Abstract: The influence of Al2O3 modification on the enrichment behavior of chromium was analyzed，meanwhile，the enrichment mechanism was deeply investigated. The samples were heated to 1600°C and holding 30min for melting completely before quenching in water. The microstructure and occurrence behavior of chromium were analyzed by X-ray powder diffraction (XRD) and scanning electron microscope-energy dispersive spectroscopy (SEM-EDS). The precipitation behavior of spinel phase was also conducted. The results showed that the main mineral phase in stainless steel slag with 4% and 8% Al2O3 content were spinel and merwinite phase，large amount of chromium was still existed in liquid and merwinitephase. As Al2O3 content increases to 12%，merwinite phase was gradually disappeared and transformed to liquid phase. Chromium in silicate phases gradually migrated to the spinel phase.Addition of Al2O3was conducive to the precipitation of the spinel phase and gradually replacing chromium in spinel phase. Thus，the activity of MgCr2O4 in Mg(Cr，Al)2O4 decreased through Al2O3 modification treatment，which provided thermodynamic driving force for enrichment of chromium in spinel.

Key words: stainless steel slag, spinel, Al2O3, chromium, influence mechanism