In 2006, at the same time he was promoted to quarry foreman of Naceville Materials in Sellersville, PA, Albert Grove inherited an ongoing challenge for the site's primary modified screen. The operation's Allis Chalmers 7-foot by 16-foot inclined (20 degrees), two-deck, polyurethane modified screen was experiencing severe blinding and plugging on both of its decks any time it processed wet material.
Located between Philadelphia and Allentown, Naceville Materials mines argillite base rock, making 3/4-inch, 1/2-inch, screenings, 3/4-inch modified and specialty products to state spec, mostly supplying the material for concrete and asphalt producers in the area. The site operates year-round – with three of the four seasons producing rain or snow that create problems with wet material. The modified screen is located at the primary jaw, where it receives the 3/4-inch modified rock from a Simplicity 6-foot by 16-foot three-deck screen, which scalps material from the jaw's grizzly feeder. The modified screen separates the modified rock into the operation's 3/4-inch, 1/2-inch and screenings products.
|Naceville Materials agreed to be a test site for the Flex-Thane screen. While the modified screen's decks were still primarily running with polyurethane screen media, there was a noticeable difference where the test panels were installed.|
“The 7-foot by 16-foot screen has a flat, dual-deck, polyurethane top deck,” says Grove. “We altered it to take on the dual decks to help alleviate the single deck from overloading and blinding. The dual decks are separated by about 6 inches but make the same size product. The bottom deck currently has a polyurethane step-deck.”
Naceville's former quarry foreman, Darren Landis (now a regional supervisor for H&K), had worked with its screen dealer, Kemper Equipment of Honey Brooke, PA, to try all of these screen media modifications and more in his attempts to solve the modified screen's ongoing blinding and plugging problems, Grove explains.
Initially, Kemper and Landis attempted to solve the screen's blinding issues by installing a splitter box, which alleviated the amount of modified stone going to the screen. “The splitter box allows us to control the amount of material going to the screen, and we use it based on the moisture content at any given time,” says Grove. “Moisture makes the material stick to the screen. When it's raining, we have to shut down the screen completely. If the material has any moisture at all, we're still shutting down the screen three or four times a day to clean it.”
With the screen still experiencing blinding, Kemper and Landis installed step-deck screens on both decks, but the screen media change did not solve the problem. The dealer and quarry foreman then tried the dual top deck configuration, essentially creating two separate decks out of the top deck. They also tried different screen opening sizes on the top layer of the dual deck to help split the screening duties of both layers more evenly – all to no avail.
“Then we got a call out of the blue,” recalls Grove, who at the time had been the quarry's maintenance foreman. “Keith (Meitzler) from Kemper wanted to bring in Brad Rice, his territory manager from Major Wire, to check out the setup and see what they could do.”
Major Wire Industries, based in Montreal, Canada, had been looking for test sites to try its new flat-deck, Flex-Mat® screen solution. Called Flex-Thane™, this screen media solution combines Major Wire's Flex-Mat technology with the easy installation of polyurethane and rubber panels to virtually eliminate blinding and pegging problems on flat-surface screen decks. Flex-Thane's independently vibrating wires, bonded in place with the distinctive lime-green polyurethane strips, also provide more open area for far greater throughput, higher production and better efficiency than polyurethane and rubber screens in hard-to-screen applications. Its modular panels, available in standard and custom sizes, install easily on most common flat-surface screen decks, similar to traditional polyurethane and rubber panels.
“Darren was ready to try anything to alleviate the blinding,” says Grove. “So he agreed to put in some test panels. They arrived in May 2007… (and) I installed the panels on the bottom section of the dual top deck.”
While the modified screen's decks were still primarily running with polyurethane screen media, Grove said he immediately noticed a difference with the test panels. “Where the other polyurethane panels were blinded, the Flex-Thane panels ran clean,” he said.
Between May 31 and December 31, 2007, Naceville Materials ran more than 50,000 tons across the test panels. “There's been no wear that I can see on these panels,” Grove says.
According to Grove, when screening “raw” material from the point of the shot, the producer will experience more problems with blinding due to the material's lack of refinement. If the material is wet, the issue is further compounded. The crushing process not only dries the material, but it also makes it a more desirable shape for screening, so it does not plug the screen. Therefore, even in dry conditions, a modified screen at the primary, handling raw material from the shot, is going to need a screen media that resists blinding.
“We definitely solved the blinding problem with the Flex-Thane panels,” says Grove.