4.0 CONCLUSION
The optimization of process variables in alumina dissolution from Ozoro clay using hydrochloric acid has been studied in order to obtain optimum conditions for alumina yield from the local clay. The influence of calcination temperature, leaching temperature, stirring speed, liquid-solid ratio and acid concentration on the yield of alumina from the clay were considered in the study based on experimental design using the central composite rotatable design of the Response Surface Methodology. The second order polynomial regression equation was appropriate for fitting the experimental data and 0.9209 was obtained as the correlation between the predicted and experimental responses. Calcinations temperature of 677.27oC; leaching temperature of 65.18oC; acid concentration of 1.9mol/cm3; liquid-solid ratio of 10.36 and stirring speed of 442.92rpm were the values of the process variables which gave the optimum alumina yield of 80.07%.