| Reusing sludge as raw cement material become more and more important, for it can not only partly take the place of raw materials, but decompose of toxicant. Through free chemical analysis, macroscopical test, XRD analysis, SEM/EDS analysis, the effect of the sludge on clinker sintering and properties of the clinker were studied, and the mechanisms were discussed also.1. Reuse of water purification sludge as silica material, with modulus (KH=0.91, IM=1.30, SM=2.37), the effect of the sludge on clinker sintering and properties of the clinker were studied. Sludge added into the cement raw meals would improve the burnability of the raw meal and the strength of the clinker, especially the early strength. The strength at 3days reached 43MPa and the strength at 28 days of the clinker was higher than 70 MPa.2. Reuse of waste water sludge as silica material, with modulus (IM=1.30, SM=2.37, but different KH), the effect of the sludge on clinker sintering and properties of the clinker were studied. Few waste water sludge addition (2wt.%) almost have no effect on clinker sintering and strength when the KH is low (0.88,0.91) ; but significant improve the burnability of the cement raw meal and the strength of the clinker while the KH is high(0.94,0.97).3. Reuse of waste water sludge as silica material, with modulus (IM=1.30, SM=2.37, KH=0.91, 0.94), the effect of the sludge on clinker sintering and properties of the clinker were studied. Few waste water sludge addition (1wt.%) improve the burnability of the raw material and the strength of the clinker, while more addition would decrease the burnability of the raw material and the strength of the clinker.4. XRD analysis show that the addition have no effect on the phases component of the clinker, the phase component of the clinker are C3S, C2S, C3A and C4AF. SEM/EDS show that the water purification would increase the homogeneity of the Alite and Belite phase, while the waste water sludge would decrease the homogeneity of the Alite and Belite phase.5. Setting time test, alkali content test, chloride ion content test and toxicitycharacteristic leaching procedure show that clinker using sludge as partly replacementof silica material would be safe enough to environment.The microelement in sludge low the liquid phase temperature, therefore it is good forsintering. The microelement trapped into the clinker's crystal structure would alsoraise the hydration activity of the clinker. Hence, reusing sludge in cement productionhas become more and more important. |
