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Hybrid Screen Solves Blinding Problems


A quarry in western Wisconsin faced an all-too-common problem: they regularly ran silica sand with some clay and rock, which constantly caused blinding and plugging of their screening media. The plugging and blinding meant that operations had to shut down more often than normal for screen maintenance and cleaning – delays that also meant loss of production and revenue.

The producer originally used wire cloth with square openings purchased from Unified Screening and Crushing. While the screens delivered about 1,000 hours of wear life, the clay content of the material continued to blind over the screen. They switched to a self-cleaning screen from a different manufacturer, only to see the wear life plunge to just 200 hours before failure.

The producer, a member of The National Stone, Sand and Gravel Association (NSSGA), reviewed the association list and decided to call in Rod Skindrud, the Unified field representative in the region, for his professional evaluation. Before joining Unified, Skindrud was a quarry supervisor.

Most Unified field reps have previous industry experience working for quarries, equipment suppliers, foundries or other aggregate/mining-related companies. “It’s a prerequisite for the job,” said Bob Kleason, Unified’s director of marketing and sales. “We don’t just sell products. We solve customer problems. To be successful in our industry, nothing beats field experience. All Unified field reps know the various local materials, local processing conditions and other factors that effect wear life and throughput.”

Skindrud visited the Wisconsin quarry and evaluated the materials and conditions. He asked the producer what specific problems they experienced. How effective were different types of screens when processing the materials that caused blinding? How much did each screening medium actually affect throughput before and after change-out?

Expertise in Engineering
Skindrud then returned to Unified, discussed his field notes with the regional engineer and posed a challenge to Unified’s engineering team: Could Unified provide the right screen or develop a new type of screen media to solve the problem?

Unified’s mechanical engineers carefully reviewed the field reports and test data. They knew that nobody knows a production problem better than the people on the jobsite.

“They take what was learned in the field,” Kleason said, “and check it against our large database of field reports. We update the database regularly to stay on top of ever-changing conditions and throughput.” Kleason added, “the work on a new screening medium combines all the field data with the engineering team’s own deep knowledge of screening media and design.”

Finding a Solution
Unified engineers realized that the key to processing wet, sticky material was to create a vibratory screen surface. They achieved this by re-designing a special hybrid of wire cloth and polyurethane support strips – a combination that lets each wire vibrate independently, eliminating wire-to-wire contact. As material falls on the screen, the wires vibrate at their own frequency. This allows material to slip through while maintaining accurate material sizing. After more development and testing, Unified’s new SuperFlow screen was ready for the field.

Skindrud and the Unified engineering team determined the right SuperFlow screen for the producer in western Wisconsin was a custom screen with a heavier “Tufflex” wire construction. Today, those screens run between 2,100 and 2,800 hours before change-out. By that time, more than a million tons of material has been processed across the screens. Customer inspection shows that, “the screens are not even broken, but we change them out as a preventative measure.”

Unified Screening and Crushing, www.unifiedscreening.com