Utilization of Steam from Thermal Power Plant to Recover the Caustic & Alumina from Red Mud Slurry

Abstract

Earth’s most powerful greenhouse gas-water vapor causes fast global climate change. Slight increase in the Earth’s atmospheric water vapor concentration plays a far greater role in global warming than CO2 or other minor gases. The highly energetic water vapor (waste steam) of thermal power plant forms brown cloud along with CO2, CO, other gaseous pollutants, carbon particles, dust particles, light metal ions, etc. To prevent burning of earth, to some extent, steam is used in the laboratory scale as a source of energy and distilled water for the recovery of caustic and alumina from red mud slurry. The pH of highly alkaline red mud slurry decreased from 13.9 to 10.5 by this process and can be brought to standard environmental level (pH < 9) by addition of small amount of common salt. The recovered caustic, pH >_ 13.5, can be used for the further digestion of bauxite ore. The use of steam led to many benefits, including conservation of distilled water, prevents the formation of brown cloud and reduces the cost of waste management.