CEE April-June 2012

The study shows Spent Potliner (SPL) waste is an excellent material as mineraliser as it contains high alkalis & fluorine. Its carbon content will also contribute to the heat value. On the negative side it requires very careful handling because of its Fluorine and Cyanide contents, though the concentration of the latter is well below <0.3%. Earlier studies [3,4] have shown that SPL could also be used as Alternative Fuel & Raw material (AFR) in Cement manufacture. 4.3: Jarosite: The particle size distribution & chemical analysis of the Jarosite sample are given in Fig Table. l'llidt'iit lilrid.• 100 llO I; 17 ro 40 20 v I/ furnace slag alleviate at least partially the negative effects of Zn & Pb. Experimental work on synthesis of novel low temperature cementitious binders have also yielded encouraging results and are being investigated further. 5. Conclusion Sustainability and optimal resource utilization are becoming increasingly important issues within today's cement industry. There is a distinct change in the attitude towards industrial wastes, which are now increasingly used as productive substitutes for conventional raw materials thereby saving natural resources. The work described here highlights the successful utilization of industrial wastes/by products from Copper, Aluminium & Steel industries. Potential uses of by products from Zinc industry are also being investigated. Large variability of these by products in terms of their chemistry, burnabilily and availability has made adaptation of these materials a challenge to the cement industry. It must be remembered that cement plants do not themselves produce wastes, but they use wastes from other branches of industry helping Ro1 0.1 10 100 HXXl 300l to clean-up the environment. Therefore, these wastes Jarosite Particle size Distribution 010-0.9J.1,050-5.4J.1, 0 90- 37J.l, Specific Surtace-8460M2/gm Jarosite Chemical Analysis Oxides % % Loss Free Basis ---~-~- -- - - --- -- LOI 32.0 Si02 6.2 9.1 Al203 1.0 1.5 Fe203 29.0 42.6 CaO 1.5 2.2 S03 26.4 38.8 ZnO 3.0 4.4 Others 0.9 1.3 The analysis shows that it is a very fine powder with mean particle size of around 5 micron and having high specific surface area of over 8000 M 2 /Kg, suggesting good reactivity. Recent experimental studies on the utilization of Jarosite as well as ISF Zinc slag in cement & concrete have brought out their potential use as a component of building material [5, 6] . However, their use in concrete results in delayed setting time, due to the rapid formation of insoluble Calcium hydroxy– Zincate, which is favored at high pH environment of the cement system. This depletes the availability of Ca+ 2 ions for the formation of C-S-H & Ca(OH)2 phases that are responsible for early hardening of cement paste. Further, Calcium Zincate coats the cement grains inhibiting hydration reactions. An attempt was made to utilize Jarosite waste as a substitute for gypsum in cement. Preliminary results suggest that use of certain accelerators in combination with fly ash & ground granulated blast should be made available to cement industry at zero cost and in certain cases at negative cost. Further, the national policy on hazardous waste management should also be formulated in such a way that the industry is encouraged to go in for increased use of industrial wastes. 6. Acknowledgement: The author thanks the Management of The India Cements Ltd for their support, encouragement and permission to publish this paper. 7. References: [1] Nikhil Supekar:, Utilisatoin of Copper Slag for Cement Manufacture, Global Slag May 2007, pp-19- 26. [2] Sahu R.M, Sadangi A, Kuchya M, Pandey S.P. , Use of Copper Slag, International Cement Review. , July 2011 ' pp-58-61 . [3] A K Singh, Alka Mishra, Ashok Khuntwal and Siharan Kumar., Utilization of Spent Potliner (SPL) as raw mix component in Cement Manufacturing. Proceedings of the 11 11 ' International Seminar on Cement & Concrete,NCBM, Nov 2009 New Delhi [4] B. !.Silveira, A. E. Dantas, J.E. Blasquez, R.K.P. Santos., Characterization of inorganic fraction of spent pot liners: evaluation of cyanides and fluorides content. Journal of Hazardous Materials, 889 (2002) 177- 183. (5] P. Asokana, M. Saxena , S.R. Asolekar., Recycling hazardous jarosite waste using coal combustion residues" Materials Characterization, (61 ),201 O,pp- 1342-1355. [6] Caroline Weeks Russell J. Hand John H. Sharp., Retardation of cement hydration caused by heavy metals present in ISF slag us. 9