Study On High-purity Aluminum Oxide Recovered From Aluminum Dross By Acid Leaching

When aluminum reacting with the furnace atmosphere, aluminum dross forms at the surface of molten aluminum. Aluminum dross is an unavoidable by-product of the aluminum production. It contains a complex mixture of large quantities of aluminum,aluminum oxide, salt-flux mixture, alloying elements and other contaminants.Normally they are regarded as waste product and disposed in landfill. However, it is an behavior of wasting aluminum resource and environment pollution. Since aluminum production is extremely energy-intensive and aluminum dross is high-polluting, dross recycling has important practice significance.In this paper, recovery method of aluminium dross is introduced. The influence factors of various parameters such as acid concerntration, dosage of leaching liquid,leaching time, reaction temperature of the process were studied to optimize the dissolution process by one-way analysis experiment. With the best process conditions:acid concerntration 2.0 mol/L, leaching temperature 373 K, n( H2SO4) /n( Al)=1.5×1.3, leaching time 120 min, dross particle size 180, the leaching rate of aluminium of this technology exceed 88.8%.Using precipitation method to de-iron of the aluminum sulfate solution. The influence material ratio was studied to optimize the de-iron process by one-way analysis experiment. With the process condition n(K4Fe(CN)6?3H2O)/n(Fe3+)=1.6, the iron removal effect of aluminium sulfate exceed 99.2%.Acid leaching method use the system of aluminum sulfate solution and ammonium bicarbonate, ammonium aluminum carbonate hydroxide(ACCH) and ammonium are produced after the reaction. After abstersion, drying and calcination of ACCH, α-Al2O3 was produced finally. The influence factors of various parameters such as drippling method, pH value, ammonium bicarbonate concerntration, material ratio, calcination temperature were studied to optimize the process by experiment.With the better process conditions: ammonium bicarbonate concerntration 4.0 mol/L,pH value of the system 9.5~10, aluminium sulfate concerntration≥0.3 mol/L,n(NH4HCO3)/n[Al2(SO4)3]=3, drippling speed≤0.5 L/h, calcinating ACCH under1150 ℃, α-Al2O3 was produced.The chemical composition of the alumina were analysised by X-ray fluorescence(XRF) spectroscopy and X-ray diffraction(XRD) analysis. The microstructure and morphology of the alumina were studied with scanning election microscopy(SEM).Thus, It is expected that the high-purity alumina powders obtained from aluminum dross can be potentially utilized as chemical raw materials. With the environment friendly and economic rocess, making economic benefits and environmental benefits at the same time is possible.