STUDIES ON IMPELLER TYPE, IMPELLER SPEED AND AIR-FLOW RATE IN AN INDUSTRIAL-SCALE FLOTATION CELL .3. EFFECT ON SUPERFICIAL GAS VELOCITY

Superficial gas velocity was measured at different locations in a 2.8m (3) portable industrial scale sub-aeration flotation cell, treating zi nc cleaner feed at Hellyer Concentrator in Tasmania, Australia. The ce ll was fitted in turn with four different impeller-stator systems, and operated over a range of air flow rates and impeller speeds. Superfic ial gas velocity values ranged from 0.29 cm/sec to 6.4 cm/sec at the a irflow rates employed. The distribution of air in the cell was very de pendent on the impeller type, as well as on the operating conditions i n the cell. For a well dispersed condition, the value of superficial g as velocity was uniform at different locations, whereas for flooding c onditions the superficial gas velocity was very high near to the impel ler and much lower away from the impeller.