Fluidisation of a mineral concentrate at reduced pressure

Abstract The behaviour of relatively deep beds of a spodumene concentrate air-fluidised at reduced pressure has been investigated at room temperature in a cylindrical column 5.72 cm bore over a range of top-pressure between 67 and 400 Pa absolute. These conditions gave a bed pressure drop for complete fluidisation at least an order of magnitude larger than the top pressure. A fluidisation front was seen to extend downwards through the bed with increasing gas flow rate. In this intermediate fluidisation regime, increasing gas velocity along the pressure gradient produces a range of behaviour within a bed that extends from settled conditions at the base towards slugging at the top. The increasing gas velocity creates a strong differential elutriation which was accompanied by a shift in the minimum fluidisation velocity as the mean bed particle size increased. Metallurgical applications and operational effects are considered.