Characterization of Clinker with Regards to Reactivity

In a cement plant, as in any industry, there are regulations of the level of emissions. One way to reduce the emissions is by decreasing the clinker content in the produced cement by addition of remains from other processes that together with lime produce the same products as pure clinker. The produced clinker varies in reactivity and in a more reactive clinker the addition could be increased, reducing the emissions per tonnage of cement. Today the produced cement is analyzed for strength and the results are then evaluated, which is about 1.5 months after the clinker was produced. Clinker samples from the kiln are analyzed every third hour with X-Ray diffraction to see that the composition is correct. If those samples could be used to predict the strength or heat evolution, parameters could be changed directly to keep a stable clinker production. This would give a more stable product and require less energy to produce, thereby producing less emission. In this study, Florida clinker samples have been mixed with 3.96 % gypsum and ground in a 5kg-mill. The ground cement has been analyzed for sulfur, loss of ignition, free lime, compressive strength and setting time. They have also been analyzed with X-Ray fluorescence, calorimetry and X-Ray diffraction. The results have been correlated with each other two by two to see if any connections could be found. The results of the correlation analysis showed 9 good correlations. No correlation was found between any clinker mineral or module to heat evolution, compressive strength or setting time. Multivariate analysis has also been used but more data is needed for it to be able to predict the cement strength. The calorimetric analyses were performed while developing a method. The method seemed robust and small changes had no large significance although the mixing time could rather be too long since shorter mixing time was not enough