Cement Energy and Environment

.. gibbsite [AI(OH)3] as major mineral phase. The purity of gypsum was found to be 70.46% with gypsum [Ca(S04)(H20)2] as major mineral constituent. The proximate analysis of coal indicated 3.87% moisture content, 7.85% ash content, 41 .80% volatile matter and 46.49% fixed carbon. In the ultimate analysis of coal , 61.65% carbon, 3.38% hydrogen, 1.08% nitrogen and 0.49% sulphur were determined. Calorific value was found to be 6038 KCai/Kg. 3.2 Preparation of cement raw mixes Different cement raw mixes RM-1 to RM-6 were designed using different doses of jarosite (0 .25-2.0%) and other raw materials, generally used in cement manufacture (Table 2). A control mix, RM-C was also taken up for reference study. The ash absorption level was calculated on clinker basis, considering the specific heat of clinker and calorific value of coal and was kept at the level of 1.0% in all designed mixes. The computed values of Fe20 3, S03, ZnO and Na20 in all mixes were in the range of 3.02-3.22, 0.08-0.65, 0.006-0.06 and 0.28-0.32% respectively as compared to control mix RM-C where these values were 3.01, 0.002, nil and 0.28% showing increase in Fe20 3,S03,ZnO and Na20 contents with addition of jarosite (Table 3). Moduli value LSF, SM and AM in clinker samples CL-1 to CL-6 corresponding to raw mixes RM-1 to RM-6 were maintained at 0.90-0.91 , 2.27- 2.40, 0.96-1.0 respectively (Table 4). The potential phases C3S, C2S, C3A, C4AF and liquid content as estimated by Bogue's method were 54.67-57.49, 20.10-21 .96, 4.20-4.48, 14.17-15.06 and 27.25- 28.32% respectively. Laboratory samples of control mix RM-C and mixes RM-1 to RM-6 were prepared by thoroughly blended and ground all the components to achieve retention on 212 and 90- ~m in the range of 1.18-1 .23 and 10.10-11 .30% respectively. The finer nature of raw mixes were maintained to improve their burnability and reduce free lime in clinker to offset the hard burning nature of raw mix due to coarse grained quartz and calcite. Table 2: Designed raw mixes and their fineness values Raw Raw materials proportioning (wt. %) Coal Percentage retention mixes Jarosite Limestone Iron ore Bauxite ash (%) R212 Rso RM-C 0.00 94.70 1.30 4.00 1.0 1.21 11.30 RM-1 0.25 94.50 1.25 4.00 1.0 1.23 11.10 RM-2 0.50 94.30 1.10 4.10 1.0 1.19 10.10 RM-3 1.00 94.05 0.75 4.20 1.0 1.22 11.30 RM-4 1.25 93.90 0.60 4.25 1.0 1.20 10.40 RM-5 1.50 93.70 0.40 4.40 1.0 1.18 10.20 RM-6 2.00 93.00 0.40 4.60 1.0 1.22 11.20 Table 3: Chemical composition of designed raw mixes and clinker samples RM-C 34.21 43.12 14.56 2.95 3.01 1.51 0.002 0.28 0.16 nil RM-C CL-C 0.05 65.00 22.30 4.61 4.63 2.31 0.09 0.43 0.25 nil RM-1 34.22 43.04 14.54 2.94 3.05 1.50 0.08 0.28 0.16 0.006 RM-1 CL-1 0.05 64.90 22.26 4.60 4.69 2.30 0.22 0.44 0.25 0.009 RM-2 RM-2 34.24 42.97 14.51 2.95 3.06 1.50 0.16 0.29 0.16 0.014 CL-2 0.05 64.81 22.23 4.62 4.71 2.30 0.33 0.48 0.25 0.02 RM-3 RM-3 34.31 42.89 14.46 2.95 3.03 1.50 0.32 0.30 0.16 0.03 CL-3 0.05 64.76 22.17 4.62 4.66 2.30 0.58 0.46 0.25 0.05 RM-4 34.35 42.84 14.43 2.95 3.02 1.50 0.40 0.30 0.16 0.03 RM-4 CL-4 0.05 64.71 22.14 4.62 4.66 2.30 0.70 0.47 0.25 0.05 RM-5 RM-5 34.38 42.76 14.40 2.98 3.02 1.50 0.49 0.31 0.16 0.04 CL-5 0.05 64.63 22.11 4.66 4.66 2.30 0.82 0.48 0.25 0.06 RM-6 RM-6 34.33 42.48 14.37 3.03 3.22 1.49 0.65 0.32 0.16 0.06 CL-6 0.04 64.16 22.05 4.74 4.95 2.28 1.06 0.49 0.25 0.09 13