Feasibility of aluminum recovery and MgAl2O4 spinel synthesis from secondary aluminum dross
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The feasibility of aluminum recovery from secondary aluminum dross by extraction with NaOH solution and the subsequent synthesis of MgAl2O4 spinel by sintering the extracted slag were studied. The extraction percentage of soluble aluminum from the dross reached 80% at a temperature of 353 K, liquid-to-solid ratio of 12 mL·g−1, stirring speed of 300 r·min−1, and an extraction time of 15 min; the hydrolysis percentage of AlN reached 40% with an extraction time of 30 min. The activation energies of the soluble aluminum and AlN extracted from the dross were 7.15 and 8.98 kJ·mol−1, respectively, indicating that their kinetics were controlled by outer diffusion without a product layer. The extracted slag was sintered in the temperature range 1373–1773 K; MgAl2O4 spinel with a compressive strength as high as 69.4 MPa was produced in the sample sintered at 1673 K for 3 h. This value exceeds the threshold (40 MPa) prescribed by the National Standard for the Magnesia and Magnesia−alumina Refractory Bricks of China (GB/T 2275–2007). These results establish the effectiveness of aluminum recovery from secondary aluminum dross and subsequent MgAl2O4 spinel synthesis.
Keywordssecondary aluminum dross reuse extraction sintering magnesium aluminate spinel
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This work was financially supported by the National Natural Science Foundation of China (No. 21577176) and the Environment Protection Scientific Research Project of Hunan Province, China (No. 59–3).
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