Effect of Pyrite Tailings Mineralizer on Calcination and Properties of Cement Clinker

The cement industry is a high energy consuming industry, and the use of mineralizers in the calcination process of cement clinker is an effective energy-saving method. Using solid waste as a mineralizer can also turn waste into treasure and achieve its resource utilization. With pyrite tailings as mineralizer, this study prepared Portland cement clinker with 0, 1.5%, 2.0% and 2.5% SO₃ at calcination temperature of 1350 ℃ , 1400 ℃ and 1450 ℃. Thermal analysis, X-ray diffraction (XRD), polarizing microscope, and other methods were used to analyze the effects of SO₃ addition on the calcination process, mineral composition, petrographic structure, and physical properties of the clinker. The results show that the best effect is achieved when the content of SO₃ is 2.0%. Under this proportion, the content of f-CaO in cement clinker decreases from 1.84% to 1.18%, which can significantly improve the burnability of raw meal. The addition of pyrite tailings can reduce the initial and peak temperatures of CaCO₃ decomposition in raw meal, and form two transition phases of calcium sulphosilicate (2C₂S·CaSO₄) and calcium sulphoaluminate (4CaO·3Al₂O₃·SO₃) at low temperature. This reduces the temperature of liquid phase by 35 ℃, promoting the formation and development of clinker minerals, and has a significant mineralization effect. The cement clinker obtained by calcination with pyrite tailings has good performance, and its compressive strength after curing for 3 days and 28 days is 33.1 and 61.8 MPa, respectively.