The aim of this work was the production of pure spinel (MgAl2O4) powder from waste aluminum dross by a leaching-precipitation-calcination process. The leaching treatment carried out in sulfuric acid (H2SO4) showed that the best leaching occurred at an acid concentration of C = 15 and a duration of 2 h at a temperature of T = 80 degrees C. The recovery efficiencies recorded for alumina and magnesia were 84.82 and 51.43, respectively. The addition of 8 wt of magnesium oxide (MgO) to the leaching solution, the precipitation with NH4OH and the subsequent calcination at 1450 degrees C leads to an almost complete spinellization ( 98 wt). The synthesized powders were pressed then sintered at 1500, 1600 and 1700 degrees C to elaborate compact discs. The increase in sintering temperature led to the grain growth (D15 approximate to mu m at T = 1500 degrees C, D approximate to 35 mu m at T = 1600 degrees C and D approximate to 70 mu m at 1700 degrees C) and notable improvement of the density (83 at T = 1500 degrees C, 90 at T = 1600 degrees C and 93 at T = 1700 degrees C). The Vickers hardness (HV) and the elastic modulus (E) increased with increasing sintering temperature. The Vickers hardness reached a value of HV = 22 GPa and the elastic modulus a value of E = 220 GPa by sintering at T = 1700 degrees C. This increase in mechanical properties is attributed to the simultaneous effect of better consolidation and notable decrease in the total porosity (17 at 1500 degrees C and 7 at 1700 degrees C).
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