Recovery of metal from dross and apparatus therefore
AssigneePyrogenesis Inc.
InventorsMichel G. Drouet, Peter G. Tsantrizos
Life of this patent
Estimating the term…
Abstract
A process and an apparatus are disclosed for improved recovery of metal from dross, wherein a dross treating furnace is provided with a refractory wall or lining with good capacity to store and conduct heat. This furnace is preheated to a desired temperature by injection of oxygen to burn non-recoverable metal remaining in the residue after tapping of the recoverable metal contained in the dross. When dross is treated in such preheated furnace, the heat emanating by conduction from the furnace wall is sufficient to melt and separate the recoverable metal contained in the dross, without addition of an external heat source, such as fuel or gas burners, plasma torches or electric arcs.
Claims15
A process for treating dross containing a recoverable metal, in order to recover said metal, which comprises:
- (a) charging a batch of hot dross, resulting from skimming of said dross in a metallurgical plant, into a furnace preheated to a high enough temperature to insure that said dross is thereby heated above the melting point of the metal to be recovered by transfer of energy stored in the furnace wall;
- (b) providing an inert atmosphere in the furnace by filling the furnace with inert gas, to prevent oxidation of the hot dross;
- (c) rotating or oscillating the hot dross within the preheated furnace to insure proper heating of the dross to a temperature above the melting point of the metal to be recovered and agglomeration of recoverable free metal at the bottom of the furnace;
- (d) removing from the furnace the recoverable free metal while leaving inside the furnace oxide residues and a fraction of non-recoverable metal which stays with said residues as it cannot be recovered;
- (e) thereafter, injecting a controlled amount of an oxidizing gas into the furnace while rotating or oscillating the furnace, so as to oxidize sufficient non-recoverable metal within the oxide residues and through resulting exothermic oxidation reaction to evenly transfer to and store in the furnace wall sufficient energy to preheat the furnace to a temperature suitable for treating a new batch of hot dross resulting from a further skimming of the dross in the metallurgical plant;
- (f) removing solid residues remaining in the furnace;
- and
- (g) charging into the furnace the new batch of hot dross and repeating the process.
Apparatus for recovering metal, such as aluminum, contained in a dross, which comprises:
- (a) a rotary or oscillatory furnace adapted for high temperature treatment of drosses, said furnace having a chamber with a refractory wall capable of accumulating and conducting heat provided by an exothermic reaction within said chamber, said refractory wall also being capable of storing a high density of heat suitable for heating a charge of dross above the melting point of the metal to be recovered, said furnace also having an opening through which dross may be charged into the chamber and solid residues discharged from said chamber, as well as a door for hermetically closing said opening during treatment of the dross, and said furnace further having a taphole for tapping recovered molten metal;
- (b) means for rotating or oscillating said furnace;
- (c) means for injecting an inert gas into said furnace;
- (d) means for controllably injecting an oxidizing gas into said furnace;
- and
- (e) means for monitoring the temperature of the dross charge inside the furnace and of residues remaining in the furnace after tapping the recovered molten metal.
Dependencies are inferred from the claim text.