Investigation of Al2O3-based ceramic production from aluminium black dross through hydrometallurgical and pyrometallurgical operations

Aluminium dross arises due to the high interest of aluminium to oxygen during melting, molten metal transfer and refining processes. The dross consists of metallic or non-metallic components depending on the charge. It can be classified as black and white. White dross has high metallic aluminium content whilst the black dross has low metallic aluminium content. In this study, it was aimed to determine the optimum conditions for the evaluation of black dross with pyrometallurgical and hydrometallurgical processes such as calcination and leaching. In the first stage of the experimental studies, the black dross was calcined at five different temperatures to remove halide-based impurities by evaporation and to convert the metallic aluminium content to Al2O3. In the second stage, original and calcined black dross samples were leached with different reagents to obtain an alumina-based ceramic as pure as possible. The purpose of leaching experiments is to extract the impurities out and to purify the alumina-based ceramics in calcination products as filter cake because the alumina does not have solubility in the acids which are used in leaching experiments. Calcined black dross, which was calcined at 1100 °C for 60 minutes, was leached in a solution of 10 mL H2SO4 and 40 mL distilled water. Obtained alumina-based ceramic powders were pressed under 600 MPa uniaxial pressure and were sintered under argon atmosphere for 60 minutes at increasing temperatures up to 1550 °C to see the use of the produced powder as refractory material. XRD, XRF, chemical analysis, TGA, Vickers hardness measurement and Archimedes density techniques were used to characterize raw materials, ceramic powders and sintered ceramics.