Limestone Quarry Increases Yearly Production Capacity up to 1.5 Million Tons
Duff Quarry Inc. (Huntsville, OH) began a new limestone crushing plant in the spring of 2005 to replace their previous plant, which had been running since 1956. While building and designing this new quarry, James Elder Duff, co-owner of Duff Quarry, focused on creating a state-of-the-art plant. “See, markets change and we wanted to go into something where we had the flexibility to do different things and different sizing,” Duff says.
In order to create a flexible, modern plant, Duff Quarry turned to Innovative Processing Solutions, an affiliate of Stedman, who designed and fabricated the automated material handling solutions for the quarry. Innovative Processing Solutions also used Stedman’s Mega-Slam™ and Grand-Slam™ size reduction impact crushers at the new quarry, for limestone crushers.
History of Duff Quarry
Duff Quarry was started in 1956 by Clayton Elder Duff and his son, James Elder Duff, after the family had been in the sand and gravel business since 1951. Today the quarry provides limestone to areas within a 25-mile radius of Huntsville, Ohio for government applications, housing developments, asphalt facilities, ready mix concrete facilities and other public and privates uses. The quarry has even shipped limestone to California, Beverly, MA, Auburn, NY and Chicago for coal gasification, a process that pressurizes coal and stone to form natural gas.
James Elder Duff (Duff) and his two sons James Scott Duff (Scott Duff) and James David Duff (David Duff) are the sole owners of Duff Quarry. The Duff family also owns companies in the ready mix concrete and lumber industries. Duff is the owner of Ohio Ready Mix, David and Scott Duff owns Ohio Lumber and David Duff is the owner of Mr. Concrete. Duff Quarry also supplies limestone to their Ohio Ready Mix and Mr. Concrete businesses.
Duff first learned about Stedman in 1956 or 1957 when the company purchased a Stedman 48” 4-row cage mill to make agricultural lime at their old quarry. At the time, the quarry’s previous equipment wasn’t able to handle the agricultural lime and it was decided to bring in a Stedman cage mill. Duff Quarry also purchased a portable plant, a 4860 Mega-Slam™ crusher, from Stedman for a different location in 1994. “We went to this crusher due to the fact that we felt it was a superior crusher with the portable plant that we were purchasing,” Duff explains. The portable plant allowed Duff to move the crusher to another location if needed.
State-of-the-Art Crushing Plant
Duff Quarry now has a 5460 Mega-Slam™ and 6460 Grand-Slam™ crusher from Stedman at their 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 states, “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. “I feel as though I’m fair in saying that these Stedman crushers will save 50% of the maintenance that we had in the other plant,” Duff explains. “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 took about two days to complete, which cost the company hours of labor, not to mention the lost production and higher 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. And not only that, but the quarry has the capability to stockpile large amounts of finished product. “We have the capabilities of stockpiling 155,000 tons of rock underneath this plant,” Duff adds, “155,000 tons of finished product.”
Duff Quarry also purchased numerous conveyors, stackers, sensors, controls, vibrating screens, feeders and other equipment through Innovative Processing Solutions, an affiliate company to Stedman who designs and purchases equipment needed to help create an operating processing system. 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 all wired to communicate information to one main processor. “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,” explains 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 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 one 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 cannot flood.
Benefits of Automation
With the ability to monitor the speed of the conveyors and feeders, the quarry can keep an eye on production and can 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 states. “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 quarry can now monitor the conveyors moving, the speeds and the 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 explains. “We can put limits on how much we want to allow it to slow down before the feeder is paused and then 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 Quarry has the ability to run production all day, where the previous plant had to be shut down for lunch and then restarted. “This plant is run with two people,” Duff asserts. “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 automation gives Duff Quarry many benefits over their previous plant and over many other limestone quarries in operation today. “Right now you can go down and change this plant and the rock size within ten minutes,” Duff declares. “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.”
The Future of Duff Quarry
Duff Quarry was able to more than double their production capacity with the help of the automated plant from Innovative and Stedman crushers at their new facility. “When we ordered the plant we received it as we had planned, no problems,” Duff notes. “Any help that we needed, which was a lot, we got from Stedman and Innovative. I can’t say anything but good things for what they’ve done for us.”
The Duff Quarry sits on a limestone reserve that runs 400 feet deep and covers 400 acres. Usually quarries can rate themselves depending on how long their reserve can last, generally in terms of years. But with this quarry the number of years seems endless with such a huge reserve of limestone. Duff Quarry will be able to continue their 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 comments. “They’ll be doing more fine grinding and coming up with a product. And that’s the future in aggregates today.”