To deal with the problems existed in partition plate on traditional tube mill, such as low screening efficiency, weak ventilation and unbalanced material level setting, the technical principle and structure design of high efficient tridimensional multi grading unit are proposed by the author. The analysis results showed that the screening efficiency, the ventilation state and service life can be improved by using this unit on tube mill.

Through different semi-industrial grinding tests, grinding was made on massive steel slag and water quenched slag. Analysis comparison was made on different grinding process. The results show that combined grinding system with roller press and ball mill is the ideal grinding method for steel slag powder production.