Potentials of Utilizing Spent Pot Refractory Lining Waste from Alumina Smelter in Cement Manufacture

摘要

About 16,000 metric tones of Spent pot refractory lining (SPRL) waste are generated annually from aluminum plants in India and are lying unutilized thereby occupying valuable land. The delined refractory waste generally contains 10-12% alkali and 8-10% fluoride and can find application as mineralizer in the manufacture of Ordinary Portland Cement. Investigation was carried out with a typical SPRL sample collected from a plant of National Aluminium Company Limited (NALCO) which was found to contain 11.78% Na2O, 0.68 %K2O and 9.45 %fluoride respectively. An optimized dose of about 1.5% SPRL in the raw mixes designed using conventional raw materials indicated well burnt laboratory clinker produced at 30 – 40OC lower burning temperature as compared to a control mix without SPRL. Different mixes were designed with low alkali raw materials and using varying dosages of SPRL. The burnability investigations of a raw mix showed free lime content of 0.56 percent containing 1.5 % SPRL when burnt at 1400oC for 20 minutes whereas in the control mix, the free lime could be reduced to the same level only at 1450oC. The clinker made using SPRL also showed well formed mineral phases at 1400oC. The resultant cement yielded compressive strength of 33.4, 48.3 and 58.0 MPa at 3, 7 and 28 days. The performance characteristic showed conformity to IS: 12269-1987 for 53 grade of Ordinary Portland Cement. The use of SPRL in cement manufacture as mineralizer showed potential for reducing the energy consumption, improving the clinker morphology and resultant cement performance besides giving value addition to SPRL.