Abstract: The combination of overflow type ball mills and hydrocyclones is used the primary and secondary closed-circuit grinding process in Qidashan Iron Mine's Concentrator, Mining Co.of AnSteel Group.Since it was put into operation, the classification efficiency of the secondary grinding had been low, restricting the downstream concentration operation.The comparison of domestic FX660-GX hydrocyclones with imported Krebs hydroclones and the optimization of the hydrocyclone parameters were then made.The results show that the hydrocyclones with 180 mm overflow tube and 135 mm underflow spigot can satisfy the site process requirements and have good classification effect.

Key words: Hydrocyclones, Classification, Ball mill