Abstract
In this paper a study of the pretreatment of magnetite concentrate by using high pressure roll grinding (HPRG) is presented, which aims to improve the pelletability, reduce bentonite dosage and increase the iron grade of pellets. The effect of the HPRG parameters on the green pellet strength was investigated. The mechanism of the pretreatment of magnetite concentrate by HPRG was revealed by determining the surface activity by means of BET nitrogen adsorption, laser size analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), micro calorimeter and pelletability index. It is demonstrated that the surface activity is improved by increases in specific surface area and the amount of micron size fractions with favored plate and flake morphologies, and higher lattice deformation and defects, resulting in more wetting heat and higher pelletability index. The effect of the HPRG is concluded as mechano-chemical activation of the magnetite concentrate. All of which is further supported by the fact that the drop number of the green pellets increased to 4.9 times by pretreating the concentrate using the HPRG compared to 3.3 times without pretreating, and bentonite reduced by 50%.
