Aluminium and its chemicals are produced mainly from
bauxite an oxidic ore, through alkali leaching by Bayer's
process. At the same time many investigators have also tried to
modify the Bayer's process (Filippou and Paspaliaris, 1993;
Dash et al., 2007) as well as to utilize raw materials other than
the bauxite ore (Hector et al., 1997). Mostly clay has been
considered as an alternative to bauxite and has been tried by
both alkaline and acidic routes to see its feasibility. For treating
clay in acidic route it is first roasted at around 1000 K. It
changes the kaolinite to meta-kaolin from which the aluminium
can be dissolved as acid salt. US bureau of mines along with
some aluminium companies made an effort to investigate acid
processes from clay (Habashi, 1997). For several reasons the
hydrochloric acid process was preferred. Pachiney and Alcoa