China Nonferrous Metallurgy

The harmless treatment and resource utilization of secondary aluminum dross have become increasingly urgent due to its massive production， low-added-value applications， and insufficient basis for large-scale effective utilization. Secondary aluminum dross is mainly composed of oxides of aluminum， silicon， magnesium， aluminum nitride and other components， which show a high compositional matching degree with cordierite， thus possessing raw material advantages for preparing cordierite composite porous ceramics. In this study， secondary aluminum dross was used as the main raw material， with silicon dioxide and magnesium oxide as additives， to prepare cordierite composite porous ceramics by solid-state reaction sintering. Firstly， the desalination process was optimized through low-temperature roasting， then the effects of sintering temperature and holding time on the microstructure， phase composition and properties of the ceramics were systematically investigated . The results show that 750℃ for 6 h is the optimal desalination process， which can effectively remove soluble salts while retaining the aluminum nitride pore-forming component. Sintering temperature and holding time significantly affect the firing loss rate， phase composition and properties of the ceramics. The firing loss rate reaches the minimum value of 6. 38% at 1 350℃ for 3 h. With the increase of sintering temperature and the extension of holding time， the cordierite phase in cordierite composite porous ceramics gradually decomposes， the number of mullite whiskers in cordierite porous ceramics increases significantly， and the material strength is greatly improved. When the sintering condition is 1 350℃×3 h， the molar ratio of cordierite/mullite in the prepared cordierite composite porous ceramics is about 6∶1. At this time， the material exhibits the best performance， with a porosity of 49. 16%， a bulk density of 1. 16 g/cm3， and a compressive strength of 12. 0 MPa. This research provides a new approach for the harmless treatment and resource utilization of secondary aluminum dross， as well as experimental evidence and technical references for preparing cordierite composite porous ceramics with high porosity and high strength.