Edward Kraemer & Sons (EKS), Plain, WI, operates a large quarry producing materials to meet the needs of contractors working primarily in the Minneapolis-St. Paul metro area.
Its Burnsville Quarry in Minnesota opened in 1959, produces dolomitic limestones used in concrete, asphalt and road-based operations. The quarry produces more than 2.5 million tons annually.
As David Edmunds, executive vice president and COO of the EKS materials division explains it, the company is always on the lookout for new ways to meet increasing production demands.
Earlier this year, EKS partnered with Metso Minerals and its local distributor R.B. Scott to install a custom built mobile crushing plant adapted from the Nordberg LT140’s design and using LLS Series mobile conveyors. Since installing the new system last spring, Kraemer has increased its production from 760 to 825 tons (684 to 742 t), with the machine operating 20 hours daily.
Custom built for EKS’ large quarry operation, this is reportedly the first multi-bench mobile crushing plant of its kind to be used in the United States. The system allows more crushing to be done at the quarry face and minimizes the need for hauling and trucking of materials.
Rock is first excavated from the quarry and run through the new crushing plant. Once crushed, the rock goes by conveyor to a 12,000 to 13,000-ton (10,800 to 11,700 t) surge pile. From that pile, rock is fed down to another link of conveyor and flows up to the main crushing plant.
By installing this system, EKS has been able to split production into two parts that can run independently of each other.
Edmunds explained how obtaining the equipment and setting up the new system all came about:
“As we’ve evaluated ways to improve our operation, this idea was introduced over a two-year period. Evaluating the impact it would have, it looked to be very favorable. In the process of looking at the equipment itself, there was nothing on this scale in the U.S., so we had the opportunity to go over to Europe to look at three plants — one in northern Finland and two in Germany.”
One of the primary benefits EKS discovered in evaluating those plants was that they would eliminate having to haul a great distance with offroad trucks.
“We were hauling about 3,000 feet from the active face to the primary crusher,” Edmunds said. “Now we haul about 100 feet from the active face to a local track and material is sized at that point, and then conveyed to a transfer point and surge pile. Then we feed out of that surge pile to the main plant, allowing us to basically streamline our operations.”
A major advantage the new system offers is flexibility.
“The setup allows us to meter at the best rate we can to feed the main plant. Also if we need to move the local track we can continue to run out of that pile from bench to bench. We have the primary and the local track. It takes us about two hours to move it from one level to another. That was another innovation.”
According to Edmunds, prior to their visit from EKS, Metso had not put a machine into a situation where there was going to be a lot of travel. The machine was initially designed to just move along the local face where there wasn’t going to be a great distance.
Edmunds credits Metso’s East Region sales manager Floyd Gast with helping to craft a solution.
“He was a key part of the project. He contributed quite a bit to the sales/engineering effort, listening to our needs, which differed from the textbook,” Edmunds said.
“When we evaluated our options, we worked with Metso to develop a ’125E Special’ that’s basically a bigger chassis and bigger undercarriage. In other words, the mainframe and tracks are the same as they use on a 140 crusher. This is a 125 jaw crusher on a 140 chassis. That’s why they call it a special. That’ll hopefully give us the longevity that we’re looking for.”
EKS is looking not only for durability, but for costs savings and productivity from its equipment, Edmunds said.
“The bottom line is, the plant is going to save us hundreds of thousands of dollars every year in fuel, labor and maintenance on those trucks, and also actually improves productivity because now we’re feeding the finishing plant a consistent size and consistent rate coming out of that surge pile, so the whole system really was quite a benefit from an economic standpoint, and also from a safety and emissions standpoint.”
Controlling emissions is crucial for companies such as EKS to keep their operations in compliance with environmental regulations.
“We’re in an area here at a river bottom, a carbon monoxide non-attainment area they call it,” Edmunds explained. “The pollution control agency is very concerned about emissions. By taking three 500-horsepower diesel trucks out of the operation, we’ve significantly reduced the amount of emissions from the operation itself, as well as the dust that gets generated from the trucks.”
Both the plant and the resulting new procedures have run smoothly.
“Metso succeeded in assuring us that we would not have problems with the undercarriage itself and the chassis,” Edmunds said. “Since late May and early June, we’ve moved it probably four times between benches, and so far, everything’s going well.
“It’s met all the productivity goals we asked for when we purchased it. It was manufactured in Finland, and shipped over here via ocean vessel. A lot of it came in containers except for the large pieces that were shipped open.
“Four fellows from the factory came over, and in about two weeks, it went from a field full of parts to what you see today. Then it took another week or so to get all the plumbing and electrical hooked up,” Edmunds recalled. “But I think from arriving on site, to the crusher being in place running was about three weeks, which was amazing to me.”
One of the main reasons for Kraemer’s positive working relationship with Metso is local distributor R.B. Scott.
“We’ve worked with R.B. Scott for probably 15 years. They’re the Metso distributor for Minnesota so they were actually involved in the research we did, and took us to Finland,” Edmunds said, crediting president John Mickelson and local rep Jim Squiers, for their work as part of the Metso team.
“We have a good relationship with them,” Edmunds said. “We purchased another Nordberg HP cone crusher from them two years ago, and they have good parts availability and product support. We’re sold that Metso is the best product, at least for our purposes in Burnsville.”