Scullett-Dean, G, Stockwell, K, Myers, L, Nyeboer, H & Santini, TC 2022, 'Accelerating soil formation in bauxite residue: a solution for long-term tailings management and storage', in AB Fourie, M Tibbett & G Boggs (eds), Mine Closure 2022: Proceedings of the 15th International Conference on Mine Closure
, Australian Centre for Geomechanics, Perth, pp. 1027-1036, https://doi.org/10.36487/ACG_repo/2215_75
Bauxite residue is the highly alkaline (pH ~12) and saline tailings material produced during the Bayer process for alumina production. Australia is currently responsible for the management of approximately 750 million tonnes of bauxite residue and produces an additional 30 million tonnes each year. Currently only 2% of bauxite residue produced is recycled (International Aluminium Institute 2017, Di Carlo et al. 2019a); however, there is growing interest in reusing residue by transforming this byproduct into a productive soil material through in situ remediation. This aims to transform the bauxite residue into a soil-like medium, by adding amendments to the residue to reduce pH and salinity and improve other unfavourable conditions.
Our work has focused on optimising the amendment application used to accelerate soil formation, using field scale lysimeters to test a combination of treatments. Here we provide an overview of a successful year-long field trial to promote soil formation, and our key insights from the trial. Combining microbially-driven bioremediation with common amendments compost and tillage accelerated pH neutralisation of the residue and leaching of excess salts, creating a material amenable to plant growth. The trials were completed under harsh Australian climatic conditions utilising available mine site water and cost-effective amendment rates, ensuring that this technology is applicable for further industrial scale-up. The data from this study will allow development of best practice remediation strategies for bauxite residue deposits based on their climate and desired end land use and is also applicable to other alkaline tailings and waste materials. Our results with bauxite residue show that in situ remediation is an innovative solution for rapid, cost-effective long-term tailings management.
Keywords: remediation, pH neutralisation, red mud, alumina refining, amendments, gypsum, compost, tillage, alkaline
Bray, AW, Stewart, DI, Courtney, R, Rout, SP, Humphreys, PN, Mayes, WM & Burke, IT 2018, ‘Sustained bauxite residue rehabilitation with gypsum and organic matter 16 years after initial treatment’, Environmental Science & Technology, vol. 52, no. 1,
Courtney, RG, Jordan, SN & Harrington, T 2009, ‘Physico-chemical changes in bauxite residue following application of spent mushroom compost and gypsum’, Land Degradation & Development, vol. 20, pp. 572–581,
Department of Industry, Science, Energy and Resources 2020, Commonwealth of Australia Resources and Energy Quarterly March 2020, Canberra.
Di Carlo, E, Boullemant, A & Courtney, R 2019a, ‘A field assessment of bauxite residue rehabilitation strategies’, The Science of the Total Environment, vol. 663, p. 915,
Di Carlo, E, Chen, CR, Haynes, RJ, Phillips, IR & Courtney, R 2019b, ‘Soil quality and vegetation performance indicators for sustainable rehabilitation of bauxite residue disposal areas: A review’, Soil Research, vol. 57, no. 5, pp. 419–446,
Gräfe, M & Klauber, C 2011, ‘Bauxite residue issues: IV. Old obstacles and new pathways for in situ residue bioremediation’, Hydrometallurgy, vol. 108, no. 1–2, pp. 46–59,
Gräfe, M, Power, G & Klauber, C 2011, ‘Bauxite residue issues: III. Alkalinity and associated chemistry’, Hydrometallurgy, vol. 108, no. 1–2, pp. 60–79,
Hazelton, P & Murphy, B 2007, Interpreting Soil Test Results: What Do All the Numbers Mean?, CSIRO Publishing, Melbourne.
International Aluminium Institute 2017, Life Cycle Inventory Data and Environmental Metrics for the Primary Aluminium Industry, International Aluminium Institute, London,
Jones, BEH, Haynes, RJ & Phillips, IR 2011, ‘Cation and anion leaching and growth of Acacia saligna in bauxite residue sand amended with residue mud, poultry manure and phosphogypsum’, Environmental Science and Pollution Research International, vol. 19, no. 3, pp. 835–846,
Khaitan, S, Dzombak, DA & Lowry, GV 2009, ‘Chemistry of the acid neutralization capacity of bauxite residue’, Environmental Engineering Science, vol. 26, no. 5, pp. 873–881,
Khaitan, S, Dzombak, DA, Swallow, P, Schmidt, K, Fu, J & Lowry, GV 2010, ‘Field evaluation of bauxite residue neutralization by carbon dioxide, vegetation, and organic amendments’, Journal of Environmental Engineering, vol. 136, no. 10, pp. 1045–1053,
Power, G, Gräfe, M & Klauber, C 2011, ‘Bauxite residue issues: I. Current management, disposal and storage practices’, Hydrometallurgy, vol. 108, no. 1–2, pp. 33–45,
Rayment, G & Higginson, F 1992, Australian Laboratory Handbook of Soil and Water Chemical Methods, Inkata Press, Melbourne.
Ren, J, Chen, J, Han, L, Wang, M, Yang, B, Du, P & Li, F 2018, ‘Spatial distribution of heavy metals, salinity and alkalinity in soils around bauxite residue disposal area’, The Science of the Total Environment, vol. 628–629, pp. 1200–1208,
Rietveld, HM 1969, ‘A profile refinement method for nuclear and magnetic structures’, Journal of Applied Crystallography, vol. 2, no. 2, pp. 65–71,
Santini, T & Fey, M 2016, ‘Assessment of technosol formation and in situ remediation in capped alkaline tailings’, Catena, vol. 136, pp. 17–29,
Santini, T & Fey, M 2018, ‘From tailings to soil: long-term effects of amendments on progress and trajectory of soil formation and in situ remediation in bauxite residue’, Journal of Soils and Sediments, vol. 18, no. 5, pp. 1935–1949,
Santini, TC, Kerr, JL & Warren, LA 2015, ‘Microbially-driven strategies for bioremediation of bauxite residue’, Journal of Hazardous Materials, vol. 293, pp. 131–157,
Santini, TC, Warren, K, Raudsepp, M, Carter, N, Hamley, D, McCosker, C, … Warren, LA 2019, ‘Accelerating bauxite residue remediation with microbial biotechnology’, in C Chesonis (ed.), Light Metals 2019, pp. 69–77, Springer International Publishing, Berlin.
Santini, TC & Banning, NC 2016, ‘Alkaline tailings as novel soil forming substrates: Reframing perspectives on mining and refining wastes’, Hydrometallurgy, vol. 164, pp. 38–47,
Santini, TC, Fey, MV & Smirk, MN 2013, ‘Evaluation of soil analytical methods for the characterization of alkaline technosols: I. moisture content, pH, and electrical conductivity’, Journal of Soils and Sediments, vol. 13, no. 7, pp. 1141–1149,
Santini, TC, Malcolm, LI, Tyson, GW & Warren, LA 2016, ‘pH and organic carbon dose rates control microbially driven bioremediation efficacy in alkaline bauxite residue’, Environmental Science & Technology, vol. 50, no. 20, pp. 11164–11173,
Santini, TC, Wang, JC, Warren, KL, Pickering, G & Raudsepp, MJ 2021, ‘Simple organic carbon sources and high diversity inocula enhance microbial bioneutralization of alkaline bauxite residues’, Environmental Science & Technology, vol. 55, no. 6, pp. 3929–3939,
Wehr, J, Fulton, I & Menzies, N 2006 ‘Revegetation strategies for bauxite refinery residue: a case study of Alcan Gove in Northern Territory, Australia’, Environmental Management, vol. 37, no. 3, pp. 297–306,
Wissmeier, L, Barry, DA & Phillips, IR 2011, ‘Predictive hydrogeochemical modelling of bauxite residue sand in field conditions’, Journal of Hazardous Materials, vol. 191, no. 1, pp. 306–324,
Wong, JWC & Ho, GE 1991, ‘Effects of gypsum and sewage sludge amendment on physical properties of fine bauxite refining residue’, Soil Science, vol. 152, no. 5, pp. 326–332,
Zhu, F, Hou, J, Xue, S, Wu, C, Wang, Q & Hartley, W 2017, ‘Vermicompost and gypsum amendments improve aggregate formation in bauxite residue’, Land Degradation & Development, vol. 28, no. 7, pp. 2109–2120,