The Larox VPF (vertical pressure filter) is used for the pregnant liquor polishing stage in the alumina process, producing both a high-quality product and a high throughput. Low impurity in pregnant liquor is required for further production of metal-grade alumina. With VPF, the impurities of pregnant liquor are polished from 100–200 mg/L down to less than 10 mg/L before aluminum tri-hydrate precipitation. The VPF filtration area is 400 m2 for a maximum capacity of 600 m3/h, and the area can be expanded to 440 m2. The filtration cycle is up to 18 h, and therefore the filter technical time, including cake sluice and cloth cleaning, is minimized, says the manufacturer. — Outotec Oyj, Espoo, Finland
A large pressure filter for the alumina industry
| By Chemical Engineering