On the Comminution of High Carbon Ferrochrome

Abstract

The particle size distribution and the specific surface area were measured on the comminution products of high carbon ferrochrome ground in rod-and ball-mill for 0.5 to 8 hr.
It was found that the Gaudin-Schuhmann equation (Eq.1) can be applied for the particle size dis-tribution in their over-micron range. On the other hand, the Charles equation (Eq. 2) on the energysize reduction relationship did not cover the whole range of comminution carried out and the size modulus, k, and the inverse of specific surface area, 1/S, were found to converge to their limiting values. On the other hand, the Harris equation (Eqs. 5 and 6) based on a modified logistic function fit well the energy-size reduction relationships. The limiting value of the size modulus k and the specific surface area S, were estimated as 22 to 26μ and 2 to 5×10⁴ cm²/cm³, respectively.
The specific surface area estimated on the basis of size distribution did not coincide with that measuredby the air permeability method. At longer grinding times, the measured values become larger than the estimated ones. This difference was supposed to be due to possible flocculation or welding during comminution which also increases with grinding time.