Bauxite residue is generated from aluminium production where bauxite ore is digested in hot sodium hydroxide (NaOH) solution via the Bayer process.
Bauxite residue is also known as red mud, Bayer process tailings or bauxite process tailings (Evans, 2015) and it may be split further into two fractions. The fine fraction, ‘red mud’ and the coarse fraction ‘process sand’ (>106μm or >150μm) (Courtney and Timpson, 2005).
Currently, the global production of bauxite residue is 150 million tonnes (Evans, 2016) and the total inventory is 2.7 billion tonnes of bauxite residues (Binnemans et al., 2015). The production of 1 ton of alumina generates between 0.8 and 1.5 tons of bauxite residue (Liu and Zhang, 2011).
With this, comes the need for some action in the utilization as well as disposal of this residue (Power et al. 2011). A major factor which hinders the more environmentally friendly methods of storage and utilization, is the residues high pH (>13) and the high soda content (Wang et al. 2008). Unless managed properly, bauxite residue may pose considerable risks to the local environment near production and deposition sites due to its alkalinity (Gomes et al. 2016; Gruiz et al. 2013).
Evans, K., 2015. Successes and challenges in the management and use of bauxite residue. Proceedings of the Bauxite residue Valorisation and Best Practices Conference. 5–7, October 2015, Leuven, Belgium. Available at: http://conference2015.redmud.org/wp-content/uploads/2015/10/Ken-EVANS-secure.pdf. Accessed 3rd February 2016.
Courtney, R.G., Timpson, J.P., 2005. Reclamation of fine fraction bauxite processing residue (bauxite residue) amended with coarse fraction residue and gypsum. Water Air Soil Pollut. 164 (1–4), 91–102. https://doi.org/10.1007/s11270-005-2251-0
Evans, K., 2016. The history, challanges, and new developments in the management and use of bauxite residue. J. Sustain. Metal. 2 (4), 316–331. https://doi.org/10.1007/s40831-016-0060-x
Binnemans, K., Jones, P.T., Blanpain, B., Van Gerven, T., Pontikes, Y., 2015. Towards zero-waste valorisation of rare-earth-containing industrial process residues: a critical review. J. Clean. Prod. 99, 17–38. https://doi.org/10.1016/j.jclepro.2015.02.089
Liu, X., Zhang, N., 2011. Utilization of red mud in cement production: a review. Waste Manage. Res. 29(10), 1053–1063. https://doi.org/10.1177/0734242X11407653
Power, G., Gräfe, M., Klauber, C., 2011. Bauxite residue issue: I. Current Management, disposal, and storage practices. Hydrometallurgy 108, 33–45. https://doi.org/10.1016/j.hydromet.2011.02.006
Wang, S.B., Ang, H.M., Tade, M.O., 2008. Novel applications of red mud as coagulant, adsorbent and catalyst for environmentally benign processes. Chemosphere 72 (11), 1621–1635. https://doi.org/10.1016/j.chemosphere.2008.05.013
Gomes, H. I., Mayes, W.M., Rogerson, M., Stewart, D.I., Burke, I.T., 2016. Alkaline residues and the environment: a review of impacts, management practices and opportunities. J. Cleaner Product. 112 (4), 3571–3582. https://doi.org/10.1016/j.jclepro.2015.09.111
Gruiz, K., Vaszita, E., Feigl, V., Klebercz, O., Ujaczki, É., Anton, A., 2013. Environmental risk assessment of red mud contaminated soil in Hungary. Proceeding of Aquaconsoil 2013 Conference, Theme C: Assessment and monitoring, 2013, paper 2292. 16–19 April 2013, Barcelona, Spain. Available at: http://soilutil.hu/sites/soilutil.hu/files/Abstract_Redmud_GK.pdf. Accessed 29th May 2014.