US3715205A

US3715205A - Method for reducing chlorides and a device therefor

Info

Publication number: US3715205A
Application number: US00104720A
Authority: US
Inventors: H Ishizuka
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-01-08
Filing date: 1971-01-07
Publication date: 1973-02-06
Anticipated expiration: 1990-02-06
Also published as: DE2100498A1; FR2075990B1; CA934168A; CH561780A5; FR2075990A1; GB1331193A

Abstract

A method for reducing a metal chloride, especially for reducing a chloride of sublimable metal by using a metallic reducing agent, and a device therefor. A tank for storing the starting metal chloride is connected to a separate reducing chamber through a pipe, which tank and chamber are heated by separate heat sources, respectively. The metallic reducing agent is heated, so as to form gaseous phase thereof which gaseous phase is kept at a temperature higher than the melting point of the metal and brought into contact with the vapor of the starting metal chloride to cause the reducing reaction. The reduction is effected while measuring and controlling the flow rate of the starting metal chloride vapor to the reducing chamber.

Description

United States Patent 1 Ishizuka [451 Feb. 6, 1973 METHOD FOR REDUCING 3,137,568 6/1964 Renner ..75/84.5 CHLORIDES AND A DEVICE 2,915,384 12/1959 Walsh ..75 s4.s THEREFOR 2,537,068 1/1951 Lilliendahl .,75/84.5 X 3,158,671 11/1964 Socci ..75/84.5 X

[76] Inventor: Hiroshi Ishizuka, 19-2 Ebara 6- chome, Shmagawa'ku Tokyo Primary Examiner-Carl D. Quarforth Japan Assistant Examiner-R. E. Schafer [22] Fil d; J 7, 1971 Att0rneyWaters, Roditi, Schwartz & Nissen [21] Appl. No.: 104,720 [57] ABSTRACT A method for reducin a metal chloride, es eciall for [301 Foreign Application Pnonty Data reducing a chloride 5f sublimable metal by usihg a Jan. 8, 1970 Japan ..45/2606 metallic reducing agent, and a device therefor. A tank Jan. 10, 1970 Japan ..45/3075 for storing the starting metal chloride is connected to 9 0 ap a separate reducing chamber through a pipe, which Aug. 8, 1970 Japan ..45/69495 tank and chamber are heated by separate heat sources, respectively. The metallic reducing agent is U-S- t ..75/84-5, heated so as to form gaseous phase thereof [51] hit. C1. ..C22b 53/00 gaseous phase is kept at a temperature higherthan h [58] held of Search 266/34 melting point of the metal and brought into contact with the vapor of the starting metal chloride to cause [56] References and the reducingreaction. The reduction is effected while UNITED STATES PATENTS measuring and controlling the flow rate of the starting metal chloride vapor to the reducing chamber. 3,071,459 l/l963 Elgcr et a1. ..75/84.5 3,519,258 7/1970 lshizuka ..75/84.5 X 8 Claims, 2 Drawing Figures IOBI 32 O IOA PATENTED FEB 6 I975 SHEET 10F 2 METHOD FOR REDUCING CHLORIDES AND A DEVICE THEREFOR This invention relates to a method for reducing a metal chloride and a device therefor, and more particularly to a method and a device for reducing a hardly reducible chloride of sublimable metal which is difficult to reduce, such as zirconium tetrachloride, hafnium tetrachloride, and columbium pentachloride, by using a metallic reducing agent, e.g., magnesium and sodium.

ln a conventional process for reducing such a sublimable metal chloride to the corresponding metal, the corresponding solid metal chloride is heated to generate vapor thereof in one portion of a retort, in another portion of which the vapor is reacted with a molten metallic reducing agent to form the metal. Since the vapor is continuously fed to the reducing portion through a passage without regulating flow rate thereof, the reducing reaction can not be controlled and there is provided no means for indicating the accomplishment of the reaction. In addition thereto, the operation efficiency of the conventional process is limited by a fact that the metal chlorides have a comparatively small evaporating rate.

Therefore, a principal object of the present invention is to provide an improved method and device for reducing a metal chloride, which can completely mitigate the aforesaid difficulties of the conventional processes and apparatuses.

In order to fulfill the aforesaid object, the present invention comprises the steps of storing metal chloride in a tank, heating the metal chloride to evaporation, introducing the resulting vaporous metal chloride into a reducing chamber which contains a molten metallic reducing agent and which is separated from and in communication with the metal chloride storage tank by a pipe which is heated and equipped with a suitable flow regulator, and recovering the reduced and desired metal, the reaction rate being controlled by regulating the vaporous metal chloride flow rate into the reducing chamber with the use of said flow regulator.

The inventors experience shows that even when the evaporation and reduction are performed in such separated chambers and the reducing reaction is controlled by regulating the flow rate of the vaporous metal chloride, there are sometimes produced a metal product from which impurities can not be removed, such impurities being unreacted reducing agent and reaction by-products. Having studied such phenomenon, it has been found that this disadvantage is caused by the presence of a comparatively large amount of lower chlorides, for example zirconium bichloride, probably formed during the reduction operation and taken into the reduced metal. When heated, zirconium bichloride (ZrCl,) partially decomposes to form zirconium metal and zirconium tetrachloride vapor. As the zirconium metal so formed has a dense structure and entraps unreacted bichloride, further reduction of such entrapped bichloride becomes impossible.

Thus another object of the present invention is to provide a method and a device for preparing a high purity metal free from such difficulties due to the lower chlorides. Such lower chlorides are probably formed by a partial reduction of the metal chloride by the reducing agent deposited on the wall of the reducing chamber below the melting point of the reducing agent.

According to the present invention, prior to the introduction of the metal chloride vapor, the reducing 5 chamber, especially the portion above the surface of the molten reducing agent, is kept at a temperature above the melting point of the reducing agent so that evaporated reducing agent may not be deposited.

Other objects and advantages of the present inven tion may be appreciated by referring to the following description, taken in conjunction with drawings, in which:

FIG. 1 is a partial sectional side view of a conventional reducing device; and

FIG. 2 is a schematic side view, in section, of a reducing device, according to the present invention.

Referring to FIG. 1, a conventional reducing device includes an outer cylindrical member 12' which is heated by a heating furnace 16, which member 12' is sealed by a lid 14 through a sealing ring 141'. The outer cylinder 12' has a support ledge 121' extending from the inner peripheral surface at a lower portion thereof, to support an inner cylindrical member 18 for accommodating a metallic reducing agent, such as metallic magnesium or sodium. An inlet opening 181' is formed at a suitable portion of the inner cylindrical member 18', and a storage tank 22' for holding a sublimable metal chloride is disposed above the inner cylindrical member 18' through a comparatively thin intermediate member 20'. The storage tank 22' includes an outlet pipe 221 directed toward a dispersing member 201' mounted in the intermediate member 20, which dispersing member 201' consists of, e.g., metallic screens, baffle plates, or grids.

In operation of the conventional reducing device of the aforesaid construction, the inner cylindrical member 18' accommodating a metallic reducing agent, e.g., metallic magnesium, is mounted in the outer cylindrical member 12, and the inner cylindrical member 18' is evacuated or deaired. If desired, an inert gas,

such as argon, may be filled in the inner cylindrical member 18 after the deairation. The intermediate starting metal chloride are mounted on the inner cylindrical member 18' within the outer cylindrical member 12. After sealing the outer cylindrical member 12' by mounting the lid 14' in place while inserting sealing ring 141' therebetween, the air in the outer cylindrical member 12' is removed, and if desired, an inert gas, e.g., argon, may be filled in the outer cylindrical member 12'. The outer cylindrical member I2 is heated from the outside by the furnace 16', so that the metallic reducing agent in the inner cylindrical member 18' is melted, and at the same time, the starting sublimable metal chloride, e.g., zirconium tetrachloride, is sublimated to generate gaseous zirconium tetrachloride. The zirconium tetrachloride vapor passes through the outlet pipe 221 and the dispersing member 201', e.g., screens, baffle plates, or grids, until the vapor enters into the inner cylindrical member 18 through the inlet opening 181'. Upon contacting the metallic reducing agent, the starting metal chloride vapor, e.g., zirconium tetrachloride vapor, is reduced in the inner cylindrical member 18'. To remove byproducts in the reducing reaction, for inmember 20' and the storage tank 22 preloaded with stance, magnesium chloride, a handle 24 is turned for opening a related valve, so as to lead the byproducts produced in the inner cylindrical member 18 to the bottom of the outer cylindrical member 12. Another handle 26' is provided to allow a valve at the bottom of the outer cylindrical member 12 to be opened for discharging the byproducts to an outlet conduit 28. The residual or excess of the reducing agent remaining in the inner cylindrical member 18 after the reaction may also be removed to the outside of the device in the same manner as the byproducts. After the reducing reaction is completed, the inner cylindrical member 18, which now holds the reaction product, is removed from the outer cylindrical member 12 and transferred to the next refining device, e.g., vacuum distillation, for separating undesirable impurities, such as the still remaining byproduct and the residual reducing agent.

With such known reducing device, the reaction is controlled only by regulating the heating temperature of the outer cylindrical member by the furnace, which furnace may include an upper heating portion and a lower heating portion. The temperature of the outer cylindrical member is, however, somewhat different from the actual temperatures of the starting metal chloride and the reducing agent. Accordingly, in practice, the temperature of the outer cylindrical member can be determined only by collecting empirical data, and experiments must be made for each case for obtaining such data. Besides, the temperature of the outer cylindrical member is difficult to control in response to changes in the reacting process. The reaction time necessary for processing each batch of material should be experimentally determined. With such known device, it is practically impossible to check the instantaneous reaction conditions during the reducing process, so that it has been necessary to limit the capacity of the reaction chamber to a comparatively small volume and to select only comparatively slow reacting speeds.

The device, according to the present invention, will now be illustrated by referring to FIG. 2. The reaction device of the invention comprises a storage or a metal chloride vapor feeder 10A, which stores the starting metal chloride for generating its vapor upon heating, and a reaction chamber 108. The starting metal chloride vapor feeder 10A and the reaction chamber 108 are separated from and communicated with each other only by a pipe means 10C.

The metal chloride vapor feeder 10A includes a storage tank 14 and a heating furnace 18. The starting metal chloride material is delivered to the tank 14 from a source (not shown) through a conduit 12, in the form of a vapor, and the material is condensed and solidified in the tank 14 by cooling it with a condenser coil 16, so that the solid material can be stored in the tank 14. Upon heating the tank 14 by the furnace 18, the material is again evaporated.

The reducing or reaction chamber 108 consists of a heating furnace 24, an outer cylindrical member disposed in the furnace 24 and having a lid which is sealingly engageable with its top opening through a sealing means 221, and an inner cylindrical member 26 supported within the outer cylindrical member 20 by legs 261.

The pipe means 10C comprises a conduit 30 and a heater 32 for heating the conduit 30 to a certain temperature within a specified range. Two valves, which are controllable by

handles

34 and 36, are provided on pipe means 10C in the proximity of the opposite ends thereof, respectively. One end of the pipe means 10C communicates with the metal chloride vapor feeder 10A, while the other or opposite end of the pipe means 10C communicates with the inner cylindrical member 26 of the reaction chamber 10B through an auxiliary pipe 262. Pressure or temperature gauges 10A and 103 are mounted on the metal chloride vapor feeder 10A and the reaction chamber 10B, respectively.

The operation of the device of the invention with the aforesaid construction will now be described for the case of reducing zirconium tetrachloride by using metallic magnesium. It should be understood that the present invention is not restricted to such reduction of zirconium tetrachloride alone, but it relates to the reduction of various sublimable chlorides. The storage tank 14 is cooled by the condenser 16, through the inlet conduit 12 upon turning a handle 121. The zirconium tetrachloride delivered thus is condensed and stored in the tank 14. The amount of the solid zirconium tetrachloride to be stored in the tank 14 is not restricted to the volume of a batch to be consumed in one reducing process, and it is preferable to store as much material as possible in the tank.

Metallic magnesium is loaded in the inner cylindrical member 26, either during the storing of the zirconium tetrachloride in the storage tank 14 or quite independently of such storing of the starting metal chloride. Upon loading the inner cylindrical member 26, the reaction chamber 108 is evacuated to a high degree of vacuum, and then an inert gas, e.g., argon is filled in the reaction chamber 10B, until the pressure of the inert gas therein becomes greater than atmospheric pressure. The reaction chamber 10B is heated by the furnace 24 to keep it at 800 to 900 C.

When the reaction chamber 103 is thus heated, the handle 121 of the inlet conduit 12 to the starting metal chloride vapor feeder 10A is closed and the storage tank 14 is heated by the furnace 18 to keep the tank at or above 350 C. The temperature and the pressure within the starting metal chloride vapor feeder 10A are monitored by the temperature or pressure gauge 10A,, and when a proper temperature is established and the pressure in the feeder 10A becomes sufficiently higher than the pressure of the reaction chamber 103, the

handles

34 and 36 are turned to open the related valves for allowing the vapor of zirconium tetrachloride to move from the tank 14 to the reaction chamber 108 through the pipe means 10C. During this movement of the starting metal chloride vapor, the heater 32 acts to keep the conduit 30 of the pipe means 10C at a temperature above the sublimating temperature of the zirconium tetrachloride, which is 330 C at one atmospheric pressure and 355 C at two atmospheric pressures. It is important to keep the zirconium tetrachloride in the vapor form throughout the pipe means 10C, so as to prevent from deposition in the pipe means MC.

The zirconium tetrachloride vapor thus delivered to the reaction chamber 108 is reduced by the reducing agent, i.e., metallic magnesium, loaded in the inner cylindrical member 26. According to the present invention, the flow rate of the zirconium tetrachloride vapor through the pipe means C can be monitored by measuring the temperature difference and the pressure difference between the starting material vapor feeder 10A and the reaction chamber 108, by using the gauges 10A and 108,. With the knowledge of the flow rate of the zirconium tetrachloride vapor through the pipe means 10C, the reaction velocity and the reacting conditions in the reaction chamber 10B can be controlled by regulating the flow rate through the pipe means 10C through the operation of the

handles

34 and 36. The end of the reducing process can also be definitely determined by means of the gauges 10A and 10B,.

Accordingly, with the reducing process of the present invention, the reaction velocity can be accelerated within the safety and the durability range of the reducing device, and the amount of each batch can also be increased, so that the productivity of the reducing process can greatly be improved.

The invention will now be described in further detail, by referring to the following manufacturing examples.

EXAMPLE 1 Zirconium tetrachloride vapor of 350 to 380 C is delivered to the storage tank 14 from a sublimating furnace (not shown) through the inlet conduit 12 while turning the handle 121 for opening the related valve, and at the same time, cold air is forced through the cooling coil 16 by a blower (not shown) so as to reduce the temperature within the storage tank 14, whereby, zirconium tetrachloride was condensed and stored in the tank 14. In this Example, the inside volume of the tank 14 was about 2 m and was capable of storing 5,000 to 7,000 Kg of zirconium tetrachloride.

After storing a suitable amount of zirconium tetrachloride in the storage tank 14, the handle 121 is reversely turned to close the related valve, so as to stop the delivery of the vapor of zirconium tetrachloride. At the same time, the blower for the cooling coil was stopped.

The storage tank 14 was heated to 350 to 380 C by the heating furnace 18, which was a kerosene furnace, for sublimating the zirconium tetrachloride in the tank 14, until the inner pressure of the tank was 1.0 to 1.5 Kg/cm.

On the other hand, the inner cylindrical member 26 containing 700 Kg of metallic magnesium loaded therein is placed in the outer cylindrical member 20, and the lid 22 is mounted on the top opening of the outer cylindrical member 20 while sealingly inserting the silica sealing member 221, therebetween. The outer cylindrical member 20 is evacuated by a vacuum pump (not shown), and then argon gas is filled in the outer cylindrical member 20 at a gauge pressure of 0.2 Kglcm The outer cylindrical member 20 was then heated at 830 C by the furnace 24 for 4 to 6 hours, until the metallic magnesium in the inner cylindrical member 26 was melted. When the outer cylindrical member 20 was heated, the argon gas pressure increased, but the excess pressure was released to the outside, so as to maintain the inside pressure of the outer cylindrical member 20 at, about 0.2 to 0.5 Kg/cm.

After the reducing device was thus prepared, the

handles

34 and 36 were so turned as to open the related valves for delivering the zirconium tetrachloride vapor from the storage tank 14 to the inner cylindrical member 26 through the pipe means 10C. In this Example, an outer cylinder 32 was formed around the connecting conduit 30 of the pipe means 10C, so that a suitable heating medium, i.e., hot Dowtherm A (which is a trade mark for one of thermal transmitting mediums manufactured by Dow Chemical Company, of U.S.A., and which consists of a eutectic compound m.p. 12 C, b.p. 257.7 Cprepared by composing biphenyl to biphenylether in a rate of 1:3 and is suitable medium for heating a substance to 250 to 400 C was forced through the outer cylinder 32 for keeping the vapor through the pipe means 10C at 350 to 370 C.

Thereby, the zirconium tetrachloride vapor delivered to the reaction chamber 10B disposed in the reducing furnace was reduced to metallic zirconium by the action of the metallic magnesium. The flow rate of the zirconium tetrachloride vapor through the connecting conduit 30 was determined, based on the pressure differential between the gauge 10A on the storage tank and the outer gauge 1013 on the reaction chamber and the length and diameter of the connecting conduit 30. If necessary, it is possible to control the

handles

34 and 36 in response to the flow rate thus determined, so as to maintain a constant reaction speed and a constant rate of production. Besides, the end of the reaction for each batch can easily and accurately be determined.

Upon completion of the reducing reaction, a handle 38 of the reaction chamber 103 was turned to open the related valve, for removing the residual metallic magnesium and by-products including magnesium chloride and zirconium biand tri-chloride to the outside of the inner cylindrical member 26, and then another handle 40 was turned to remove such residual metallic magnesium and the byproducts to the outside of the reaction chamber 108. As a result, 900 Kg of metallic zirconium sponge was produced in the inner cylindrical member 26. It proved that the reaction rate of over 48 percent of zirconium tetrachloride was reduced to metallic zirconium by using about 68 percent of metallic magnesium loaded.

After removing the lid 22, the metallic zirconium thus produced was removed from the reaction chamber. The oxygen content in the resulting zirconium sponge thus produced was less than 500 ppm, and is Brinnel hardness was not more than 120.

EXAMPLE 2 Zirconium tetrachloride was stored in the storage tank 14 and sublimated as in Example 1. The reaction chamber 10B was also prepared in the same manner as in Example 1 under the identical conditions. In this example, an auxiliary heater (not shown) was mounted on the connecting conduit 30 at a suitable intermediate point thereof, for heating its vicinity (about 50 to 100 cm in length) to about 450 C. The remaining portion of the connecting conduit 30 of the pipe means 10C was kept at 350 to 3 C in a similar manner to that of Example 1.

The flow rate of the zirconium tetrachloride vapor was determined by using thermometers mounted on the two portions having different temperature, for measuring the temperature variations of the zirconium tetrachloride vapor at such portions. The reducing reaction was controlled in response to the variation of the flow rate thus determined.

The reducing reaction was carried out in the same manner as Example 1 in the reaction chamber B. By using 700 Kg of metallic magnesium, 950 Kg of zirconium sponge was obtained in the inner cylindrical member 26, after removing the residual metallic magnesium and the byproducts. The rate of over 98 percent of the zirconium tetrachloride fed was reduced to metallic zirconium by using about 71.9 percent of metallic magnesium loaded. The oxygen content of the resulting zirconium sponge was 0.03 to 0.05 percent, and its Brinnel hardness was 1 10 to 120.

EXAMPLE 3 Zirconium tetrachloride was reduced by metallic magnesium in a similar manner to that in Examples 1 and 2, excepting that the reaction chamber 10B was prepared as follows:

The inner cylindrical member 26 which accommodates 700 Kg of metallic magnesium as the reducing agent was heated by the furnace 24 in the following manner.

In the first place, the upper portion of the furnace 24 was heated until thermometers T T and T indicate 800 C, while keeping the temperature of the lower portion of the furnace 24 less than the melting point of metallic magnesium (about 680 C) as indicated by thermometers T and T After thermometers T,, T and T reached to 800 C, the lower portion of the furnace 24 was heated so that the thermometers T and T indicate 800 C. The upper portion of the furnace was further heated to raise thermometers T,, T and T reach to 850 C.

The reducing agent, metallic magnesium was melted or by maintaining the furnace 24 said conditions for 4 to 6 hours.

The reducing reaction was then carried out to obtain a high purity zirconium sponge with a chlorine content of 0.03 0.05 percent and Brinnel hardness number of 110-120 at 3,000 Kg.

In the aforesaid reducing reaction, if a comparatively large amount of impurities consisting of lower chlorides is present in the final reaction product, it is sometimes extremely difficult to completely remove such impurities by vacuum distillation or the like. The inventors have found that such lower chlorides are formed due to the uneven temperature distribution in the reaction chamber, especially within the inner cylindrical member 26, during the melting process of the metallic reducing agent.

For instance, when reducing the vapor of zirconium tetrachloride by metallic magnesium for producing metallic zirconium, if magnesium below its melting point is present within the inner cylindrical member 26, especially between the connecting conduit 30 and the surface of the molten magnesium, the evaporated or Sublimated magnesium vapor is forced to condense at such comparatively low temperature portion. When the

handles

34 and 36 are so operated as to open the related values for delivering the vapor of the zirconium tetrachloride to the reaction chamber 108, the zirconium tetrachloride vapor reacts with the metallic magnesium according to the following chemical formulas, so as to produce the desired zirconium sponge, while forming magnesium chlorides as byproducts.

It is preferable to effect the reaction between the zirconium tetrachloride and the metallic magnesium at the surface of the molten magnesium, because a high rate of contact can be achieved. It is, however, possible to effect such reaction in the gaseous phase spaced from the surface of the molten magnesium. In the case of the gaseous phase reaction, the metallic zirconium, zirconium chloride, and magnesium chloride produced during the reducing process deposit on the surface of the molten magnesium, so that the zirconium chloride may be further reduced by the molten magnesium. However, if the sublimated or evaporated magnesium should be recondensed at a comparatively low temperature portion, the reaction products between the zirconium tetrachloride vapor and magnesium thus recondensed will deposit on the wall of the reaction chamber and stay there. As the reducing process advances, the surface of the molten magnesium rises, so that the reaction products deposited on the wall of the reaction chamber will be trapped in the molten magnesium. The residual amount of the molten metallic reducing agent at such moment may or may not be sufficient for effecting the complete reduction of the zirconium. As a result, the purity of the final reduction product will be deteriorated.

Another reason for the deterioration of the purity of the reaction product is that, if the zirconium produced in the early stage of the reducing process should be too dense, intermediate product in the succeeding stage of the process (e.g., zirconium bi-chloride) may often be entrapped in such zirconium sponge. The zirconium bichloride may be decomposed according to the following chemical formula during the subsequent high-temperature vacuum distillation process.

The zirconium tetrachloride formed thus may react with the residual magnesium remaining in the zirconium sponge, but other lower chlorides formed in the refining process may be entrapped in such metallic or crystalline zirconium. Consequently, if the purity of the reduction product prior to the refining process is lower than a certain limit, it is impossible to obtain a metallic sponge with a high purity by the refining process.

For instance, a test was made by reducing the zirconium tetrachloride to metallic zirconium by using metallic magnesium in the device, as shown in FIG. 2, while keeping the gaseous phase of the reducing metal at a comparatively low temperature. More particularly, the heating furnace 24 was controlled so that the temperatures at T T and T were 400 C, 500 C, and 800 C, respectively. After the reduction, the excess metallic magnesium and the byproducts mainly consisting of magnesium chloride in the inner cylindrical member 26 were removed from the inner cylindrical member 26 and out of the outer cylindrical member 20 to the outlet conduit 42, by properly operating the

handles

38 and 40 in the aforesaid manner. The reduction product or a crude zirconium sponge, which remained in the inner cylindrical member 26 after such removal of the residual material and the byproducts, contained 0.5 to 1.0 percent of chloride, and could not be directly applied to the succeeding high-temperature vacuum distilation process. It was necessary to leach the crude zirconium sponge with a dilute sulfuric acid solution, until the chloride content of the crude zirconium sponge was reduced to 0.1 to 0.2 percent. The hardness of the zirconium sponge, which was made by applying the leaching and vacuum distillation, proved to be 150 to 160 at 3,000 Kg.

Another test was made by using a higher temperature at the reaction chamber, than that in the preceding test so as to ensure that the metallic reducing agent is kept at a temperature above its melting point but below the alloying temperature for making an alloy of the reducing metal and the metal forming the reaction chamber wall. More particularly, the heating furnace 24 was so controlled that its temperature at all the thermometers T to T were about 850 C and at thermometers T and T about 800 C. The reduction of the zirconium tetrachloride was effected while keeping the temperature distribution of the reaction chamber as described above. The zirconium sponge thus formed contained 0.03 to 0.05 percent of chlorine immediately after the reduction, and the Brinell number of the zirconium sponge after the high-temperature distillation proved to be 110 to 120 as disclosed in Example 3.

What I claim is:

1. A method for reducing a metal chloride, comprising providing a reducing chamber with a metallic reducing agent therein, delivering a vapor of the metal chloride to be reduced into a storage tank, condensing the vapor in said tank, melting the metallic reducing agent, evaporating the metal chloride in said tank by heating, transferring the now vaporous metal chloride to the reaction chamber for reaction with the metallic reducing agent, and controlling the reaction by regulating the flow rate of the vaporous metal chloride to the reaction chamber.

2. A method as claimed in claim 1 wherein said flow rate of the metal chloride vapor is determined by measuring the temperature or pressure differential between the reaction chamber and the storage tank.

3. A method as claimed in claim 1 wherein that portion of said reaction chamber, at which the delivered metal chloride vapor encounters the surface of the molten metallic reducing agent, is kept at a temperature above the melting point of the metallic reducing agent but below the alloying temperature of the metallic reducing agent and the material of the reaction chamber wall.

4. A method as claimed in claim 1 wherein said metal chloride is selected from the group consisting of zirconium tetrachloride, hafnium tetrachloride, and columbium pentachloride.

5. A device for reducing a metal chloride, comprising a metal chloride vapor feeder including a metal chloride storage tank having a condenser, and a first heating means surrounding the storage tank; a reducing chamber independent of and separate from said metal chloride vapor feeder and including an outer cylindrical member, a lid capable of sealing the inside of the outer cylindrical member from the outside, an inner cylindrical member disposed within the outer cylindrical member with a metallic reducing agent therein, and a second heating means surrounding the outer cylindrical member; a pipe means connecting the metal chloride vapor feeder and the reacting chamber and including a third heating means; and a measuring means for determining the flow rate of the metal chloride vapor through the pipe means.

6. A device as claimed in claim 1 wherein said measuring means comprises at least one thermometer or one pressure gauge mounted on the metal chloride vapor feeder and at least one thermometer or pressure meter mounted on the reaction chamber.

7. A device as claimed in claim 1 wherein said reaction chamber includes at least two thermometers and said second heating means is used to maintain the portion of the inner cylindrical member within a tempera ture range between the melting point of the metallic reducing agent and the alloying temperature of the metallic reducing agent and the metal of the reaction chamber wall.

8. A device as claimed in claim 1 wherein said third heating means is operative to the connecting pipe means to a temperature above the sublimating temperature of the metal chloride.

V UNITED STATES PATENT OFFECE CERTIFECATE OF COEQ'HN Patent No. 3,715,205 I Dated Februarn 6., 1973 vInventor(s) Hir OShi Ishizuka Q It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Columno, line 1 change "Btinnel" to --Brinell=-- Column 7, line 16: change "Brinnel" to,--Brinell=-- line 44: change "Brinnel" to -=-Brinell==- Column 8, line 6: change "MgCl to -==-MgC1 Column lO,line 30: change "1" to --5--=- line 35: change "1" to ---5- 'line +3: change "1" to --5- Signed and sealed this 29th day of January 1974.

(SEAL) Attest EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents F M'P (10-69) usco M-oc 60376-P69 I U-S GOVERNMENT PRINTING OFFICE 1 i969 Q-JBF-QLW.

V UNITED STATES PATENT orrrcr CERTIFICATE OF CCECTWN Patent NO. 3.715.205 v Dat February 6 1973 Inventofls) Hire Shi Ishizuka Q It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

C0lurnn 6, line 1 change "Brinnel" to --Brinell==- Column 7, .line' 16: change "Brinnel" to,--Brinell=- line 44: change "Brinnel" to -=-Brinell Column 8, line 6: change "MgCl to MgCl Column lO,line 30: change "1" to ----5-- line 35: change "1" to --5=-- line 43: change "1" to --=--5---- Signed and sealed this 29th day of January 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents F (w'sg) usco M-Dc 60376-P69 I V U.$. GOVERNMENT PRINTING OFFICE I 1969 O'36 6'334'

Claims

7. A device as claimed in claim 1 wherein said reaction chamber includes at least two thermometers and said second heating means is used to maintain the portion of the inner cylindrical member within a temperature range between the melting point of the metallic reducing agent and the alloying temperature of the metallic reducing agent and the metal of the reaction chamber wall.