| A screen deck at Great Lakes Aggregates screening limestone. |
Great Lakes Aggregates Inc. produces approximately 1 million tpy of limestone at its Sylvania Minerals Quarry located in South Rockwood, Mich. As the quarry increased the number of saleable products that it produced, it encountered screening challenges along the way such as limited open area, screen breakage and severe blinding.
“With only nine months of production time each year it’s important that we keep production on track,” said Bill Begley, quarry manager at Sylvania Minerals Quarry.
The quarry’s goal was to increase its throughput on all three decks of the wash screens, while producing four different product sizes from clean, high-quality minus 3/4-in. material. After several failed attempts to achieve these results, Begley meet with Kevin Hinkley at Conveyall Industrial Supply Inc. and Brad Rice from Major Wire who recommended they try Major Wire’s Flex-Mat 3 screen media.
All three decks of both screen boxes were originally fitted with modular polyurethane panels. The top deck screen had a 1/2-in. opening, the middle deck had a 3/8-in. opening and the bottom deck screen had a .212-in. opening.
This system worked fine as long as the load of base materials and washed products were split equally. However, as the quarry increased the amount of washed products, the results were poor quality and lower production rates. The screens needed more open area.
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| Great Lake Aggregates installed Flex-Mat 3 Tensioned Series D on both the top and middle screen decks to improve throughput and for its longer wear life. |
More Open Area
To achieve more open area, the previous screen media provider then suggested changing to their diamond-shaped (“D” style) wire openings and supplied urethane bucker bar covers for the flat deck rail bars on the screen boxes to create a crown for the side-tensioned panels. These new panels were installed on the top and middle decks of both screen plants. After running for only a few days the screen media panels broke apart causing production to come to a halt.
Hinkley visited the quarry to take measurements of the screen boxes to ensure everything would fit correctly. Next, they installed Major Wire’s Flex-Mat 3 Tensioned Series D, a diamond-shaped media that works well for most standard applications, on both the top and middle decks of one screen box. On their second screen box, for comparison, they installed more of the D-style screen panels that they had been using previously on the top and middle decks as well.
After just a few days of production the screen box with the previous screen media on it broke again but the Flex-Mat 3 screen media lasted nearly four more months. It was then installed on the comparison screen and increased production on both screens.
“We were really impressed with the wear life of Flex-Mat 3 and excited about the extra production. The other self-cleaning screen media we used didn’t have enough open area and didn’t screen as well as Major Wire’s Flex-Mat 3,” comments Begley. “It has been a good product, very reliable and the price is competitive with other self-cleaning screen media, but Flex-Mat 3 has a longer wear life.”
Flex-Mat 3 Tensioned Series D is now installed on both of Sylvania Minerals’ triple-deck wash screen boxes. Production has gone from 39 tph to an impressive 80-85 tph, more than doubling the production of minus ½-in. by plus 3/8-in. limestone, which is a premium product used in asphalt. The production of other washed products also increased.
“The durability of Flex-Mat 3 screen media has meant far less time performing maintenance and changing screens, saving valuable operating hours,” said Begley. The plant can now run fewer hours and still put more material on the ground. “The only challenge now is that the tertiary crusher feeding the wash screens can’t feed material fast enough to keep up with the new Flex-Mat 3 screen media.”
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| Great Lakes Aggregates’ South Rockwood, Mich., facility produces nearly 1 million tpy of limestone. |
Problem Solving
Begley wasn’t completely surprised by the performance of Flex-Mat 3 as he had experience with the product while working in one of Great Lake Aggregates’ other quarries. “We were experiencing severe blinding; it was so bad that every 90 minutes the operation would shut down for 20-30 minutes to beat the blinded material out of the screen media with a hammer. The quarry switched to Flex-Mat 3 and never had a problem with blinding again.”
Another challenge faced by Sylvania Minerals was their overflowing settling ponds. Their initial solution was just to build another settling pond but the $100,000 price tag made exploring other options more appealing. In another area of the plant they installed Major Wire’s HyperSlot screen media.
It is a slotted screen media with unique alternating crimped and straight wires that result in an uneven surface with one straight wire followed by one crimped wire. The crimped wire causes the material to slow down giving the material more time to pass over the openings and also results in better fines removal.
Since installing the HyperSlot screen media on the bottom deck, quarry personnel have noticed a 50 percent decrease in material entering the settling pond – down from the former 220 tph to only 110 tph. This change to HyperSlot screen media has allowed the quarry to delay the creation of an additional settling pond while providing another saleable product.
Information for this article courtesy of Major Wire Industries.