However, in the flotation of coarse-grained ore, the interaction between mineral particles and air bubbles is weak, and the flotation of coarse-grained ore is inhibited. The probability of adhesion between mineral particles and air bubbles is low. After the coarser particles collide with the air bubbles, the air bubbles will undergo a large deformation and recover immediately. This process will generate elastic vibration, which lowers the adhesion probability of particles and bubbles. The deformation of bubbles will also increase the gap between particles and bubbles, and many liquid phases will be mixed in the middle. If it is too late to discharge, the ore particles and air bubbles will not stick together. Generally, the degree of dissociation on the surface of minerals increases with the decrease in particle size, and a larger degree of dissociation provides more locations for the attachment of bubbles. Coarse-grained minerals have large particle sizes and small dissociation degrees.

Reasons for poor coarse-grained flotation:

For some unevenly distributed ore, the cost of grinding is high and the ore is easy to be over-grinded, so the rough grinding flotation process is often used. However, the coarse grains are relatively heavy, and are not easy to suspend in the flotation machine, and the chance of colliding with the air bubbles is reduced. After the coarse grains are attached to the air bubbles, they easily fall off from the air bubbles due to the strong shedding force. Therefore, under general process conditions, the effect of coarse-grained flotation is poor.

    (1) Useful minerals and gangue minerals have not been fully separated;

    (2) It is not easy to suspend in the flotation machine, and the probability of collision with air bubbles is reduced;

    (3) Coarse particles move in the pulp and encounter turbulent vibration, causing them to fall off from the air bubbles.