 |
 |
||||||
[March 2005]
Screening 1 Million Tons Uninterrupted
A Pneumati-Sifter Vibroscreen(r) circular vibratory separator from Kason Corporation (Millburn, NJ, USA) has reached a landmark achievement - the screening of over 1 million tons of clay over 25 years without an equipment failure and with no signs of quitting either, according to John Taylor, the Production Manager of The Pfaltzgraff Co (Thomasville, PA, USA), the 190 year-old manufacturer of ceramic dinnerware.
The system moves raw materials from any of 10 50ft-high silos containing clay, silica, alumina, lime and other ingredients through a pneumatic conveying system to a central weigh hopper. Ingredients are weighed in sequence and discharged as 1360kg batches into a pressurised surge hopper equipped with a rotary airlock valve that meters 273kg/min of material into the 1525mm diameter in-line sifter.
The sifter, designed for 14.7psig pressure, removes agglomerates, paper scraps and other foreign particles larger than 1880 micron, preparing the clay that will form the stoneware body and determine its finish. Magnets upstream and downstream of the screener remove iron particles.
"Elbows of the pneumatic conveyor lines wear out every 10 to 12 months because the system runs highly abrasive materials three shifts per day, five days a week," explained John Taylor, "but aside from screen changes every two years, nothing on the Kason unit has worn out, including the gyratory motor which we lubricate periodically."
The screener is equipped with an imbalanced-weight gyratory motor that imparts multi-plane inertial vibration to two spring-mounted screening decks, causing oversize particles to vibrate across the screen surface in controlled pathways to the screen periphery where they are discharged. Screening efficiency improves by forcing the particles to pass over a maximum amount of screen surface.
The unit screens a 1360kg batch in 5 minutes in-line with the pneumatic conveying system. To prevent sharp, angular particles from blinding screen apertures, the screener is equipped with a 'ball tray' anti-blinding device consisting of elastomeric balls that are captive in a narrow space below the top no.10 mesh (1880 micron) working screen and above the no.4 mesh (4750 micron) ball screen. Vibratory action of the screener causes the balls to bounce against the underside of the working screen, dislodging particles wedged in the screen apertures.
Oversize particles exit through a discharge spout at the periphery of the top frame. Screened clay exits the bottom frame discharge into a holding hopper, then into a pugmill which mixes the clay with water before it is conveyed through an auger, cut, wrapped in plastic and stored for up to three months.
www.kason.com
ENDS