The Particle Size Determination of Clay Minerals by Centrifugal Photo-Extinction Method

Abstract

Most of the existing gravitational sedimentation methods have shortcomings in the particle size determination of powders below about 2 microns.For example, 2 micron particles of kaolinite powder (density=2.65), require about 15.5 hours toMoreover convection and displacement current all tend to disturb the sedimentation. The centrifugal photo-extinction method is based upon the determination of the opacity of suitable dispersing liquid caused by the suspension of the powder in a centrifugal field.However, the lack of knowledge in the basic law of transmission of light through the suspension in a centrifugal field leaves the method still open to question.For this reason first we studied the centrifugal photo-extinction apparatus and the method of measurement by its means.Secondly we studied the effects that this centrifugal photo-extinction method of measurement would have on the particle size distribution of kaolinite in respect of the reproducibility, the dispersion agent and the concentration of powder, and made comparative studies of various other effects that other methods of measurement would have.We have found the centrifugal photo-extinction method to be adequate with considerable accuracy for the determination of the particle size of fine powders.