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Ohio's Duff Quarry Can Operate its Plant On the Go With an iPad, and That's Only One of its Many Creative Ideas and Innovations.

At Duff Quarry in Huntsville, Ohio, you get a little bit of everything – decades of experience, processing innovation, cutting-edge technology, new inventions, a diversified business model, four generations of family involvement and even a piece of history from the 1964 New York World’s Fair (see sidebar). But mostly what you get is a plant designed for efficient production, and a company with a long tradition of serving its markets well, and going above and beyond the call of duty to satisfy its customers.

“We’ve been here more than 50 years,” said company President/CEO Jim Duff. We must be doing something right.”

According to mineralogist Joseph W. Vasichko, who has studied the geologic and mineral make-up of the quarry, the material mined there is dolomitic limestone, or dolostone, of upper Silurian age and recognized as a member of the Salina group.  The dolostone is likely part of the Tymochtee formation. This strata lies just below the Columbus Limestone of Devonian age.  

The material quarried from the upper level is generally bluish gray in color and shale-like. Due to the high levels of iron in the strata, some of the thinner layers of the dolomite are red in color. The lower level of the quarry is characterized by a more dense and siliceous brownish-gray material well-suited for aggregate needs. For more than 30 years, pyrite crystals from the quarry have been a source of study for mineralogists.

Production and Processing
Materials production begins at the plant with blasting at the quarry face. Blasting is contracted out to Northern Ohio Explosives.  According to Plant Manager Ross Duff, frequency these days is “very much dependent on the economy. We blast weekly when business is good,” he said.

With each blast, material drops 65 ft. to the quarry floor. At the muckpile, two Caterpillar loaders, a 992C and a 992G, load Caterpillar 769D 35-ton haul trucks. The trucks then cycle between the muckpile and a primary surge pile.

Primary crushing is executed in efficient fashion using a Stedman 6460 Horizontal Shaft Impactor (HSI). From the primary, secondary crushing is also performed with a Stedman, in this case, a 5460 HSI. “The Stedman crushers have done a great job for us,” Ross Duff said. “We have enjoyed a great partnership with the people at Stedman for many years.”

Screening at the 650-700 tph plant is taken care of using a Deister 8 x 20-ft. triple deck. Duff Quarry almost exclusively uses Durex screens, including flex deck rubber, urethane and some wire cloth as well.

Extra screen media are stored in two shipping containers that were once used to store and ship frozen materials. The highly insulated containers were installed near the screening tower, and do a great job keeping rubber screens from dry rotting and wire cloth from rusting,” according to Ross Duff.

The Blind Buster
One of the ongoing production challenges at the quarry is screen blinding due to moisture content in the processed material. Bill Page, a foreman with more than 30 years experience at the plant, tried multiple methods of preventing the screen media from clogging: spraying decks, dragging chains and even electrically heating the decks. No method worked, so he developed his own automated screen cleaner, which in effect, is a tracked motor on rollers attached to a chain that creates powerful ongoing screen vibration that keeps the openings clear.

The idea worked so well, Page decided to patent the product, now called the Blind Buster, and made it available to the public. An affiliated company, Aggregate Innovators LLC ,, was formed to produce the new product.  

The Blind Buster screen cleaner is sold in a package with two major components. The Control Assembly and the Motor Assembly.

  • With the control assembly, each control box comes wired with three different leads: the 110V AC standard plug, a 90V DC female twist lock, and the control wire. The 90V DC line comes factory standard at 100 feet. The 110V AC line goes in any outlet; it does not have to be GFCI. The control wires are designed to be connected to the normally open auxiliary contact of the screen’s magnetic starter. The screen cleaner can be set up to manually start if the motor start is not available.
  • The motor assembly comes standard with a 20-ft., 3/8-in. chain. The chain can be cut to any length or extended to accommodate all screen sizes. All that is needed on the customers end is a 2-in. black steel pipe mounted level approximately 6-in. above the opening of the screen. The pipe has to be fixed and attached in a way where it does not vibrate with the screen.

“It’s amazing how well the idea works,” Ross Duff said. “It simple in design and execution, and producers with blinding problems can save themselves a lot of headaches by using the product. Trust me, it’s had testing under the most difficult conditions.”

Conveying and Stacking
Material at the plant is stockpiled using a series of radial stackers. The stackers were designed and fabricated by Innovative, a subsidiary of Stedman. “They were installed by my crew, and have worked very well for us,” Ross Duff said.

Another innovation in use at material-transfer points at the plant are pneumatic cylinders that allow for production changes at the throw of a lever. The cylinders are the same ones in use on ready mix trucks at sister company Ohio Ready Mix.

The Dawn of the iQuarry
The most innovative technological achievement in use at Duff Quarry revolves around an iPad. When Apple introduced the product to the consumer market, it was conceived as a convenient tablet-style device for those on the go. Ross Duff conceived of it as a perfect way to monitor production while on the go, and an ingenious tool that would allow him to tweak processes and get real-time data to help him operate the plant more efficiently.

“Really, the set up was simple,” Ross Duff said. “Our plant uses AB Rockwell automation. The iPad we use is the basic model. We loaded iRdesktop, a free remote desktop client and LogMeIn Ignition (S29.99 one-time fee) to be able to access it from anywhere with a good Wi-Fi signal. The set-up allows the plant operator to actually be at the plant and not stuck in a control room. This not only allows us the opportunity for greater production, it also allows for safer operation of the plant because a MCC doesn’t always allow for the best view of the machinery it controls.”

One of the concerns about using the iPad onsite was the fear of dust disrupting the electronics. “The iPad are a little more conducive to a quarry environment than a laptop,” Ross Duff said. “There are no vent holes or keyboards to plug up with dust.  They are also cost effective as there is zero proprietary software loaded on the iPad. Programming takes less than an hour. The iPad is basically a touch-screen remote for the main control computer running XP.”

Ross Duff also notes that in effect, you can control a plant using an iPhone. “But that is not realistic due to screen size limitations,” he said.

“I can, however, shut down the plant using my iPhone in case of an emergency.”

The plant solved the Wi-Fi access challenges it faced initially by installing a router right down in the quarry. “The signal sometimes varies,” Ross Duff said, “But it is strong enough to get the job done.”

The plant actually has two iPads configured for use in the quarry. Their system is set up, however, so that only one of them can make changes to processing at a time, to avoid the chance that two people might be trying to make similar changes at once.

Is Duff Quarry’s unique iPad-enabled system the template for other quarry operations interested in applying the latest consumer technology to business use? There is a good chance we have seen the future at Duff Quarry.

Duff Quarry: History
What is now Duff Quarry was started by Elder Duff and his son Jim Duff as a sand and gravel operation in Allen County, Ohio. In 1950, they purchased the property on Route. 117 in Huntsville, Ohio, where the quarry currently operates. “We paid $200 an acre for 200 acres of farm land,” said Jim Duff, president/CEO. “That was a lot of money back then.”

In 1954, they broke ground, and using a portable plant, began production. “I bet we did only 20,000 tons that first year,” Duff said. “It isn’t easy starting up a new operation.”

In 1959, they purchased a quarry across the road, and for a time transported material to be processed over to the new plant. They eventually closed the second quarry, and began to fill in the hole using overburden and soil material excavated from the new site.

After a number of years of steady production, the company made a decision to open up a second level of the quarry, and in 2005 added new equipment anda new plant configuration. Where the primary crusher once stood, they roofed over the quarry face and created a garage to keep equipment out of the

Over the years, the company has created a unique suite of diversified businesses that operate on both sides of Rt. 117. In addition to the quarry, they operate:

  • Ohio Ready Mix Inc.
  • Ohio Lumber & Building Supply
  • Mr. Concrete (J Duff Inc.)
  • COMSTOR Outdoor Ltd.
  • Community Storage & Properties Ltd.

This may be one of the few quarry sites in the country that also serves as a one-stop building-materials shop where contractors can buy aggregates, ready mix, landscaping materials, lumber, hardware and even store a truck for the winter.

Duff and the 1964 New York World’s Fair
If you’re driving down state Route 117 in Huntsville, Ohio, as you approach the entrance of Duff Quarry, it is hard to miss the two steel arches in front of the company’s headquarters. The arches have an interesting history that dates back to the 1964 New York World’s Fair.

The fair was held in Flushing Meadows Corona Park in Queens, N.Y. Hailing itself as a “Universal and International” exposition, the fair occupied nearly a full square mile of space. Fifty-one million people attended the fair in 1964 and 1965. The fair's theme was "Peace Through Understanding," dedicated to "Man's Achievement on a Shrinking Globe in an Expanding Universe" and was often referred to as an "Olympics of Progress." The theme center was a 12-story high, stainless-steel model of the earth called Unisphere with the orbit tracks of three satellites encircling the giant globe.

During the fair, General Foods built 11 arches scattered about the World’s Fair grounds that served as an information kiosk and as a rendezvous destination for fair goers. Unfortunately, after the fair the company sold off or scrapped the arches. World’s Fair enthusiasts know that some of the original arches still exist in West Hempstead, N.Y.; Rocky Point, R.I.; and a few in New Jersey. Many are not aware that two arches made their way to Russell’s Point, Ohio.

During the 1960s, Indian Lake Playland Amusement Park brought the arches in by railroad with plans to eventually erect them at the park. However, the plans never came to fruition leaving the arches sit in the weeds for more than 20 years. Over the years, the arches fell into the hands of a restaurant owner in Russell’s Point; and there they continued to sit.

In 1990, Jim Duff, owner of Duff Quarry bought the structures from Anthony Guisliano, the owner of Pier 33, a restaurant in Russell’s Point. Finally, in 1991 the arches were erected in front of the Duff Quarry headquarters in Huntsville, Ohio. It was quite a process to get them up, as Jim relates, “I had to use two 100-lb. jacks and a bulldozer to straighten those two pieces. It was a lot of work,” he said. They have been standing ever since outside of the Duff Quarry headquarters.

Rock Products contacted Bill Cotter, one of the hosts of a commemorative website dedicated to the fair at and sent along a photo of the Duff Quarry arches. “It was great to see those arches again,” Cotter said. “I knew they were there but my travels haven't led me there just yet. We've tracked down most of those arches but there's still two or so that have eluded us.”