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A number of samples from the pre-burnhag zone of a wet-process cement rotary kiln were examined by combined DTA/TG and XRD for estimation of spurrite (2Ca2SiO4. CaCO3). It was found that decarbonation temperatures of spurrite range from 1130 to I 190 K and they are 45 to 75 K higher than that of calcite occurring in the same sample. In the TG curves calcite and spurrite can be easily distinguished and accordingly both can be estimated from the same TG scan. Combined DTA/TG, supplemented by XRD, is a very effective method for qualitative and quantitative estimation of spurrite in cement rotary kiln materials.The mineral spurrite, 2Ca2SiO4.CaCO3 is generally reported to be present in the coating rings formed in the pre-burning zone of the rotary cement kiln. Occasionally its presence has also been reacorded in the cement kiln materials [1][2][3]. As spurrite may cause excessive ring formation and thus affect the clinker output, its estimation is very essential in the cement manufacturing process. Consequently in recent years, the formation of spurrite, either from industrial cement kiln feed or from cement clinker components has been examined extensively [4][5][6][7][8]. In most of these investigations spurrite is identified by XRD and microscopic methods. Thermal analysis has been applied very rarely for the quantitative estimation of spurrite. Hung Chen [3] examined spurrite in cement kiln material s by DTA and TG separately and showed that by determining CaCO3 in the acid extracted part of the material, the quantity of spurrite in the original sample could be determined by TG. In the present study combined DTA/TG has been used for both qualitative and quantitative estimation of spurrite in the samples collected from different points in a wet-process cement kiln. Thermal analysis has been supplemented by XRD. ExperimentalA 165 m long, 700 tons per day (tpd) wet-process rotary cement kiln was stopped during normal operating conditions, allowing the kiln materials to remain in John Wiley & Sons, Limited, Chichester Akaddmiai Kiadr, Budapest

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