Characterization for Effective Management and Utilization of Red Mud

Abstract

The bauxite residue or red mud (RM) is generated during the production of alumina. Every year, approximately 120 million tons of RM is generated worldwide. Due to high alkalinity, red mud is a threat to the environment in terms of land and water pollution. Though various attempts has been made to utilize other industrial waste like fly ash and steel slag but the characterization of red mud is very limited and scattered.
The present study aims at the characterization of two Indian red mud from a different type of disposal system as a geotechnical construction material. A detailed study on different physical, chemical, morphological, and geotechnical characterizations of the basic and modified/stabilized red mud were made to correlate the findings. The red mud was found to be dispersive, which could be controlled through stabilization using biopolymer and NaCl. The sedimentation properties improved with the addition of NaCl and phosphogypsum and its impact on red mud pond management is discussed. The stabilization of red mud using other industrial waste like ground granulated blast furnace slag was found to be effective in terms of increase in unconfined compressive strength. But, the durability in terms of alternate wet-dry cycle was found to be depend upon the chemical reaction of the red mud with the stabilizer. The leachate analysis of the stabilized red mud showed an increase in heavy metal, due to high alkaline condition, but the value was within permissible limit. Based on the comparison with Indian standard sand, the coarse fraction (> 75m) of red mud can be alternate of fine aggregate replacing natural sand. The findings of the present study can help in proper management and utilization of red mud, thereby helping in the sustainable development of the aluminum industries. However, its compatibility with cement in mortar and concrete need further investigation. The future challenges are in the implementation of the developed methodology as a pilot project to transfer the technology.