Effect of Fe₂O₃ on the formation of calcium sulphoaluminate mineral

Testing methods such as chemical analysis, X-ray diffraction and differential scanning calorimetry were used to study the influence of Fe₂O₃ on the formation of anhydrous calcium sulphoaluminate (C₄A₃S). The results show that adulterating Fe₂O₃ can increase the quantity of liquid phase, boost the f-CaO absorption and also can improve the burnability of raw materials of C₄A₃S̄ mineral. C₄A₃S̄ mineral does not form at below 850°C, and large quantities of C₄A₃S̄ are formed at nearly 1000°C. The maximum quantity of C₄A₃S̄ occurred at 1300°C. The quantity of C₄A₃S̄ in specimens doped with 1% Fe₂O₃ reaches the maximum at 1300°C too, the absolute quantity decreases in a degree. The quantity of C₄A₃S̄ in specimens doped with 3% and 5% Fe₂O₃ reaches the maximum at 1350°C, there was a half-hour time delay compared with the specimens without Fe₂O₃ and the absolute quantity has a great drop. The Fe³⁺ in the specimen doped with Fe₂O₃ is replaced with Al³⁺ at 1200°C to 1400°C, which causes Fe³⁺ to melt into C₄A₃S̄ to form C₄(A_0.95F_0.05)₆ O₁₂(SO₄).