Froth stability plays an important role in coarse particle flotation. Higher froth stability offsets the downward gravity force of
coarse particles and reduces their drainage from froth thereby
increasing coarse particle flotation. However, higher froth stability
also increases mechanical entrainment which is a transfer process
by which mineral particles suspended in water enter the flotation
froth, move upwards, and finally leave the flotation cell [39]. In
mineral flotation, true flotation by the collision of hydrophobic
particles with bubbles followed by the rising of bubble–particle
aggregates from the pulp phase to the froth phase and eventually
the transport of bubble–particle aggregates into the concentrate
is the primary mechanism for selective separation of valuable minerals from gangue minerals. In this study the true flotation of combustible matter was calculated to evaluate the net benefit of saline
water and clay minerals in the coarse coal flotation. Results are shown in Fig. 5. Combustible recovery by true flotation was calculated based on the following equations