Fig. 11. The aluminum dissolved percent during leaching process of 100 g of sample for different acid concentrations, leaching temperature of 90 °C.
Because of the complicated composition of the dross sample, it was difficult to exactly calculate the stoichiometric quantity of H2SO4 with respect to the dross. Therefore, four different solid/liquid ratios (1/12; 1/10; 1/8 and 1/6) were used to study the rate of leaching of aluminum.
Fig. 12 shows the results of these studies. Curve 1 (the highest solid/liquid ratio, 1/6) shows an initial rapid increase in the amount of aluminum leached up to a maximum value. It falls dramatically afterward until it reaches a minimum.