<p>The leaching of Cr⁶⁺ from chromium-containing stainless steel slag causes serious environmental pollution, limiting the large-scale application of stainless steel slag. Recovering chromium from stainless steel slag has become the key to fully utilizing chromium-containing stainless steel slag. In order to achieve sustainable recycling of chromium-containing stainless steel slag, this paper explores the synergistic treatment method of secondary aluminum dross and stainless steel slag. Secondary aluminum dross (SAD) contains a certain amount of Al₂O₃, which can replace Al₂O₃ as a modifier for chromium-containing stainless steel slag, and Al in SAD can also reduce Cr₂O₃. The article studied the effect of adding Al₂O₃ and different contents of SAD to chromium-containing stainless steel slag on chromium partition. The results calculated by FactSage thermodynamic software show that with the increase in the content of Al₂O₃ and SAD, the content of spinel precipitation increased, while the proportion of MgCr₂O₄ and FeCr₂O₄ decreased. After adding Al₂O₃ and SAD, the main component of chromium-containing spinel phase is Mg(Cr,Al)₂O₄. The experimental results indicate that the average size of the spinel phase increases with adding Al₂O₃ and SAD. The large-sized spinel phase is beneficial for its separation and recovery from slag. Meanwhile, the metal Al in SAD can undergo a reduction reaction with FeO and Cr₂O₃ in the slag to form Cr-Fe alloy, which can be directly separated and recovered from slag. Therefore, the synergistic treatment of secondary aluminum dross and chromium-containing stainless steel slag can selectively enrich chromium, making it a promising comprehensive utilization method.</p> Graphical Abstract <p></p>