Bauxite grindability at elevated temperature in various mills

• Rod mill tests under alkaline conditions can be undertaken using the modified Rod Mill in order to simulate process parameters.
• Grindability test will have differing effects on bauxite milled under special conditions and is characteristic of the mill type.
• Differences can be observed using porosity and surface area measurement which will affect the subsequent processes.

The present paper deals with the grindability experimental results of an Australian bauxite sample in the Universal Hardgrove mill, the Universal Bond ball mill and the heat insulated Bond Rod Mill in the temperature range from 20 up to 80 °C. As previously observed the grindability of the bauxite has improved at elevated temperature. The specific grinding energy decreased. Correlation between the Bond Work Indices calculated from three different method (HGI, Bond Ball Mill Work Index and Bond Rod Mill Work Index) was established. Appropriate correlation in the investigated temperature interval was found. Pore size distribution, SEM and BET results show that in spite of the good correlation between the grindability characteristics, the material properties of the ground products have significant differences. Namely, the various grinding stresses resulted in different material pore size distribution and specific surface area.