Low chromium white cast iron is used as the grinding ball of low chromium cast iron. The chromium content is generally 1%~3%, and the iron mold casting process is generally used. Low chromium cast iron grinding ball is relatively cheap because of its simple production process, low alloy content, and low requirements for workers’ skills and production conditions. Low chromium cast iron has been widely used as a kind of casting grinding ball material in China since the 1970s.
Low chromium cast iron grinding balls still have a certain market share, mainly because the price is relatively cheap and there is a certain market for small mills with low performance requirements. However, it has certain defects, mainly including:
1) Low hardness, poor toughness and high wear. Low chromium grinding ball hardness HRC ≥ 45, impact toughness ≥ 2 J/cm2; According to the annual wear statistics of domestic concentrators, the average wear of low chromium cast iron grinding balls in nonferrous alloy copper ores is 0.8 kg/t~1.0 kg/t Iron ore is about 1.2 kg/t~1.5 kg/t, with high wear.
2) It is easily broken and out of round. As the low chromium cast iron grinding ball has low hardness, is easy to be out of round, has high crushing rate, and is easy to cause the mill spacer to be blocked, which greatly reduces the grinding efficiency, as shown in the figure.
3) Low chromium grinding balls still contain a certain amount of chromium, which is a rare element in China. The consumption of grinding balls is accompanied by the complete disappearance of chromium.
As the size of the ball mill in the mining field becomes larger and larger, the requirements for the anti crushing ability, wear and energy saving of the grinding ball become higher and higher, and the exposed use problems of low chromium cast iron grinding balls become more and more prominent. Therefore, the low chromium cast iron grinding balls have gradually decreased in the domestic market.