DISSOLUTION OF SOLIDS IN PROCESS WASTE STREAMS

Solid wastes from the Bayer process include a variety of neutral and caustic solids. Some of the caustic compounds also contain aluminium, including solids in forms that are considered to be stable, such as desilication product and tricalcium aluminate (TCA). Caustic, aluminium and other components of waste solids are labile or soluble under various conditions. The conditions of dissolution, the identity of the source solids and rates of dissolution were explored in laboratory work.

A method for neutralising alkaline components of Bayer waste streams is the use of seawater as a neutralising agent. The current laboratory work concentrates on characterising the solid products of seawater neutralisation and evaluating the rate of dissolution of some of the red mud waste components, not detailed in previous work.