When a long time customer came to Elcan Industries Inc. asking about sieving nickel powder at 88 and 44 micron and limit the amount of undersize in the product fraction to 2.5%, Elcan answered are you serious? Spherical nickel powder is extremely complicated to sieve and having only 2.5% fines left in the product on a 44um spec is not an easy task on any powder. Regardless, Elcan told the customer to send them the powder and they would find a solution for them.
Upon receival of the nickel powder, Elcan realized that these particles were not shaped like nickel they had seen before. It had a very porous construction and almost looked like individual pieces of coral. Elcan tried everything they could on their advanced sieving systems and couldn’t reach the spec.
Either there were too many fines in the oversize and product fractions, or there was too much oversize in the product fraction. How Frustrating! Ready to tell the customer that the spec they wanted was not achievable, Elcan decided to go back to the basics of screening. Since their inception in 1993, Elcan has always held a line of Minox Tumbler Screeners. With these screeners, they made a name for themselves as they call it “The Experts in Difficult to Screen Product.” As time progressed however, Elcan began to move away from the finesse approach of the Minox and focused on selling high energy screeners, capable of fines removals down to 10 microns.
They knew the end user of the product was using a ROTAP to measure the results and were against this because ROTAPs do not efficiently translate to high energy screeners. They were noticing on the high energy systems, that the powder was jumping too much and then would discharge out. The powder that came off the top was clearly oversize, but upon testing on the ROTAP, it read as undersize. Elcan quickly realized that in the ROTAP Machine, the particles sat on the sieve for a period and the consistent motion of this machine allowed these angular particles to stand up and slide through the screen hole. Sieving nickel powder
Elcan decided the best next step would be to employ a finesse approach that mimicked the ROTAP machine. Standard Vibratory screeners struggle mightily below 100 microns and the rate they got would not be economically viable for their tolling operation. They set up a MINOX Tumbler screener at 88 and 44 microns and began playing with it to see what would work best. The Minox machine has multiple screen cleaning devices so they went back and forth, inching closer and closer to the spec. Eventually they honed it in. Using a Minox Tumbler Screener, with brush arms on the lower deck and the top deck, Elcan began to see good results.
The out of spec began to fall rapidly, but it still wasn’t where it needed to be. Now, they used their 25 years experience and were able to adjust the throw on the screener and the residency time on the screen. A couple tweaks to the motion, and they finally found the perfect combination. That was a year ago. Since then Elcan has been successfully producing product grade nickel powder at a 2.5 % spec on a daily basis. The customer was able to deliver a high quality powder to their end user, and Elcan was able to develop a new method for sieving nickel powder, and satisfy their customer’s lofty requests.
As seen in October 2018 Edition of Powder Bulk Solids