JP6524492B2 - Method of manufacturing vanadium metal - Google Patents

Description

  The present invention relates to a process for the production of metallic vanadium, in particular highly pure metallic vanadium.

  Metallic vanadium is widely used as a coating material, additive to titanium, aluminum, zirconium and steel, heat resistant material such as jet machine and induction missile, sputtering target, vacuum tube evaporation, alloy based superconducting material etc. It is also used as a reactor material due to its characteristics.

Metallic vanadium is expected to be a single metal as a hydrogen storage material because it has a hydrogen storage / release characteristic of about 2.2 mass% at normal temperature and pressure. For example, utilization of a vanadium-based hydrogen storage alloy is considered as a cathode of a Ni-hydrogen battery that can be a substitute for a nickel cadmium battery.
Furthermore, its application to electrolytes of vanadium redox flow batteries and vanadium-air batteries with higher energy density is also considered, and is expected as a basic material for future technology.

  Conventionally, as a method of producing metallic vanadium, there is a method of repeatedly using the thermit reaction and the electron beam melting method. Briefly, in this production method, vanadium pentoxide is first thermally reduced with aluminum to produce crude vanadium containing a large amount of aluminum and oxygen. Thereafter, dissolution and solidification of the obtained crude vanadium are repeated using an electron beam to produce metallic vanadium. According to this method, vanadium of high purity can be produced by repeating dissolution and solidification to achieve high purification. However, this method of production requires much equipment and energy and is laborious, so the metallic vanadium produced is very expensive.

  Further, as another manufacturing method, a Ca thermal reduction method of vanadium oxide has been developed (see Patent Document 1). Using this production method, metallic vanadium can be produced from vanadium pentoxide at a lower cost than the above-described production method. However, since vanadium pentoxide has a relatively low melting point, the metal vanadium produced is likely to be stuck to the reaction vessel used in the manufacturing process, and it is easy to prevent the mixing of impurities such as reducing substances in the reaction vessel. Not

  Furthermore, as another production method, there is a production method of metallic vanadium using a halide of vanadium as a raw material (see Patent Document 1). However, since the halide of vanadium is very difficult to handle and the process design for removing by-products generated in the process is complicated, the enlargement of the apparatus is difficult, and it has not been put to practical use.

  By the way, in recent years, as another method for producing metallic vanadium, a production method using a technique of calcium reduction of vanadium pentoxide using a melt electrolysis has been developed. This manufacturing method is an application of technology (so-called "OS method"), which has attracted attention as a manufacturing method (new reduction method) of metals such as titanium oxide, to vanadium manufacturing in recent years. The “OS method” is simply a reduction method using molten calcium chloride, and is a technology in which the “calcium chloride-calcium oxide electrolytic method” and the “calcium thermal reduction method” are integrated (patent document) 2).

Akihiko Miyauchi, Toru Okabe "Development of new manufacturing technology of vanadium and vanadium alloys" Journal of the Japan Institute of Metals, Vol. 74, No. 11 (2010) 701-711 commentary Patent No. 3981601

Okaichi Koichi, Suzuki Akira "Direct Reduction of Vanadium Oxide Using Molten Calcium Chloride Bath" Journal of the Japan Institute of Metals, Vol.72, Vol.3 (2008) 181-187 R. O. Suzuki etc. "Direct reduction of vanadium oxide in molten CaCl2" Mineral Processing and Extractive Metallurgy (Trans. Inst. Min. Metal. C) 2008, Vol. 117, No. 2, 108-112 Y. Oka, and R. O. Suzuki "Direct Reduction of Liquid V2O5 in Molten CaCl2" ECS Transactions, 16 (49) 255-264

  However, in the method of producing metallic vanadium to which the “OS method” is applied, vanadium pentoxide having a low melting point is used as a raw material, and as described above, there is a possibility that impurities may be mixed in the production stage. Manufacturing is not easy. Although it is thought that this problem will be improved by using vanadium trioxide having a higher melting point, in this case, since it is necessary to reduce vanadium pentoxide to vanadium trioxide, it takes time and effort to Manufacturing efficiency is reduced.

  The present invention has been made in view of such problems, and provides a method for producing metallic vanadium which can produce metallic vanadium of high purity more easily, at lower cost and with energy saving. .

The inventors of the present invention, while developing a vanadium battery such as a redox flow battery, thought that a manufacturing technique that can easily and inexpensively manufacture the metallic vanadium necessary for these batteries is necessary. Further, as described above, metallic vanadium is widely used in various applications, and it is considered that the demand is also increased in this respect.
Based on these facts, we conclude that we need a manufacturing technology that can produce metallic vanadium simply and at low cost, and based on the judgment that the need for metallic vanadium of high purity will increase in the future We decided to develop a simple and low-cost manufacturing method.
Therefore, focusing on the method of producing metallic vanadium to which the above-mentioned "OS method" is applied, research and development have been advanced from the viewpoint of preventing the mixing of impurities, and the present invention as described below has been made.

  The invention according to the present application electrolyzes a part of the inorganic molten salt of the inorganic molten salt forming the molten salt electrolytic bath in the reaction tank to form a reductive decomposition product, and the reductive decomposition product It is a manufacturing method of metallic vanadium which carries out thermal reduction of a vanadium compound and manufactures metallic vanadium, and one or two sorts chosen from a group which consists of a sulfide, a sulfuric acid compound, and an oxide of calcium as said some inorganic molten salt. The above is included, and the reductive decomposition product contains calcium obtained by electrolyzing the above-mentioned part of the inorganic molten salt, the above-mentioned vanadium compound is a vanadium sulfide, a vanadium sulfate compound, A metallic vanadium, which is a mixed vanadium compound containing one or more selected from the group consisting of a thiosulfate compound of vanadium, ammonium metavanadate and vanadyl sulfate Is a method of producing

While examining methods for preventing the contamination of impurities, attention was paid to using vanadium sulfide or vanadium sulfate compound having a high melting point as a raw material, and research and development were further advanced to achieve the present invention.
These vanadium compounds having a high melting point are easy to handle at the production stage, such as when they are introduced into a molten salt electrolytic bath. Therefore, it is possible to more easily prevent the mixing of impurities caused by the raw materials and the handling thereof, and it is possible to more easily manufacture high-purity metallic vanadium. For example, comparing the melting points, V ₂ S ₃ is about 2,400 ° C., V ₂ O ₃ is about 1,970 ° C., and V ₂ O ₅ is about 690 ° C.
Further, as a result of further research, when a vanadium compound having a high melting point is used as a part of the raw material, mixing of impurities is tended to be prevented even when a vanadium oxide having a relatively low melting point is contained in a part of the raw material. I found it to be. It is thought that if the vanadium compound having a high melting point is mixed in the raw material, the vanadium oxide is difficult to melt or, even if the vanadium compound is melted, the decrease in the handling property is prevented by the presence of the vanadium compound having a high melting point in the periphery. Be

  Furthermore, research was conducted focusing on inorganic molten salts for producing reductive decomposition products necessary for thermal reduction. As a result, regardless of whether vanadium sulfide or vanadium sulfate compound is included as a vanadium compound as a raw material, calcium sulfide and calcium sulfate are contained as a part of inorganic molten salt necessary for the formation of reductive decomposition products. It has been found that high purity metal vanadium can be easily produced by including one or more selected from the group, and the following invention has been achieved.

  Another invention according to the present application electrolyzes a part of the inorganic molten salt of the inorganic molten salt forming the molten salt electrolytic bath in the reaction tank to form a reductive decomposition product, and the reductive decomposition product Method of producing metallic vanadium by thermally reducing a vanadium compound with a metal to produce metallic vanadium, wherein the partial inorganic molten salt contains one or more selected from the group consisting of calcium sulfide and calcium sulfate The reductive decomposition product contains calcium obtained by electrolysis of the inorganic molten salt of the part, the vanadium compound is vanadium sulfide, vanadium oxide, vanadium sulfate compound, A mixed vanadium compound containing one or more selected from the group consisting of thiosulfuric acid compounds of vanadium, ammonium metavanadate and vanadyl sulfate It is a method for producing a metal vanadium.

Even when vanadium oxide having a relatively low melting point is used as the raw material, by including one or more selected from the group consisting of calcium sulfide and calcium sulfate as the inorganic molten salt forming the molten salt electrolytic bath It is considered that the contamination of impurities is prevented.
That is, in the invention according to the present application described above, the vanadium compound as the raw material includes one or more selected from the group consisting of vanadium sulfide and vanadium sulfate compounds, and It is considered that high purity metal vanadium can be more easily produced by combining calcium sulfide and calcium sulfate with the inorganic molten salt of the above.

In addition, when vanadium sulfide or a vanadium sulfate compound is used as a vanadium compound which is a raw material, metallic vanadium can be produced with less electric power. That is, metallic vanadium can be efficiently produced at low cost. This point was specifically studied, and V ₂ S ₃ , V ₂ O ₃ or V ₂ O ₅ was used as an example to compare the theoretical quantity of electricity Q ₀ when producing metallic vanadium from these raw materials. Doing this _{calculation, Q 0 = 2,923C / gV 2} S 3, Q 0 = 3,863C / gV 2 O 3, Q 0 = 5,305C / gV was ₂ O _5. The relatively small amount of theoretical electrical charge of vanadium sulfide is advantageous in producing metallic vanadium.

Incidentally, the inorganic molten salt to form a vanadium compound and an electrolytic bath which is a raw material, if it contains a compound containing sulfur, components discharged from the molten salt electrolytic bath reacts with S ₂ gas or anode carbon product When become CS ₂ gas, the gas is not to discharge into the environment from the reaction vessel to precipitate by cooling, it is excellent in that it can easily be recovered as each solids and liquids.

  And according to the manufacturing method of both inventions mentioned above, metallic vanadium can be manufactured continuously. It can be said that the manufacturing method which can manufacture metal vanadium continuously can be advantageous at the time of industrialization or mass production.

  Moreover, according to both the inventions described above, granular or powdered metallic vanadium can be easily produced. As described above, metallic vanadium is used in a wide variety of applications such as, for example, catalysts, hydrogen storage alloys, and chemical batteries. And in these applications, although powdered metallic vanadium is required, if metallic vanadium which is not a powder is manufactured, it will take time and effort to make a powder, and that part will become expensive. In this respect, both of the above-described manufacturing methods of the present invention are extremely excellent in that granular or powdered metallic vanadium can be easily manufactured, and low cost can be realized.

  Furthermore, according to both the inventions described above, granular or powdery and porous metallic vanadium can be easily produced. The reason why the metallic vanadium of the powder is required may be, for example, the excellent mixing property, solubility and reactivity, and the large surface area, etc. However, the porous property is not particularly limited. It is the property of further improving the characteristics. Therefore, granular or powdery and porous metallic vanadium is more preferable as metallic vanadium used in the above-mentioned catalyst, hydrogen storage alloy, chemical battery and the like. That is, both of the above-described inventions are extremely excellent in that granular or powdery and porous metallic vanadium can be easily produced, and low cost can be realized.

Furthermore, according to both the inventions described above, metallic vanadium with lower oxygen concentration can be easily manufactured. Metallic vanadium having a low oxygen concentration is excellent in that the hydrogen storage characteristics are significantly improved and when it is used for reactor materials, the activation of impurities is reduced.
That is, both of the above-described inventions are extremely excellent in that metallic vanadium with low oxygen concentration can be easily produced and low cost can be realized.

And as a manufacturing method of the above-mentioned metallic vanadium, a part of inorganic molten salt is generated as an inorganic molten salt generated by thermal reduction or thermal decomposition in a cathode, and a generated inorganic molten salt is the above-mentioned molten salt. It may be a manufacturing method of forming a part of the electrolytic bath.
In addition, it may be a method of producing metallic vanadium that produces sulfur by an anodic reaction at the anode.
Furthermore, an oxide is contained in at least one of the vanadium compound and the part of the inorganic molten salt, and a carbon material is used as an anode for electrolysis, and carbon dioxide gas is produced by the anode reaction at the anode. May be a method of producing vanadium metal.

Then, a part of the inorganic molten salt in the molten salt electrolytic bath is electrolyzed using a carbon material as an anode for electrolysis, and at least a sulfur gas is generated by an anode reaction at the anode, along with the formation of metallic vanadium. The method may be a method for producing vanadium metal, which produces at least calcium sulfide, and the product is dissolved in a molten salt electrolytic bath.
In addition, a carbon material is used as an anode for electrolysis, the above-mentioned part of the inorganic molten salt in the molten salt electrolytic bath is electrolyzed, and at least a carbon dioxide gas is generated by an anode reaction at the anode. It may be a method of producing vanadium metal which produces calcium oxide and the product is dissolved in a molten salt electrolytic bath.
Furthermore, a carbon material is used as an anode for electrolysis, the above-mentioned part of inorganic molten salt in the molten salt electrolytic bath is electrolyzed, and at least one of the above-mentioned vanadium compound and the above-mentioned part of inorganic molten salt The production method of metallic vanadium may be such that at least calcium sulfide is produced along with the production of metallic vanadium due to the inclusion of the sulfuric acid compound, and the product is dissolved in the molten salt electrolytic bath. Note that calcium sulfide CaS and calcium oxide CaO may be produced as by-products as the metal vanadium is produced. These products are also dissolved in the molten salt electrolytic bath and electrolyzed again. Furthermore, at least sulfurous acid gas may be generated by the anode reaction at the anode.
Also, vanadium compounds containing part of sulfur (for example, vanadium sulfate compounds, thiosulfuric acid compounds of vanadium, vanadyl sulfate vanadium) are removed by sulfurization as sulfur dioxide gas by thermal decomposition at elevated temperature, and vanadium pentoxide V ₂ O ₅ can be made. For this reason, other than vanadium sulfide, a portion of the vanadium compound containing sulfur in the reaction temperature may be a vanadium compound as a vanadium pentoxide V ₂ O ₅ containing residual sulfur.

And it is preferable that the said one part inorganic molten salt is a calcium compound, and the addition amount of the said calcium compound is 0.01 mol%-30 mol%.
Moreover, as for the addition amount of the said calcium compound, it is more preferable that it is 0.01 mol%-20 mol%.
Furthermore, the temperature (reaction temperature) of the molten salt electrolytic bath in the electrolysis is preferably 873 K or more and 1423 K, and the electrolysis voltage is preferably 1.6 V or more and 3.21 V or less.
Furthermore, the vanadium sulfide is one or more selected from the group consisting of VS, V ₂ S ₃ , V ₅ S ₈ , V ₃ S ₄ , and V ₂ S ₅ , and the vanadium thiosulfate is VS ₂ O ₃ is preferable, and the vanadium sulfate compound is preferably one or more selected from the group consisting of VSO ₄ , V ₂ (SO ₄ ) ₃ and VOSO ₄ .

  According to the method for producing metallic vanadium as the invention according to the present application, metallic vanadium with high purity can be produced more simply and at low cost.

  Next, a method of producing metallic vanadium according to the present invention will be described with reference to the drawings.

  SUMMARY OF THE INVENTION The present invention is generally a method of thermally reducing a vanadium compound in a molten salt to produce metallic vanadium. As a vanadium compound, the oxide of vanadium and a sulfide can be mentioned, for example.

As shown in FIG. 1, first, the crucible 3 installed in the stainless steel closed vessel 4 that can be heated by the heater 5 is prepared. Here, a crucible made of dense magnesium oxide was used.
In addition, an anode 1 and a cathode 2 disposed in the crucible 3 were prepared. The anode 1 is composed of an upper titanium rod (titanium rod) 1a and a lower end carbon rod 1b. The cathode 2 is composed of a titanium rod 2a and a container 2b for containing a vanadium compound. The container 2 is a cage-shaped container composed of a mesh made of titanium, and is disposed at a position surrounding the titanium rod 2a in the production of metallic vanadium (see FIG. 1). Then, a DC power supply (not shown) for applying a DC voltage between the anode 1 and the cathode 2 was prepared.

After that, the raw material of the mixed molten salt 8 is put into the crucible 3 and vacuum dewatering treatment is carried out in the closed vessel 4, then argon gas Ar is injected into the closed vessel 4 from the intake port 9 and under argon gas atmosphere. Allow the temperature to rise. Here, the temperature was raised to 900 ° C. Thus, the mixed molten salt 8 was prepared in the crucible 3. The mixed molten salt 8 is a mixture of calcium chloride (CaCl ₂ ) and calcium sulfide or calcium oxide as described later. The temperature of molten salt 8 in stainless steel closed vessel 4, crucible 3 and crucible 3 is measured by a thermometer such as thermocouple 6, and the voltage and current at the time of energization are measured by a measuring device (not shown). It measured and recorded these measured values on a personal computer by a data logger.

When the temperature is stabilized, the cathode 2 containing the vanadium compound 12 is immersed in the molten salt 8 in the anode 1 and the container 2 b which are disposed in advance in the container 4 before the container 4 is sealed. Start electrolysis.
Here, the calcium necessary for the reduction of the vanadium compound, in order to reducing generated just enough by electrolysis, as an indication of current amount, the quantity of electricity Q of supplying the theoretical quantity of electricity Q ₀ required to generate calcium The ratio (Q 1 / Q ₀ ) was used. In the embodiment described later, the applied voltage was fixed at 3.0V. Further, the amount of supplied electricity was 200 to 307% of the theoretical amount of electricity.

  After completion of the electrolysis, the cathode 2 extracted from the molten salt 8, that is, the titanium rod 2a container 2b was cooled to room temperature in argon gas and then washed. In the washing, washing was performed using distilled water, acetic acid, distilled water, ethanol and acetone in this order as a washing solution. Then, the cleaned cathode 2 was vacuum dried. A scanning electron microscope (see FIGS. 6 and 7) attached with an X-ray diffraction measurement apparatus (see FIGS. 4 and 5) and an energy dispersive X-ray spectrometry apparatus for the sample (manufacturing sample) obtained in this manner. The quantitative analysis of the contained impurities was performed using (see Table 1).

By the way, at the time of production of metallic vanadium, two reactions proceed simultaneously in the mixed molten salt.
For example, in the case where the mixed molten salt contains calcium chloride, calcium sulfide and calcium oxide, and the vanadium compound is a sulfide and an oxide of vanadium, the two reactions proceeding simultaneously may be expressed by the following formula (1) and Thermal reduction reaction as shown in formula (3) (thermal reduction reaction of vanadium compounds with calcium), high temperature chemical reaction as shown in formulas (2) and (4) (sulfur in reduced vanadium and It is a high temperature chemical reaction that is desulfurization and deoxidation of oxygen.
V ₂ S ₃ + 3Ca → 2V + 3CaS (1)
S (in V) + Ca → V + CaS (2)
V ₂ O ₃ + 3Ca → 2V + 3CaO (3)
O (in V) + Ca → V + CaO (4)

The reducing agent CaS oxidized in the thermal reduction reaction performs an electrochemical reaction which is electrolysis and regeneration (see Formulas (5), (6) and (7)).
Anode: 2S ^2- → S ₂ + 4e- (5)
Cathode: 2Ca ²⁺ + 4e-→ 2Ca (6)
Total: 2CaS → 2Ca + S ₂ (7)

Further, the reducing agent CaO oxidized in the high temperature chemical reaction performs the electrochemical reaction which is also the electrolysis and regeneration (see the formulas (8), (9), (10), (11) and (12)). Oxygen, which is more reactive than sulfur, reacts with anode carbon to form carbon monoxide and carbon dioxide.
Anode: 2O ^2- + C → CO ₂ + 4e- (8)
O ^2- + C → CO + 2e- (9)
Cathode: 3Ca ²⁺ + 6e-→ 3Ca (10)

Total: 2CaO + C → 2Ca + CO ₂ (11)
CaO + C → Ca + CO (12)

  Such reactions are simultaneously carried out in one vessel, and thermal reduction of vanadium compounds and electrolysis of CaS and CaO are continuously performed.

At the cathode 2, calcium having a reducing power is generated. The evolved calcium is present in dissolved form in liquid calcium or calcium chloride. The calcium is used to reduce and deoxidize the vanadium compound.
Further, in the carbon rod 1b which is the anode 1, when vanadium sulfide contains vanadium sulfide, S ₂ gas (and / or CS ₂ gas) is generated, and vanadium oxide contains vanadium oxide. In the case, CO ₂ gas (and / or CO gas) is generated. Then, the generated gas is released from the molten salt and discharged from the exhaust port 10 (see FIG. 1). The S ₂ gas (CS ₂ gas) can be easily precipitated and recovered by cooling, which is effective for exhaust gas countermeasures.

That is, when the vanadium compound contains vanadium sulfide, S ₂ (and / or CS ₂ ) is discharged, and when the vanadium compound contains vanadium oxide, the anode 1 has a carbon rod 1 b Carbon is consumed and CO ₂ is emitted. And other substances are recycled and used continuously. If these are shown by reaction formula, it will become as follows.
2V ₂ S ₃ → 4V + 3S ₂ (13)
2V ₂ O ₃ + 3C → 4V + 3CO ₂ (14)
V ₂ O ₃ + 3C → 2V + 3CO (15)

  The metallic vanadium obtained by reducing the vanadium compound on the cathode 1 side is in the form of powder (see FIGS. 7 and 8). Therefore, the metallic vanadium powder can be easily obtained by washing (washing with water, washing with acetic acid, etc.) the metal vanadium taken out from the crucible after electrolysis to remove calcium chloride and the like adhering to the surface and drying it. In addition, since the obtained metallic vanadium is porous (see FIG. 7 and FIG. 8), powderization is easy even for the non-powder part. In addition, when vanadium sulfide is used as the vanadium compound, since the carbon electrode (carbon rod) 1b of the anode 1 is not consumed, powder metal vanadium can be produced more efficiently.

Next, an example will be described.
In this example, a crucible 3 (containing 0.5 mol% of calcium sulfide (Wako Pure Chemical Industries, special grade reagent) added to 600 g of calcium chloride (Wako Pure Chemical Industries, reagent special grade) as molten salt (mixed molten salt) 8) The inner diameter was 90 mm and the depth was 200 mm). The crucible 3 was put in a closed vessel 4 (inner diameter 105 mm, depth 480 mm), a flange was attached and closed, and after vacuum dehydration treatment, the temperature was raised to 900 ° C. under an argon gas atmosphere.
In addition, a titanium rod 1a and a carbon rod 1b of the anode 1 and a container 2b attached so as to surround the titanium rod 2a and the titanium rod of the cathode 2 were prepared. Into this container 2b, 1.502 g of vanadium sulfide 12 (99% purity manufactured by Fluuchi Chemical Co., Ltd.) was inserted.
After the temperature of the molten salt in the crucible became stable, both electrodes 1 and 2 were inserted into the molten salt 8 to start electrolysis. The applied voltage was fixed at 3.0 V, and the amount of electricity necessary to generate Ca necessary for the reduction was applied according to the amount of vanadium sulfide of the loaded sample. Here, electrolysis was performed using an electrical charge of 307% of the theoretical electrical charge.
After completion of the electrolysis, the cathode 2 was extracted from the molten salt 8 and cooled to room temperature in argon gas. After cooling, the sample was washed in order of distilled water, acetic acid, distilled water, ethanol and acetone, and then vacuum dried to obtain a sample (manufacturing sample).

In this example, crucible 3 (inner diameter: 90 mm, depth) containing 0.5 mol% of calcium sulfide (Wako Pure Chemical Industries, special grade reagent) added to 600 g of calcium chloride (Wako Pure Chemical Industries, reagent special grade) as molten salt 8 Put in the 200 mm). The crucible 3 was put in a closed vessel 4 (inner diameter 105 mm, depth 480 mm), a flange was attached and closed, and after vacuum dehydration treatment, the temperature was raised to 900 ° C. under an argon gas atmosphere.
Further, a titanium rod 1a and a carbon rod 1b of the anode 1, a titanium rod 2a of the cathode 2 and a container 2b attached so as to surround the titanium rod were prepared. 1.488 g of vanadium trioxide 12 (purity of 99% or more manufactured by Solar Mining Co., Ltd.) was inserted into this container 2 b.
After the temperature stabilized, both electrodes 1 and 2 were inserted into the molten salt 8 to start electrolysis. The applied voltage was fixed at 3.0 V, and an amount of electricity necessary to generate Ca necessary for reduction was applied in accordance with the amount of vanadium trioxide in the loaded sample. Here, electrolysis was performed using an electrical charge of 200% of the theoretical electrical charge.
After completion of the electrolysis, the cathode 2 was extracted from the molten salt 8 and cooled to room temperature in argon gas. After cooling, the sample was washed in order of distilled water, acetic acid, distilled water, ethanol and acetone, and then vacuum dried to obtain a sample (manufacturing sample). The description of items common to the first embodiment is omitted.

In this example, 4 g of ammonium metavanadate (special grade reagent from Wako Pure Chemical Industries, Ltd.) and vanadyl sulfate (emerging chemistry) were prepared as raw materials (vanadium compound 12). Then, heat treatment (heating temperature: 600 ° C., heating time: 10 minutes) was applied as pretreatment to each prepared raw material to obtain a treated substance. The obtained substances were analyzed and all were vanadium pentoxide oxides (V ₂ O ₅ ).
The vanadium pentoxide oxides (V ₂ O ₅ ) thus obtained were used to produce metallic vanadium. At this time, the amount of vanadium oxide (V ₂ O ₅ ) put into the vessel 2 was 1.500 g in each case. The production conditions other than the amount of vanadium oxide (V ₂ O _5), so were common to Example 2 was omitted here.

The analysis results of the sulfur content and the oxygen content (oxygen concentration) of the samples (production samples) produced by molten salt electrolytic reduction in each example are shown in Table 1 below. In addition, the analysis method of sulfur content is a dissolution infrared spectroscopy in oxygen gas flow, and the analysis method of an oxygen content is a dissolution infrared spectroscopy in helium gas flow.
As shown in Table 1 and FIGS. 4 and 5, according to the manufacturing method of each example, powder metal vanadium having low sulfur content and low oxygen content was obtained. In addition, since the analysis result of the sample obtained in Example 3 was equivalent to the analysis result of the sample obtained in Example 2, the data publication was omitted here.

  In addition to vanadium oxides and sulfides, vanadium compounds include, for example, sulfuric acid compounds of vanadium, thiosulfuric acid compounds, ammonium metavanadate (NH_FourVO₃) And vanadyl sulfate (VOSO)_FourCan be used. And, as vanadium oxide, V₂O, VO, V₂O₃, VO₂, V₂O_FiveCan be mentioned. Also, as vanadium sulfide, VS, V₂S₃, V _FiveS₈, V₃S_Four, V₂S_Five, V₃S, V_FiveS_Four, VS, V₂S₃, V₂S_Five, V₇S₈, V₃S₈, VS_FourCan be mentioned. Furthermore, as a sulfuric acid compound of vanadium, VSO_Four, V₂(SO_Four)₃, VOSO_Four, V (SO_Four)₂Can be mentioned. As the thiosulfate compound of vanadium, VS₂O₃Can be mentioned.
  Among these, when using ammonium metavanadate, it is preferable to carry out the thermal decomposition step as the previous step. When the pyrolysis step is carried out, vanadium oxide is obtained by pyrolysis. As the conditions of the thermal decomposition step, for example, when a thermal decomposition step at 550 ° C. for 4 hours is performed in air, vanadium pentoxide is obtained by thermal decomposition. In addition, vanadium trioxide can be obtained by reduction treatment of vanadium pentoxide in hydrogen gas at 600 ° C. for 4 hours using a rotary kiln.

  In addition to calcium sulfide and calcium oxide, examples of the inorganic molten salt mixed with calcium chloride when forming the molten salt include calcium thiosulfate compounds and calcium sulfate.

It is a schematic diagram which shows the manufacturing apparatus of metal vanadium. (A) And (b) is a graph which shows the electrolytic current curve at the time of electricity supply in Example 1. FIG. (A) And (b) is a graph which shows the electrolytic current curve at the time of electricity supply in Example 2. FIG. It is a graph which shows the X-ray-diffraction measurement result of the sample manufactured in Example 1. FIG. 5 is a graph showing the results of X-ray diffraction measurement of the sample produced in Example 2. FIG. 2 is a scanning electron micrograph of the sample produced in Example 1; 3 is a scanning electron micrograph of the sample produced in Example 2.

DESCRIPTION OF SYMBOLS 1 ... anode electrode, 1a ... titanium rod, 1b ... carbon rod, 2 ... cathode electrode, 2a ... titanium rod,
2b ... A bowl made of titanium, 3 ... A crucible made of dense magnesium oxide,
4 ... Sealed container made of stainless steel (container and flange), 5 ... heater,
6 Thermocouple (thermometer), 8 Molten salt (mixed molten salt, CaCl ₂ + CaS (CaO),
9: Intake port, 10: Exhaust port, 12: Raw material powder (vanadium compound, V ₂ S ₃ , V ₂ O ₃ ).

Claims (2)

A portion of the inorganic molten salt of the inorganic molten salt forming the molten salt electrolytic bath in the reaction vessel is electrolyzed to form a reductive decomposition product, and the vanadium sulfide is thermally reduced by the reductive decomposition product. A method of producing metallic vanadium to produce metallic vanadium,
Wherein as part of the inorganic molten salt, are included sulfurized calcium,
Wherein the reducing decomposition products, the contains calcium obtained by electrolysis of a portion of inorganic molten salt method for producing a metal vanadium. A portion of the inorganic molten salt in the molten salt electrolytic bath is electrolyzed using a carbon material as an anode for electrolysis, and at least a sulfur gas is generated by an anodic reaction at the anode, and at least with the formation of metallic vanadium, at least The method for producing metallic vanadium according to claim 1 , wherein calcium sulfide is produced, and the product is dissolved in a molten salt electrolytic bath.