Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1997-04-04
1999-01-05
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
75433, 75671, C22B 2100
Patent
active
058556443
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method for recovering aluminium from materials containing metallic aluminium, in which method it is intented to improve the recovery rate of aluminium and to promote recycling of resources. Hereupon by the materials containing (or accompanying) aluminium are meant such ones as aluminium can, aluminium laminated foil, aluminium scraps, aluminium chips, and other aluminium containing materials.
BACKGROUND OF THE INVENTION
Conventionally various methods have been proposed to recover aluminium from materials containing metallic aluminium, but they have demerits in that the recovery rate of aluminium is low, it is difficult to separate the accompanying impurities (or unnecessary materials) such as paint, organic materials (paper, resin and the like) and iron, and therefore the metallic aluminium content in the reclaimed aluminium is low.
The known techniques for recovering aluminium are, for example, as follows. articles of metallic aluminium (see Patent Publication No. 52-19180). medical tablets (see Patent Kokai No. 52-112673). Publication No. 59-37337). subjecting it to a pre-treatment for reclaiming and melting it (see Patent Publication No. 2-53494). comprises 1) heating the Al-laminate in non-oxidised atoms. at 400-600 deg. C. to carbonize paper and plastics; 2) subjecting the carbonized substances to crushing to pulverise the carbonized materials, followed by separation of Al-foil from the carbonized materials (see Patent Kokai No. 60-230942).
Each of the above-mentioned known techniques involves a great number of complicated steps, and the recent wastes which contain or accompany metallic aluminium have various components, so that such techniques are very costly in equipment to recover metallic aluminium in a simple way, and evidently they have difficulty in their workability.
DISCLOSURE OF THE INVENTION
The object of the invention is to provide a method for recovering metallic aluminium easily and at high recovery rate and low cost from metallic aluminium containing wastes disposed recently in great amounts, said wastes being, for example, aluminium can, aluminium laminated foil, aluminium scraps, aluminium chips, and other aluminium containing (or accompanying) materials. The present invention is technically constituted such that the combustible substances of metallic aluminium containing materials are carbonized in a kiln in an atomosphere where oxygen concentration is not higher than 10% by volume or an atomosphere of a carbon dioxide gas, and which kiln is in the temperature range of 300.degree.-600.degree. C., and that after cooling, carbonized material and iron content are separated by sieving or magnetically.
BEST MODE OF CARRYING OUT THE INVENTION
The method of recovering aluminium materials, which is technically constituted as above in the present invention, will be described below in detail. metallic aluminium
The materials containing metallic aluminium are crushed into pieces of not greater than 40 mm by a crusher of shearing type (like a single axle crusher) or impact type (like hammer crusher). articles
The metallic aluminium containing materials now crushed are fed into a kiln where the oxygen concentration is controlled below 10% by volume, the combustible substances such as of resin or paper are carbonized in the temperature range of 300.degree.-600.degree. C. without oxidizing metallic aluminium, and after discharging and cooling, iron carbonized material and content are removed by sieving or magnetic separation.
The reason of making the oxygen concentration in the second step 10% by volume is that in excess of 10% by volume the recovery rate is significantly lowered because of oxidation of aluminium.
On the other hand, by making the interior of the kiln in the second step a CO.sub.2 gas atmosphere it is possible to the metallic aluminium in the materials to be protected from oxidation.
In that case, referring to nitrogen usable for the same purpose, it generates harmful non-metallic inclusions as AlN so that CO.sub.2 is pref
REFERENCES:
patent: 5405428 (1995-04-01), Dube et al.
Aikoh Co. Ltd.
Andrews Melvyn
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