Rai S.B.,Jawaharlal Nehru Aluminium Research Development |
Wasewar K.L.,Visvesvaraya National Institute of Technology |
Wasewar K.L.,Kyung Hee University |
Mishra R.S.,Jawaharlal Nehru Aluminium Research Development |
And 4 more authors.
Research Journal of Chemistry and Environment | Year: 2013
Red mud' or 'bauxite residue' is a waste generated from alumina refinery in an enormous quantity posing a very serious and alarming environmental problem due to its high causticity. Red mud is highly alkaline in nature with a pH of 10.5-12.5 due to caustic soda solution used in extraction of alumina from bauxite ore using Bayer process. It can be made less hazardous and capable for utilization by ameliorating the caustic properties of red mud. One of the options may be neutralization of red mud using inorganic acid. To see the feasibility of using acid for the treatment of red mud, a systematic, methodological and comparative study of pH was carried out using three different inorganic acids (HCl, H2SO4, HNO3) for neutralizing red mud from two different Indian alumina refineries having different composition. The work describes the chemical characterization of red mud before and after neutralization at different pH values with all the three acids. Parameters such as weight of red mud and volume of acid are optimized. Phases of different constituents in neutralized red mud have also been studied. It has been observed that nearly 35- 40% of the total caustic soda can be reduced by acid treatment. Source