Aluminum dross recovery process
OwnerDan Yerushalmiinventor
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Abstract
A method for recovering reusable materials from aluminum dross is disclosed comprising crushing the dross and extracting solubles therefrom with water in a digester. The brine so obtained is processed in a crystallizer to obtain fluxing materials contained therein, and the insolubles are furnaced to separate the free aluminum metal therefrom. To prevent undesirable reactions from occurring in the digester which result in the production of hazardous and noxious products, the pH in the digester is controlled below about 8, and preferably above about 5, by withdrawing a magnesium chloride-containing stream from the crystallizer and introducing it into the digester.
Claims12
In a batch process for recovering reusable materials from aluminum dross, said dross including fluxing magnesium chloride, and aluminum-containing compounds, and aluminum metal, the process comprising the steps of:
- crushing the dross;
- treating the crushed dross in a digester vessel with water to dissolve water-soluble compounds contained therein, to produce an aqueous solution of soluble compounds and insolubles, the pH of the solution sometimes having a value different from a desired value;
- separating an aqueous solution of the soluble compounds thus obtained from insolubles;
- furnacing the insolubles to obtain aluminum metal;
- and
- evaporating some of the separated aqueous solution of soluble compounds in an evaporator to crystallize fluxing compounds from evaporator liquor contained in the evaporator, the evaporator liquor having magnesium chloride therein;
- the improvement that comprises recycling part of the evaporator liquor back to the digester vessel in an amount sufficient for the magnesium chloride in the evaporator liquor to control the pH of the material in the digester vessel at a desired value and monitoring the pH of the material in the vessel to determine when the desired value has been achieved.
A batch process for recovering reusable materials from aluminum dross, the process comprising the steps of:
- crushing the dross;
- treating the crushed dross in a digester vessel with water to convert water-soluble compounds contained therein into an aqueous solution of fluxing compound-containing solubles having magnesium chloride therein, and to produce insolubles;
- separating an aqueous solution of fluxing compound-containing solubles from insolubles in slurry leaving the digester vessel;
- furnacing the insolubles to obtain aluminum metal;
- treating the aqueous solution in a crystallizer to crystallize the fluxing compounds from magnesium chloride-containing liquor in the crystallizer,
- drying the crystallized fluxing compounds in a dryer,
- removing a stream of magnesium chloride-containing liquor from the crystallizer, and
- recycling said stream to the digester vessel in an amount sufficient to control the pH of the material in the digester vessel at a desired value, and monitoring the pH of the material in the vessel to determine when the desired value has been achieved.
A batch process for recovering reusable materials from aluminum dross that includes fluxing, magnesium, and aluminum-containing compounds, and aluminum metal, comprising the steps of:
- crushing the dross;
- treating the crushed dross in a digester vessel with water to dissolve water-soluble compounds contained therein to produce a slurry containing insolubles and an aqueous solution of fluxing compound-containing solubles having magnesium chloride therein;
- separating an aqueous solution of fluxing compound-containing solubles from insolubles in slurry leaving the digester;
- furnacing the insolubles to obtain aluminum metal;
- treating the aqueous solution in a crystallizer to crystallize the fluxing compounds from liquor contained in the crystallizer, the liquor having magnesium chloride therein;
- drying the crystallized fluxing compounds in a dryer,
- monitoring the pH of the material in the digester vessel, and
- removing two streams of liquor from the crystallizer, and recycling one of the streams to the digester vessel in an amount sufficient for the magnesium chloride to control the pH of the material in the digester vessel at no more than about 8, and feeding the other stream to the dryer.
Dependencies are inferred from the claim text.