Experimental Study on Denitrification of Black Aluminum Dross

Abstract

A novel process for denitrification of black aluminum dross has been studied. The effects of the baking temperature, reagent addition ratio, and holding time on the denitrification ratio of aluminum dross were studied. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) with energydispersive spectrometry (EDS), x-ray fluorescence (XRF), and nitrogen element analysis were used to evaluate the aluminum dross before and after baking. Aluminum nitride in aluminum dross could be removed effectively by baking a mixture of the aluminum dross with a reagent. A satisfactory denitrification ratio was obtained when applying a baking temperature of 890°C to 920°C, reactant additive dose of 30 wt.% to 40 wt.%, and holding time of 2 h to 3 h, reaching a maximum value of 98.13%. During the baking process, AlN reacted with O 2 in air to form Al 2 O 3 and N 2 , CaCO 3 in carbonates reacted with fluorides and changed into CaF 2 , and Na 2 CO 3 in carbonates reacted with Al 2 O 3 and SiO 2 to form Na 1.95 (Al 1.95 Si 0.05 O 4 ), called zeolite, a compound with cellular structure. This denitrification process is environmentally friendly and could accelerate reutilization of aluminum dross.

Effects of Additive and Roasting Processes on Nitrogen Removal from Aluminum Dross

“…05 O 4 , which makes the surface of the material loose and porous, with many micropores inside. Therefore, more air will enter the sample, which improves the denitrification degree [18]. For the sample with sodium carbonate added, Al2O3, NaAlO2, and Na1.95Al1.95Si0 were mainly present in the sample during roasting.…”

“…CO2 will be produced during the formation of Na1.95Al1.95Si0.05O4, which makes the surface of the material loose and porous, with many micropores inside. Therefore, more air will enter the sample, which improves the denitrification degree [18].…”

Effects of Sodium Carbonate and Calcium Oxide on Roasting Denitrification of Recycled Aluminum Dross with High Nitrogen Content

“…Therefore, the formation of NaAlO2 from sodium carbonate and alumina is the main reaction during calcination. SiO2 react with sodium carbonate and alumina to generate Na1.95Al1.95Si0.05O4, see reaction formula (6) [22].…”