Morphology and wear of high chromium and austempered ductile iron balls as grinding media in ball mills

Abstract

High chromium balls are recognized as better grinding media in terms of wear rates than forged steel balls, which are conventional grinding media in the milling process of iron ore. In this research work, the wear rate of high chromium balls and austempered ductile iron (ADI) balls as crushing media in a ball mill are compared. ADI are prepared by austenitizing the spheroidal graphite (SG) iron balls at 920 °C for one hour, and step austempering heat treatments were given, which includes the first step austenitizing at 300 °C for 15 min, followed by a second step austenitizing at 400 °C for 60 min. The wear rates were estimated when both balls were used separately by maintaining the same machining conditions and when the balls are mixed. The grinding wear conduct of both materials is evaluated for wear loss in wet grinding conditions. The experimental results reveal that the performance of ADI balls is better than high chromium balls when tested separately and mixed. Results also indicate that the wear rates/revolutions will decrease when the operating period increases.