Recently, a chemical company opening a new $60 million manufacturing plant discovered a major problem. The company built the plant to manufacture a spherical bulk solid product, but the manufacturing process also generated particulate fines that were forming agglomerates.
As the 1/8-inch product spheres dried, the fine powder would clump together and stuck to the product. These agglomerates needed to be removed before the product could be delivered to the client. Traditional screening methods weren’t working because the agglomerates were similar in size to the product and the screeners weren’t capable of breaking up the agglomerated material.
“We attempted to remove these particulates in the plant by both a gyrator screener and a standard circular vibrating screener,” says the plant’s senior manager. “However, these processes were not vigorous enough to either break up the large agglomerates or break the agglomerates off the product.”
Searching for a solution
With a production deadline approaching, the company needed a fast solution to remove the agglomerates. The company turned to Elcan Industries, a screening equipment supplier basic in Tuckahoe, NY.
“Elcan Routinely does a particle separation work for us,” says the plant’s senior manager. “We knew they had several types of equipment that we could explore to solve this problem.”
The supplier has a 20,000-square-foot testing facility with 10 tolling bays, where equipment can be set up to either perform a test or for full-scale processing. Elcan tested several different models of screeners with the product to try of screeners with the product to try to remove the agglomerates. Once option was a tumbler screener that used air wands underneath the screen to push the material up and break off the agglomerates. However, the agglomerates were too aged to be broken up by the action of forcing the particle up and into the roof of the screener.\
Next, the supplier tried a high-energy screener that imparted energy directly into the 1,500-micron screen cloth. The hope was that the energy in the screen would break up the agglomerates to a small enough size to pass through the screen cloth but this didn’t work either.
Breaking down the agglomerates
While talking about the problem in a conference room, the supplier’s engineers noticed that if they dropped a marker pen with enough force, the agglomerates would break, but the final product was strong enough to withstand the impact. The supplier went back to a curricular, high-energy screener but added several hundred 35-millimeter polyurethane balls on top of the mesh to impact the mixture of agglomerates and products.
The high-energy screen vibration shot the balls into the air, and when the balls came down, they broke the unwanted material off the product and crushed the agglomerates. This allowed the fine material to pass through the screen while leaving the finished product behind. However, the screeners circular shape encouraged everything to discharge from the top of the screen, including the balls.
To combat this, the supplier decided to use a rectangular, high-energy screener and placed partitions inside the divide the screen into three sections and prevent the balls from being discharged. A small gas below the partitions allows the product and agglomerate to pass through freely. The balls break around 70 percent of the agglomerates in the first section, finish up most of the remaining agglomerates in the second section, and polish off whatever remains in the third section.
A vacuum then sucks down the crushed material through the screen and collects it in a bathhouse. The product exits the screener and can then be shipped tp the client. The supplier set ip four large machine in two of the tolling bays to process the truckloads of product, allowing the the chemical company to meet its deadline. PBE