High chromium white cast iron is selected as the grinding ball of high chromium cast iron, and the mass fraction of chromium is generally 10%~13%. Most of them adopt the production process of iron mould sand coating, and carry out oil quenching+tempering heat treatment process. After adding chromium to high chromium cast iron grinding balls, the hardenability and hardness of the grinding balls are increased. High chromium grinding balls are widely used in cement and metallurgical mining industries, and have been widely recognized by the industry. It has the following characteristics:
1) High hardness: according to the production experience of high chromium grinding balls in domestic mines, the surface hardness of high chromium grinding balls generally reaches above HRC56, and the impact toughness is ≥ 3 J/cm2
2) High price: because a large amount of chromium alloy is added, the cost is much higher than that of low chromium grinding ball.
The hardness of high chromium casting ball is higher than that of low chromium grinding ball, and the toughness is also better than that of low chromium cast iron grinding ball. At present, the market share of high chromium cast iron grinding balls relative to low chromium cast iron grinding balls in the domestic and foreign grinding ball markets is growing gradually. However, there are also two problems when using high chromium cast iron grinding balls:
1) Chromium is a precious alloy element: the chromium element lost after grinding cannot be recycled and is discharged into nature through tailings. China is short of chromium resources, and most of them are imported. From the perspective of world resource protection and the potential possibility of future market fluctuation of chromium alloy price, as a grinding ball product with long-term industrial application and large consumption, using high chromium alloy elements as grinding ball materials is not an ideal technical direction.
2) Although the toughness of high chromium cast iron grinding balls is slightly higher than that of low chromium cast iron grinding balls, it still cannot meet the requirements of large ball mills and SAG mills on the toughness and crushing resistance of large diameter grinding balls. Due to the high alloy content and insufficient toughness, its market share is also limited.