Leaching behavior and stabilization/solidification characterization of heavy metals from silicomanganese slag

The utilization of silicomanganese slag (SMS) for the partial substitution of cement holds significant importance in handling environmental risks and achieving the harmless and resourceful utilization of industrial solid wastes. Nevertheless, an in-depth analysis of the leaching behaviors of heavy metals and the solidification/stabilization mechanisms in SMS and cementitious materials is still lacking. In this study, we adopted the toxicity characteristic leaching procedure and horizontal vibration method to simulate the natural leaching environment, thereby exploring the leaching risks related to heavy metals in the aforementioned materials. The results indicated that the release and migration of heavy metals were highly reliant on environmental pH values. Among them, Mn predominantly existed in SMS in the form of acid extractable fraction, and its dissolution was mainly governed by rhodochrosite and hausmannite. Fortunately, cementitious materials fabricated from SMS can conspicuously prevent the leaching of heavy metals such as Mn, Cr, Ni and As. The mechanism analysis disclosed that heavy metals can be effectively immobilized by silicon-aluminum structures through physical encapsulation,