A Novel Clinkerization Process for Fly-Ash Utilization
S.A. Khadilkar, M.V. Karandikar, D.Ghosh and
Appears on pages(s):
alkalies; clinker; fly ash.
In India approximately 45 million tonnes per annum of fly ash is generated from the thermal power plants. Disposal of these fly ashes is a major issue endangering the environment. It is a challenge to the Research Scientists to innovate technologies for bulk usage. As a part of a comprehensive programme on utilisation of fly ashes, several approaches are being pursued at The Research and Development Division of The Associated Cement Companies Ltd. Thane, India, both In traditional and non traditional technological areas. Among the newer technologies being developed, one approach which merits attention is the synthesis of reactive belite cement and cementitious composites through hydrothermal processing, as developed by the Material Research Laboratory, Pennstate University USA. The Indian fly ashes were found to be not responsive to such hydrothermal activation. Keeping in view the chemistry of Indian fly ashes a novel process route has been developed in the author’s laboratory. This process involves activation of fly ash with alkali under non-hydrothermal conditions. The activated fly ash is reacted with hydrated lime in pre-determined proportions to produce the Calcium silicate /aluminate hydrates gels (hydrogel), which is de-watered, dried and sintered at 11 50-1350°C to produce the cement clinker. The sintering temperature depends on the type of cement intended to be produced. The above hydrogel process makes it possible to use about 30 % fly ash in the manufacture of cement clinkers. The present paper highlights the activation technique and the process of hydrogel clinkering route. The chemico-mineralogical, microstructural characteristics of the clinkers produced through this process is also illustrated.