Review on the Applications of Apparent Mean Shape Factor on the Integration of Coarse and Fine PSDs Measured by Different Techniques: Quartz Example

Abstract

In most industry where grinding is utilized, particle size, which is a decisive element in establishing the productivity of production processes and execution of the end product, is analyzed to describe the size distribution of particles in a given sample. In mineral and coal processing, particle size distributions (PSDs) of particulate materials were traditionally accomplished by sieving, which gives inaccurate particle size and PSD below 38 μm. This paper reviews the studies related to the combinations PSDs of different mill products of the same quartz mineral by using different particle size measurement techniques to build the whole PSDs including coarse and fine PSDs. For this purpose, almost pure quartz mineral (which is the most suitable brittle material that gives first order grinding kinetics) ground by ball and rod mill products that are the most widely used conventional mills in mineral processing were measured by different size analysis techniques, i.e. sieving for coarse sizes, Andreasen pipette sedimentation, and laser diffraction for fine sizes below 38 μm and combined them to construct whole size distribution by using apparent mean shape factor, r. The results were satisfactorily well for both cases; PSDs by laser diffraction size distributionsieving and PSDs by Andreasen pipette sedimentation-sieving, i.e., a smooth overlap of corrected laser diffraction and sieving PSDs and Andreasen pipette sedimentation and sieving PSDs were obtained by applying to the particle size distribution with r shifting to the right side of the curves. In the case of determination of PSDs by laser diffraction and sieving, r values determined from the corrected particle size distributions were found to be 1.29 and 1.25 for ball and rod milled products, respectively. The results indicates that there is not significant differences between the shape factors of ball and rod milled products of quartz mineral, i.e. both of them have irregular particles, which deviates from the spherical shape as proved by their SEM microphotographs. On the other hand, for the PSDs by Andreasen pipette sedimentation and sieving, the corrected sedimentation data came closer to the sieving data. It was found that r values determined from the corrected PSDs of the same quartz mineral ground by ball and rod mill were 1.00 and 1.12, respectively. The results show that the rod milled products were not more regular in shape than ball milled products as evidenced by SEM pictures and previous works. Thus, this approach can be utilized for the integration of PSDs analyzed by different techniques for coarse and fine sizes of fine particulate coals, minerals, and similar materials ground finely.