DE1222686B - Process for better deposition of metals, especially in the production of aluminum, magnesium and titanium, by fused-salt electrolysis - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

C22d

German KL: 40 c -3/00

Number: 1222 686

File number: E 24507 VI a / 40 c

Filing date: March 16, 1963

Opening day: August 11, 1966

Relatively low-melting metals, especially the light metals aluminum and magnesium, are still used today technically by melt electrolysis at temperatures that are more or are less above their melting point, obtained so that they are withdrawn in liquid form can.

With the application of fused-salt electrolysis to the refractory transition metals, in particular Titanium and zirconium, one went over to the extraction of these metals in solid form and works at temperatures that are in some cases far below the melting point of the metals.

After a not yet become known procedures, more recently, light metals, such as Al umi minium and magnesium, won far below their melting points by igneous.

The deposition of the metals on the cathode in solid form has certain disadvantages. The ao Metal does not deposit in a tightly fitting form, but rather forms a tip for a longer or shorter period of time Needles, skewers, or leaves that can trap significant amounts of the electrolyte. The melt is already enclosed by the metal while it is being deposited. This can take place in two forms that merge into one another:

1. The metal grid is open to the outside, like pores in a sponge;

2. The metal grid is closed to the outside, the melt is enclosed in it, e.g. Water in foam.

Further considerable amounts of melt remain when removing the cathodes in addition to the Melt parts encased during electrolysis adhere to the surface. This adherent melt and the melt parts bound in the form of a sponge succeed, to a large extent, by heating and optionally Spin to drain. From the foam-like bonded melt parts the melt does not remove itself in a simple manner.

In the fused-salt electrolysis of titanium, the molten metal precipitate of the cathode separated and washed in water or acid, the salt goes into solution and that Titan remains behind. The slight oxidation of the titanium which occurs in the process, but which is already too significant Can lead to increases in hardness, attempts are made to prevent various measures, e.g. B. by crushing the recovered metal and sorting out the average degrees of fineness that make the

Process for better separation of
Metals, especially in the manufacture of
Aluminum, magnesium and titanium
Molten electrolysis

Applicant:

Electrophysical Institute Bernhard Berghaus, Vaduz (Liechtenstein)

Representative:

K. Gerlings, lawyer,

Siegburg, Mühlenstr. 14th

Named as inventor:

Bernhard Berghaus, Zurich;

Dr.-Ing. Marie Staesche, Wettingen (Switzerland)

Claimed priority:

Switzerland of March 23, 1962 (3477,3479)

have the lowest oxygen content, or through the deposition of larger crystals (with cheaper Ratio of volume to surface), which absorb correspondingly less oxygen, namely by means of increased electrical power during electrolysis.

Another titanium electrolysis process works to reduce the proportion of melt in the deposited Metal with a basket cathode, which, however, leads to a relatively low current yield.

While only a certain oxidation of the titanium is to be feared when separating the titanium metal from its melt by washing with water, washing out the melt leads to noticeable metal losses in the case of light metals, since the free HCl resulting _{from the hydrolysis of AlCl 3} or MgCl _{2 is the result} Partly attacks the metal powder obtained and converts it into hardly usable salts.

The object on which the invention is based was therefore to find a method with which Help the proportion of the melt in the precipitate on the cathode of the electrolytic cell significantly can be reduced.

According to the invention, this is in particular in a method for better deposition of metals in the production of aluminum, magnesium

609 609/324

1 222 086 "^;: - ^;

3 4

and titanium, by fused-salt electrolysis, if they contain up to 1% addition of an-Mg; Cl, H and N double halides at bath temperatures below the melting point of the catalyst contained according to the German Ausabzuidenden Metals legend 1209 757, achieved at a temperature of 540 in that the electrolyte is obtained by partial up to 560 ⁰ C, titanium by electrolysis _a temperature increase in the main area , the ion 5 melt of sodium-titanium-fluoride with up to'1% migration and / or by adding the toughness addition of a Ti; Cl, H and N-containing catalysis * reducing substances is made thinner. tors according to the German interpretation document 1209 757, at

The center of the 'partial temperature increase 680 to 750 ° C.

can with advantage Aa the end point of the ion wall- 'The metal deposited on the cathode became

tion, i.e. in the separation room. io not like in the extraction of aluminum under

In this case, the partial temperature increase in the protective gas is melted into a regulus,

expediently by heating the cathode of the elec- tric but in water (with Mg) or 5% sulfur

trolysis cell causes. Another advantageous possible acid (in the case of Ti) dissolved, the 0.01 to 5 g / l of an upper

possibility is to find the center of the partially surface-active sulfonated substance according to the German

Temperature increase in the starting point of the 15 see Auslegeschrift 1200 554 were added. as

Bend ion migration. In this case the surfactant was Teepol, a sulfonating

partial temperature increase expediently by means of the best petroleum product, used,

causes heating of the anode of the electrolytic cell. This is invented using the following examples

Preferably, however, both methods are explained in more detail in the embodiments, the

starting point as well as in the end point of the ion 20 Examples 1 and 2 the production of aluminum

migration Centers of partial temperature increase ^: concern,
placed, with the partial temperature increase

expediently by heating the anode and example 1
Cathode of the electrolytic cell is effected. The electrodes are preferably heated from 25 a) On a cathode made of aluminum sheet, the interior of the electrodes was off, that is, by using, after the electrolysis, 8.47 g of precipitate of hollow electrodes, which were heated inside. been beating that after melting together

The toughness-reducing substances under protective gas were a regulus of 1.04 g of aluminum, preferably silica gel, gelatin, organic sulfonium, corresponding to 12.3% aluminum ,
acids and organic metal compounds, such as 3 °. b) On one by embedded electrical heating metal alkyls, into consideration. When using organospirally internally heated aluminum cylinders as Käscher compounds as substances to reduce the method, it is of course necessary to ensure that the externally adhering melt is allowed to drip off the externally adhering melt when heated to a precipitation of 23 , 87 g from, doors of the: Do not decompose the electrolysis bath, unless it was 35 that resulted in an aluminum regulation of 8.40 g, discover that the decomposition products of these substances are equivalent to 35.2% aluminum,
also have a toughness-reducing effect or even to a greater extent. Example2

The decrease in the viscosity of the electrolyte,

be it by means of a partial temperature increase in the 40 a) were on a cathode made of aluminum sheet

Main area of ion migration or by means of the 8.47 g of precipitate deposited after electrolysis

Toughness-reducing substances, leads to a size that becomes larger after melting

reduce mobility of the ions in the electrolyte. A regulus of 1.04 g of aluminum under protective gas

Proof of this can be seen in the fact that it resulted in 12.3% aluminum (same as

Metal precipitation occurs when using the inventive example 1, a).

according to the method evenly over the b) In an alkali-aluminum-chloride melt

total cathode area both on that of the anode was 0.5% (based on the total weight of the

facing side as well as melt) silica gel added on the opposite side. After electrolysis

distributed while without application of the invention, 6.56 g of precipitate were found, the one

proper method in the. Usually the main part 50 regulus of 3.09 g = 47% aluminum resulted,

of the precipitate on the seal on the cathode facing the anode, pure aluminum was removed.

Side of the cathode and deposited on the opposite, while after the outer layer

Side is a much lower rainfall. mend more melt together with the aluminum

Due to the increased mobility of the ions when deposited and the outer layer, the main application of the method according to the invention occurs 55 amount of the melt contained,
From the outset, a more uniform distribution of the. Examples 3 to 6 relate to the production of ions and thus also of the deposit on the magnesium on Mg cathodes.
Cathode on, so that the formation of points, edges, spikes and ramifications of the deposit in Example 3
the cathode surface and thus of course also 60. _(without applying the previous procedure)
the inclusion of melt in the deposition 00 /
is significantly reduced. Unheated cathode (plate-shaped) - 10.72 g

That these measures also give the melt flow precipitation 1.47 g of magnesium = 13.7%.
electrowinning of other metals in

The following 65 Example 4
Examples of the production of magnesium

and titanium. Magnesium was obtained by electrolysis of a heated cathode (cylindrical) - 22.36 g of low

Carnallite melt (KCl-MgCl ₂ ), given 7.25 g of magnesium = 32.4%.

Example 5
Addition of 0.5% silica gel

Unheated cathode (plate-shaped) - 8.24 g of precipitate give 2.96 g of magnesium = 36.0%. 5

Example 6
Addition of 0.5% silica gel

Heated cathode (cylindrical) - 23.58 g low-io 10.78 g of magnesium = 45.8%.

Examples 7 to 9 relate to the production of titanium on Ti cathodes.

Example 7 * 5

(without applying the present procedure)

Unheated cathode (plate-shaped) - 6.58 g of precipitate give 1.04 g of titanium = 15.8%.

ao example 8

Heated cathode (cylindrical) - 24.59 g of precipitate gives 8.22 g of titanium = 33.5%.

Example 9
Addition of 0.5% silica gel

Unheated cathode (plate-shaped) - 7.15 g of precipitate give 2.47 g of titanium = 34.6%. 30th

Example 10
Addition of 0.5% silica gel

Heated cathode (cylindrical) - 25.02 g of precipitation give 12.2 g of titanium = 48.7%.

Claims (7)

Patent claims: 1. Process for better deposition of metals, especially in the production of Aluminum, magnesium, and titanium, by fused-salt electrolysis of their double halides at bath temperatures below the melting point of the metal to be deposited, thereby characterized in that the electrolyte by partial temperature increase in the main area of ion migration and / or is made thinner by adding toughness-reducing substances. 2. The method according to claim 1, characterized in that the partial temperature increase is effected by heating the cathode and / or the anode of the electrolytic cell. 3. The method according to claims 1 and 2, characterized in that internally heated hollow electrodes be used. 4. The method according to any one of claims 1 to 3, characterized in that as the toughness Degrading substance silica gel is used. 5. The method according to any one of claims 1 to 3, characterized in that as the toughness degrading substance gelatin is used. 6. The method according to any one of claims 1 to 3, characterized in that as the toughness an organic sulfonic acid is used as a degrading substance. 7. The method according to any one of claims 1 to 3, characterized in that as the toughness Degrading substance, organic metal compounds, especially metal alkyls, are used will.