Abstract: A modified air-sparged hydroclone has been used to reduce the overgrinding of valuable mineralnin fine grindig circuit, and the effects of important design and operating variables on separation perfor-manc e examined. In order to reduce the complexity of the analysis, the separation per formance of theair-sparged hydrocyclone was studied by dimensionless analysis. Two important dimensionless vari-ables, i. e. dimensionless area ratio of overflow area to under flow area and dimensionless flowrate ratioof air flowrate to slurry flowrate, are mainly studied in this paper. The research results will facilitatescale-up procedures for the modified air-sparged hydrocyclone separation system.