COLLOID MILLS - THEORY AND EXPERIMENT

In a colloid mill utilizing a rotating and a stationary plate, a high shear field exists. Particles rotate, generating a lift force moving them to the rotating plate. When particles collide, a substantial energy transfer occurs because their surface velocities are opposite. A mathematical model has been developed relating the particle rotational speed to the parameters of the colloid mill such as gap size, speed, slip viscosity, and particle size distribution. A slurry of the material being ground is forced into the gap. Grinding is autogenous as a result of collisions between rotating particles. All of the material in the process stream is ground finer than the gap setting and grinding can be optimized by adjusting mill operating parameters. However, the mill is not able to grind the incoming stream to submicrometer sizes and there is molecular contamination from the surface of the B4C cones.