Experiment on calcination⁃sintering characteristics of clinker

The cement industry is a traditional industry with high coal consumption and high emission. Under the back⁃ ground of “carbon peaking and carbon neutrality”，the cement company is facing severe pressure on energy conserva⁃ tion and emission reduction. The norm of energy consumption per unit of cement published in 2021 has made clear re⁃ quirements for clinker coal consumption. Reducing the coal consumption per unit mass of clinker and improving the ef⁃ ficiency of the clinker production process have become the keys to meeting the requirements. The cement industry is in urgent need of innovative clean and low⁃carbon coal combustion technology. The heat transfer efficiency of the rota⁃ ry kiln of the existing new dry process cement production line is low and the reactions concentrate in the rotary kiln， resulting in high coal consumption for cement clinker manufacturing. In order to further reduce the coal consumption and emission of clinker production，based on the characteristics of main components and main intermediate reactions of cement clinker，the idea of “step⁃by⁃step reaction and staged sintering” in cement clinker firing was proposed， and mineral formation and emission reduction of the new process of fluidized calcination⁃sintering of cement clinker was studied. In the new process，the solid⁃phase reaction (including the decomposition of raw meal and the formation of dicalcium silicate) was carried out during the calcination process，and the liquid⁃phase reaction (mainly the forma⁃ tion of tricalcium silicate) was carried out during the calcination process. By studying the effect of calcination⁃sintering on mineral formation， using Rietveld full spectrum fitting to calculate mineral content and observing mineral morphology with scanning electron microscope in this research，the optimal calcination time and suitable sintering con⁃ ditions of calcination⁃sintering were obtained，and it was confirmed that the pre⁃synthesized dicalcium silicate contribu⁃ ted to the tricalcium silicate formation during the calcination⁃sintering process. And the suitable liquid phase range for calcination⁃sintering is 20%-30%.Through calculating and comparing the annual CO2 emission of the 1 000 t/d staged calcining device and the rotary kiln of the same scale，it is concluded that the annual CO2 emission of the 1 000 t / d staged calcining device was reduced by 23 152 t.