How Utah’s Geneva Rock solved a metal contamination problem

By |  June 2, 2020
PQ0620 Geneva Rock

The Eriez Series 7000 suspended electromagnet removes tramp metal from a variety of materials, including limestone and sand and gravel. Photo: Eriez

Geneva Rock Products, established in 1954, is among the most respected and experienced rock processors and contractors in the state of Utah. 

From aggregate materials to asphalt paving, Geneva Rock is dedicated to finding the right solution for every job.

Like most profitable companies, Geneva Rock understands that its success hinges on suppliers providing them with solutions when problems and challenges arise. When the company began to experience excessive equipment downtime because of metal contamination, company leaders understood they would need to find a supplier capable of putting the situation to a quick, definite end.

The problem

The particular process line on which a problem was identified was a conveyor feeding raw stone into a vertical impact crusher. Geneva Rock found that tramp metal contamination was mixed with product flows and would find its way into crushers. 

The cost of equipment failure was proving expensive. It was particularly severe within the crusher, where the rotor has a number of wear parts. The company was regularly repairing these wear parts, causing downtime for maintenance and adding costs.

Geneva Rock personnel attended a ConExpo-Con/Agg and sought out a magnet supplier that could offer a solution to its costly problem. While at the trade show, the company discovered Eriez.

The solution

Eriez determined that the Geneva Rock application called for an Eriez Series 7000 suspended electromagnet. The magnet has effectively removed damaging tramp metal from material burdens such as coal, limestone and sand and gravel for decades. 

“The most important factors in the selection of the proper suspended electromagnet are burden depth, belt width, suspension position and tramp iron size,” says Darrell Milton, director of heavy industry at Eriez. “Other considerations relate to the size and density of the aggregate material and functional issues that relate to the line itself, including belt speed and belt incline.”

For Geneva Rock’s specific application, there was another consideration: altitude. 

The Geneva Rock electromagnet would be installed at an elevation of 5,500 ft. above sea level. Heat dissipates slower at higher elevations, so a special electromagnet coil assembly was specified to ensure proper heat dissipation and long coil life. 

Despite its custom requirements, Geneva Rock found that Eriez had the engineering experience, software and technical expertise to design a magnet tailored to their application. 

The Eriez 7000 Series suspended electromagnet is sold with a five-year coil warranty, which factored into the  purchasing decision for Geneva Rock. 

‘”Eriez uses coil design techniques that ensure a longer and more productive magnet life,” Milton says. “The warranty demonstrates confidence in that design.”

According to Eriez, significant improvements were noted immediately following the installation of the suspended electromagnet. The magnet was successful in removing the damaging tramp iron, therefore reducing wear part replacement in the crusher rotor.  Because of the success of this first installation, Geneva Rock purchased three units – two for itself and one for a sister company.

In addition, the suspended electromagnets at Geneva Rock feature a self-cleaning belt that travels across the magnet face over the main conveyor, providing automatic tramp iron discharge into a tramp iron bin. 

An effective measure of both the problem and the solution to the situation at Geneva Rock can be found in the pile of tramp metal that gathers in the collection area. The tramp metal, which once caused costly damage, is now recycled.

Information for this article courtesy of Eriez.

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