Sintering characteristics of red mud compact

Abstract

It is beyond doubt that activity of primary industries often yields substantial amounts of byproducts. The disposal in the original industrial site is favoured by economic reasons though traditional storage in nearby dumps can be impractical owing to the considerable masses involved and environmental restrictions. The local exploitation of these by-products is therefore a growing technological aspect of basic industries and one tenable option is their re-use as starting materials for other productions.This huge amount of industrial yproducts/wastes which is becoming a client for increasing environmental pollution & generation of a huge amount of unutilized resources. With a view to the above, this research is aimed at finding out utilization of such things/material/industrial byproducts for value added applications & also helps to solve the environmental problems. The present piece of my research work aims at, to provide a valued input/utilization to industrial byproduct/waste. An emblematic case is the ‘red mud’ discharged by industry producing alumina from bauxite: alkaline digestion of 2.5 t of bauxite affords alumina and ≈1.5 t of red mud ,so that an average Al2O3 productivity of 5×105 t year−1 involves a mass of by-products of ≈7.5×105 t year−1 discharged as slurry retaining variable water contents. This amount is composed of Fe and Ti oxides, behaving as chemically inert matter, with variable percentages of nominal SiO2,Al2O3 and Na2O. The material is available as a watery mixture which settles slowly and may easily be conveyed from station to station by continuous fluid-carrying machinery.The recycling of the mud, after curing or high temperature annealing — up to 1200°C — for large-rate daily mass consumption industries such as bricks and tile kilns has been put forward in a number of papers[2,3,4,5,6,7,8,9]Most of the above reports appear fragmentary and, to some extent surprising, characterization work is limited to the elemental analysis of the raw material and the identification of the crystalline phases in dried samples. However, the definition of thermal behaviour in a wide working range of temperatures appears mandatory for a feasible exploitation of the mud in high temperature applications. Indeed, the reactivity of red mud components on heating may promote ceramization and shrinkage and, apart from other qualities, may affect the mechanical features of clay-based items fabricated with bauxite-waste addition.Accordingly, we focus here on the thermal behaviour of the mud, the solid-state transformations and solid–liquid phase transitions. The use of thermal analysis coupled with of X-ray diffraction methods seemed well suitable for the problem at hand. The present study is a part of a long-term project on the exploitation of red mud as a clay additive for the ceramic industry or as a compound for self-binding mortars in the fabrication of stoneware.