| 摘要 |
<p>1. A method of recovering aluminium from dross and other aluminium oxide containing waste for re-use in fusion electrolysis cells, in which a) the dross is firstly by comminution separated into a coarse fraction which still contains a lot of pure metal, to be fused in a salt bath, and a fine fraction which mainly contains oxides, a dross dust, b) this dross dust with salt-rich residues from a fusion furnace (2) is washed with hot water in a reaction container (1) to decompose the carbides and nitrides and to dissolve the salts, c) this brime is filtered, a filtrate which runs off in the process being evaporated, the salts crystallised out being fed back to the smelting furnace (2) while a remaining filter residue is disintegrated as a washed out salt-free dross dust in the reaction container by the addition of heated sulphuric acid, d) then this sulphuric dross dust suspension is filtered, a sulphuric filtrate which results is washed until it is free from acid while a remaining filter residue is dried, calcined and then partially fed to the electrolysis cell (8), e) finally the filtrate which has been washed free from acid and in which the aluminium is dissolved as an aluminium sulphate, is neutralised in the reaction container, lye being added slowly, attended by constant agitation, during which aluminium hydroxide is precipitated, magnesium sulphate remaining in solution, whereupon f) the precipitated aluminium hydroxide is filtered out of this solution, dried and calcined and introduced into the electrolysis cell, while filtrate running off as a residual fluid is discharged with the dissolved magnesium sulphate as waste.</p> |
