MANUFACTURING SUPPLEMENTARY CEMENTITIOUS MATERIAL FROM INDUSTRIAL WASTE

摘要

A process is described which was developed for manufacturing supplementary cementitious material (MSCM)rnfrom waste by-products, based on submerged combustion melting technology. The results of the laboratory phasernof the project were reported at the 1996 IT3 Conference.rnThe proposed process can utilize cement kiln dust (CKD), coal residues, and other by-products or low-valuernmaterials. The product is a manufactured supplementary cementitious material (MSCM), which is used as an activernmineral ingredient in blended cements and ready-mixed concretes. In submerged combustion melting the fuel andrnoxidant are fired directly into the volume of material being melted. Combustion under the surface of molten materialrnsignificantly improves heat- and mass exchange in the bed of material. The intense mixing increases the speedrnof melting, rate of chemical reactions, and improves the homogeneity of the melt. Gas phase emissions of NO_x andrnCO are reduced compared to conventional combustion.rnThe pilot studies confirmed the choice of the field of compositions and temperature levels, produced sufficientrnamounts of the product for testing its performance in mortars and concretes, and allowed estimates to be made ofrngases and trace metal emissions. Testing of the pilot melter demonstrated that it was possible to produce a meltrnfrom CKD-based mixes at temperatures of 1200 to 1300℃ that could be quenched to a vitreous solid. It was furtherrndemonstrated that the resulting material in blends with portland cement contributed measurably to the cementrnstrength and resistance to deleterious alkali-aggregate reactions in concrete. This proves that the use of this materialrnin blended cements can reduce the amount of portland cement clinker required for cement production.