Synergistic use of electrolytic manganese residue and barium slag to prepare belite- sulphoaluminate cement study

• B-CSA cement was produced using electrolytic manganese residue, barium slag, bauxite and limestone as raw materials. • The synergistic mechanism of electrolytic manganese residue and barium slag in the B-CSA preparation was analyzed. • The effect of barium slag on the phase composition, microstructure and mechanical strength of B-CSA cement was investigated Electrolytic manganese residue (EMR) and barium slag (BS) are solid wastes produced during industrial production, which are rarely recycled in large quantities. In this study, we investigate the feasibility of preparing belite-calcium sulphoaluminate (B-CSA) cement by synergistic reaction of EMR, BS, limestone, and bauxite. Thermogravimetry (TG)-differential scanning calorimetry (DSC) is used to study the pyrolysis of raw meals. X-ray diffraction (XRD) and scanning electron microscope (SEM)-energy dispersive spectra (EDS) are used to analyze the phase transformation behavior and microstructure of clinkers. In addition, the relationship between phase composition and mechanical properties of clinker was discussed. The results show that the low melting point compound introduced by EMR can reduce the clinker formation temperature. Belite–ye'elimite–alite (BYA) cement was prepared at 1350 ℃ for 1.5 h. The calcination temperature and preservation time of B-CSA cement are 1300 ℃ and 30 min, respectively. In clinkers BYA and B-CSA, the characteristic peak of ye'elimite shifts to the left as barium replaces calcium sulphoaluminate to form barium calcium sulphoaluminate. The doping of barium ions changed the crystal morphology of ye'elimite and activates the lattice. The results of quantitative phase analysis showed that 18.53% of ye'elimite and 2.47% of alite coexisted in clinker A 1.5h , and the maximum contents of ye'elimite and belite in clinker D were 35% and 42.13%, respectively. When the gypsum content is 5%, the 28d compressive strength of the BYA cement is 30 MPa. However, the compressive strength of B-CSA cement increased with the increase in gypsum content, and the compressive strength of B-CSA-D10 samples at 3, 7, and 28d was 37.9, 47.3, and 60.0 MPa, respectively, which was better than that of OPC425. Therefore, this innovative research method of using EMR and BS to prepare B-CSA cement is feasible, which promotes the recycling of the two kinds of industrial solid waste.