US 4,386,956 A · Metal recovery process from aluminum dross

Abstract

An improved method for recovery of metal, particularly aluminum, from metal bearing dross utilizes a trough for collection of the dross. A wedge member compresses the dross in the trough. In this manner, metal is decanted from the compressed dross and flows through slots in the bottom or passages in the walls of the trough for collection in a pan, or becomes concentrated at the edges or walls of the volume of dross. The trough and wedge members also serve to cool the dross material thereby diminishing metal loss due to thermite reaction. The compressed dross coalesces and solidifies, is broken and is mechanically separated. The larger dross components from the separation process are substantially metallic and may be recycled through the furnace. The remaining components are charged in a vortex melting furnace for the lowest possible melt loss. This also effects segregation of the remaining metal from the dross by melting the metal and allowing the dross to rise to the top of the bath. The improved method of the present invention provides for recovery of about 95% of aluminum metal from a dross which contains about 70% aluminum as compared with a recovery rate of about 50% aluminum metal utilizing a generally known prior art technique.

Claims18

Dependent claims

An improved method for recovery of free aluminum metal from a metal bearing dross containing free aluminum metal and oxides of said metal, said method comprising the steps of:

(a) collecting the dross in a receptacle of the type having at least one trough with at least one downwardly and inwardly inclined side wall with metal flow passages through the wall;
(b) collecting the free aluminum metal which decants through the passages;
(c) mechanically compacting the dross by applying a compressive force on the dross and against the inclined wall above a threshold pressure to pool free aluminum metal within a dross, effect migration of the free aluminum metal toward a boundary surface of the compacted dross, decant a portion of said free aluminum through the passage and inhibiting the oxygen supply to the free aluminum metal in the dross;
and
(d) cooling the compacted dross and free aluminum metal to solidify the free aluminum metal;
such that thermite reaction of free aluminum metal and oxygen in the dross is diminished by the combination of compacting above the threshold pressure and cooling of the metal.

3 more elements

An improved method for recovery of free aluminum metal from aluminum metal bearing dross where said dross also includes oxide impurities, said method comprising the steps of;

(a) collecting the dross in a receptacle of the type having at least one trough with at least one downwardly and inwardly inclined sidewall having metal flow passages through the wall;
(b) collecting free aluminum metal which decants through the passages;
(c) mechanically compacting the dross by applying a compressive force on the dross and against the inclined wall above the threshold pressure to pool free aluminum metal within the dross, effect migration of the free aluminum metal toward a boundary surface of the compacted dross, decant a portion of said free aluminum metal through the passages and inhibit the oxygen supply to the free aluminum metal in the dross;
(d) cooling the compressed dross and free aluminum metal to solidify the free aluminum metal;
such that thermite reaction of free aluminum metal and oxygen in the dross is diminished by the combination of compacting above the threshold pressure and cooling of the metal;
(e) removing compacted dross from the receptacle;
(f) mechanically breaking the compacted dross to form components including oxide dust;
(g) separating the components of the dross having a larger mean diameter from the remainder of the dross, said larger mean diameter components generally comprising metal, said remainter including a granulate and an oxide dust;
and
(h) melting substantially the granulate remainder of the dross to thereby segregate a multon metal portion from the remainder of the dross.

7 more elements

Dependencies are inferred from the claim text.

Metal recovery process from aluminum dross

Life of this patent

Metal recovery process from aluminum dross

Life of this patent

Abstract

Claims18