Swenson - Top Feed Filter for Dewatering and Drying Crystalline Material

The feed, at low density, is pumped into the feed hopper where suspended solids settle to the bottom while excess liquor overflows and returns to the process. Solids are carried through the nozzles by injecting saturated liquor, generally filtrate. The magma, formed of solids and liquor, strikes the spreader apron and flows over the feed dam. Baffles focus the feed stream onto the surface of the drum. As the drum rotates, the liquor enters the internal sections after being sucked through the filter medium, on which the solids are continuously deposited as a uniform, porous cake. The cake is washed to displace mother liquor, then moves into the heat zone, where much of the wash water is removed mechanically, and the remainder is heated to the boiling point.

Drying now takes place, followed by removal of the outer dry crust by the intermediate scraper blade, allowing the thinner, partly dried cake to travel through the final part of the drying cycle. The cake is then completely removed by the final scraper. Sprays clean the filter medium and the cycle is repeated.

• Two units in one (filter and dryer) – Reduces initial cost of equipment and installation
• Bone-dry product – Thoroughly dried by hot air under closely controlled conditions
• High capacity – Hot air comes in intimate contact with each grain, resulting in quick drying
• High thermal efficiency – Mechanical removal of much of the liquor reduces heat consumption per unit output
• No dust – As hot air is filtered through the cake; floating particles attach themselves to coarse particles and are removed from the system
• Low operating cost – Automatic control reduces amount of attention required. Cost is further decreased by high capacity and high thermal efficiency
• Long service life – All parts move at low speed and are built of high-grade materials
• Clean filter stations – Operates under vacuum and under controlled conditions, minimizing spillage and waste
• Flexible – Can dry salts which normally form hydrated crystals to the anhydrous phase without special method of operation