Cement, Energy and Environment

Requirements as Insoluble Residue S.No. Particulars UOM per IS 12089:1987 FRESH SLAG DUMP SLAG Moisture 10-12% 18-22% 1 Manganese Oxide (MnO) % by Mass 5.5 Max 0.19 0.48 2 Magnesia (MgO) % by Mass 17.0 Max 8.26 8.92 3 Sulphide Sulphur (S) % by Mass 2.0 Max 0.37 0.3 4 Sulphate (as SO3) % by Mass 3.0 Max 0.36 0.67 5 % by Mass 1.07 3.28 6 Chloride Content (Cl) % by Mass -- 0.01 0.008 8 (Cao+Mgo+1/3 Al2o3)/Sio2+2/3Al2o3 % by Mass 1.0 Min 1.12 1.03 9 Cao+Mgo+Al2o3/Sio2 % by Mass 1.0 Min 1.76 1.74 10 Glass Content % by Mass 85.0 Min 97 89.2 1 Fineness CHEMICAL REQUIREMENTS PHYSICAL REQUIREMENTS as per GGBS ( IS 16714:2018) Slag activity index m 2 /Kg 320 Min 376 370 2 Normal Consistency % - 30.5 30.5 b. 7 Days (168 + 2 hr) MPa 12 Min 28.2 26.8 c. 28 Days (672 + 4 hr) MPa 32.5 Min 48.1 46.8 Another key challenge identified was the inconsistency in coal flow rate, which resulted in operational instability. Upon investigation, the coal screw feeder and its associated equipment were found to be improperly calibrated, leading to large variations in coal feed rates. These fluctuations not only affected burner performance but also led to uneven fuel combustion, further compounding the heat consumption problem. The team first emptied the coal screw and simplex bin, followed by a complete recalibration of the screw under both no-load and load conditions. The error margins in the load cells were corrected, and the control system was switched from gravimetric to volumetric mode. This change proved effective as the volumetric mode provided a consistent feed rate, significantly reducing flow variability and enhancing material handling uniformity. This adjustment stabilized the fuel supply, directly contributing to improved combustion efficiency and reduced heat consumption. Coal Flow Rate Variation Control Actions Reference - Figure 2.1 & 2.2 Table:1 Figure 2.1 Glass Content of Dump Slag is 89.2 which is less compared to 97 as that of Fresh Slag. Moisture is coming high 18-22 % as compared to Fresh Slag 10-12% Insoluble Residue % is High 3.28 as compared to Fresh 1.07 % Slag Activity Index at 7 days for Dump slag is 26.8 as compared to 28.2 in Fresh Slag. Slag Activity Index at 28 days for Dump slag is 46.8 as compared to 48.1 in Fresh Slag. 17