For the purpose of volume reduction and detoxification of the low-grade aluminum dross (abbreviated as L-dross) with low content of metallic Al, the leaching behavior of two kinds of L-dross was investigated using 2 mol/dm3 H2SO4 and 2 mol/dm3 NaOH with or without heating operation. Ettringite with an anion removal ability was synthesized from the L-dross leachate generated after the volume reduction and detoxification treatment. A series of wet treatment process composed of L-dross leaching and ettringite synthesis was tried to develop in this study.
In the case of leaching with 2 mol/dm3 H2SO4, the Al3+ concentration in leachate and leaching percentage are increasing with an increase in leaching temperature in the order of 85°C > 50°C > Room temperature. On the other hand, the effect of heating on L-dross leaching using 2 mol/dm3 NaOH is not remarkable. In terms of volume reduction, it is found that the H2SO4 leaching with heating is effective and the residual ratio shows approximately 50 mass%.
According to the detoxification due to the dissolution of metallic Al and the hydrolysis of AlN, the heating effect appears to both leachates. The NaOH solution is found to be more valid than the H2SO4 for the acceleration of Al dissolution and AlN decomposition. Ettringite was synthesized easily from both leachates treated with 2 mol/dm3 H2SO4 and 2 mol/dm3 NaOH, by adding Ca(OH)2 and CaSO4 · 2H2O. It is considered that the wet treatment process suggested in this study makes contribution to the volume reduction and detoxification of the L-dross and the synthesis of ettringite using the L-dross leachate.
