Question

Beads of about 1 mm may be effective for the grinding of calcined powders containing weak aggregates, but are ineffective when grinding very dense particles.Why?

Answer 1

The calcined powders are produced by thermal treatment at high temperatures in absence or limited supply of air by bringing about the thermal degradation. This leads to the formation of weak bonding within the particles which can be easily grinded on application of even a little force but the dense particles require heavy impact and compression for grinding operations. Beads of 1 mm diameter are not capable enough to provide a hard impact thus are ineffective for grinding of dense/ heavy particles.