3.1 Response surface plots for alumina dissolution in hydrochloric acid.
The interaction effects of the variables on the alumina production by the dissolution of clay in acid medium were studied by plotting 3D surface response curves against any two independent variables while keeping another variable at its central level. The 3D plots of the calculated response (alumina production) plots from the interactions between the variables are shown in the following plots. The order of graphs is according to the degrees of the influences of factors on the dissolution process.