Alumina production results in the creation of large quantities of caustic red mud that must be stored indefinitely or reused; long term storage costs and liabilities are high and reuse usually requires some neutralisation of the caustic material. Of the various alternative red mud neutralisation methods, we find that the most useful involves treatment with seawater or other natural or artificial Ca-and Mg-rich brines to convert the basicity and other soluble alkalinity into low solubility hydroxide, carbonate and hydroxycarbonate minerals. The resulting neutralised red mud is an ideal raw material for the manufacture of commercial reagents to treat acidic and/or metal contaminated waters or sulphidic waste rock, tailings or soils, industrial waste water and sewage effluent. This paper describes the BASECON™ neutralisation procedure and the geochemical processes involved in red mud neutralisation using Ca-and Mg-rich fluids, and outlines ways to optimise the neutralisation procedure to reduce the quantities of neutralising fluid required and total treatment costs. Optimisation involves the use of a geochemical model to indicate the most cost-effective neutralisation procedure for the red mud; it can also be applied to neutralisation of the supernatant liquor that can be separated from raw red mud by compaction and drainage. The treated red mud is environmentally safe to store or transport and some examples of the market for this material will be presented. After minor additional treatment, the spent neutralising fluid can be safely discharged to the sea or retained in an evaporating basin for salt recovery.