The effects of gas rate and froth depth on flotation performance of an industrial self-aerated cell

The overall flotation recovery depends on the recovery in the pulp zone as well as recovery in the froth zone. The froth retention time affects the froth recovery and it has an inverse relationship with both froth recovery and overall recovery. On the other hand, the froth retention time depends on gas rate and froth depth. The gas rate is an independent factor in induced-air flotation machines, whereas in self-aerated cells it depends on various variables and the froth depth is one of them with significant effect. Therefore, adjusting the gas rate is more complicated and more difficult in the induced-air flotation machine. This study attempts to investigate the effects of froth depth and gas rate on superficial gas velocity, froth retention time and metallurgical performance of the cell. The operation of these types of cells can be improved, by understanding the relationship between these parameters particularity the adjustment of froth depth and gas rate. Experimental tests were carried out in a 50 m3 self-aerated cell in Gol Gohar iron ore processing plant. The results showed that although the froth depth variations, changed the gas rate, but the gas rate variations did not have a significant effect on the froth retention time and the metallurgical performance. Also, the froth depth was not a good option to change the gas rate and the superficial gas velocity in this type of flotation cells, because the range of superficial gas velocity variations was low when the froth depth was changed in industrial-scale.