Temperature and pH Dependence of Steel Wear in Grinding Hematite Ore Available to Purchase

The critical pH for passivation of steel balls during wet grinding of hematite ore was found to be 10.5. With slurry pH below this critical value, corrosion played a significant role in the total wear of steel and the wear was temperature dependent. Above this critical value, corrosion was prevented and wear of steel, mainly due to abrasion, was independent of grinding temperature. Potential measurements also indicated that steel balls were passive at pH 10.5. In the region of passivation, protection of steel by lime additions was 24–26 per cent and by silicate additions was 30–32 per cent over the temperature range 25°–65°C. Neither grinding temperature nor slurry pH had a significant effect on work done on ore as measured by the increase of minus 200 mesh ore during grinding.