Drainage aids are designed to assist in filter cake dewatering by reduction of surface tension. By the early 1980's several specialist chemical manufacturers had developed drainage aids specific to the alumina industry. Thus, after some initial laboratory work, drainage aid addition to the product hydrate filter cake was first tried at Gove in early 1981. Encouraging results led to further plant trials and a laboratory trial comparing eight different products. From this last trial a product was chosen and a plant trial run in March 1982. The results achieved encouraged a further plant trial to be run during April and May, 1982 and a decision was then made to adopt the full-time use of drainage aid on the plant._x000D_
Optimisation work with the drum filters and drainage aid continued until late 1983._x000D_
This work not only led to optimisation of dose rates, concentrations etc., but also to significant improvements in the mode of operation of the product filtration area.