US1382808A - Process of precipitating aluminium compound - Google Patents

Description

M. 0. SEM.

PROCESS OF PRECIPITATING ALUMINIUM COMPOUND-S.

APPLICATION FILED APR. 23, 1918.

Patented June 28, 1921.

Ovrom S em 98 rm mh mm 6 VM n I flWM Aflorneys v trolysis the reduction taking place at the.

pNlTE/D STATES.

PATENT OFFICE.

MA'l I-IIAS OVROM SEM, 0F GHRISTIANIA, NORWAY, ASSIGNbR- TO DET NORSKE AKTIESELSKAB FOR ELEKTROKEMISK 'INDUSTRI, 0F CHIRIST'IANIA, NORWAY..

PROCESS OF IPRECIPITATING ALUMINIUM COMPOUND.

T 0 all w ham zit may concern:

Be it known that l, MATHIAs OvRoM SEM, a subject of Norway, and a resident of Christiania, Kingdom of Norway, have invented certain new and useful Improvements in position of minerals containing aluminium by means of acid. Decomposition by means of an alkali is generally used in the production of aluminium compounds. l have however found a simple method fo precipitating aluminium compounds from solutions containing aluminium combined with a mineral acid. 1 cause a precipitation of aluminium compounds by means of elec-- trolysis. The electrolysis is preferably carried out in a suitable vessel divided into anode and cathode compartments by a porous diaphragm. Preferably an insoluble anode is employed and a small amount of alkali salts isadded to the electrolyte.

When electrolysis is started aluminium hydrate, or in a sulfate solution basic 3111- minium sulfate containing varying amounts of SO will precipitate at the cathode.

Tn neutral solutions which in themselves have no oxidizing effect the precipitate -ob-' tained will be practically free from iron for the known reason. that ferrous iron will not precipitate as long as an excess of aluminium compounds is present in the solution, and because of the hydrogen evolved at the i v cathode ferric iron originally present "will be reduced and kept in the ferrous state or precipitated on the cathode as metallic iron.

On account of their low content of iron,

aluminium compounds precipitated as'above described are very well adapted for the man'- ufacture of aluminium and for similar purposes where a great purity is required.

If a nitric acid solution is used in the eleccathode will result in the formation of ammonia from nitric acid. The ammonia Wlll specification of Letters .Patent. Patented June 28, 1921, Application filed April 23, 1918. Serial No. 230,250.

tion process and use it for the decomposition of new amounts of raw material. But I, have found that if the raw material used. is fairly easily soluble as is the case with bauxite and some silicates such as labradorite, I can suspend the raw material in the anode compartment and it will then become dissolved as soon as sufficient acid is liberated, without special concentration of the acid.

As the raw materials used always contain other soluble compounds than aluminium compounds, these will combine with an equivalent amount of the acid used and must from time totime be removed from the process in the form of salts. In this case an amount of acid corresponding to that removed in the form of salts must be added to the process.

I have found that my above described method may be carried out continuously and that it is especially. suited for minerals of ment. Therefore aluminium must be supplied to the cathode compartment by other means. Also from time to time the undissolved residue from the rawmaterial must be removed from the anode compartment.

. Inthe following specific example, I will illustrate the preferred way of carrying out my process by using a sulfuric acid solution, reference being had to the accompanying drawing forming part of this application and diagrammatically" illustrating an electrolytic vat in vertical section, but t 1s of a diaphragm B of the type ordinarily used for such purposes, cocks H and I being provided to withdraw the contents of the compartments. The temperature of the solution is preferably kept at 6080 C. When electric current is supplied the voltage between anode and cathode will be about 5 volts. During electrolysis a precipitation will take place near the cathode E and at the same time the iron in the solution will be deposited on the cathode. The precipitation consists of aluminium hydrate containing small amounts of S0 in the form of adsorbed acid or a basic sulfate and is removed from the solution from time to time, subjected to washing and if pure A1 0 is desired is calcined, whereby the S0 is eliminated. The calcined product will contain less than 0.1% Fe O and is very well-adapted for the manufacture of aluminium.

In the anode compartment free sulfuric acid is formed. This acid serves to dissolve the raw material, in this case pulverized labrodorite, which is continuously added to the anode compartment, dissolution of the raw material being facilitated by agitation.

When a considerable amount of undissolved residue has accumulated inthe anode compartment electrolysis is interrupted. The anolyte is separated from undissolved residue by means of filtration and the residue, principally consisting of SiO is rejected, the filtrate being returned to the process but being in part poured into the cathode and part into the anode compartment.

At the same time a part of the catholyteis removed and subjected to crystallization in order to remove the salts which accumulate in the solution. These are principally alkali salts, as the calcium present in the raw material remains in the anode compartment in the form,of calcium sulfate, and crystallize out together with aluminium sulfate giving alum as a by-product.

The solution removed from the cathode compartment for crystallization is replaced by a corresponding amount of the filtrate obtained from the anolyte. v

The anode compartment is then supplied 3 with sulfuric acid of such a strength that the H,SO,, contained therein will replace the H SO removed from the catholyte in the form of salts. The electrolysis is then continued as before.

eeaeoe The foregoing detailed description has been given for clearness of understanding and no undue limitation should be deduced therefrom, but the appended claims should be construed as broadly as permissible in view of the prior art.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In the recovery of aluminium compounds, the process which comprises effect-' ing precipitation thereby subjecting a solution containing an aluminium mineralacid salt to electrolysis and thereby effecting precipitation of an aluminium compound at the cathode.

2. In the recovery of aluminium compounds, the process which comprises effecting precipitation thereof by subjecting a solution containing an aluminium sulfate to electrolysis and thereby effecting precipitation of a basic aluminium sulfate at the cathode.-

3. Tn the recovery of aluminium compounds, the process which comprises efiecting precipitation thereof by subjecting a solution containing an aluminium mineral acid salt to electroylsis in the presence of an alkali salt and thereby effecting precipitation of an aluminium compound at the cathode.

4. In the recovery of aluminium compounds, the prooesswwhich comprises effecting precipitation thereof by subjecting a s0- lution containing an aluminium mineral acid salt to electrolysis in a diaphragm cell and thereby efi'ecting precipitation of an aluminium compound at the cathode.

5. In the recovery of aluminium compounds, the process which comprises efiecting precipitation thereof by subjecting a so-. lution containing an aluminium sulfate to electrolysis in a diaphragm cell and thereby effecting precipitation of a basic aluminium cipitation of an aluminium compound at the cathode.

8. In the recovery of aluminium compounds, the continuous process Which comprises efl'ecting precipitation thereof by subjecting a solution containing an aluminium mineral acid salt to electrolysis in a dia-' phragm cell and thereby eifecting precipitation of an aluminium compound at the cathode and liberation of the mineral acld at the anode, and dissolving at the anode by,

the liberated acid a substance containing combined alumlnlum.

9. In the recovery of alumlnlum comv pounds, the continuous process Which comprises effecting precipitation thereof by subjecting a solution containing aluminium sulfate to electrolysis in a diaphragm cell and thereby eifecting precipitation of a basic aluminium sulfate at the cathode andliberation of sulfuric acidat the anode, and dissolving at the anode by the liberated sulfuric acid a substance containing combined aluminium.

10. In the recovery of aluminium compounds, the continuous process which comprises effecting precipitation thereof by subjecting a solution containing an aluminium mineral acid salt in the presence of an alkali salt to electrolysis in a diaphragm cell and thereby efiecting precipitation of an aluminium compound at the cathode and liberation of the mineral acid at the anode, and dissolving at the anode by the liberated acid a substance containing combined aluminium.

11. In'the recovery of aluminium compounds, the process Which consists in making a solution of aluminium salt by subjecting a mineral containing combined aluminium to the action of a mineral acid, subjecting the solution so formed with the addition thereto of an alkali salt to Vel'ectrolysis in a diaphragm cell having an insoluble anode, thereby efiecting pre-' clpitation of aluminium compound at the cathode and liberation of the mineral acid at the anode, and dissolving at the anode by the liberated acid more of said mineral. Signed at Christiania, Norway, this 7th day of March, 1918.

MATHIAS OVROM SEM.

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