Preparation of Ordinary Portland Cement Clinker from Vanadium-titanium Magnetite Tailing

To efficiently utilize the vanadium–titanium magnetite tailing in Chengde area,ordinary portland cement clinker was prepared by high temperature calcination using the tailing,limestone and quartz sand as raw materials.The evolution of phase compositions and microstructure of the cement clinker during calcination and curing was discussed,and the comprehensive physical properties of the cement were analyzed.The clinker having a better properties than 42.5 R ordinary portland cement can be prepared by calcination at 1 400 ℃ for 30 min with the ratio of vanadium-titanium magnetite tailing∶limestone∶quartz=20∶75∶5.The clinker obtained is mainly composed of C₃S,C₂S,C₃A,C₄AF and glass phases.The formations of C₃S and C₃A phases are promoted by increasing the calcination temperature and prolonging the calcination time.After hydration,needle and bar like ettringite,plate like calcium hydroxide and amorphous C-S-H are formed in the clinker.With extension of the hydration time,the content of C-S-H increases,improving the compactness and strength of the sample.An ordinary portland cement with better performances than 42.5 R grade in GB 175-2007 standard can be obtained by compounding the clinker prepared with 5% gypsum.