JP2007084847A - METHOD AND DEVICE FOR PRODUCING Ti - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing Ti where the reduction reaction of TiCl<SB>4</SB>is efficiently performed, and a stable operation can be performed on an industrial scale; and to provide a production device used therefor. <P>SOLUTION: The method includes: a reduction stage where Ca in a CaCl<SB>2</SB>-containing molten salt in which Ca is dissolved is allowed to react with TiCl<SB>4</SB>to produce Ti grains in the molten salt; a separation stage where the produced Ti grains are separated from the molten salt; and an electrolysis stage where the molten salt in which Ca concentration is reduced is electrolyzed to increase the Ca concentration. The molten salt in which the Ca concentration is increased using the main electrolytic cell 5 in the electrolysis stage is introduced into a regulation tank 6 having a Ca feed source, and is brought into contact with the Ca feed source, so as to make the Ca concentration in the molten salt constant, and thereafter, it is used for the reduction of TiCl<SB>4</SB>in the reduction stage. When a molten Ca-Mg alloy is used as the Ca feed source, the replenishment of Ca can be easily performed. The method for producing Ti can be easily performed by the production device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a Ti production method for producing Ti by reducing TiCl ₄ with Ca, and a production apparatus used therefor.

As an industrial method for producing metal Ti, a crawl method in which TiCl ₄ is reduced with Mg is generally used. In this crawl method, metal Ti is produced through a reduction process-vacuum separation process. In the reduction step, liquid TiCl ₄ supplied from above in the reaction vessel is reduced by molten Mg to form particulate metal Ti, which is successively settled downward to obtain sponge-like metal Ti. In the vacuum separation step, unreacted Mg and by-product MgCl ₂ are removed from the spongy metal Ti in the reaction vessel.

In the production of metal Ti by the crawl method, it is possible to produce a high-purity product. However, since it is a batch type, the manufacturing cost increases and the product price becomes very high. One of the causes of increased manufacturing cost is that it is difficult to increase the supply rate of TiCl ₄ .

There are several possible reasons for this, but one is that if the supply rate of TiCl ₄ is increased too much, TiCl ₄ is supplied from above to MgCl ₂ that does not settle and remains on the liquid surface. The supplied TiCl ₄ is discharged out of the reaction vessel as unreacted TiCl ₄ gas or TiCl ₃ gas with insufficient reduction, and the utilization efficiency of TiCl ₄ is lowered.

In the crawl method, the reaction is performed only in the vicinity of the liquid level of the molten Mg liquid in the reaction vessel, so that the heat generation area is narrow. For this reason, if TiCl ₄ is supplied at a high speed, cooling cannot be performed in time, which is a major reason that the supply speed of TiCl ₄ is limited.

  Furthermore, due to the wettability (adhesiveness) of the molten Mg, the Ti powder that has been formed settles in a coherent state, and during the sedimentation, particles are grown by sintering with the heat of the high-temperature melt. It is difficult to recover outside the container. For this reason, manufacture of metal Ti cannot be performed continuously but productivity is inhibited.

Regarding Ti production methods other than the crawl method, Patent Document 1 describes that, for example, Ca can be used as a reducing agent for TiCl ₄ in addition to Mg. And as a manufacturing method of Ti using the reduction reaction by Ca, in Patent Document 2, a molten salt of CaCl ₂ is held in a reaction vessel, and metallic Ca powder is supplied into the molten salt from above to melt A method is described in which Ca is dissolved in a salt and TiCl ₄ gas is supplied from below to react the dissolved Ca and TiCl ₄ in a molten salt of CaCl ₂ .

  However, in the method described in Patent Document 2, the metal Ca powder used as a reducing agent is extremely expensive, and if this is purchased and used, the manufacturing cost is higher than that of the crawl method. It cannot be established as a manufacturing method. In addition, highly reactive Ca is very difficult to handle, and this is also a major factor that hinders industrialization of the Ti production method by Ca reduction.

As another Ti production method, Patent Document 3 describes Olson's method in which TiO ₂ is directly reduced by Ca without passing through TiCl ₄ . This method is a kind of direct oxide reduction method. However, this method must use expensive high-purity TiO ₂ .

On the other hand, in order to industrially establish a Ti production method by Ca reduction, the present inventors must reduce TiCl ₄ with Ca, and economically reduce Ca in molten salt consumed in the reduction reaction. In consideration of the necessity of replenishment, a method of using Ca generated by electrolysis of molten CaCl ₂ and circulating this Ca, that is, “OYIK method (Oic method)” was proposed (Patent Document 4, Patent Document) 5). Patent Document 4 describes a method in which Ca is generated and replenished by electrolysis and Ca-rich molten CaCl ₂ is introduced into a reaction vessel and used to generate Ti particles by Ca reduction. Furthermore, a method of effectively suppressing back reaction accompanying electrolysis by using an alloy electrode (for example, Mg—Ca alloy electrode) as a cathode is shown.

US Pat. No. 2,205,854 U.S. Pat. No. 4,820,339 U.S. Pat. No. 2,845,386 JP 2005-133195 A JP 2005-133196 A

As described above, many researches and developments have been made on Ti production methods other than the crawl method. In particular, in the “OYIK method (Oic method)” proposed by the present inventors, Ca in the molten salt is consumed along with the reduction reaction of TiCl ₄ , but if the molten salt is electrolyzed, the Ca is contained in the molten salt. If Ca thus obtained is reused in the reduction reaction, it is not necessary to replenish Ca from the outside, and it is not necessary to take out Ca alone, thereby improving the economic efficiency.

  Therefore, the inventors of the present invention are based on this OYIK method, and further develop a metal Ti manufacturing process capable of performing an efficient and stable operation, and examine the entire manufacturing process. It was decided. The manufacturing method of Ti or Ti alloy of the present invention, which is an evolution of the OYIK method, was the initials of four people “Ogasawara, Yamaguchi, Ichihashi, Kanazawa” who were deeply involved in the development and completion of the idea. (Oic-II method) ".

The object of the present invention is to make TiCl ₄ reduction reaction efficient and stable on an industrial scale in the production of metallic Ti by Ca reduction in which TiCl ₄ is reduced by Ca generated by electrolysis of molten CaCl ₂ . An object is to provide a Ti production method capable of operation and a production apparatus used therefor.

In order to perform the above-described problem, that is, to efficiently perform the reduction reaction of TiCl ₄ and to enable stable operation, the high content of Ca in the CaCl ₂ -containing molten salt charged into the reduction tank for reducing TiCl ₄ is high. Concentration and suppression of fluctuations in concentration are important, and in order to enable production of Ti on an industrial scale, an increase in the supply rate of Ca to the reduction tank (in other words, a large amount of CaCl in the electrolysis process). ₂ continuous treatment of molten salt containing).

When the Ca concentration of the molten salt charged into the reduction tank is too low, unreacted TiCl ₄ gas is discharged out of the tank. Furthermore, a gas of lower titanium chloride such as TiCl ₃ and TiCl ₂ is generated and dissolved in the molten salt, and when this molten salt is returned to the electrolytic cell for electrolyzing CaCl ₂ to generate Ca, the generated Ca Ti reacts with lower titanium chloride and Ti is deposited on the cathode surface, which may cause a short circuit between the electrodes or clogging in the cell depending on the shape of the electrolytic cell. In addition, the occurrence of TiC that causes C contamination of Ti is also a concern.

  On the other hand, when the Ca concentration of the molten salt is too high, a large amount of Ca is contained in the molten salt withdrawn from the reduction tank, and there is also a molten salt containing Ca in Ti separated from the molten salt in the separation step. Part of it will remain attached. The remaining molten salt is completely removed when the separated and recovered Ti is melted. However, Ca is evaporated and lost, and it adheres to the inner wall of the melting furnace, so that extensive cleaning and removal is required.

  In addition, since the Ca concentration in the molten salt after Ti is separated in the separation step is also high, when returned to the electrolytic cell, a reaction (back reaction) between this Ca and chlorine generated by electrolysis occurs, and the current Efficiency is reduced. In addition, the uniformity of the temperature of the molten salt (bath salt) in the electrolytic cell is disturbed by the reaction heat at that time, which may hinder the temperature control of the bath salt.

  Therefore, the Ca concentration of the molten salt charged into the reduction tank does not change and is always constant, and it is desirable that the concentration be high in order to allow the reduction reaction to proceed efficiently. However, for example, it is very difficult to control the Ca concentration constant while measuring the Ca concentration in the molten salt extracted from the electrolytic cell in real time, and the Ca concentration accompanying the slight variation in the electrolysis conditions in the electrolytic cell. Variation is inevitable. Therefore, it is difficult to keep the Ca concentration constant at all times as long as a technique is adopted in which molten salt with an increased Ca concentration in the electrolytic cell is directly introduced into the reduction tank.

  Therefore, the present inventors have made various studies in order to suppress the fluctuation of the Ca concentration of the molten salt charged into the reduction tank and maintain it at a high concentration. As a result, an adjustment tank equipped with a Ca supply source was installed between the electrolytic cell (hereinafter referred to as “main electrolytic cell”) and the reduction tank, and molten salt with an increased Ca concentration in the main electrolytic cell was introduced into the adjustment tank. It was found that it was effective to use for reduction after making Ca concentration constant. It has also been found that a molten Ca—Mg alloy is suitable as the Ca supply source.

Furthermore, as a result of detailed investigations on the shape of the electrolytic cell vessel of the main electrolytic cell, electrode shape, electrolysis conditions, distance between electrodes, etc., the main electrolytic cell was electrolyzed while flowing the molten salt in one direction near the cathode surface. By recovering the molten salt having an increased Ca concentration on the outlet side, the back reaction is suppressed and high current efficiency is maintained, and only the molten salt in which Ca is concentrated can be effectively taken out, It was found that a large amount of molten salt containing CaCl ₂ can be continuously processed.

  The present invention has been made based on these findings, and the gist of the present invention is the following (1) Ti production method and (2) production apparatus.

(1) A reduction step of causing TiCl ₄ to react with Ca in a molten salt containing CaCl ₂ and dissolving Ca to produce Ti particles in the molten salt; and Ti particles generated in the molten salt A separation step for separating from the molten salt, and an electrolysis step for increasing the Ca concentration by electrolyzing the molten salt having a reduced Ca concentration with the formation of Ti grains, and using the main electrolytic cell in the electrolysis step, the Ca concentration After introducing the molten salt with increased Ca into a regulating tank having a Ca supply source and bringing it into contact with the Ca supply source, the Ca concentration of the molten salt is made constant, and then the Ti salt used for the reduction of TiCl _{4 in} the reduction step Production method.

Here, “a molten salt containing CaCl ₂ ” means a molten salt containing only molten CaCl ₂ or a molten salt obtained by adding KCl, CaF ₂ or the like to molten CaCl ₂ in order to lower the melting point or adjust viscosity. It is. Hereinafter, it is also simply referred to as “molten salt”.

  In this Ti manufacturing method, if the Ca supply source is a molten Ca—Mg alloy (this embodiment is referred to as the first embodiment), it is desirable because Ca of this molten Ca—Mg alloy can be easily replenished.

In the first embodiment, if the Ca concentration in the molten Ca—Mg alloy is increased by electrolyzing a molten salt containing CaCl ₂ in an electrolytic cell for an alloy and supplemented with Ca (second embodiment). , Ca can be easily replenished without affecting the operation.

  In this Ti manufacturing method, if the molten salt after the Ti grains are separated in the separation step is once charged into the alloy electrolytic cell, and the Ca concentration of the molten salt is reduced, then the molten salt is charged into the main electrolytic cell. (Third embodiment) This is desirable because the residual Ca in the molten salt returned from the separation step to the electrolysis step is removed and the residual Ca can be used effectively.

  Moreover, if the adjustment tank used with the method as described in said (1) is provided with a cooling function (4th Embodiment), the increase in the tank internal temperature based on an exothermic reaction can be relieved in the reduction tank of a post process, The Ca concentration of the molten salt charged into the reduction tank can always be kept constant and high, allowing the reduction reaction to be performed efficiently and contributing to stable operation.

(2) A reducing tank for holding a molten salt containing CaCl ₂ and dissolving Ca, reacting TiCl ₄ supplied in the molten salt with Ca to generate Ti particles, and in the molten salt Separating means for separating the Ti particles produced from the molten salt, and holding the molten salt after the Ti particles are separated, provided with an anode and a cathode, and performing electrolysis in the molten salt to form a cathode After having a main electrolytic cell for generating Ca on the side and a Ca supply source, and introducing the molten salt in the main electrolytic cell and bringing it into contact with the Ca supply source, the Ca concentration of the molten salt is made constant An apparatus for producing Ti having an adjustment tank for charging the molten salt into the reduction tank.

  In this Ti manufacturing apparatus, if the Ca supply source is a molten Ca—Mg alloy and includes an electrolytic cell for an alloy for increasing the Ca concentration of the molten Ca—Mg alloy, the first and second embodiments are used. It can use suitably for implementation of the manufacturing method of Ti which concerns on a form.

  In addition, if an electrolytic cell for an alloy is installed between the high-temperature decanter and the main electrolytic cell in the separation step, and the molten salt with an increased Ca concentration in the electrolytic cell for the alloy can be introduced into the adjustment tank, It is suitable for carrying out the Ti manufacturing method according to the third embodiment.

In the Ti production method of the present invention, the molten salt with the Ca concentration increased in the main electrolytic cell is introduced into a regulating tank equipped with a Ca supply source and the Ca concentration is made constant, and then used for the reduction of TiCl _4. Fluctuations in the Ca concentration of the molten salt introduced into the can be suppressed and maintained at a high concentration. Thereby, the reduction reaction of TiCl ₄ can be performed efficiently, and stable operation is possible. Moreover, continuous treatment of a large amount of CaCl ₂ -containing molten salt in the electrolysis process is possible, and Ti can be produced on an industrial scale by increasing the Ca supply rate to the reduction tank.

  This method can be easily and suitably performed by the Ti production apparatus of the present invention.

  The (1) Ti production method and (2) production apparatus will be specifically described below with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration example of the Ti production apparatus of the present invention described in (2) above, which is an apparatus used when the Ti production method described in (1) is performed.

As shown in FIG. 1, this apparatus holds a molten salt containing CaCl ₂ and dissolved in Ca, and reacts TiCl ₄ supplied in the molten salt with the Ca to generate Ti grains. A reduction tank 1; separation means for separating Ti particles generated in the molten salt from the molten salt; holding the molten salt after the Ti particles are separated; and an anode 2 and a cathode 3; A main electrolytic cell 5 for electrolyzing the molten salt to generate Ca on the cathode side and a Ca supply source are provided, and the molten salt in the main electrolytic cell 5 is introduced to reduce the Ca concentration of the molten salt. After making it constant, it has an adjustment tank 6 for introducing the molten salt into the reduction tank 1. Further, in this example, a diaphragm 4 is provided between the anode 2 and the cathode 3 of the main electrolytic cell 5.

  Further, as the separation means, in the apparatus shown in FIG. 1, a decanter type centrifugal sedimentator (high temperature decanter) 7 and a separation tank 8 are used.

The method for producing Ti according to the present invention described in (1) described above is “a reduction step of causing TiCl ₄ to react with Ca in a molten salt containing CaCl ₂ and dissolving Ca to produce Ti particles in the molten salt. And a separation step of separating the Ti particles generated in the molten salt from the molten salt, and an electrolysis step of increasing the Ca concentration by electrolyzing the molten salt in which the Ca concentration is reduced as the Ti particles are generated. Including the molten salt whose Ca concentration is increased using the main electrolytic cell in the electrolysis step into a regulating tank having a Ca supply source and contacting the Ca supply source, the Ca concentration of the molten salt is kept constant. And then used for the reduction of TiCl _{4 in} the reduction step ”.

That is, in this Ti manufacturing method, for example, using the apparatus shown in FIG. 1, first, the molten salt in which Ca supplied from the adjustment tank 6 is dissolved at a constant concentration is held in the reduction tank 1, its Ca in the molten salt, by reacting TiCl ₄ was supplied from the TiCl ₄ feed port 9 to produce a Ti particles in the molten salt. That is, the “reduction process”.

In this case, the molten salt is not held in the reducing tank 1 in a stationary state, but is held while gradually flowing down from the upper side of the reducing tank 1, while TiCl ₄ is retained by Ca in the molten salt. Reduced to produce Ti grains.

  Ti particles generated in the reduction step are separated from the molten salt in a “separation step”.

  In the separation step, first, Ti particles are separated and recovered from the molten salt by the high-temperature decanter 7, and then the molten salt adhering to the Ti particles is removed by the separation tank 8.

  The decanter type centrifugal settling machine is a type of centrifugal separator that spins suspended solids by rotating a rotating cylinder at high speed. It is capable of high-speed processing and has high dehydration performance. Etc. are used. A type capable of high-temperature treatment has also been developed, and can be applied as a high-temperature decanter 7 in this separation step.

  Ti particles extracted from the high-temperature decanter 7 are heated and melted by the plasma irradiated from the plasma torch 10 in the separation tank 8, poured into the mold 11, and become a Ti ingot 12. On the other hand, fine particles of Ti may be mixed in the adhered molten salt separated from the Ti particles. For this reason, there is a possibility that a problem may occur when the adhering molten salt is returned to the electrolysis step. Therefore, as shown in FIG. In addition, since Ca remains in the adhered molten salt to some extent, it is reasonable to return it to the reduction tank 1 from the viewpoint of effective utilization of Ca. In addition, since the flow rate of the adhering molten salt is very small compared with the flow rate of the molten salt introduced into the reduction tank 1 after the Ca concentration is made constant in the adjustment tank 6, the flow from the adjustment tank 6 to the reduction tank 1. Variations in the Ca concentration of the molten salt introduced can be ignored.

  The molten salt having a reduced Ca concentration separated by the high-temperature decanter 7 is returned to the “electrolysis step”, and is introduced and held between the cathode 3 and the diaphragm 4 of the main electrolytic cell 5. Although the configuration, action, and the like of the main electrolytic cell 5 used in this step will be described in detail later, in this case as well, the molten salt is not held in a stationary state in the main electrolytic cell 5, but the main electrolytic cell 5 It is held while gradually flowing down from above, electrolyzed during that time, and the molten salt Ca concentration is increased.

However, fluctuations in Ca concentration due to slight fluctuations in the electrolysis conditions in the main electrolytic cell 5 are inevitable. Therefore, when the molten salt subjected to the electrolytic treatment in the main electrolytic cell 5 is directly charged into the reducing cell 1, the Ca concentration is not always maintained constant. As described above, the generation of lower titanium chloride, the current due to the back reaction, The efficiency may decrease, and the efficiency of the TiCl ₄ reduction reaction may be reduced, making it difficult to perform stable operation.

Therefore, in the Ti production method of the present invention, the molten salt whose Ca concentration is increased using the main electrolytic cell 5 in the electrolysis step is introduced into the adjustment tank 6 having a Ca supply source and brought into contact with the Ca supply source. Thus, after the Ca concentration of the molten salt is made constant, it is used for the reduction of TiCl _{4 in} the reduction step.

  As the Ca supply source, molten metal Ca or molten Ca—Mg alloy can be used. That is, molten metal Ca or molten Ca—Mg alloy is floated on the molten salt with increased Ca concentration, and these Ca supply source and molten salt are kept in contact with each other. Thereby, if the Ca concentration of the molten salt is less than its saturation solubility, Ca can be supplied from the Ca supply source to the molten salt, and the Ca concentration can be maintained at a concentration close to the saturation solubility. When the Ca concentration is the saturation solubility and the precipitated metal Ca is also present, the metal Ca floats and separates due to the difference in specific gravity in the adjustment tank 6, and the Ca concentration can be maintained at a concentration near the saturation solubility. Furthermore, if the temperature of the molten salt extracted from the adjustment tank 6 is controlled to be constant, the Ca concentration can be controlled to a constant concentration in the vicinity of the saturation solubility at that temperature.

Therefore, regardless of whether the Ca concentration of the molten salt is saturated solubility or less, by installing the adjustment tank 6 and introducing the molten salt with the Ca concentration increased in the main electrolytic tank 5 to the Ca, A molten salt having a constant concentration in the vicinity of its saturation solubility is introduced into the reduction tank 1 to allow the TiCl ₄ reduction reaction to be performed efficiently, thereby allowing stable operation.

  However, if electrolysis is performed in the main electrolytic cell 5 until the Ca concentration exceeds the saturation solubility, metallic Ca is deposited inside the main electrolytic cell 5 and may cause troubles such as the clogging of the electrolytic cell described above. Therefore, when increasing the Ca concentration in the main electrolytic cell 5, electrolysis is performed while controlling so as to increase the Ca concentration until just before the saturation solubility, and molten salt having a high Ca concentration but less than the saturation solubility is obtained. It is desirable to introduce it into the adjustment tank 6 and bring it into contact with a Ca supply source so that the Ca concentration is a constant concentration in the vicinity of the saturation solubility.

  FIG. 2 is an apparatus used when the Ti manufacturing method according to (1) is carried out in the same manner as the apparatus shown in FIG. 1. The Ti manufacturing apparatus according to the present invention described in (2) is shown in FIG. It is a figure which shows the other schematic structural example. The difference from the apparatus shown in FIG. 1 is that a sedimentation separation tank (thickener) 13 using gravity is used instead of a high-temperature decanter as a separation means, and a larger installation area is required compared to the case where a high-temperature decanter is used. Although necessary, there is an advantage that the power cost is small.

  The first embodiment of the present invention is a method of “using a Ca supply source as a molten Ca—Mg alloy” in the Ti manufacturing method of the present invention described above.

  When the Ca supply source is a molten Ca—Mg alloy, when Ca is dissolved from the molten Ca—Mg alloy into the molten salt and it becomes necessary to replenish Ca of the alloy, it can be easily replenished as described below. So desirable.

The second embodiment of the present invention is a method of “increasing the Ca concentration in the molten Ca—Mg alloy by electrolyzing a molten salt containing CaCl ₂ in an alloy electrolytic cell” in the first embodiment.

  FIG. 3 is an explanatory diagram for replenishing Ca to the molten Ca—Mg alloy by the alloy electrolytic cell.

In FIG. 3, the alloy electrolytic cell 14 is divided into an anode side and a cathode side by a partition wall 15 having an opening on the lower side so that movement of the molten salt (molten CaCl ₂ ) is not hindered. An anode 2 is attached, and on the cathode side, a molten Ca—Mg alloy 16 having a specific gravity smaller than that of molten CaCl ₂ constitutes the cathode. An electrode rod 17 is inserted into the molten Ca—Mg alloy 16. On the other hand, molten salt whose Ca concentration has been increased in the electrolysis process is introduced into the adjustment tank 6, and a molten Ca—Mg alloy 16 serving as a Ca supply source is held thereon.

When molten CaCl ₂ is electrolyzed using this alloy electrolytic cell 14, chlorine gas is generated at the anode 2, and Ca is generated at the interface between the molten Ca—Mg alloy 16 serving as the cathode and the molten CaCl ₂ . Since a voltage is applied between the molten Ca—Mg alloy 16 and the electrolytic cell (a potential difference is generated), the generated Ca is not dissolved in the molten CaCl ₂ but is absorbed by the molten Ca—Mg alloy 16. The Ca concentration of the Ca—Mg alloy 16 increases.

Therefore, the molten Ca—Mg alloy 16 having an increased Ca concentration is transferred to the upper part of the molten Ca—Mg alloy 16 in the adjustment tank 6 (indicated as “Mg / Ca” in FIG. 3), and is present in the lower part. When Ca is supplied to the molten salt (that is, melted), the molten Ca—Mg alloy 16 having a reduced Ca concentration is returned to the molten Ca—Mg alloy 16 in the alloy electrolytic cell 14 (indicated as “Mg”). . In the electrolytic cell 14 for alloy, Ca generated by the electrolysis of molten CaCl ₂ described above is absorbed by the molten Ca—Mg alloy 16 and the Ca concentration increases.

  As described above, by applying the second embodiment of the present invention, it is possible to easily replenish Ca to the molten Ca—Mg alloy used as the Ca supply source without affecting the Ca production process. it can.

  FIG. 4 is a diagram showing a schematic configuration example of an apparatus when the alloy electrolytic cell shown in FIG. 3 is incorporated in an apparatus used when the Ti manufacturing method of the present invention is carried out.

  If the first and second embodiments of the present invention are applied using this apparatus, Ca can be easily replenished to the molten Ca—Mg alloy used as the Ca supply source without affecting the operation. it can.

In carrying out the method of the present invention, if the molten salt is operated at a reducing condition such that the Ca concentration of the molten salt is too low and Ca is completely consumed for the reduction of TiCl _{4 in} the reducing tank, as described above, TiCl ₄ Is discharged out of the tank as unreacted gas, and lower titanium chloride is generated. Therefore, it is desirable to adjust the supply amounts of TiCl ₄ and Ca so that a trace amount of Ca remains. However, if molten salt with Ca remaining, even in a trace amount, is charged into the main electrolytic cell, there is a concern that current efficiency may decrease due to back reaction between the residual Ca and chlorine generated by electrolysis in the main electrolytic cell. .

  The third embodiment of the present invention uses the alloy electrolyzer used in the second embodiment, and “puts the molten salt after the Ti grains are separated in the separation step into the alloy electrolyzer and melts it once. By reducing the Ca concentration of the salt and then throwing it into the main electrolytic cell, it is possible to eliminate concerns such as a decrease in current efficiency due to the back reaction.

  FIG. 5 is a diagram showing a schematic configuration example of an apparatus in which an alloy electrolytic cell is incorporated in the molten salt path returned from the separation step to the main electrolytic cell in the schematic configuration example of the Ti production apparatus shown in FIG. 1.

  As shown in FIG. 5, an alloy electrolytic cell 14 is installed between the high-temperature decanter 7 used in the separation step and the main electrolytic cell 5, and the molten salt after the Ti particles are separated and recovered is temporarily used for this alloy. To the electrolytic cell 14. Since a voltage is applied between the molten Ca—Mg alloy 16 and the electrolytic cell of the electrolytic cell 14 for alloy, Ca remaining in the molten salt is absorbed by the molten Ca—Mg alloy 16 by electrophoresis and is contained in the molten salt. Ca is removed. The molten salt with reduced Ca concentration is charged into the main electrolytic cell 5.

  FIG. 5 shows an example in which an alloy electrolytic cell 14 is installed between the high-temperature decanter 7 and the main electrolytic cell 5, but in the apparatus shown in FIG. 2, between the thickener 13 and the main electrolytic cell 5. An alloy electrolytic cell 14 may be installed.

When this third embodiment is adopted in carrying out the method of the present invention, the decrease in current efficiency due to the back reaction in the main electrolytic cell 5 is suppressed, and the Ca removed from the molten salt is molten Ca- Since it is absorbed by the Mg alloy 16 and used again in the adjustment tank 6 for the reduction of TiCl ₄ , Ca remaining in the molten salt can be effectively used.

  4th Embodiment of this invention is a manufacturing method of Ti which is "the adjustment tank used with the method as described in said (1) is provided with a cooling function."

By adopting this embodiment, the following two effects can be expected. One is to adjust the Ca concentration of the molten salt in the adjustment tank 6 and then perform a reduction reaction of TiCl ₄ with Ca in the next reduction step. The heat removal from the molten salt supplied to the reduction tank 1 can be relaxed to some extent.

  The other is that the saturated Ca solubility of the molten salt can be reduced by lowering the temperature of the molten salt in the adjustment tank 6. By this action, even if the Ca concentration of the molten salt introduced from the main electrolytic cell 5 to the adjustment tank 6 does not reach its saturation solubility, the saturation solubility can be reached by lowering the temperature in the adjustment tank 6. Even if Ca is precipitated by cooling, it floats and becomes a supply source of Ca.

That is, if the molten salt supplied from the adjustment tank 6 is cooled and controlled so as to have a constant temperature, the Ca concentration of the molten salt charged into the reducing tank 1 is always kept constant and high. Therefore, the reduction reaction of TiCl ₄ can be performed efficiently and stable operation can be achieved.

The Ti production apparatus described in (2) above is an apparatus used when the Ti production method described above is carried out. “The molten salt containing CaCl ₂ and dissolved in Ca is retained, and the molten salt is contained in the molten salt. A reduction tank for reacting the supplied TiCl ₄ with the Ca to generate Ti particles, a separation means for separating the Ti particles generated in the molten salt from the molten salt, and the Ti particles are separated. A main electrolytic cell for holding the molten salt after being formed, comprising an anode and a cathode, electrolyzing the molten salt to produce Ca on the cathode side, and a Ca supply source, wherein the main electrolytic cell An apparatus for producing Ti having an adjustment tank for introducing the molten salt into the reduction tank after introducing the molten salt therein and bringing it into contact with a Ca supply source to make the Ca concentration of the molten salt constant. It is.

  The apparatus illustrated in FIGS. 1 and 2 is an embodiment of the apparatus of the present invention, and as described above, the Ti manufacturing method of the present invention can be suitably implemented using this apparatus.

  The apparatus shown in FIG. 4 is another embodiment of the apparatus, and as described above, the molten Ca—Mg alloy 16 is transferred between the adjustment tank 6 and the alloy electrolytic tank 14 and used as a Ca supply source. It is suitable for carrying out the Ti manufacturing method according to the first and second embodiments for replenishing Ca in a molten Ca—Mg alloy.

  The apparatus shown in FIG. 5 is another embodiment of the apparatus, and an alloy electrolytic cell 14 is installed between the high-temperature decanter 7 used in the separation step and the main electrolytic cell 5, and the alloy electrolytic cell 14. The molten salt having a reduced Ca concentration can be charged into the main electrolytic cell 5. If this apparatus is used, as described above, the Ti manufacturing method according to the third embodiment can be easily implemented.

According to the Ti production method and apparatus of the present invention described above, it is possible to increase the concentration of Ca in the CaCl ₂ -containing molten salt charged into the reduction tank and to suppress fluctuations in concentration, and to reduce the TiCl ₄ reduction reaction. Efficient and stable operation can be performed.

  Furthermore, in the Ti production method of the present invention, in the electrolysis step, the molten salt is electrolyzed while gradually flowing down the molten salt from the upper side to the lower side of the main electrolytic cell, so that a large amount of molten salt can be continuously processed. Yes, thereby increasing the supply rate of Ca to the reduction tank and making it possible to produce Ti on an industrial scale.

  Therefore, a molten salt electrolysis method that enables production of Ti on such an industrial scale and an electrolytic cell used therefor will be described in detail.

  FIG. 6 is a longitudinal sectional view showing a configuration example of a main part of an electrolytic cell used when carrying out the molten salt electrolysis method used in the present invention.

The electrolytic cell 5 is disposed in the vessel 5a along the longitudinal direction of the electrolytic cell vessel 5a, which is a pipe (cylindrical) shape that is long in one direction and holds the molten salt containing CaCl _2. Furthermore, it has a cylindrical anode 2 and a columnar cathode 3, and a molten salt supply port 20 is provided at one end (bottom plate 18) in the longitudinal direction of the electrolytic cell container 5 a, and the other end ( The upper lid 19) is provided with a molten salt outlet 21. The anode surface and the cathode surface face each other and are arranged in a substantially vertical direction, and a diaphragm 4 is provided between the anode 2 and the cathode 3 to suppress the passage of Ca generated by electrolysis of the molten salt. A cooler 22 is attached to the outer surface of the anode 2.

  This electrolytic cell 5 is used as a main electrolytic cell in the Ti production method of the present invention.

  The molten salt electrolysis method performed using this electrolytic cell is as follows. That is, a molten salt containing a metal fog forming metal chloride is continuously or intermittently supplied from one end of the electrolytic cell between the anode and the cathode, thereby giving a one-way flow rate to the molten salt near the cathode surface. In this molten salt electrolysis method, the molten salt is electrolyzed while flowing in one direction near the cathode surface to increase the metal fog forming metal concentration of the molten salt.

The above-mentioned “metal fog forming metal” has a property that the metal itself dissolves in a metal chloride such as Ca, Li, Na, Al, etc. (that is, Ca is dissolved in CaCl ₂ and Li Is a metal that dissolves in LiCl) and reduces TiCl ₄ . Since these metals all act in the same manner when TiCl ₄ is reduced to produce Ti, the case where the metal fog forming metal is Ca will be described below.

Also, the "molten salts containing chloride of metal-fog forming metal (Ca)", as described above, only the molten CaCl _2, or, in the molten CaCl _2, lowering the melting point, in order to adjust the viscosity or the like It is a molten salt to which KCl, CaF _{2 and the} like are added.

In the molten salt electrolysis method, first, a molten salt containing CaCl ₂ is continuously or intermittently supplied from one end of the electrolytic cell 5 between the anode 2 and the cathode 3.

  Since the electrolytic cell 5 has a shape that is long in one direction (in the illustrated example, a vertically long pipe (cylindrical shape)), the molten salt is continuously supplied from one end of the electrolytic cell 5 between the anode 2 and the cathode 3. By supplying periodically or intermittently, a flow rate in one direction is given to the molten salt near the surface of the cathode 3, and the molten salt can flow in one direction near the cathode surface. In this case, it is sufficient that at least the molten salt near the surface of the cathode 3 flows in one direction, and the entire molten salt between the anode 2 and the cathode 3 may flow in one direction. The term “near the cathode surface” refers to a region adjacent to the cathode surface where Ca generated on the cathode surface is present.

  Although the supply of the molten salt is normally performed continuously, the supply of the molten salt may be intermittently stopped, that is, the supply of the molten salt may be temporarily stopped or continued again. When the supply of molten salt is temporarily stopped, the flow of molten salt near the cathode surface is also stopped. Therefore, strictly speaking, the “flow velocity” at the time of “giving a flow rate in one direction to the molten salt in the vicinity of the cathode surface” includes a state of zero flow velocity.

  Subsequently, the molten salt is electrolyzed.

  That is, the molten salt is electrolyzed while flowing in one direction near the cathode surface to generate Ca on the cathode surface, but the electrolytic cell 5 has a long shape in one direction, and is further shown in FIG. In this example, since the distance between the anode 2 and the cathode 3 is made relatively small in order to keep the electrolysis voltage low, the molten salt in the vicinity of the molten salt supply port 20 having a low Ca concentration and the molten Ca concentration increased by electrolysis. Mixing with the molten salt near the salt extraction port 21 can be prevented, and only the molten salt enriched with Ca can be effectively extracted.

The technique described in Patent Document 3 described above uses Ca for reduction, but is a direct reduction method in which TiO ₂ is not directly TiCl ₄ but reduced directly with Ca to Ti, and the molten salt electrolysis method used in the present invention is used. Is different. Furthermore, in the direct reduction method described in this document, the carbon electrode as the anode is consumed as CO ₂ and titanium carbide (TiC) is generated in the molten salt, so that the resulting Ti is contaminated with C. Since Ti is mixed and workability deteriorates, it becomes a problem when this Ti is used as a wrought material.

  Further, this document describes a technique of “forming a molten salt flow near the cathode in the production of Ti by Ca reduction in a molten salt”. However, the anode and the cathode are arranged to face each other in the longitudinal direction in the electrolytic cell, and in the cathode chamber formed near the cathode surface or between the cathode surface and the diaphragm when a diaphragm is provided. The technical idea of suggesting or recovering molten salt with increased Ca concentration on the outlet side of the electrolytic cell by forming a flow of molten salt in one direction along the cathode surface and performing electrolysis in that state Not shown.

  Accordingly, the molten salt electrolysis method used in the present invention and the technique described in Patent Document 3 are completely different from each other even though they are common in that a one-way flow is formed in the molten salt in the electrolytic cell.

In this molten salt electrolysis method, an anode surface and a cathode surface are arranged to face each other in a substantially vertical direction, and a partition wall is provided between the anode and the cathode so that a diaphragm or a part of the molten salt can flow therethrough. If a tank is used, it is easy to recover chlorine gas generated on the anode side. Further, it is possible to the Ca and chlorine generated by electrolysis can be inhibited back reaction back to CaCl ₂ reacts desirable. In addition, “substantially” in the “substantially vertical direction” means “substantially” and “substantially”, and “substantially vertical direction” is slightly inclined from the vertical direction or from that direction toward the horizontal direction. The direction.

The molten salt electrolysis method using the electrolytic cell in which both the electrodes are arranged opposite to each other in a substantially vertical direction can be suitably carried out by using the electrolytic cell illustrated in FIG. In addition, in the electrolytic cell illustrated in FIG. 6, CaCl ₂ is supplied from below the electrolytic cell 5 into the electrolytic cell 5 and extracted from above, but conversely, it is supplied from above the electrolytic cell 5 and below. It is also possible to adopt a method of extracting from the.

  In the electrolytic cell used in this method, the anode surface and the cathode surface are opposed to each other in a substantially vertical direction. On the other hand, the molten salt in the vicinity of the cathode surface is given a flow rate in one direction. The flow direction is vertical, and the chlorine gas generated on the anode side floats easily and is easy to recover.

As the diaphragm provided between the anode and the cathode, for example, a porous ceramic body containing yttria (Y ₂ O ₃ ) can be used. A porous ceramic body obtained by firing yttria has selective permeability of allowing Ca and chlorine ions to pass through but not allowing metal Ca to pass through, and has excellent resistance to being reduced by Ca having a strong reducing power. It has calcium reducibility and is suitable as a diaphragm in the molten salt electrolysis method used in the present invention.

If an electrolytic cell in which such a diaphragm is provided between the anode and the cathode is used, back reaction occurs in which Ca produced on the cathode side immediately reacts with chlorine produced on the anode (graphite) side and returns to CaCl _2. It is difficult to perform electrolysis with high current efficiency.

  Instead of the diaphragm, a partition configured to allow a part of the molten salt to flow may be used. The partition does not allow molten salt such as Ca and chlorine ions as well as metal Ca, but by providing a slit or a hole through which molten salt can pass in a part of the partition, electrolysis is possible. It is possible to limit the passage to some extent and suppress back reaction.

  In this molten salt electrolysis method, the cathode is hollow, has a gap or a hole through which molten salt can flow into the cathode from the cathode surface, and the Ca-concentrated molten salt flowing into the cathode can be extracted out of the electrolytic cell. If an electrolytic cell having such a cathode is used, back reaction can be effectively suppressed.

  FIG. 7 is a diagram schematically showing a configuration example of a part of an electrolytic cell using a hollow cathode. As shown in FIG. 7, in this electrolytic cell, the anode 2 and the hollow cathode 3a are arranged in a substantially vertical direction so as to face each other along the longitudinal direction in the electrolytic cell 5, and between the anode 2 and the cathode 3a. A diaphragm 4 is provided. Although not shown, the cathode 3a is provided with a gap or a hole through which molten salt can flow from the cathode surface into the cathode.

  If the electrolytic cell constructed in this way is used, the molten salt is extracted from above the hollow part of the cathode 3a, so that the melt from the cathode outer surface side to the inside (hollow part) as shown by the white arrow in the figure. A salt flow is formed, and Ca generated on the outer surface of the cathode 3a is immediately taken into the cathode 3a without diffusing and moving to the anode side. Thereby, a back reaction can be suppressed effectively. Since the electrolytic cell illustrated in FIG. 7 has the diaphragm 4, the back reaction suppressing effect is further increased as compared with the case without the diaphragm.

  There are no particular limitations on the size, position, etc. of the gaps and holes provided in the hollow cathode. Considering the distance between the anode surface (diaphragm surface if a diaphragm is provided) and the outer surface of the cathode, the amount of molten salt extracted (the amount of molten salt supplied), etc., the effective molten salt on the inner surface of the cathode It is good to determine appropriately so that a flow may be formed.

Moreover, in this molten salt electrolysis method, if the Ca concentration of the molten salt in the electrolytic cell is controlled to be less than its saturation solubility, the Ca concentration is increased to increase the TiCl ₄ generation rate, Defects such as blockage inside the tank can be suppressed. The above-mentioned “controlling the Ca concentration to be lower than the saturation solubility” means “electrolysis under the condition that the Ca concentration is close to the saturation solubility and does not precipitate”.

  Specifically, the shape of the electrolytic vessel container, the electrode shape, and the distance between the electrodes so that the “condition where the Ca concentration is close to the saturation solubility and does not precipitate” is satisfied at the site where the Ca concentration in the electrolytic cell is highest. The optimum electrolysis conditions according to the distance, the amount of molten salt extracted per unit time, etc. are determined empirically. In particular, when a diaphragm or partition is used between the anode and the cathode, the Ca concentration in the vicinity of the molten salt outlet on the cathode side is the highest, so by controlling the Ca concentration in this part to be less than the saturation solubility, Electrolytic operation that does not deposit metal Ca at any part of the electrolytic cell is possible.

  In the Ti production method of the present invention described in the above (1), the molten salt whose Ca concentration has been increased in the electrolysis step is obtained by satisfying this “condition for Ca concentration close to saturation solubility and not precipitating”. The molten salt is introduced into an adjustment tank having a supply source and brought into contact with the Ca supply source, and the Ca concentration of the molten salt is made high and constant. A certain degree of control is also possible by empirically determining the above.

  When carrying out the molten salt electrolysis method used in the present invention, large heat of reaction is generated in the electrolytic cell, so it is desirable to effectively remove the heat. Specifically, whether or not the hollow cathode described above is used, it is desirable to install a cooler at the center of the cathode and extract reaction heat from the inside of the cathode. As the cooler, for example, a tubular heat exchanger is suitable.

  If a cooler (heat exchanger) is also installed on the anode side, the heat removal efficiency is further increased. The cooler 22 installed so as to surround the anode 2 shown in FIG. 6 is an example of this.

  In the electrolysis, in order to increase the amount of energization and increase the amount of Ca generation, it is necessary to increase the energization surface area. As for the inner surface of the anode 2, that is, the surface facing the cathode surface in the electrolytic cell illustrated in FIG. 6, it is desirable to provide fine irregularities on the inner surface in order to ensure a large current-carrying surface area. As a method therefor, for example, a groove process for forming a groove on the electrode surface can be applied.

  According to the molten salt electrolysis method described above, it is possible to relatively stably obtain a molten salt in which Ca is concentrated to close to the saturation solubility, while suppressing adverse effects such as clogging inside the electrolytic cell, so that metal Ti can be efficiently used. Can be manufactured well. Moreover, since the molten salt is electrolyzed while flowing in one direction near the cathode surface, a large amount of molten salt can be processed continuously.

An electrolytic cell used for carrying out this molten salt electrolysis method includes an electrolytic cell container that is long in one direction holding a molten salt containing CaCl ₂ , and an anode and a cathode that are arranged along the longitudinal direction of the electrolytic cell container. A molten salt supply port is provided at one end in the longitudinal direction of the electrolytic cell container so as to supply molten salt between the anode and the cathode, and electrolysis of the molten salt is performed at the other end. This is an electrolytic cell provided with a molten salt extraction port for extracting the molten salt with increased Ca concentration produced by the above method.

  The electrolytic cell illustrated in FIG. 6 includes an electrolytic cell in which an anode surface and a cathode surface are opposed to each other in a substantially vertical direction and a diaphragm is provided between the anode and the cathode. . Instead of the diaphragm, a partition wall configured to allow a part of the molten salt to flow therethrough may be provided.

  If the electrolytic cell shown in this FIG. 6 is used, as mentioned above, the molten salt electrolysis method used by this invention can be implemented suitably.

According to the Ti production method of the present invention, the molten salt whose Ca concentration has been increased in the electrolysis step is introduced into a regulating tank equipped with a Ca supply source to make the Ca concentration constant, and then used for the reduction of TiCl _4. Variations in the Ca concentration of the molten salt charged into the tank can be suppressed and maintained at a high concentration. In the electrolysis process, since the molten salt is electrolyzed while flowing in one direction near the cathode surface, a large amount of molten salt can be continuously processed. As a result, the reduction reaction of TiCl ₄ can be performed efficiently, stable operation is possible, and furthermore, Ti can be produced on an industrial scale.

  Therefore, the Ti production method of the present invention and the Ti production apparatus of the present invention capable of easily and suitably carrying out this method can be effectively used for the production of Ti by Ca reduction.

It is a figure which shows the example of schematic structure of the manufacturing apparatus of Ti of this invention. It is a figure which shows the other schematic structural example of the manufacturing apparatus of Ti of this invention. It is explanatory drawing about replenishment of Ca with respect to the molten Ca-Mg alloy by the electrolytic bath for alloys. It is a figure which shows the example of schematic structure of the manufacturing apparatus of Ti of this invention incorporating the electrolytic cell for alloys. It is a figure which shows the schematic structural example of the manufacturing apparatus of Ti of this invention which incorporated the electrolytic cell for alloys in the path | route of the molten salt returned to a main electrolytic cell from a isolation | separation process. It is a longitudinal cross-sectional view which shows the structural example of the principal part of the electrolytic vessel used when implementing the molten salt electrolysis method used by this invention. It is a figure which shows typically the structural example of a part of electrolytic vessel using the hollow cathode used when implementing the molten salt electrolysis method used by this invention.

Explanation of symbols

1: Reduction tank 2: Anode 3, 3a: Cathode 4: Diaphragm 5: Main electrolytic tank, electrolytic tank 5a: Electrolytic tank container 6: Adjustment tank 7: High temperature decanter 8: Separation tank 9: TiCl ₄ supply port 10: Plasma torch 11: Mold 12: Ti ingot 13: Thickener 14: Electrolyzer for alloy 15: Partition 16: Molten Ca-Mg alloy 17: Electrode rod 18: Bottom plate 19: Upper lid 20: Molten salt supply port 21: Molten salt outlet 22: Cooler

Claims (9)

A reduction step of causing TiCl ₄ to react with Ca in the molten salt containing CaCl ₂ and dissolving Ca to produce Ti particles in the molten salt; and Ti particles generated in the molten salt from the molten salt A separation step of separating, and an electrolysis step of increasing the Ca concentration by electrolyzing a molten salt having a Ca concentration decreased with the formation of Ti grains, and the Ca concentration was increased using the main electrolytic cell in the electrolysis step The molten salt is introduced into an adjustment tank having a Ca supply source and brought into contact with the Ca supply source to make the Ca concentration of the molten salt constant, and then used for the reduction of TiCl _{4 in} the reduction step. A method for producing Ti.   The method for producing Ti according to claim 1, wherein the Ca supply source is a molten Ca-Mg alloy. The Ca concentration in the molten Ca-Mg alloy, a manufacturing method of Ti according to claim 2, the molten salt is characterized by enhanced by electrolysis of an alloy electrolyzer containing CaCl _2.   The molten salt after the Ti grains are separated in the separation step is once charged into an alloy electrolytic cell, and the Ca concentration of the molten salt is reduced and then charged into the main electrolytic cell. A method for producing Ti.   The method for producing Ti, wherein the adjustment tank used in the method according to claim 1 has a cooling function. A reducing tank for holding a molten salt containing CaCl ₂ and dissolving Ca, reacting TiCl ₄ supplied in the molten salt with the Ca to generate Ti particles, and generated in the molten salt A separation means for separating the Ti particles from the molten salt, and the molten salt after the Ti particles are separated are held, and an anode and a cathode are provided. Electrolysis is performed in the molten salt, and Ca is provided on the cathode side. And a Ca supply source. The molten salt in the main electrolytic cell is introduced into contact with the Ca supply source to make the Ca concentration of the molten salt constant, and then melted. An apparatus for producing Ti, comprising an adjustment tank for introducing salt into the reduction tank.   The Ti production apparatus according to claim 6, wherein the Ca supply source is a molten Ca—Mg alloy.   The Ti production apparatus according to claim 7, further comprising an alloy electrolytic cell for increasing a Ca concentration of the molten Ca—Mg alloy. The Ti manufacturing apparatus according to claim 6, wherein the adjustment tank further has a cooling function.

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