Current Status of an Industrial Waste: Red Mud an Overview
Abstract: – Red mud is a solid residue Produced during the alumina production by the bayer process from bauxite. The red mud generated by this process is highly alkaline with pH usually ranging from 10 to 13. Due to its hazardous corrosive nature its posing a very serious and alarming environmental problem. Globally there are approximately 90 million tonnes of red mud being produced every year. More than 4 million tons of red mud is generated annually in India only. The amount of the red mud generated per ton of the alumina processed, varies greatly with the type of the bauxite ore used. Due to its hazardous nature it is a great challange to researcher to develop new methods for the application of red mud. Various research work going on for the storage, disposal and utilization of the red mud in all over the world. This paper reviews the current status and future trend of the red mud characterization, disposal, various neutralization methods and utilization in world as well as in Indian context.
Key words: – Bauxite, alumina, Red mud, characterization, neutralization and utilization.
Aluminium is the third most abundant element in the earth‘s crust which constitutes about 7.3% by mass. The first commercial production process of aluminium was started from the year 1854 . Since then it has become the world‘s second most used metal after steel. The aluminium metal has play very important role in the social progress because its contribution to the society is too high. Now-a day the demand for aluminium products is increasing year by year because it has various benefits which make it unique from all. It can provide strength of steel when forming alloys, durability, flexibility, impermeability, lightweight, corrosion-resistant, recyclable and many other benefits. Metallic aluminium is not found in nature, it occurs in the form of hydrated oxides or silicates (clays) with combination of various mixture of silica, iron oxide titania, aluminium silicates and other impurities in minor or trace amounts. Primary aluminium is hot molten metal (as opposed to secondary, or recycled, aluminium) in the smelter. Secondary aluminium is a used aluminium part or used finished goods into a new usable form. The primary aluminium production occurs from bauxite through two steps. In the first step alumina is produced by wet chemical, caustic leach method (Bayer process). In the second step aluminium is produced from alumina by Hall-Heroult process. The alumina production is a chemical enrichment process where alumina is separated from the undesirable components like oxides of iron, titanium, silicon, calcium, vanadium, manganese etc from bauxite ore. In the bayer production of alumina red bauxite sludge or residue is produced as a by-product called red mud.