Corrosion Behaviour of Various Steels In Ore Grinding

CIM Bulletin, Vol. 70, No. 778, 1977

G. R. Hoey, Head, Corrosion Section, W. Dingley, Technologist, and C. Freeman, Technician, Physical Sciences Laboratory, Mineral Sciences Laboratories, CANMET, Department of Energy, Mines and Resources, Ottawa

Wear of six types of grinding balls was compared with, and without corrosion inhibition in grinding Ni-Cu sulphide and hematite ores in laboratory ball mills. Forged steel balls (R,. 60 to 65) and three types of white cast iron balls (R<. 50 to 65) were susceptible to corrosive wear and two types of stainless steel balls [AISI Type 440C (Rc 65) and AISI Type 302 (Rc 35)} were relatively immune. The relative wear rates of the five types of hard balls (R, 50 to 65) were dependent on the corrosivity of the ore. Ranking of the hard balls with respect to wear resistance was consistent for the sulphide and hematite ores in the presence of corrosion inhibition, whereas their ranking was different for the two ores in the absence of inhibition. The electrochemical potential of the grinding balls was measured during grinding and was found to be a useful measurement for assessing the susceptibility of an alloy to corrosive wear. Reduction of ball wear for forged steel and white cast irons with corrosion inhibition was concomitant with a shift of ball potential to less active values. Ball potentials in the presence of inhibition were indicative of non-corroding metal surfaces.
Keywords: Corrosion, Grinding, Ball mills, Steel balls, Cast iron balls, Wear resistance, Alloys, Sulphide ore, Hematite ore.