US3028233A - Recovery of manganese from metallurgical slags, dusts, and ores - Google Patents

Description

3,028,233 RECOVERY oF MANGANESE FROM METALLURGICAL D1 RANA. E ,m Emy Awa HDM c@ S51 .mi CLF .S J

April 3, 1962 .All

. S Eg www VE O EE@ oo Nw mm J l Mm VIJIIIIJ ME Y B Q; @N E @n mE/mw. 4 @N\ -Smmwm Em :dffwwwmr @E Q: N UI @2 5/m: N mia II|\ mm m32/ M651@ 3,028,233 RECUVERY F MANGANESE FRM METALLUR- GlCAL SLAGS, DUSTS, AND @RES .lames C. Schaefer, North Roy-alten, and Ernest C. Schmidt, Euclid, Ghia, assiguors to Walter M. Weil, Shaker Heights, Ohio Filed May 31, 1960, Ser. No. 32,910 Claims. (Cl. "iS-112) This invention relates to the recovery of substantially pure manganese from metallurgical dusts, slags, and natural and synthetic ores containing manganese in the form of metal or oxide, or both, generally in admixture with relatively large quantities of undesired materials such as carbon, oxides of alkali metals, alkaline earth metals, iron, aluminum, silicon, and the like. The invention is particularly suited for the recovery of manganese from so-called precipitator dusts collected in the course of various metallurgical operations, such as the production of steel. However, the invention is also applicable to the recovery of manganese from metallurgical slags and natural and synthetic ores in which the commonly occurring undesired materials are present in varying quantities compared to the manganese content.

In Patent No. 2,877,110 of Cooper, Schaefer, and Schmidt, a process is disclosed for the recovery of manganese from the above-described dusts, slags, and ores. ln accordance with that patent, the iron, alkaline earth metals, and gangue are iirst removed by a series of steps including chloridizing and leaching operations, leaving a mixture of alkali metal chlorides and manganese chloride. The production of this mixture of manganese chloride and alkali metal chlorides was considered to be one of the advantages of the process of the Cooper et al. patent because commercially feasible fused salt bath electrolysis of manganese chloride was thought to require the employment of alkali metal chlorides in the bath as a vehicle for the manganese chloride.

In accordance with the present invention, at least a portion, and preferably substantially all, of the alkali metal chlorides are separated from the manganese compounds at an early stage in the process. The removal of at least a portion of the alkali metal chlorides at an early stage provides a number of advantages not attainable by the process of the Cooper et al. patent or by any other known processes. For example, it is not necessary to heat and dry the alkali metal chlorides removed by the present invention, thereby saving a substantial amount of the heat energy formerly necessary to dry the salt mixture for electrolysis. Moreover, we have now found that, by eliminating the alkali metal chlorides from the fused bath in the electrolytic cell, the fused salt electrolysis may be conducted at lower temperatures with considerable savings in heat energy and no reduction in electrical efficiency or product purity or other undesirable results. In addition, the bath may be operated for longer electrolysis periods without interruption, and in some cases, substantially continuously, because the build-up of alkali metal chlorides in the cell isgreatly reduced.

The separation of at least a portion of the alkali metal chlorides from the manganese chloride is accomplished in the process of the present invention after the iron, alkaline earth metals, and gangue have been removed in the manner described in Cooper et al. Patent No. 2,877,110.

The iron is removed during the chloridizing of the mass by maintaining the temperature above about 315 C. Above this temperature, the ferrie chloride formed during the chloridizing step sublimes and is withdrawn from the reaction chamber and condensed in conventional condenser apparatus.

During the chloridizing step, the manganese and alkali metal compounds are also converted to chlorides,.while 3,523,233 Patented Apr. 3, 1962 ICC the alkaline earth metal compounds and other gangue remain unconverted. Advantageously, the temperature is maintained below the melting point of manganese chloride (about 650 C.) during the chloridizing of the manganese and alkali metal compounds. In this manner, the corrosion problems encountered in the handling of molten manganese chloride are avoided.

Since the manganese and alkali metal chlorides formed during the chloridizing step are soluble in hot water, the reaction mass remaining after the sublimation of the ferrie chloride is leached with hot water to dissolve the manganese and alkali metal chlorides. After these chlorides have been dissolved, the slurry maybe filtered to remove the alkaline earth metal compounds and other gangue which are insoluble in the hot Water.

To separate the alkali metal chlorides from the manganese chloride, the leach liquor is treated to precipitate the alkali metal chlorides while allowing the manganese chloride to remain in the solution. This may be accomplished either by cooling the leach liquor, -by adding hydrogen chloride to the liquor, or by a combination of these steps.

lf the alkali metal chlorides are removed by the addition of hydrogen chloride, the hydrogen chloride or aqueous solution thereof (hydrochloric acid) which is recovered from the liquor during the evaporating step subsequent to the removal of the alkali metal chlorides, may be recycled for use in the treatment of additional quantities of leach liquor.

Advantageously, substantially all of the alkali metal chlorides are separated from the manganese chloride solution at this point. However, the benets derived from employing the process of the present invention are still achieved, but to a lesser degree, when only a portion of the alkali metal chlorides are removed.

The process of the invention will be more fully described with reference to the accompanying drawing. It will be apparent from the following description that various steps of the process are not critical and may be performed in a number of generally equivalent ways. Accordingly, the details of such steps, for the most part, are shown in a schematic manner in the drawing.

The starting manganese-containing material 1 is fed into a suitable preliminary drying device 2 from which the dried material is fed, intermittently or continuously, into 'a reactor 3. Although the drying step is usually necessary to remove the moisture from the charge, it may be omitted if the material being processed is substantially moisture free. In the reactor, the dried materialto be processed for the recovery of manganese is subjected to a chloridizing operation.

The dried material fed into the reactor generally is heated to the desired temperature range between about 315 and 650 C. before the gaseous chloridizing agent is introduced into the reactor from a source 4 through conduits 6 and 7. The chloridizing agent is preferably chlorine gas, although other chloridizing materials which produce ferric chloride may be employed.

As the ehloridizing agent -reacts with the iron present in the dried material, ferrie chloride is formed which volatilizes since the temperature of the reactor is above 315 C. The gaseous ferrie chloride passes out of the reactor through a conduit 8 into a condenser 12 where it is condensed. Any non-condensable gases in the gaseous stream from reactor 3, including any excess chlorine which may be present, are not condensed in condenser 12 but passed therethrough and out through a conduit 13. When an appreciable amount of excess chlorine is present, the gaseous 4stream may be returned to reactor 3 through a conduit 18 (shown by dotted lines in the drawing) and the conduit 7.

Since the temperature of the reaction mass need only be .above 315 C. to sublime the ferrie chloride formed, the chloridizing operation, if desired, may be started when this temperature is reached but before the temperature in the reactor h-as attained the desired manganese reaction temperature. As the heating continues, the temperature will approach the 650 C. maximum speciiied above. Maintaining the temperature Vat or close to this higher .level accelerates the chloridizng of the manganese and alkali metal constituents of the mass.

The time required to complete the removal of the iron from the dried `material and that necessary to chloridize the managese and alkali metal constituents will vary with the temperature employed, the size, composition, and porosity of the charge, the nate of ow of the chloridizing agent, and other factors.

When the chloridizing of the alkali metal constituents is substantially complete, the reaction mass is removed from the reactor and transferred to a suitable leaching apparatus 21. The water employed for leaching the mass is maintained at an elevated temperature to dissolve the manganese and alkali metal chlorides formed during the chloridizing operation. Advantageously, the slurry is agitated to facilitate dissolution of the soluble chlorides.

Since the alkaline earth metal and other gangue constituents are not converted to chlorides during the chloridizing operation, these materials are not dissolved in the leaching apparatus. After the dissolution of the soluble constituents is substantially complete, the slurry is transferred to a suitable liquid-solids separator, for ex ample, a filter 24, to separate the undissolved `alkaline earth metal constituents and gangue yfrom the dissolved chlorides.

The iiltrate comprising substantially exclusively dissolved manganese chloride and alkali metal chlorides is then treated in a suitable precipitation apparatus 25 to precipitate the alkali metal chlorides. As pointed out above, this precipitation may be accomplished by cooling the filtrate, by the addition of hydrogen chloride, or by a combination of these steps.

After Iall or a desired proportion of the alkali metal chlorides have been precipitated, the precipitated salts are separated from the liquor by a suitable liquid-solids separator, for example, a lter 26. The remaining liquor is then transferred to an evaporator 23 where the water and 'any hydrogen chloride are removed leaving crystallized manganese chloride. The manganese chloride salt is then dried in a suitable drying device 29 to remove the remaining moisture `and any hydrogen chloride occluded in the salt.

The hydrogen chloride gas recovered from the evaporator vand drier may be recycled to precipitate additional quantities of the alkali metal chloride in the liquor. In addition, the alkali metal chloride separated from the liquor, if desired, may be reacted with concentrated sulfurie acid to form quantities of hydrogen chloride which also may be employed to precipitate additional alkali metal chlorides in precipitation apparatus 25. The alkali metal sulfate luy-products formed may be sold `as an ingredient for fertilizers.

The dried manganese chloride salt may be dissociated to recover manganese metal by any of the applicable methods Vknown in the art. For example, the manganese chloride may be reduced with hydrogen to form manganese metal, as described in Kinney Patent No. 2,290,843. In that case, the hydrogen chloride gas formed as a by-product in the process may be recycled for use in the precipitation of additional alkali metal chlorides, as described above.

Particularly advantageous results are achieved when the manganese chloride salt is dissociated by fused salt electrolysis. By this method, the dried manganese chloride with or Without some alkali metal chlorides may be charged into an electrolytic cell of the fused salt bath type shown in the drawing as cell 30.

A suitable electrolytic cell for the purpose of invention may comprise a simple heat-resistant iron alloy pot 31 constituting the cathode and a carbon rod 32 suspended in the bath constituting the anode. Electrical leads 33 and 34 connect the anode and cathode to the appropriate terminals of a motor generator set 35. The voltage applied may be varied along with the spacing of the anode and cathode to provide a suitable current iiow.

Dissociation of the manganese chloride in the electrolytic cell releases chlorine from the anode in a substantially completely anhydrous form which is suitable for recirculation through conduit 6 for use in the chloridizing step taking place in reactor 3. I-f a substantial proportion of alkali metal chlorides is present in the charge to the electrolytic cell, the concentration of these chlorides will build up in the bath as electrolysis continues necessitating the periodic interruption of the electrolysis to remove the accumulated alkali metal chlorides. Thus, as pointed out above, the removal of substantially all of the alkali metal chlorides during the cooling or HC1 treatment permits longer electrolysis periods without interruption.

The manganese deposited on the cathode as indicated at 36 may be removed from the electrolytic cell at suitable intervals and transferred While still hot to a heated centrifuge 37 to separate entrained molten alkali metal chloride from the solid manganese metal.

By means of the process described, from to 95% or more of the manganese content of precipitator dusts may be recovered as manganese metal of a purity around 98% or better, depending on the inal puriiication procedure employed. If high purity is not of great importance and appreciable surface oxide is not objectionable, the manganese granules may simply be recovered from the electrolytic cell. Obviously, if desired, other recovery and inal purification procedures may be performed on the metal product of the electrolytic cell, according to any special requirements of particular end uses for which the metal product is intended.

As indicated above, the process is equally applicable to the recovery of manganese from a variety of ores, metallurgical slags and tailings, and similar materials containing appreciable amounts of manganese, with or Without iron in almost any proportion.

From the above description, it is apparent that the process of the present invention provides a highly eficient process for producing substantially pure manganese from metallurgical dusts, slags, and similar materials. Moreover, the process of the invention permits a considerable savings in heat energy since the alkali metal carrier salts are removed at an early stage in the process. Furthermore, the removal of these alkali metal salts prior to the electrolysis step, permits longer electrolysis periods and, in some cases, substantially continuous operations of the electrolytic cell.

As will be apparent from the foregoing specification, the invention is not limited to the specic details of manipulative operations, reagents and apparatus speciiically shown or described, but is subject to numerous modifications without departing from the invention as dened in the appended claims.

What is claimed is:

1. A process for recovering manganese values in useful form from materials containing manganese as metal, or as oxide, or both together with gangue materials including alkali metal oxides, the process comprising contacting a mass of such material With a gaseous chloridizing agent containing free chlorine, at a temperature below about 650 C. to convert the manganese to manganese chloride and the alkali metal to alkali metal chloride, leaching the mass With Water to dissolve manganese and alkali metal chlorides from insoluble components of the mass, separating the chloride leach liquor from the insoluble components, treating said leach liquor to precipitate at least a portion of the alkali metal chloride dissolved therein, separating the precipitated .alkali metal chloride and removing water from the remaining liquor to recover manganese chloride.

2. In a process for recovering manganese values in useful form from materials containing manganese as metal, or as oxide, or both together with gangue materials including alkali metal oxides, which process comprises contacting a mass of such material with a gaseous chloridizing agent containing free chlorine, at a temperature below about 650 C. to convert the manganese to manganese chloride and the alkali metal to alkali metal chloride and leaching the mass with water to dissolve manganese and alkali metal chlorides from insoluble components of the mass, the steps comprising separating the chloride leach liquor from the insoluble components, treating said leach liquor to precipitate at least a portion of the alkali metal chloride dissolved therein, separating the precipitated alkali metal chloride, removing water from the remaining liquor to recover manganese chloride, and dissociating said manganese chloride to form manganese metal.

3. A process for recovering manganese values in useful form from materials containing manganese as metal, or as oxide, or both together with gangue materials including alkali metal oxides, the process comprising contacting a mass of such material with a gaseous chloridizing agent containing free chlorine, at a temperature below about 650 C. to convert the manganese to manganese chloride and the alkali metal to alkali metal chloride, leaching the mass with water to dissolve manganese and alkali metal chlorides from insoluble components of the mass, separating the chloride leach liquor from the insoluble components, treating said leach liquor to precipitate at least a portion of the alkali metal chloride dissolved therein, separating the precipitated alkali metal chloride, removing water from the remaining liquor to recover manganese chloride-containing solids, electrolyzing said manganese chloride-containing solids in a fused salt bath to deposit manganese as metal, and separating the manganese metal from the fused salt bath.

4. A process for recovering manganesevalues in useful form from materials containing manganese and iron as metals, or as oxides, or both together with gangue materials including alkali metal oxides, the process comprising contacting a mass of such material with a gaseous chloridizing agent containing free chlorine, at a temperature between about 315 and 650 C. to convert the manganese to manganese chloride, the iron to ferrie chloride, and the alkali metal to alkali metal chloride, separating the ferrie chloride by sublimation without appreciable fusion or volatilization of the manganese and alkali metal chlorides, leaching the mass with Water to dissolve manganese and alkali metal chlorides from insoluble components of the mass, separating the chloride leach liquor from the insoluble components, treating said leach liquor to precipitate at least a portion of the alkali metal chloride dissolved therein, separating the precipitated alkali metal chloride, and removing water from the remaining liquor to recover manganese chloride.

5. A process for recovering manganese values in useful form from materials containing manganese as metal, or as oxide, or both together with gangue materials including alkali metal oxides, the process comprising contacting a mass of such material with a gaseous chloridizing agent containing free chlorine, at a temperature below about 650 C. to convert the manganese to manganese chloride and the alkali metal to alkali metal chloride, leaching the mass with water to dissolve manganese and alkali metal chlorides from insoluble components of the mass, separating the chloride leach liquor from the insoluble components, cooling said leach liquor to precipitate at least a portion of the alkali metal chloride dissolved therein, separating the precipitated alkali metal chloride, and removing water from the remaining liquor to recover manganese chloride.

6. A process for recovering manganese values in useful form from materials containing manganese as metal, or as oxide, or both together with gangue materials including alkali metal oxides, the process comprising contacting a mass of such material With a gaseous chloridizing agent containing free chlorine, at a temperature below about 650 C. to convert the manganese to manganese chloride and the alkali metal to alkali metal chloride, leaching the mass with water to dissolve rmanganese and alkali metal chlorides from insoluble components of the mass, separating the chloride leach liquor from the insoluble components, adding hydrogen chloride to said leach liquor to precipitate at least a portion of the alkali metal chloride dissolved therein, separating the precipitated alkali metal chloride, and removing liquid from the remaining liquor to recover manganese chloride.

7. A process for recovering manganese values in useful form from materials containing manganese as metal, or `as oxide, or both together with gangue materials including alkali metal oxides, the process comprising contacting `a mass of such material with a gaseous chloridizing agent containing free chlorine, at a temperature below about 650 C. to convert the manganese to manganese chloride and the alkali metal to alkali metal chloride, leaching the mass with water to dissolve manganese and alkali metal chlorides from insoluble components of the mass, separating the chloride leach liquor from the insoluble components, adding hydrogen chloride to said leach liquor to precipitate at least a portion of the alkali metal chloride dissolved therein, separating the precipitated alkali metal chloride, removing water and hydro gen chloride from the remaining liquid to recover manganese chloride, and adding the hydrogen chloride removed to additional quantities of leach liquor to precipitate alkali metal chloride.

8. A process for recovering manganese values in useful form from materials containing manganese and iron as metals, or as oxides, or both together with gangue materials including alkali metal oxides, the process comprising contacting a mass of such material with a gaseous chloridizing agent containing free chlorine, at a temperature between labout 315 and 650 C. to convert the manganese to manganese chloride, the iron to ferrie chloride, and the alkali metal to alkali metal chloride, separating the ferric chloride by sublimation without appreciable fusion or volatilization of the manganese and alkali metal chlorides, leaching the mass with ywater to dissolve manganese and alkali metal chlorides from insoluble components of the mass, separating the chloride leach liquor from the insoluble components, cooling said leach liquor to precipitate at least a portion of the alkali metal chloride dissolved therein, separating the precipitated alkali metal chloride, removing water from the remaining liquor to recover manganese chloride-containing solids, electrolyzing said manganese chloride-containing solids in a fused salt bath to deposit manganese as metal, and separating the manganese metal from the fused salt bath.

9. A process for recovering manganese values in useful form from materials containing manganese and iron as metals, or as oxides, or both together with gangue materials including alkali metal oxides, the process comprising contacting a mass of such material with a gaseous chloridizing agent containing free chlorine, at a temperature between about 315 and 650 C. to convert the manganese to manganese chloride, the iron to ferrie chloride, and the alkali metal to alkali metal chloride, separating the ferrie chloride by sublimation without appreciable fusion or volatilization of the manganese and alkali metal chlorides, leaching the mass with water to dissolve manganese and alkali metal chlorides from insoluble components of the mass, separating the chloride leach liquor from the insoluble components, adding hydrogen chloride to said leach liquor to precipitate at least a portion of the alkali metal chloride dissolved therein, separating the precipitated alkali metal chloride, removing Water and hydrogen chloride from the remaining liquor to recover manganese chloride-containing solids, electrolyzing said manganese chloride-containing solids in a fused salt bath `to deposit manganese as metal and release chlorine, separating the manganese metal from the fused salt hath, and utilizing the released chlorine to chloridize additional material in the process.

li). ln a process for recovering manganese values in useful form from materials containing manganese and iron as metals, or as oxides, or both together with gangue materials including alkali metal oxides, which process comprises contacting a mass of such material with a gaseous chloridizing agent containing free chlorine, `at a temperature between about 315 and 650 C. to convert the manganese to manganese chloride, the iron to ferrie chloride, and the alkali metal to alkali metal chloride, separating the ferrie chloride by sublimation without appreciable fusion or volatilization of the manganese and alkali metal chlorides, leaching the mass with water to dissolve manganese and alkali metal chlorides from insoluble components of the mass and separating the chloride leach liquor from the insoluble components, the steps comprising adding hydrogen chloride to said leach liquor to precipitate at least la vportion of the alkali metal chloride dissolved therein, separating the precipitated alkali metal chloride, removing water and hydrogen chloride from the remaining liquor to recover manganese chloride-containing solids, adding the hydrogen chloride removed to additional quantities of leach liquor to precipitate alkali metal chloride, electrolyzing said manganese chloride-containing solids in a fused salt bath to deposit manganese as metal and release chlorine, separating the manganese metal from the fused salt bath, and utilizing the released chlorine to chloridize additional material in the process.

Mitchell Aug. 19, 1930 Cooper et al. Mar. l0, 1959

Claims (1)

10. IN A PROCESS FOR RECOVERING MANGANESE VALUES IN USEFUL FORM MATERIALS CONTAINING MANGANESE AND IRON AS METALS, OR AS OXIDES, OR BOTH TOGETHER WITH GANGUE MATERIALS INCLUDING ALKALI METAL OXIDES, WHICH PROCESS COMPRISES CONTACTING A MASS OF SUCH MATERIAL WITH A GASEOUS CHLORIDIZING AGENT CONTAINING FREE CHLORINE, AT A TEMPERATURE BETWEEN ABOUT 315* ANDF 650*C. TO CONVERT THE MANANESE TO MANGANESE CHLORIDE, THE IRON TO FERRIC CHLORIDE, AND THE ALKALI METAL TO ALKALI METAL CHLORIDE, SEPARATING THE FERRIC CHLORIDE BY SUBLIMATION WITHOUT APPRECIABLE FUSION OR VOLITILLIZATION OF THE MANGANESE AND ALKALI METAL CHLORIDES, LEACHING THE MASS WITH WATER TO DISSOLVE MANGANESE AND ALKALI METAL AND SEPARATING FROM INSOLUBLE COMPONENTS OF THE MASS AND SEPARATING THE CHLORIDE LEACH LIQUOR FROM THE INSOLUBLE COMPONENTS, THE STEPS COMPRISING ADDING HYDROGEN CHLORIDE TO SAID LEACH LIQUOR TO PRECIPITATE AT LEAST A PORTION OF THE ALKALI METAL CHLORIDE DISSOLVED THEREIN, SEPARATING THE PRECIPITATED ALKALI METAL CHLORIDE, REMOVING WATER AND HYDROGEN CHLORIDE FROM THE REMAINING LIQUOR TO RECOVER MANGANESE CHLORIDE-CONTAINING SOLIDS, ADDING THE HYDROGEN CHLORIDE REMOVED TO ADDITIONAL QUANTITIES OF LEACH LIQUOR TO PRECIPITATE ALKALI METAL CHLORIDE, ELECTRLYZING SAID MANAGANESE CHLORIDE-CONTAINING SOLIDS IN A FUSED SALT BATH TO DEPOSIT MANAGANESE METAL FROM THE FUSED SALT BATH SEPARATING THE MANGANESE METAL FROM THE FUSED SALT BATH, AND UTILIZING THE RELEASED CHLORINE TO CHLORIDIZE ADDITIONAL MATERIAL IN THE PROCESS.

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