The analysis of all elements present was performed on the quantitatively collected filtrate and washing solution. On the other hand, one hundred grams of the purified residue dross were placed in a porcelain dish, and the appropriate amount of concentrated H2SO4 was added carefully to the sample. The acid was mixed well with the sample using a glass rod until a homogeneous paste was obtained. Then the dish was kept in an oven (maintained at the selected temperature for 1 h). The content of the dish was quantitatively transferred to a beaker, boiled for 15 min with 1000 ml of distilled water, and stirred to dissolve the anhydrous aluminum sulfate. The slurry was washed several times with distilled water. The filtrate and washing solution were collected in a measuring flask, which was marked, and consequently a full analysis was made.