Influence of bed material density on fluidized bed flotation performance: A study on the flotation performance of quartz and alumina beds in the HydroFloat

Abstract

This work investigated the influence of bed material density on fluidized bed flotation performance. Experiments were carried out in a HydroFloat cell to investigate the influence of bed material density on required bed masses and bed behaviour at a bed level of 15 cm and water rate of 1.19 cm/s. Bubble size image analysis was carried out under four different fluidization conditions: water only, water and frother (1 ppm), water, frother (1 ppm) and quartz, and water, frother (1 ppm) and aluminium oxide. Flotation experiments were undertaken to investigate the influence of the resulting bed density and characteristics on concentrate recovery and grade performance. The results confirm that there is an upper particle size limit on fluidization. Apparent bed density was higher for the denser bed material (aluminium oxide) even though bed behaviour remained identical with both being highly permeable. The product Cu grades for the quartz bed were lower (8.42 % and 15.82 %) compared to the alumina bed (23.81 % and 21.86 %). This was due to the elutriation of quartz into the concentrate with Si concentrations of 25.85 % and 15.69 % compared to 2.4 % in the feed. In contrast, Al concentrations were 2.44 % and 1.09 % in the concentrates compared to the 0.38 % in the feed. However, recovery performances for both bed materials were identical (39.72 % and 40.88 % at low collector concentrations and 98.93 % and 97.95 % after ethylenediaminetetraacetic acid (EDTA) cleaning and increased collector concentration for the quartz and aluminium oxide beds respectively). This indicates that apparent bed density may have only a slight influence on flotation recovery compared to other direct control variables such as fluidization water rate and bed height.