Outotec Launches a New Filter for the Alumina Industry
VPF technology is used for pregnant liquor polishing in the alumina process. Outotec is a major provider of alumina refinery plants as well as provider of filtration solutions for the minerals and metals processing industries. VPF technology has a solid reference base, with the first installations occurring in Australia back in 1979. VPF polishing filters are specially designed for removal of suspended solids impurities before hydrate precipitation. With Outotec Larox VPF the pregnant liquor polishing (also known as security filtration) produces both a high quality product and a high equipment throughput. With VPF the impurities of pregnant liquor are polished from 100–200 mg/l (ppm) down to less than 10 mg/l before aluminum tri-hydrate precipitation. Low impurity in pregnant liquor is required for further production of metal grade alumina. The VPF filtration area is 400 m² with a maximum capacity of 600 m³/h and the area can be expanded to 440 m². Outotec Larox VPF ensures high filtration rate per filtration building floor area. The filtration cycle is up to 18 h, and therefore the filter technical time, including cake sluice and cloth cleaning is minimized. Automatic (PLC) control of the cloth cleaning and cake discharge steps at the end of each filtration cycle ensures maximum filtration time in subsequent cycles, which leads to low impurities in filtrate and reduces manpower requirements by eliminating the need for frequent supervision (12/2011).