US935796A - Production of magnesium. - Google Patents

Description

P. VON KfiG LGBN & G. 0. SBWARD.

' PRODUCTION OF MAGNESIUM.

APPLIOATION FILED JULY 8, 1907.

935,796, Patented Oct 5, 1909."

FIG.

FIG. 2.

outrun PATENT orrion CIRA'NZ VON xuemn'enn, or HoLcoMns ROCKVIRGINIA. Ann enonen'o. snwnnn; or

EAST ORANGE, NEW JERSEY, ASSIGNORS TO vmemre NEW YORK, n. Y., A oonronarron or NEW roux.

ILABORATORY COMPANY, OF

. rizoimc'rron or MAGNESLUM.

Specification of Letters Patent. Patented Oct. 5, 1909.

Application filed July 8, 1907.. Serial Nb. 332,596.

To all'whom it may concern: .1

Be it known that we, FRANLyoN KilGEL- only, a ubject of the-*GermanEmperor, res ding Holcombs Rock, in the county of Bedford and State of Virginia, and GEORGE O. SEWAnD, a citizen ofthe United States, residing at East Orange, in the county of Essex and State of New Jersey, have jointly invented certain new and usefullmprovements in the Production of Magnesium, of

' .which the following is a specification.

can be used tolower the specific gravity of to insure a good The production of magnesium by the electrolysis of its molten chlorid is drfiicult for the reason that the specific gravity of the electrolyte is very nearly the same as that of the metal and there are no fluxes which the electrolyte sutficient-ly separation of the metal therefrom.

Moreover, it is exceediugly difficult to avoid the introduction of impurities such as iron when preparing the electrolyte, and

such impurities,-being.-less 'electro-positive than magnesium and deposltxing together with magnesium,cause the formation of a I spongy deposit of metal at the cathode which prevents the merging of the globules of ma nesium.

he present invention provides a method for the production of magnesium which overcomes the above-mentioned difiiculties and which is characterized by being a pr'oc- I ess 1n two steps or operations.

The first step produces an alloy of magnesium with a less electro-positive metal-by clectrolyzing a molten magnesium electrolyte With'a-n insoluble anode and a cathode of a molten me al, less 7 electro-positive than magnesium. T esec such alloy,

ondstep produces 'pure magnesium by consecutivefdissolution and deposition from the latter being used as the anode in -a suitable electrolyte. In the first step the initial electrolyte, are separated together with the magnesium and are absorbed by the molten alloy of the cathode. In the second step these impurities, being les'selectro-positive than magnesium, are not dissolved there with 'but remain in the molten anodenpure magnesium being lthus produced. In the first'step an electrolyte of lows ecific gravity is used so 'thatan alloy very ich in mag nes1u1ir:can be. produced Without danger of electrolytic vessel. In the second step an I electrolyte is used of sufiiciently high spegcific gravity to insure the rapid flotation i of the magnesium to the surface as soon as fdeposited and its collection there. As a 1 cathode in the first step, We select a metal j which (1) alloys easilywith magnesium and forms a sufficiently fusible alloy therewith; (2) is capable of dissolving the impurities of the electrolyte which are less electro-positive than magnesium, and hence are deposited therewith; (3) is less electro-positive than magnesium so that, in the second step of the process, it remains unchan ed while the magnesium dissolves in' the electrolyte. Aluminum combines these three properties and is a suitable metal for the cathode alloy. In practicing our invention We proceed preferably as follows :-We subject a molten electrolyte of the approximate composition MgClH-KCI to the action of a continuous electric current in a suitable vessel, using carbon anodes and a cathode of molten aluminum. The magnesium produced at the cathode alloys with the aluminum. As the electrolysis proceeds the alloy becomes richer in magnesium; when it contains from '50 to 60 per cent. of magnesium it is removed either in whole or in part and is used as the anode in the second step of the process,

The electrolyte in the second step may-be that a certain proportion of a heavy salt of a more electro-positive metal than magnesium- (e. g. lmrilnn-chlorid) is added to increase the specific gravity and facilitates the flotation of the magnesium. As magnesium is dissolved from the anode to the same extent as it is deposited. at the cathode, the electrolyte in the second step ofjthe process remains substantially unchanged. A Magne- -sium,being the most electro-positive constituent of the molten anodedncthe second step of the process, is alone dissolved and redeposited, care being taken to avoid exhaustng the anode content.

is a Vertical-section of a suitable electrosuitable for the second step.

too much of its magnesium lytic cell for use; in the first step of the process, and Fig. 2 as similar section of a cell Referiing to Fig. 1,the electrolytic cellsimilar to that in the first step excepting In the accompanying drawings, Figure 1 or vessel Ais shown as constructed with a. receptacle C, which may be of cast metal, having a carbon lining D in its lower part and a water-jacket E surrounding 1ts upper portion, whereby the electrolyte 1s chilled or incrusted to form a protective coatmg'F. The vessel is covered by a top or lid G, which may be of graphite, and which is separate'd from the metal vessel below by an insulating layer H. Through the graphite top project one or more anodes J J which may be of graphite. These are connected to the positlve terminal of the dynamo or other generator K, its'negative terminal being connected tb' the vessel C or carbon l1 ning D. A tap-hole L is provided through which to draw o'fi the aluminum. An opening Q may-be for the escape 0 chlorin.

Referring to Fig.2 the electrolytic cell or vessel B in which the second step of the process is performed, may be in general of somewhat similar construction to the vessel A. Its body or receptacle C may be a duplicate of the vessel C, with a carbon lining D and a water jacket E, forming a chilled layer of salt F and having a tap-hole L.

The cover G is here shown of cast metal separated from the vessel C by insulation H. The cover has a flange I projecting down beneath the surface of the electrolyte, so that it may serve initially as the cathode. It may also have a suitable lid M. The positive terminal of the generator K is connected to the vessel G or lining D, while its negative terminal is connected to the cover G. j

In operation, the alloy of magnesium and aluminum which is, obtained in vessel A is used as the anode in vessel B. After the second step has been in progress for a short time the separated magnesium covers the surface of the electrolyte and acts as the true cathode. I

The operation in vessel A is made continuous by tapping off a part of the electr'olyte from time to time and replacing it by exhausted alloy from the anode of vessel B.

The operation in vessel B is made continuous by removing alarge part of the magnesium from time totime, and bytapping most of the nearly exhausted alloy of 1 the anode from time to time and replacing by rich alloy from vessel A. r

Though we have described the use of a chlorid electrolyte in both steps of our invention, we do not confine ourselves to such use, but may use any suitable electrolyte for 1 either stepof the process. a

We are aware that impure aluminum has been purified by using it. as the anodeand dissolving it by electrolyzingwith a solvent electrolyte, redepositing the resulting pure aluminum at the cathode. But we are not aware that this process-has been applied rovided through the lid G duction of magnesium by the electrolysis of its chlorid as hereinbefore stated, are dift'erent from those existing with aluminum. .4 .By our invention we make as the first step of the process asuitable alloy of magnesium, solely in order that we-may use this alloy as the anode in the final step of the process, from which to dissolve out therefrom the pure magnesium and collect it at the. to of the electrolyte. We thus avoid the di culty herein stated that in the direct production of magnesium from its molten chlorid the specific gravity of the electrolyte is so nearly that of themetal as to impede the separation of the metal therefrom.

We claim as our invention 1. The process of obtaining magnesium which consists in producing an alloy of magnesium with a less electro-positive metal by electrolyzing a suitable electrolyte with a cathode of said metal; and subsequently dissolving the magnesium out of said alloy by using the latter as an anode with a suitable molten electrolyte and' depositing the magnesium at the cathode.

2. The process of obtaining magnesium which consists in electrolyzing a magnesium salt with a cathode of a metal less electropositive than magnesium and 'whichforms therewith an alloy of lower melting point; and subsequently dissolving athe magnesium out of said alloy by using the latter asan anode with a suitablemol'ten electrolyte and depositing the magnesium at the cathode.

3. The. process of obtaining magnesium which consists in electrolyzing fused magnesiumchlorid with a cathode of a metal less electro-positive than ma nesium'to form an alloy therewith; and su sequently dissolving the magnesium out of said alloy by using the latter as an anode with a suitable molten electrolyte and depositing the magnesium at the cathode.

4. The process of obtaining magnesium.

which consists in electrolyzing a magnesium J1 salt with a cathode of molten alumlnum to produce a magnesium-aluminum alloyg'and,

subsequently dissolving the magnesium-out of said alloy by using the latter'as ananode' witl 1 a suitable molten electrolyte and. depositing the magnesium at the cathode;

5. The process-of. obtaining mag esimn.

aluminum alloy thereby addin ma'gnesiumto such alloy; and subsequent y dissolving the magnesium out of said alloy and using the latter as an anode witha suitablemolten electrolyte and depositing-the magnesiinnat the .cathode.

which consists in electrolyzlngmagnesium 6. The process of obtaining magnesium gravity,,whereby the magnesium separated. at the cathode is caused to float upon the l0 chlorid with a cathode of molten aluminum to form a niagnesiinn-aluminum alloy; and subsequently dissolving the magnesium out of said alloy by using the latter as an anode with an electrolyte of magnesium chlorid. to which is added a heavy salt of a more electro-positive metal to increase its specific electrolyte.

7. In the process of obtaining magnesium by first electrically producing an alloy thereof with another metal, the step of recovering the magnesium from said alloy which consists in electrolyzing'an electrolyte of a magnesium salt to which a heavy salt of a more electro-positive metal has been added to increase its specific gravity, using said alloy as the anode whereby magnesium is dissolved out therefrom and deposited at the 20

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