Abstract: C₃S mineral is the main ingredient of clinker and the main provider of cement clinker strength. The strength of clinker is not only affected by the content of C₃S, but also directly related to the C₃S crystal form. In order to study the effects of cooling methods on the mineral composition and crystal structure of the clinker, the industrial raw materials from different manufacturers were calcined at 1 450 ℃ for 30 min, then quenched by liquid nitrogen immediately, cooled by air quickly and cooled slowly with furnace. The mineral composition, content, crystal form, morphology and solid solution of clinker were analyzed by TG-DSC, XRD, Rietveld method and petrography analysis. The experimental results show that the cooling rate increases, the C₃S content in the clinker increases, and the β-C₂S, C₃A and C₄AF content decreases. The cooling rate in the raw material with a larger aluminum ratio has a more significant impact on the C₃S and C₃A content. The crystal form of C₃S is different under different cooling methods. The C₃S is mostly M1 or M3 type under liquid nitrogen cooling and air cooling, and the C₃S is mostly T-type under furnace cooling. The slow cooling rate makes the crystal form of C₃S change from M-type to T-type.

Key words: cooling method, cement clinker, liquid nitrogen quenching, C₃S crystal form, Rietveld method