US2039483A - Production of metallic magnesium - Google Patents

Description

May 5, 1936. F. HANsGlRG PRODUCTION OF' METALLIC MAGNESIUM Filed Nov. 27, 1934 3 Sheets-Sheet 1 env?,

F. HANSGIRG PRODUCTION 0F METALLIC MAGNEIUM May 5, 1936.

Filed Nov. 27,v 1934 5 sheets-sheet 2 May 5, 1936. F. HANsGlRG 2,039,483

- PRODUCTION OF METALLIC MAGNESIUM Filed Nov. 27, 1954 3 sheets-sheet 3 Fig. 4.

v -4 MTAL ou. MTN/5555 l INYENTOR.

@Q5 4M/M ATTORNEYS.

Patented May 5, 1936 UNITED STATES PATENT OFFICE PRODUCTION F METAILIC MAGNESIUM Application November 27, 1934, Serial No. 755,027 In Austria December 21, 1933 9Claima.

This invention relates to the production of metallic magnesium. i

It is an object of the present invention to provide a simple, cheap and efficient smelting method admitting of the recovery of a metallic product which is relatively pure from the outset, in a continuous one-stage thermal reduction process. As to this subject matten. the instant case is a continuation in part of im' co-pending aplo plication Ser. No. '753,631 filed November 19, 1934.

Another object of the invention is directly to' obtain in the course of the smelting operation a` metallic product in the form of globular grains.

Further features and advantages of the invenl5 itzioln will appear in the detailed description given e ow.

In my co-pending application Ser. No. 722,278 relating to a process for producing substantially pure magnesium, which was filed April 25, 1934,

20 I have described andclaimed a method of separating substantially pure magnesium from nonvolatile concomitant substances by the procedure of vaporizing the magnesium, condensing the val 35 A suitable apparatus for carrying out this process described and claimed in the same co-pending application Ser. No. 722,278 comprises, in'a preferred embodiment, a distillation chamber, connected by a heated conduit with a hollow ves- 40 sel, the upper portion of which is heated whereas the lower portion is not heated, and which contains in its upper portion a condenserand forms in its lower portion a receiver provided with a discharging device and connected with a con- 45 veyer device for withdrawing liquid and returning the said liquid in circulation, a device for separating solid impurities from the liquid being interposed in the way of the circulating liquid.

It has now been ascertained that this method' 50 of and apparatus for the continuous distillation of metallic magnesium are also suitable for the 4 direct recovery of metallic magnesium, in a continuous working operation, from starting material which does not contain metallic magnesium 55 in a preformed slate, but yields metallic magneslum when heated with the addition of a reducing agent which such as for instance aluminium, silicon or mixtures-or alloys thereof) yields no gaseous reaction products in the course of the reduction. Since the reduction of the magnesium 5 oxide is in practice carried out at temperatures above the boiling point of metallic magnesium, the magnesium is thus obtained in the form of vapors which are then conducted to a condenser and condensed to a liquid deposit. The liquid l0 condensate obtained is caused to drop into a bath of a hydrocarbon oil placed to receive it. The reduction is carried out at reduced pressure.

For the practising of the invention, in a preferred embodiment, the charge is prepared by intimately mixing sintered magnesia or a mixture of MgO-l-CaO such as is obtained by the baking of dolomite to the point of sintering, with aluminium or silicon or mixtures oralloys of these two metals. The charge is then continuously passed, preferably ina current of an inert or reducing gas, to a chamber in which it is heated to the boiling point or to a temperature above the boiling point of metallic magnesium to liberate magnesium vapors from the material under treatment without the said material becoming amassed in the reduction zone. After this the disengaged magnesium vapors are carried, by the inert or reducing gas, through an interposed dust separating device, into a condenser, measures being taken to prevent the vapors from cooling down to condensation temperature on their way from the heating chamber to the condenser, in which the said vapors are then sud-- denly chilled down to a temperature above the solldiilcation point of magnesium. The liquid deposit drops into a bath of a hydrocarbon oil placed to receive it while the residue leaves the apparatus in a solid state, preferably continuously. y

The accompanying drawings illustrate diagrammatically andby way of example a typical embodiment of apparatus suitable for use in carrying out the method according to the present invention.

In said drawings Fig. 1 is a front elevation of the entire apparatus partly in vertical section; Fig. 2, on an enlarged scale, a vertical section on the line II-lI in Fig. 1; Fig. 3, a detail in cross section on the une -n-m in Fig. 2; and Fig. 4, 50 an elevational view of a modified discharge means for use with the apparatus.

Like reference characters denote like parts in the several figures of the drawings.

According to the example shown in Figs. 1 55 closure members and 6".

to 3. the reduction chamber I is in the form of a tube, which extends through a suitable heating apparatus, such as an electric radiation furnace 2. The mixture of magnesium oxide and reducing agent is placed in the charging hopper 3 and passes through the lock chamber 4-the closure members 5 and 6 coacting with levers-into a stock vessel 1, from which it is continuously fed, by means of a worm 8 or the like, into the reduction chamber I, through which the material is conveyed by means of a worm 9 or the like. The residue falls into a collector III, from which it is discharged through a lock chamber II, with the The collector I0 and chamber II, as also the chamber 4 and stock vessel 1, are connected with a vacuum pump by means of pipes adapted to be closed independently.

A pipe I 2 (Fig. 2) issues from the middle of the reduction chamber I, said pipe debouching tangentially into a cylindrical dust precipitating chamber I3, which tapers conically in a downward direction. The lower end of the chamber is connected with the dust collecting space I4. The vertical limb of a bent pipe I5 passes through the centre of the cover of the chamber I3 and constitutes the connection between said chamber and the cylindrical hollow vessel I6.

The dust contained in the vapors which enter the dust-removing chamber I3, is precipitated chiefly on the cylindrical jacket of the chamber by the action of centrifugal force and falls into the collecting space I4, whilst purified vapors pass on to the condenser via pipe I5.

In the upper portion of the vessel I6 the condenser I1 is fitted in such a manner that the in coming vapors bathe the lower-most portion of the cooling surface. The pipe I8 leads to the vacuum pump. The lower portion of the hollow vessel passes through the heating chamber 2, and may even be cooled, by means of suitable auxiliary devices that are not represented in the drawings.

'Ihe bottom of the hollow vessel is tapered and opens into a discharging device which permits of the withdrawal of the distillate without breaking the vacuum. In the embodiment shown, this purpose is served by the chamber I9 which is fitted with the valves 20' and 2'I and which forms a lock for the discharge of the solidified material.

This lock chamber may be replaced by any other known discharging device, such as a double receiver connected with the distillation chamber through pipes controlled by valves so as to permit an alternative connection therewith. The lower portion of the hollow vessel l5 is connected with the suction side of a pump 22 by means of a tube 23 and forms a receiver, which is charged with hydrocarbon oil. The delivery side of the pump 22 is connected, through a tube 24, with a lter 25 from which the rened liquid discharges into a stock vessel 26, whence it is returned to the receiver by way of the pipe line 21.

Fig. 4 illustrates a double receiver discharging device of the type Just referred to for replacing lock chamber I9 just described. 'I'his double receiver is based on the form shown in Ullmanns Enzyklopaedie der Technischen Chemie (2d Ed., 1929), vol. 3, page 610. It comprises a pair of receivers 30 and 30a which may be connected alternately through a valve 3| to a conduit 32 connected to the lower end of vessel I6. At their lower ends the receivers 30 and 30a are provided with discharge conduits which can be closed independentlyby valves 33 and 33a, respectively. As illustrating the use of this apparatus, it Will be assumed that receiver 3Ii-has been receiving condensed metal and oil from vessel I6. In such operation valve 3i is positioned as shown in Fig. 4, and valve 33 is closed. When receiver 30 has received a suiiicient amount of metal and oil, valve 33a is closed and valve 3| is turned to place receiver 30a in communication with vessel I6, thereby cutting receiver 30 oil from vessel I6. Thereupon receiver 30 can be dumped by turning valve 33 to place receiver 30' in communication with a discharge line 34. When suiilcient metal and oil have collected in receiver 30a., the flow is directed to receiver 3D by reversing the operation of the valves as just described.

The magnesium vapors entering the hollow vessel. I6 are condensed on the cooling surface of the condenser I1 and drop into the hydrocarbon oil below. The metallic granules are lock-discharged, together With oil, by means of the valves 20 and 2i. The circulation of the liquid through the filter 25 eects the continuous elimination of the impurities taken up by the oil, and prevents undesirable heating of the latter.

I use the term magnesium oxide in the following-claims to include not only preformed magnesium oxide but also material containing magnesium oxide or yielding the same under the temperature conditions of the reduction process, and mixtures of magnesium oxide with such material.

I claim:-

1. A process of obtaining metallic magnesium from a charge containing magnesium oxide and a reducing agent, which process comprises passing the charge, under reduced pressure, continuously through a'heating zone in an atmosphere free from gases of a nature to react with magnesium at the reduction temperature, to liberate magnesium vapor from the charge, condensing the vapor in the form of a liquid deposit, and causing the liquid condensate to drop into hydrocarbon oil; the residue leaving the reduction zone in a solid state.V

2. A process of obtaining metallic magnesium from a charge containingmagnesium oxide and a reducing agent, which process comprises passing the charge, under reduced pressure, continuously through a heating zone in an atmosphere free from gas of a nature to react with magnesium at the reduction temperature, to liberate magnesium vapor from the charge without the material becoming amassed in the reduction zone, thereafter passing the vapor into a condensation zone to-condense the same in the form of a liquid deposit, and causing the liquid to drop into hydrocarbon oil; the residue leaving the reduction zone continuously.

3. A process of obtaining metallic magnesium from a charge containing magnesium oxide and a reducing agent, which process comprises passing the charge, under reduced pressure, continuously through a heating zone, in a current of a non-oxidizing gas, to liberate magnesium vapor by reduction, from the charge without the material becoming amassed in the reduction zone, and thereafter passing the vapor into a condensation zone to condense the same in the form of a liquid deposit, and causing the liquid to drop into hydrocarbon oil; the residue leaving said reduction zone continuously. l'

4. A process of obtaining metallic magnesium from a charge containing magnesium oxide and a reducing age'nt, which process comprises passing the charge, under reduced pressure, continuously through a heating zone in an atmosphere freefrom gases of a nature to react with magnesium at the reduction temperature, to liberate magnesium vapor from'the charge by reduction, separating out dust from said vapor, passing same into a condensation zone, to condense it to a liquid deposit, and causing the liquid to drop into hydrocarbon oil; the residue leaving the reduction zone continuously.

5. The process of obtaining metallic magnesium from a charge containing magnesium oxide and a reducing agent, which process comprises passing the charge, under reduced pressure, continuously through a heating zone in a stream of a non-oxidizing gas, to liberate magnesium in the form ot vapor by reduction, separating out dust from said vapor, and thereafter conveying it to a condensation zone to condense it to a liquid deposit, and causing the liquid to drop into hydrocarbon oil, premature condensation being prevented by heating the vapor on its way between the reduction zone and the condensation zone to a temperature above condensation temperature of metallic magnesium; the residue leaving the reduction zone continuously.

6. A process of obtaining metallic magnesium from a charge containing magnesium oxide and a. reducing agent, which process comprises passing the charge. under reduced pressure, continuously through a heating zone in an atmosphere free from gases ot a nature to react with magnesium at the reduction temperature, to liberate magnesium vapor from the charge by reduction, removing the resulting vapor by a non-oxidizing gas from the .reduction zone, separating out dust from said vapor, and thereafter passing it into a condensation zone where it is caused to condense in the form of a liquid deposit, and collecting the said deposit under a layer of hydrocarbon oil in the form of globular grains; the residue leaving the reduction zone continuously.

7. A method of obtaining metallic magnesium from a charge containing magnesium oxide and a reducing agent, which comprises passing the charge continuously, in a closed system, through a heating zone in a current of a non-oxidizing gas, to liberate magnesium vapor therefrom by reduction, the residue of the reduction process leaving the said zone continuously, thereafter passing the disengaged vapor into a condensation zone to condense it in the form. o1' a liquid deposit, and collecting the said deposit under a layer of hydrocarbon oil, the'system being maintained under reduced pressure.

8. A process for producing metallic magnesium from a charge containing magnesium oxide and a reducing agent which yields no gaseous reaction product in the course of the reduction, which process comprises passing the charge, under reduced pressure, continuously through a heating zone, to liberate magnesium vapor from the 1 charge by reduction without the material under treatment becoming amassed to any appreciable extent, conveying the vapor to a condensation zone maintained under reduced pressure to condense it in the form of a liquid deposit, and collecting the said liquid under a layer of hydrocarbon oil; the residue leaving the reduction zone continuously.

9. The method of producing metallic magnesium, which comprises passing a charge containing magnesium oxide and a reducing agent which yields no gaseous reaction product in the course of the reduction continuously, -in a closed system, through a heating zone, to liberate magnesium vapor from the charge by reduction, while discharging the residue continuously, removing the resulting vapor from the heating zone by Va nonoxidizing gas, separating out dust from said vapor, and thereafter passing it into a condensation zone to condense it in the form of a liquid def

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