Abstract: In order to improve the particle size composition of grinding products in Luohe Concentra⁃ tor of Masteel，the grinding characteristics comparison test and magnetic separation verification test of steel balls and nano-ceramic balls were carried out for the second stage grinding products of the concentrator in view of the serious overgrinding of grinding products. The test results show that under the same open circuit grinding conditions，the qualified particle size of ceramic ball mill products is 3.74 percentage points high⁃ er than that of steel ball mill products，with an increase range of 4.21%. The over-abrasive level decreased by 5.64 percentage points，or decrease range of 81.27%. The qualified fraction yield of ceramic ball milled products is 7.32 percentage points higher than that of steel balls，which increases the concentrate grade by 0.13 percentage points and the recovery rate increased by 4.12 percentage points. As a new ball milling me⁃ dium，ceramic ball can effectively improve the particle size distribution characteristics of grinding products and has broad application prospects.

Key words: nano-ceramic ball, grinding, magnetite, overgrinding