it,” Duff says. “It's a very important part in crushing equipment to know the amount of amps that the electric motor is pulling. It tells us how many tons it's pulling per hour, how many went through so far in a day and how many tons have gone through for the year.”

Duff Quarry also has the ability to run at full capacity during most weather conditions. The plant was designed to handle and adjust its screening procedure accordingly.

“If we had two inches of rain come down tonight we could go in and make full-capacity stone,” Duff says. “We could make really large rock and rock from 1 inch on down in size. This plant is designed with so much capability to do so many different things.” Duff also installed pumps and drain lines under the plant so that the plant will not flood.

The system monitors the speed of the conveyors and feeders. This allows the operators to keep an eye on production and troubleshoot maintenance issues.

“The reason for having an automated control system is that if something goes wrong on one of those conveyors, you aren't going to see it fast enough to stop a catastrophe,” Page says. “And a catastrophe means that we have to dig out a conveyor. But now if something goes wrong, the computer takes over and begins dropping conveyors, discharging material and shutting the feeder down.”

Since the system can now monitor the conveyors' speeds and tons per hour, limitations can be set to help catch problems before they become too serious.

“If something is going wrong, say this conveyor 2A is slowing down,” Page says. “We can put limits on how much we want to allow it to slow down before the feeder is paused. We can limit how long that feeder stays paused. Then hopefully the limitations will start clicking that feeder on and off so the operator knows something is wrong.”

With the automated plant, Duff can run production all day. The previous plant had to be shut down for lunch and then restarted.

“This plant is run with two people,” Duff says. “We have an operator who starts in the morning and works until noon and then another operator gets on the loader and we never shut down.”

The automated plant allows for flexible production. “Right now you can go down and change this plant and the rock size within 10 minutes,” Duff says. “We have a conveyor with dual responsibilities where we could shut one size off and then go to another size and use the same conveyor to put the new size in the crusher. The automation that controls this plant far exceeds most other plants that I've seen.”

Automation combined with the better crushers has allowed Duff to more than double production capacity at the new facility.

Duff Quarry sits on a limestone reserve that runs 400 feet deep and covers 400 acres. The number of years seems endless with such a huge reserve of limestone. Duff Quarry will be able to continue its crushing plant far into the future and into the next generation of Duffs.

“I feel sure that my grandsons will work harder in developing something special out of this stone,” Duff says. “They'll be doing more fine grinding and coming up with a product. And that's the future in aggregates today.”

Today this quarry provides limestone to areas within a 25-mile radius of Huntsville, Ohio, for government applications, housing developments, asphalt facilities, ready-mixed concrete facilities and other public and privates uses. The quarry has even shipped limestone to California, Beverly, Mass., Auburn, N.Y., and Chicago for coal gasification, a process that pressurizes coal and stone to form natural gas.

Information Provided by Stedman