Abstract:Electrolytic manganese residue (EMR) is a kind of solid waste produced in the wet smelting process of manganese metal. The accumulation of EMR is large and causes serious pollution to the environment. However, EMR is rich in sulfate, and according to its characteristics, it can be combined with mineral powder (GGBFS) to prepare cementitious materials. With EMR as the main raw material, electrolytic manganese slag as sulfate exciter of mineral powder and hydrated lime as alkali exciter, electrolytic manganese slag - mineral powder composite cementitious material was prepared. The optimal ratio of EMR, GGBFS and hydrated lime was explored, and on this basis, the EMR was calcined and modified at different temperatures, and the optimal calcination temperature was determined by mechanical test. The hydration products and hydration mechanism of the cementitious materials were characterized and analyzed by XRD, FT-IR, TG-DTG and SEM, and the toxicity of the hardened body was tested. The results show that EMR has a good excitation effect on mineral powder, the optimum mass ratio of EMR, GGBFS and hydrated lime in the composite cementitious material is 2︰7︰1, its compressive strength of 28 d is 27.2 MPa, and the compressive strength of the composite cementitious material prepared by EMR calcined at 350 ℃ reaches 30.5 MPa. The hydration products of the composite cementitious material are mainly calcium alumina (AFt) and hydrated calcium silicate (C-S-H). The concentrations of heavy metals in leachate of the hardened body for 28 d are within the standard limits of “Standards for Drinking Water Quality：GB 5749—2022”, and the composite cementitious material has a good safety.