Abstract: The phase transition in stainless steel slag during solidification was studied with the thermodynamic software of FactSage 6.2. The results show that the temperature for merwinite and di-calcium silicate to precipitate can be decreased to lower values and the formation of melilite was accelerated with decreasing the basicity and increasing the Al₂O₃ content of the slag. The Cr content in the spinel phase increases obviously with decreasing the slag basicity. When the basicity decreased from 1.6 to 1.0， the Cr content in the spinel phase increased from 24.93% to 48.27%， thus leading to lower chromium content in liquid slag during solidification. When the Al₂O₃ content increased to 10% in the slag，the Al₂O₃ favored the precipitation of spinel phase. The chromium bounded in spinel phase was gradually replaced by aluminum with the lowering of temperature， and the Cr content in the spinel phase decreased from 30.39%(1500℃) to 13.88%(1300℃).

Key words: stainless steel slag, solidification, thermodynamic analysis, basicity, Al₂O₃