Influence of water rate, gas rate, and bed particle size on bed-level and coarse particle flotation performance

• Minimum fluidization water rate increases with increasing bed particle size. • The relationships between bed-level and superficial water rate, and bed-level and superficial gas rate are more apparent at finer bed sizes compared to coarser bed sizes. • At constant bed masses, flotation performance is optimal at finer bed sizes due to the higher bed levels that can be attained. • After adjusting for bed level, flotation performance remains optimum at finer bed sizes due to low porosity at coarser bed sizes leading to poor bubble-dissipation. • This indicates a potential upper bed particle size limit, beyond which fluidization is unfeasible. This work investigates the effect of superficial water rate, superficial gas rate, and bed particle size on bed-level and coarse particle flotation performance. 5 kg of quartz in three size ranges (- 1180 + 850 µm, − 850 + 425 µm, − 425 + 250 µm) were used to study the effect of bed particle size on bed-level at varying superficial water rates and superficial gas rates. The influence of bed particle size on flotation performance was studied in two stages. One stage maintained constant bed masses, and another maintained constant bed-level, superficial water rate, and superficial gas rate. Results showed that bed-level increases with increasing superficial water rate after a minimum is attained but the rate of increase is limited by increasing bed particle size. Bed level decreases with an increasing superficial gas rate within a stable bed but this rate of decrease is also lowered at relatively coarser bed particle sizes. At constant bed masses, flotation performance tends to be better for the − 425 + 250 µm bed due to the high range of bed levels that can be attained. However, after adjusting for these parameter differences, we found that there may be an inherent upper bed particle size limit beyond which fluidization is unfeasible.