US2552423A - Process for the direct production of refined aluminum - Google Patents

Description

A. GLAZUNOV May 8, 1951 PROCESS FOR THE DIRECT PRODUCTION OF REFINED ALUMINUM Filed Nov. 30, 1948 FIG.

ELECTROLYTE I 950 c \ELECTROLYTE aoo-=c (sacl +AIF33KF) CINDERS REFINED ALUMINUM FIG- 2 IN V EN TOR. ALEXANDRE GLAZUNOV AT TORNEY Patented May 8, 1951 PROCESS FOR THE DIRECT PRODUCTION OF REFINED ALUMINUM Alexandre Glazunov, Geneva, Switzerland Application November 30, 1948, Serial No. 62,643 In Switzerland November 30, 1947 1 Claim. 1

Alloys having the best properties are obtained, when produced from the purest metals. Industrial plants therefore demand the highest possible purity and the problem of refining is becoming more and more important.

Processes for refining aluminium have been known for a long time; among the chief methods employed is that of purification by means of electrolysis, in a furnace. This method is known as the three layers refining.

The various furnaces employed for this procedure (Hoopes, Pchiney) differ only in the details of their construction; the procedurerequires rather complicated and expensive manipulation, as well, as an addition of 30% copper, which increases the specific weight of the lower layer.

The present invention eliminates these difiiculties and enables the purest aluminium to be obtained in one furnace, by means of a single operation, starting from A1202, without addition of copper, or any other manipulations.

The furnace consists of two containers, communicating at their bases, where two electrolyses may proceed simultaneously.

(a) The first electrolysis of A1203 dissolved in cryolite and CaFz (the usual electrolyte for this operation) produces crude aluminium.

(b) The second electrolysis refines this crude aluminium by means of the electrolyte usually employed in refining furnaces.

The crude liquid aluminium, obtained in the first electrolysis acts as a bipolar electrode, functioning simultaneously as cathode for the first and as an anode for the second electrolysis, since it flows between the two electrolytes.

The annexed drawing indicates one possible rendering of such a furnace, which could, of course, be modified to any appropriate form.

In the drawings:

Fig. 1 is a central vertical sectional view of a furnace embodying my invention; and

Fig. 2 is a plan view of the same.

As shown in the drawing the furnace indicated generally at P includes an outer container I preferably provided with a lining 2 of suitable refractory material, such as MgO, resistant to the corrosive action of the melted salts used for the electrolysis. If desired, the walls of this container may be provided with auxiliary electrodes for the initiation of the procedure within the furnace. As illustrated, the bottom of the container I may either be formed from refractory material, like the walls, or it may be partially or completely constructed of an auxiliary electrode, also intended for use in connection with the initiation of the procedure.

Within the outer container I is an inner container 4, open at the top and bottom, and spaced from the bottom of the outer container, thus forming two compartments. Preferably the inner container is provided with a suitable lining 5, of graphite or the like, which terminates short of the lower extremity of said inner container.

Positive electrodes 6 are positioned within the inner container l so as to dip into or be immersed in the solution B of A1203 in cryolite, an electrolyte normally used for the production of crude aluminum. The negative pole of this electrolysis is composed of melted crude aluminum, indicated at All beneath the solution B within the inner container.

The second electrolysis, effected by the electrolyte C which is of higher specific gravity than molten aluminum, has a soluble anode, comprising crude aluminum, as a positive pole and the negative pole comprises the layer of refined aluminum indicated at A12, in contact with the negative electrodes 3 which are positioned in a zone located within the outer container I, exteriorly of the inner container 4.

I claim:

An improvement in the process of producing refined aluminum, which comprises arranging a layer of aluminum refining electrolyte of higher specific gravity than molten aluminum below a layer of crude molten aluminum, placing a layer of aluminum producing electrolyte of lower specific gravity than molten aluminum on the upper surface of the crude aluminum, passing an electrolyzing current from a fixed anode through the aluminum producing electrolyte in contact therewith to the crude aluminum as a bipolar electrode and through the aluminum refining electrolyte to a fixed cathode in contact therewith, feeding A1203 into said aluminum producing electrolyte, and collecting the refined molten aluminum formed at the cathode at a portion of the upper surface of the refining electrolyte which is in a zone electrically and physically separated from the fixed anode, the aluminum producing electrolyte and the crude aluminum layer.

ALEXANDRE GLAZUNOV.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name I Date 830,051 Carrier Sept. 4, 1906 1,833,425 Jessup Nov. 5, 1931 1,937,509 Burgess Dec. 5, 1933 FOREIGN PATENTS Number Country Date 500,509 Great Britain Feb. 10, 1939 220,856 Germany Apr. 8, 1910

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