One tough crush: Sergeant Stone’s journey

By Kevin Yanik| November 20, 2015

John Powell knew a challenge loomed when he first encountered the material Sergeant Stone planned to crush at a startup site in Corning, Ohio.

The material, which Powell perceived to be limestone, was as hard as any he had seen within Ohio during his 19 years with Eagle Crusher Co. In fact, after Powell sent initial samples to Bowser-Morner, a testing firm within the state, one came back with a compressive strength of 49,360 psi.

That’s abnormally high for limestone. A second Bowser-Morner test was later conducted, revealing a Mohs hardness of 5. Most limestone has a hardness of about 3, so Sergeant Stone’s material technically has more characteristics of siltstone than it does limestone.

“This stone is a lot like the stuff that’s up in the Northeast,” Powell says. “That is extremely hard rock up there. That stone gets so hard that you will struggle to impact crush it. You will go broke trying.”

Jaw crushers are often preferable when stone gets to a certain hardness, Powell adds, but they produce sharper, more fragmented products.

“When you compression crush you get a lot of elongated, arrowhead type of points that cut tires and things like that,” Powell says. “You can’t have that.”

Impact crushing, on the other hand, punches material, meaning cubic products are more feasibly produced, Powell says. Impact crushers can take a beating when raw material is too hard, though.

Still, Sergeant Stone’s Claude Imler wanted to produce stones that offer the cubic qualities coveted for road construction. The challenge, then, was to find an impactor that could withstand the material Sergeant Stone planned to mine.

Ultimately, Sergeant Stone selected a 1200 closed-circuit impactor from Eagle Crusher as its primary crusher. The machine has been in use at Sergeant Stone since the company launched in October 2014, producing six gradations of stone that possess the cubicity the operation sought for road construction materials.

According to Imler, the 1200 impactor is producing about 250 tph and effectively meeting Sergeant Stone’s needs.

“As our rock gets more into the market, people realize it makes a good concrete product,” he says.

Full speed ahead

Imler, who partnered with engineer Tim Linn and excavation contractor Ron Scurlock to launch Sergeant Stone, had his eye on his new company’s property for a number of years. Imler says he knew about the limestone in 2004 because the property’s owner notified him about it.

Imler had a core drilling company at the time. About a dozen holes were drilled across the expansive property to determine the depth and spread of the limestone – and the potential opportunity ahead.

About a decade after doing those first drills, Imler leased the property.

“I didn’t bid on the property at the time he told me about this lime rock,” says Imler, who spent a number of years in coal mining. “But I never forgot about it.”

Once Imler and his partners decided to launch their company, which employs five people, they didn’t need much time to prepare a crushing and screening site.

“We uncovered the crusher area in two-and-a-half to three weeks,” Imler says.

Powell was astounded at how quickly Sergeant Stone prepared the area. He had visited the site when it was as green as the rest of the rural community around it, so the rapid turnaround caught him by surprise.

“The overburden on it is soft,” Powell says, “so it didn’t take that long.”

As an operation, Sergeant Stone’s goal is to mine and reclaim as it goes. The operation has been running for about a year now, but it completed one section this summer and reclaimed the space in four days, according to Imler.

“We stockpiled the overburden so we could put it right back in,” he says.

Imler adopted the reclaim-as-he-goes philosophy from his coal mining days.

“We stripped coal for years, and in two months the land was reclaimed,” he says. “You’d reclaim right behind you.”

Currently, the operation is mining about 17 ft. deep. Overburden represents about 8 of the 17 ft., Imler says, leaving about 9 ft. of saleable rock.

“They call this area a Brush Creek seam,” Imler says. “It’s kind of unique. The whole area through here is about 8 to 9 1/2 ft. thick. That makes it unique because it’s usually 3 ft.”

Operational adjustment

Most of the rock blasted at Sergeant Stone is ready for the primary crusher, which handles rocks up to 24 in. in diameter. A breaker prepares the rest for the crusher, and all material is currently hauled about 1,000 ft. from the mine to the crushing plant across the road.

In all, Sergeant Stone’s 1200 impactor produces six gradations of stone. Among the gradations produced is 57 stone, which was in particularly high demand over the past 12 months. The operation couldn’t keep up with the demand at one point, so it added a UM 400 secondary impactor from Eagle Crusher to produce more 57s.

“There’s a certain percentage from the primary crusher that comes off as 1s and 2s,” says Tim Smith, environmental division sales manager at Columbus Equipment, a dealer that assisted Sergeant Stone in opening its quarry. “Their market for 1s and 2s is smaller – they were making more than they could sell – but they were selling out of 57s.”

So, Sergeant Stone invested in the UM 400, running 1s and 2s into the secondary crusher.

“They reduced the 1s and 2s and doubled the 57s,” Smith says.

Sergeant Stone also uses a McCloskey S190 vibrating screener, which produces 4s, 8s, 57s and fines. But the 1200 impactor is Sergeant Stone’s starting point to meet Ohio Department of Transportation specifications on six stone gradations.
“All the products coming out of that crusher meet state spec,” Smith says.

Still growing

Sergeant Stone’s business has been so steady that Imler is considering adding a second plant at another location on the property. A similar setup with Eagle Crusher equipment is a possibility, he says.

A second plant is bound to keep Imler busy. He retired for about seven years before getting the itch to start up Sergeant Stone. Now, he spends his days making sales and searching for opportunities to move Sergeant Stone’s products.

The operation sits about 65 miles southeast of Columbus, Ohio. Most of Imler’s sales success has been to the south.

While Imler focuses on sales, Kyle Scurlock, son of business partner Ron Scurlock, manages Sergeant Stone’s operations. The operation works six days per week, although it doesn’t crush on Saturdays. Workdays range between five and eight hours, but the loading area remains open longer for customers.

“Good people and good equipment are the name of the game,” Imler says.

Quality stone is key too, he adds. Imler believes his operation has a chance to excel because of the deposit available to him and the crushing equipment he selected.

“We know it’s going to make a better concrete,” he says.

Powell agrees Sergeant Stone has an opportunity to separate itself.

“A big contributing factor to roads and concrete coming apart is that the stone doesn’t hold up,” Powell says. “They have state specifications on stone for a reason. It’s got to be a hard rock; it’s got to be cubical; and it’s got to have the binding matrix of asphalt and concrete.

“It has to hold to that, and this [stone] is exactly what you want.”