Aluminium recovery during black dross hydrothermal treatment

The purpose of present research work was to present a process for the recovery of Al, by treating aluminium black dross (ABD), a by-product formed during aluminium scraps melting. The proposed process consists of the following four (4) unit operations:a.Crushing the initial ABD by a jaw crusher to “−1 mm” and recovery of metallic Al by sieving and screening (distorted or flattened particles).b.Further grinding of the material by ball mill to “−100 μm”, and recovery of the residual metallic Al. The total quantity of metallic Al recovered was estimated at 10.25% of the ABD.c.Recovery of soluble salts (NaCl, KCl), at atmospheric pressure, by water leaching of the grinded ABD at 90 °C. During leaching, about half of the nitrides were also decomposed.d.Aluminium recovery from the water leached residue, by pressure leaching at 240 °C, with NaOH strong solution (260 g/L). The total aluminium leaching efficiency on the basis of ABD weight reached 57.5%.