Modelling the effect of froth depth in flotation

The role of the pulp-froth interface on particle detachment and selectivity

The region between the pulp and the froth also known as pulp/froth interface in mineral flotation processes separates the pulp from the froth. Various researchers suggest particle detachment occurs around this region significantly affecting mineral recovery and grade. One of the causes pointed out is sudden deceleration of bubble-particle aggregate upon collision with the interface while another theory suggests detachment to be caused by bubble coalescence. A possible cause of divergence in views may be in the different methods of investigation employed. Though, more than several researchers indicate that detachment occurs, it is not conclusive whether kinetic energy changes or bubble coalesce or a combination of the two is responsible for detachment if any. Thus, this review examines and presents work that has been done on the role of the pulp-froth interface on particle detachment and selectivity. The review also considers the behaviour of a bubble with various interface as found in literature with a view of inferring the dominant cause of detachment at the interface.

Effect of operating parameters on desulphurization of mine tailings by froth flotation

A site-specific study is carried out to assess the suitability of froth flotation for desulphurization of reactive mine tailings at the Musselwhite Mine, Northern Ontario, Canada, to prevent acid mine drainage (AMD). The results from pilot scale flotation tests on an Outokumpu flotation unit are presented, which confirm that froth flotation is effective to reduce sulphide contents of tailings. The factors affecting the treatment effectiveness, such as the froth depth, air flow rate, pulp density and impeller speed are studied. The sulphur recoveries after 0.25, 0.5, 1, 2, 5, and 12 min of flotation time are fitted to a second-order kinetic model. It is found that the second order rate constant, k(2) is negatively correlated with the froth depth and positively correlated with the air flow rate. Based on the data presented in this study; the maximum recovery of total sulphur was achieved when the operational parameters were set to the froth depth of 5 cm, air flow rate 125 L/min, impeller speed 1300 rpm and pulp density 35%.