Cement Energy and Environment

• - 3.5 Microstructure of clinker samples by Optical Microscope Microstructure of clinker sample CL-5 showed moderately developed and in-homogeneously distributed clinker phases. Majority of alite grains were pseudo-hexagonal to hexagonal in shape with sharp grain margins and numerous inclusions whereas most of belite grains were rounded to sub rounded in shape with fused grains and numerous inclusions. Both alite and belite grains were found to be developed in clusters. Microstructure of clinker CL-5 showed fine grained alite and belite phases as compared to control clinker CL-C (Fig 3) revealing improved reactivity of clinker phases in presence of jarosite. The granulometry of alite and belite grains in clinkers CL-C and CL-5 is given in Table 5. The average size of alite and belite grains in the mineralized clinker CL-5 were detected to be 32 and 26 1-1m respectively as compared to control clinker where the average size of alite and belite grains were 26 and 23 1-1m respectively indicating the finer nature of alite and belite grains in presence of jarosite. Table 5: Granulometery of clinker samples Phases CL-C CL-5 detected Granulometery (IJm) Granulometery (IJm) Minimum Maximum Average Minimum Maximum Average Alite Belite 2 2 (a) 64 56 32 26 2 2 (b) 58 52 26 23 Fig 3: Distribution of a/ite and belite grains in (a) control clinker (CL-C) (magnification, 20x) and (b) mineralized clinker (CL-5) (magnification Sx) 3.6 Optimization of dose of jarosite and evaluation of bulk clinkers Burnability of raw mixes RM-1 to RM-6 showed mineralizing effect of jarosite in terms of improved lime assimilation, phase formations and micro-structural developments. Keeping in view of maximum utilization of jarosite and compositional parameters, mineralized clinker CL-5 doped with 1.5% jarosite and fired at the temperature of 1450°C was taken up for the preparation of bulk clinker along with control clinker CL-C fired at similar temperature. The above clinkers were analyzed for their oxide constituents and clinker phase formations. Chemical analysis of bulk mineralized clinker CL-5 showed the presence of usual oxide constituents comparable to OPC. The chemical analysis of control clinker CL-C and mineralized clinker CL-5 is given in Table 6. Heavy elements in clinker sample CL-5 were found to be 40 ppm chromium, 40 ppm copper, 320 ppm manganese and 300 ppm strontium. Zinc and lead were found to be below detectable limits of 0.0002 and 0.015 ppm respectively. Semi-quantitative estimation of clinker mineral phases developed in clinker sample CL-5 by XRD indicated 49% alite, 28% belite, 4% C3A and 14% C4AF as compared to control clinker CL-C where these values were 47% alite, 31% belite, 4% C3A and 13% C4AF. 15