Abstract:For the purpose of optimizing grinding process for separating the RO phase from steel slag solids by pneumatic separation, five kinds of steel slag powder prepared by three kinds of grinding equipments were examined for the uniformity of size distribution and the difference of RO phase concentration in individual size fractions. The results show that the particle size distribution of five kinds micron steel slag powder conforms to RRB(Rosin Rammler Bennett) model and the fractal dimension equation; according to uniformity coefficient n and fractal dimension D there is the better uniformity of steel slag powder with coarser powder so that the RO phase density separation effect is better. The superior RO phase density separation effect in samples obtained from three grinding processes can be listed in the order:vertical roller mill, roller press mill, ball mill. For steel slag powder with -55μm size fraction, the content of RO phase increases with particle size increasing which shows the RO phase granularity separation effect; for steel slag powder with +55μm size fraction, the content of RO phase decreases depending on particle size increasing, in which a majority of RO phase maintains in mineral aggregate with gangue. In comparison with impact, there are high RO phase content in coarser fraction of steel slag powder processed using crushing by compression, as it has better RO phase preferential liberation of composite mineral particles. According to the efficiency of the RO phase granularity separation effect by sieving, the optimization order of grinding processes can be ranked as follows:roller press mill, vertical roller mill, ball mill. The pneumatic separation of RO phase from steel slag powder by industrial facilities coexists of density separation effect and granularity separation effect, and the former is larger than the latter.