CA1069315A

CA1069315A - Method for preparing manganese chloride and manganese by igneous electrolysis of the manganese chloride obtained

Info

Publication number: CA1069315A
Application number: CA253,489A
Authority: CA
Inventors: Rene F.P. Winand
Original assignee: Universite Libre de Bruxelles ULB
Current assignee: Universite Libre de Bruxelles ULB
Priority date: 1975-05-27
Filing date: 1976-05-27
Publication date: 1980-01-08
Also published as: SE7605989L; GB1536041A; JPS5217392A; JPS5537491B2; DE2623436A1; IT1063201B; SE409850B; ATA384476A; AT349434B; NL7605625A; CH601112A5

Abstract

ABSTRACT OF THE DISCLOSURE

This invention relates to a method for preparing manganese chloride from at least one oxidized manganese com-pound. The oxidized manganese compound is lixiviated with any one of calcium chloride, magnesium chloride or alkaline and alkaline-earth chlorides. The reaction between the oxidized compound and the chloride produces the manganese chloride in a liquid form. The method provides a high productivity yet obviates the problems of corrosion in the equipment and the requirement of condensing gases as in known methods.

Description

10~ 15 This invcntion has for object a method ~or preparing manganese chloride from at least one oxidized manganese compound.
This method is particularly useful for elabo-rating metal manganese with more than 95% maganese by igneous electrolysis.
It is known in the present art, as described in the following disclosures:A.H. SULLY - Manganese -Butterworths - London (1955~, Ullmans Encyklopadie der Technischen Chemie- Band 12 - Urban und Schwartzenberg -M~nchen - (1960), DURRER/VOLKERT - Mettalurgie der Ferrole-gierungen-Springer Verlag Berlin ~1972), to elaborate the metal manganese by silicothermic or aluminothermic reduction of oxidized manganese compounds, by electrolysis in aqueous sulfuric solution (R.S. DEAN-Electrolytic Manganese and its Alloys - The Ronald Press Company - New-York - 1952) or in aqueous hydrochloric solution (J.H. JACOBS and P.E. CHURCHWARD
Trans. Electrochem. Soc. 94 (1948) 108-121), by electrolysis of oxidized manganese compounds dissolved in calcium fluoride (U.S. Pat. 3,018,233) or by electrolysis of molten oxide mixtures (Belgian Pat. 683,660~. Many works show moreover that it is easy to obtain manganese at the cathode of an electrolysis cell operating with molten chloride baths in which the manganese is present as manganous chloride MnC12 ~U.S. Pat. 2,752,299 ; 2,752,303 ; 2,877,110 ; 3,024,106 ;
Brit. Pat. 880,017).
It thus became clear that the manganous chloride could form an attractive raw material for the preparation of metal manganese by electrolysis as long as it is possible to obtain an electrolyte containing manganous chloride under ~ .
- 1 - ~

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attractive cost conditions.
For instance to elaborate manganous chloride, many writers have studied the chlorinating of oxidized manganese compounds by chlorine gas and by hydrochloric acid gas:U.S. Pat. 2,752,299 ; Brit.Pat. 880,017 ; G.Pat. 1,106,622 ;
Y. OKAHARA and I. IWASAKI - Trans. AIME 247 (1970)73-80 ;B.T.
MAC MILLAN and T. L. TURNER - U. S. Bureau of Mines R.I. 5082 (1954) and 5281 (1954) ; A.A. COCHRAN and W. L. FALKE - J. of Metals-(1967) 28-32 - U.S. Bureau of Mines R.I. 6859 (1967);
H. HOHN, B. JANGG, L. PUTZ and E. SCHMILD, Progress in Mineral Dressing - Ed. Almgvistand Wiskell (Sweden) (1958)683-703 -Y. G. BUCHU - KURI and M. I . MEHEDLISHVILI Soobshch. Akad. Nauk.

Gruz . S . S . R. 57 ( 2) ~1970) 349-352~ .
Such a chlorinating reaction leads either to volatilizing the manganous chloride which is thereafter condensed, or to the forming of a chlorinated mass obtained with said reaction and containing said manganous chloride, which manganous chloride can be separated by aqueous lixiviating.

In the latter case, the manganous chloride is crystallized by ~vaporating the water from the aqueous solution and thereafter it is dehydrate by heating.
Said elaborating methods have however many drawbacks which are notably associated with the treatment instal-lations being corroded by the chlorine or hydrochloric acid, w~ th~ problems for condensing chloride gases or with the diffi-culty for dehydrating the manganous chloride without conta-minating same with oxides or hydroxides.
Still another method lies in performing the volatilizing chlorinating of manganese from oxidized manganese compounds by making use of calcium chloride as chlorinating 3~5 agent, as described by M~C MILI~N and ~rul~ER (U.S. Bureau of Mines R.I. 5082 (1954) and 5281 (1954) above), and A.
BOYADZHIEV (Minne Delo Met. (Sofia) 18 (7) (1963) 29-33).
A technical and economical study of this latter method shows that even if it is easier to perform than chlorinating with chlorine gas or hydrochloric acid gas due to the better behaving of the installations relative to corrosion, it is however required to use a very high flow rate of carrier gas to insure a high enough productivity on an industrial scale, and the condensing of MnC12 vapour even if it is possible causes technological problems which are difficult to solve to ob~ain satisfactory condensing through-puts.
The object of the invention is to provide a new method for preparing manganese chloride from oxidized manga-nese compounds, particularly the preparation of an electro-lyte for the igneous electrolysis used to produce manganese chloride, method with which it is possible to obviate the drawbacks of the above-described known methods.
For this purpose according to the invention, the oxidized mansanese compound is lixiviated with at least one chloride selected in the group formed by the calcium chloride anf the magnesium chloride~ so as to obtain by the reaction of the oxidized compound with said chloride, the manganese chloride in the liquid form.
Advantageously the oxidized manganese compound is lixiviated with a molten salt bath that contains besides one compound selected in the group formed by the calcium chloride and the magnesium chloride, alkaline and alkaline-earth chlorides other than the ones mentioned above.

Other details and ~eatures of the invention will stand out from the description given below by way of non limitative example, of some embodiments vf the invention.

The method according to the invention lies essetially in the lixiviating of the oxidized manganese compounds with calcium dichloride, magnesium dichloride or mixtuxes of alkaline or alkaline-earth chlorides that contain at least one of both said c~lorides so as to elabo-rate directly manganous chloride in liquid form, in solution in a molten salt bath. Thus the problem associated with the volatilizing and condensing of the manganous chloride as in the known art, is avoided.
It has been noticed according to the invention that it is easily possible to separate by decanting and filtering, the solid residue obtained by reacting calcium chloride and/or magnesium chloride with oxidized manganese compounds from the molten chloride bath formed so as to obtain directly an electrolyte which after puryfying, for example by a pre-electrolysis under low voltage or by a treatment with crushed ferro-manganese as described in ano ther patent in the name o~ the Inventor, could be subjected to electrolysis for elaborating metal manganese.
Advantageously in the method according to the invention, the chlorine contained in the calcium chloride or magnesium chloride used for lixiviating and released at the electrolysis cell anode can be recovered and commercia-lized. This is a remarkable advantage relative to the known methods for chlorinating with chlorine gas or hydrochloric acid gas.

The exidized manganese compounds to be r~acted ~0~1315 with the calcium chloride anc~or mac3nesium chloride are manganous oxide, manganese carbonate, hlgher oxicles such as Mn304, Mn203 or MnO2, hydrated, carbonated, siliceous or oxidized manganese ores, or else metallurgy residues such as slag from Martin furnace, electric steel furnace or ferro-manganese or silicomanganese-elaborating furnace, that is any material containing manganese combined with oxygen.
In a particularly advantageous embodiment, use is made as oxidized manganese compound, of a compound in which the manganese is bivalent; under such conditions, said oxidized compound is comprised of manganese carbonate, it is not required to decompose same before performing thereon the chlorinating; the decomposition may indeed occur together with the chlorinating.
On the other hand, if the manganese present in the oxidized compound to be treated has a valence higher than two, it might beadvantageous but not indispensable to perform a previous reduction of the oxidized manganese compound down to valence two for example by means of carb~n monoxide, hydrogen or carbon, or to perform the chlorinating in a reducing atmosphere in the presence of a solid reducing agent such as carbon.
In a preferred embodiment of the invention, silica, alumina or a mixture of both said materials is added to the oxidized manganese compound to be chlorinated, so as to form silicates, aluminates or silico-a]uminates together with the calcium or magnesium oxides produced by the chlo-rinating reaction. Under such conditions, the temperature to he reached for the lixiviation may be lower by a hundred Celsius degrees relative to that temperature which would ~0~:3~5 be required in the absence of sllica or alumina to obtain the same manganous chloride concentration in the molten salt bath.
It is clear that the silica or alumina could also be part of the oxidized manganese compound to be chlori-nated, which would be the case for slag or ore for example.
- Moreover in some cases to lower the melting point of the ~lectrolyte, to lower the vapour pressure or to influence the thermodynamic action of one component in the molten salt bath before or after the chlorinating reaction, it might be useful to add to the molten salts, small amounts of other haloids or oxides.

A practical example of a particular embodiment of the method according to the invention will be ~iven hereinafter.

Example.
Loads each comprising one mole MnO or MnC03 have been heated in the presence of one mole CAC12 and one half mole SiO2 under cover from air during one half hour at various temperatures. After decanting, it did appear that the overfleoting liquid phase comprising MnC12 and CaC12 had molar ratios MnC12/CaC12 from 0.2 to 0.8 when the reaction temperature is raised from 800 to 1000Co The tests have shown that the reaction is very fast and that the balance appears to be reached. Moreover, the solid residue is easi-ly de~anted and the hot filtering does not cause any problem.
The elaboratea MnC12-CaC12mLxture~éæ suitable f~ a direct electrolysis which gave solid, powdery and dendritic manganese deposits. After melting said deposits, it was pos-sible to obtain massive manganese metal with a puritybetter than 99.9% manganese.
It is o be noticed that the usable temperature ~0~,315 range is very large, said temperature being limited on the one hand but by the melting temperature of the chloride mixture used for lixiviating and on the other hand but by the boiling point of the manganous chloride that lies at 1230~C when it has a unit thermodynamic activity and a higher temperature when this thermodynamlc activity is lower than a unit value. However due to kinetic reaction conditions on the one hand and to spare the energy required on the other hand, it has been noticed that temperatures lying between 300 and 1200C and preferably between 500 and llOO~C
allow to obtain valid industrial resu~ts.
The calcium chloride used can be a~y-product of the Solvay method for elaborating sodium carbonate or it can originate from more complex salts extracted from underground rock-salt mines or salt-pans, or even rom brine from sea-water unsalting installations after evaporating and dehydrating.
It must be understood that the invention is in no way limited to the above embodiments and that many changes can be brought therein without departing from the scope of the invention as defined by the appended claims.

Claims

The embodiments of the invention in which an exclu-sive property or privilege is claimed, are defined as follows:

1. Method for preparing manganese chloride from at least one oxidized manganese compound, in which the oxidized manganese compound is lixiviated with at least one chloride selected in the group formed by the calcium chloride and the magnesium chloride, so as to obtain, by the reaction of the oxidized compound with said chloride, the manganese chloride in the liquid form.

2. Method as defined in claim 1, in which the oxidized manganese compound is lixiviated at a temperature lying between 300 and 1200°C.

3. Method as defined in claim 2, in which the oxidized manganese compound is lixiviated at a temperature lying between 500 and 1100°C.

4. Method as defined in claim 1, in which the oxidized manganese compound is lixiviated with a molten salt bath that contains besides one compound selected in the group formed by the calcium chloride and the magnesium chloride, alkaline and alkaline-earth chlorides other than the ones mentioned above.

5. Method as defined in claim 4, in which after the reaction of the oxidized manganese compound with the calcium chloride or magnesium chloride, a decanting is performed followed by a hot filtering so as to separate the reaction solid residue.

6. Method as defined in claim 1, in which after the reaction of the oxidized manganese compound with the calcium chloride and/or magnesium chloride, the metals nobler than manganese are removed from the molten salt bath.

7. Method as defined in claim 1, in which the liquid manganese chloride is subjected to an igneous electro-lysis so as to settle the manganese on the cathode.

8. Method as defined in claim 7, in which the manganese settled on the cathode is subjected to a melting followed by solidifying.

9. Method as defined in claim 1, in which the compound subjected to lixiviating is selected in the group comprised of MnO, Mn304, Mn203, MnO2, manganese carbonate, hydrated, carbonated, siliceous or oxidized manganese ores, metallurgy residues such as slag from Martin furnace, electric steel furnace and ferromanganese or silicomanga-nese-elaborating furnace.

10. Method as defined in claim 9, in which when the oxidized manganese compound contains at least a portion of manganese with a valence higher than two, said lixiviating is made in the presence of a reducing agent such as carbon monoxide, hydrogen or carbon.

11. Method as defined in claim 9, in which when the oxidized manganese compound contains at least a portion of manganese with a valence higher than two, said compound is subjected to a reducing treatment for bringing substantially all of the manganese down to valence two before said lixiviating.

12. Method as defined in claim 1, in which before lixiviating, to the oxidized manganese compound is added at least one compound selected in the group compri-sed of silica and alumina.