Effects Of Liquid Phase At High Temperature On The Formation Kinetics Of Portland Cement Clinker

The calcining of cement clinker is a multiple phase and non-equilibrium reaction system.Reducing the reaction resistance is always one of the important clinker researchs throughstudying the rate of reaction and mechanism. The formation reaction rate and quality ofclinker correlate closely to the produce temperature, the quantity and the property of the liquid.It’s significant for promoting the clinker’s calcinations and improving the clinker’s productionto study the influencing rules and factors of liquid phase at high temperature on the formationof clinker. But there is no direct method for measuring the liquid phase of clinker system inthe actual clinker burning process under the current condition. The effects of liquid at hightemperature on formation kinetics of clinker were discussed by pre-burning the liquid phase. Theliquid components, pre-burned in molten, was made up raw material with other components,and then calcined into clinker. The formation reaction rate G was calculated with the free limecontent and loss on ignition of clinker. Then the reaction-rate constant K was counted according tothe Gentling equation, and the apparent activation energy Ea was figured up on the basis of theArrhenius formula. The resulting samples’ phase compositions, morphology and meltingtemperatures were characterized by means of XRD, SEM and image-based sintering point tester.The research contents and final results are illustrated below.1. Effects of liquid phase quantity on clinker formation are studiedThe results show, by consolidate the theoretical value and changing the actual value ofliquid content in process, as follow: the clinker’s Ea value, calcined in conventional method,is343.609kJ/mol, and the liquid phase produced totally, is226.365kJ/mol, the meltingtemperature of the former is much higher than the latter about80°C. The result shows that thetheoretical value of clinker’s liquid content is much higher than the actual value in process ofclinker calcinations; with the ratios of the liquid content pre-burned in liquid amount totalincrease, the K values increase and the Ea values decrease.Results, with changing the theoretical value of liquid content: X, of liquid amount total,accounts for about38%,46%and51%at1400°C,1425°C and1450°C respectively; withthe liquid phase increase from20%to100%, the G values grow, and the K values increase firstly and then decrease in a local extreme value of70%at1400°C and1425°C, but in alocal extreme value of60%at1450°C, and the Ea values first decrease then increase in alocal extreme value of80%.2. The sintering point testing results show that the fluid temperature (Tf) of liquid phase isabove1330°C, the Tfof liquid phase with MgO0.8wt.%is about1325°C, and the Tfofliquid phase with MgO1.0wt.%is about1320°C.3. Effects of liquid phase with MgO on clinker formation are discussed by pre-burning theliquid in moltenThe effects of quality of liquid phase with MgO on the clinker formation are researched.With the MgO content in liquid increase from0wt.%to1.2wt.%, the G and K values ofclinkers, liquid produced all, first increase and then decrease, and the Ea values’ trend isreverse in local extreme value of MgO1.0wt.%; the G values of clinkers, liquid producedpartly (60%~75%), increase gradually, and the trend of K and Ea remain intact.The effects of quantity of liquid with MgO on the clinker formation are studyed. Withthe liquid quantity increase from60%to100%, the effects of the amount of liquid on clinkerformationcare associated with the liquid quality: the G and K values of the clinkers, withMgO0.8wt.%and1.0wt.%in liquid, increase gradually, and Ea values decrease; the G andK values of clinkers, with MgO1.2wt.%in liquid, first increase and then decrease, and theEa values first decrease and then increase in local extreme value of75%.4. Impacts of liquid phase with SiO2on clinker formation are considered with the liquidpre-burning in moltenEffects of liquid quality with SiO2on the clinker formation are considered. With the SiO2content in liquid increase from0wt.%to8wt.%, the G and K values of clinkers, liquidproduced totally, increase firstly and then decrease, and the Ea values’ first decrease and thenincrease, in a local place of SiO26wt.%; the G values of clinkers, liquid produced partly(60%~75%), increase and the tendency of K and Ea are invariable.Effects of liquid quantity with SiO2on the clinker formation are discussed. With theliquid quantity increase from0%to100%, the G and K values of the clinkers, with SiO24wt.%and6wt.%in liquid, increase gradually, and Ea values decrease; the G and K values ofclinkers, with SiO28wt.%in liquid, increase firstly and then decrease, and the Ea values’ trend is opposite in local extreme value of75%.5. Effects of MgO and CaF2on clinker formation are researched as a preliminaryexploratory experiment. With the MgO content increase from0.0wt.%to2.5wt.%, the Kvalues increase firstly and then decreased, and the Ea values’ tendency is counter in localextreme value of2.0wt.%. With the CaF2content increase from0.0wt.%to2.5wt.%, thetrends of K values and Ea values are consistent with the effect of MgO.