Abstract
Red mud is a waste from the Bayer process of alumina production. This paper is concerned with the dispersion and classification of red mud in a suspension and the improvements made on classified red mud in order to utilize it as a red-colored pigment. Conclusions derived from this study are as follows.
1. It was found that Na salt of formalin condensate of alkil (C4) naphthalin sulfonic acid (Al-NSF) as well as sodium-hexa-metaphosphate (NaHMP) was effective as a dispersant to disperse red mud in water. The fraction of recovery in classifing the red mud in a suspension was also found to be estimated approximately by using the equations that have been proposed in the literature.
2. It became clear that a red-colored pigment having essentially the same characteristics as ferric oxide, could be obtained by processing red mud. The process consists of classification, treatment with acid, calcination and modification on the surface of red mud.
