Grinding of highly viscous bentonite containing slurries

The influence of bentonite on the grinding efficiencies of ores has not been investigated. In this work, the relationships between the properties of bentonite-containing slurries (such as rheology and settling behaviour) and grinding efficiency are examined. The results demonstrated that the presence of bentonite in the ore negatively affected the grinding performance of the ore, and the negative effect of bentonite was mitigated by adding Ca2+ ions. The additions of Ca2+ ions reduced the repulsive forces between bentonite particles as confirmed using the zeta potential measurements as well as the water-swelling capacity of bentonite as found using the settling tests. Therefore, the ore-bentonite slurries in the presence of Ca2+ ions had reduced shear forces between particles, leading to improved settling rates and grinding performance. This is particularly true when the solid percentage of the bentonite-containing slurries was 62% or higher than that even at a lower bentonite concentration (i.e. 5%). This paper demonstrated that the changes in pulp chemistry or solid percentage can significantly improve the grinding performance of bentonite-containing ores.