Edward Kraemer & Sons, Inc.

Edward Kraemer & Sons, Inc. (EKS) is a family-owned company whose roots in the aggregates business stretch back to the 1920's. Nonetheless, despite its sense of tradition, EKS was eager to find an advanced, cost-effective solution when inefficiency began hampering operations at its company quarry.

The quarry in Burnsville, Minnesota, from which limestone is mined from two levels, had been experiencing production bottlenecks for a number of years. Haul trucks were the standard mode of transportation, moving rock from the quarry face to the primary crusher, but due to quarry expansion they were having difficulty providing a steady flow of material. The secondary plant was inefficient due to major swings in feed material rates.


Tracks over trucks

After reviewing the purchase of additional haul trucks, which would have increased labor, dust emissions and the cost of maintaining haul roads, EKS decided to explore a mobile primary crushing solution. Doubts remained, however, as to whether a track-mounted crushing plant could handle the challenges of a multi-bench operation, and produce tonnages required to increase the plant's production.

Having already provided the quarry with a successful HP400 cone crusher, Metso Minerals and the local Metso distributor, RB Scott Co. Inc., set about convincing EKS that track-mounted systems were indeed up to the task. EKS visits to Metso customer sites in Finland and Germany were arranged, and based on the resulting insights a custom-built system was agreed upon for the Burnsville operation.


A tailored solution

The Metso Minerals system, a Lokotrack LT125E mobile crushing plant with Nordberg LL Series mobile conveyors, was specifically designed to meet EKS needs. A 10,000-ton live surge pile was implemented to steady the flow into the secondary plant. Metso also worked with EKS to develop a 10-year operational mine plan to assist with adjustments to the site.

Most notably, the crusher itself was customized for the Burnsville quarry. While it provided the necessary crushing capacity, the Metso Lokotrack C125 crusher was fabricated on a larger LT140 frame to accommodate the multi-bench work.


Advantage for all

Since start-up in July 2003, the Metso Minerals system has achieved 90 percent uptime and greatly enhanced quarry production. Today the secondary plant receives a steady feed, which has increased its production rate by 11 percent. Lower fuel and labor costs combined with higher profitability will let EKS pay off its investment in only four or five years.

Yet money is not the only measure of the Metso system's success. Cutting back on truck transport has reduced both dust emissions and haul road maintenance, and the elimination of cross-quarry traffic has helped to minimize safety risks. This means that the solution is as much a benefit to those who work in the quarry as it is to the EKS management.