Effect of ball to powder ratio and media density on fine grinding and mechanical activation of hematite ores in planetary mill

Abstract

Raw hematite ore from Kulim, Kedah was mechanically activated using physical technique of powder ball milling. Operational parameter during fine grinding of the hematite ore are ball to powder ratio (3:1, 5:1, 7:1), milling speed (300rpm and 400rpm) and time (1 hour) and media density may influence the specific surface area, particle size and morphology of the particles. Therefore, this research is to study the mechanically activated hematite ore powder associated with the ball-to-powder ratio and grinding media density in the fine grinding process for advance application. XRF analysis showed that the sample consist of 76.74% Fe2O3 which is in high grade iron ore classification. Ground hematite ore (29.192m2/g) at 300rpm and BPR 7:1 have higher surface area than raw (12.762m2/g) and calcine product (12.351m2/g). This is due to the reduction of particles size during milling which exhibit high surface area as milling speed and BPR increase. It also proved by d50 (median size) of raw (19.60μm) is greater than ground hematite ore (2.33μm). However, based on the morphology studies, particles will agglomerate at high milling speed (400rpm) and BPR (7:1). It is due to the higher impact force between feed charge and stainless steel ball during fine grinding. It also showed that raw material have coarse, large and various particles shape than ground product have fine particles and more spherical shape. In a conclusion, higher surface areas of the particles are suitable for the adsorbent application to enhance the adsorption efficiency.