RECENT ADVANCES IN THE TREATMENT AND REUSE OF BAUXITE REFINERY RESIDUES (BAUXSOL™)

At the previous Alumina Quality Workshop (Brisbane, 2002) we described a cost effective new procedure (the Basecon™ process) for treating caustic red mud residues from alumina refineries such that they were safe to store and revegetate, or to reuse in a wide range of environmental applications. The mineral cocktail (Bauxsol™) prepared by the Basecon™ process is now in commercial production at several sites around the world and has been registered as a safe new product by regulatory agencies in both North America and Europe. Furthermore, Bauxsol™ reagents have now been used successfully in large-scale trials and commercial applications in many countries and a lot more has been learned about their geochemistry and how to use them.

In this paper we report on the outcomes of further research into the properties of Bauxsol™ reagents and on the results of several large-scale trials and commercial applications. Examples involving the use of these reagents to treat acid rock drainage and pit lake water; tannery, wood treatment and electroplating plant effluents; acid sulphate soils, sulfidic waste rock and mine tailings; effluents from sewage and organic waste processing facilities; discharge water from power stations and ash ponds; and to remove arsenic and fluoride from human drinking water will be presented. These examples have been selected to illustrate important aspects of the geochemical processes involved when Bauxsol™ reagents are used in practical applications; this knowledge is necessary to improve their performance still further and to identify potential new applications.