A method for preparing high-purity metallic vanadium

Abstract

The present invention belongs to the technical field of non-ferrous metal smelting, and specifically relates to a method for preparing high-purity metallic vanadium. During an aluminothermic reduction reaction, the present invention uses elemental aluminum as a reducing agent to reduce vanadium oxide to elemental vanadium metal. The aluminum participating in the reaction is oxidized to aluminum oxide, releasing a large amount of heat energy to melt various elemental metals to form an alloy liquid. The aluminum oxide floats on the surface of the resulting alloy liquid. After cooling, the aluminum oxide and the metal alloy naturally separate, and the aluminum oxide is removed to obtain a vanadium-aluminum alloy. A calcium compound acts as a slagging agent to lower the primary crystallization temperature of the aluminum oxide, providing a longer floating time for impurities, thereby increasing the purity of the resulting vanadium-aluminum alloy. After obtaining the high-purity vanadium-aluminum alloy, the present invention extracts the metallic vanadium from the vanadium-aluminum alloy by electrolysis and protects it with a protective gas. The resulting metallic vanadium has high purity and a high recovery rate. The present invention utilizes vanadium oxide to smelt the vanadium-aluminum alloy, thereby reducing the cost of raw materials.

Description

Technical Field

[0001] The invention belongs to the technical field of nonferrous metal smelting, and particularly relates to a method for preparing high-purity metallic vanadium. Background Art

[0002] With the rapid advancement of science and technology, humanity's demand for new materials is increasing. Vanadium possesses numerous excellent physical and chemical properties, making it widely applicable. Vanadium can be used in steel, refining its structure and grain size and increasing its grain coarsening temperature, thereby increasing its strength, toughness, and wear resistance. Vanadium is also used in titanium alloys, driving breakthroughs in the aerospace industry. At the same time, the high-purity, high-grade vanadium metal required in high-tech fields like aerospace is in short supply.

[0003] Chinese patent CN103498060A provides a method for preparing vanadium metal. This involves ball-milling vanadium oxide and aluminum powder, followed by ignition and smelting to produce vanadium metal. While this method offers advantages in energy efficiency and cost reduction, it also involves the formation of a metallic solid solution between vanadium and aluminum, resulting in an excessively high aluminum content and low purity.

[0004] Chinese patent CN201580078650.0 provides a method for preparing vanadium metal. This method involves reducing vanadium compounds with calcium generated by electrolyzing a portion of an inorganic molten salt in an electrolytic cell. The resulting vanadium metal has the advantage of high purity, but contains interstitial impurities such as carbon, hydrogen, and oxygen, resulting in a low recovery rate.

[0005] Chinese patent CN111957984A provides a method for preparing metallic vanadium powder. Vanadium trioxide, calcium, and CaO are mixed and ignited under an inert gas atmosphere to react. After the reaction, a reduced material is obtained. The reduced material is then washed with water, acid-washed, and heat-treated in a vacuum to obtain metallic vanadium powder. The method provided in this patent has simple equipment and low cost. However, due to the reactivity of metallic calcium, it is difficult to store and use in large quantities, and the resulting metallic vanadium contains a high concentration of impurities.

[0006] In summary, there is currently no method in the art for preparing high-purity metallic vanadium with high recovery rate. Summary of the Invention

[0007] The object of the present invention is to provide a method for preparing high-purity metallic vanadium. The method provided by the present invention has high purity of metallic vanadium and high recovery rate.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] The present invention provides a method for preparing high-purity metallic vanadium, comprising the following steps:

[0010] (1) mixing vanadium oxide, elemental aluminum and a calcium compound and performing an aluminothermic reduction reaction to obtain a vanadium aluminum alloy;

[0011] (2) heating and melting the chloride salt to obtain a chlorinated electrolyte;

[0012] (3) using the vanadium-aluminum alloy as an anode, adding the anode and cathode into the chlorinated electrolyte, introducing chlorine gas, sealing, and performing electrolysis under a protective atmosphere to obtain metallic vanadium;

[0013] (4) boiling the metallic vanadium in a hydrochloric acid solution to obtain high-purity metallic vanadium;

[0014] The purity of the high-purity vanadium metal is not less than 99.94 wt%;

[0015] There is no requirement for the time sequence of step (1) and step (2).

[0016] Preferably, the vanadium oxide is vanadium pentoxide or vanadium trioxide;

[0017] When the vanadium oxide is vanadium pentoxide, the mass ratio of the vanadium oxide to elemental aluminum is 1.685-1.977:1, and the mass ratio of the elemental aluminum to the calcium compound is 1:1.142-1.158;

[0018] When the vanadium oxide is vanadium trioxide, the mass ratio of the vanadium oxide to elemental aluminum is 2.137-2.574:1, and the mass ratio of the elemental aluminum to the calcium compound is 1:0.835-0.974.

[0019] Preferably, the calcium compound comprises one or both of calcium fluoride and calcium oxide;

[0020] The chloride salt includes one or both of KCl and LiCl.

[0021] Preferably, the mass concentration of the chlorine gas in the chlorinated electrolyte is 5-6%.

[0022] Preferably, the temperature during electrolysis of the chlorinated electrolyte is 650-700°C.

[0023] Preferably, the temperature of the aluminothermic reduction reaction is 1820-1920°C.

[0024] Preferably, the boiling time is 1 to 1.5 hours; and the concentration of the hydrochloric acid solution is 24.6 to 25.4 wt%.

[0025] Preferably, the power source for the electrolysis is direct current, the voltage is 0.35 to 3.5 V, and the electrolysis time is 2 to 20 hours.

[0026] Preferably, before adding the anode to the chlorinated electrolyte, the process further comprises crushing and shot blasting the vanadium-aluminum alloy in sequence; the particle size of the aluminum-vanadium alloy obtained after the crushing is 10 to 100 mm.

[0027] Preferably, the cathode is a molybdenum rod.

[0028] The present invention provides a method for preparing high-purity metallic vanadium. During an aluminothermic reduction reaction, elemental aluminum is used as a reducing agent to reduce vanadium oxide to elemental vanadium metal. The aluminum participating in the reaction is oxidized to aluminum oxide, releasing a large amount of heat energy to melt various elemental metals (including aluminum, vanadium metal, and impurities such as tin, molybdenum, and silicon) to form an alloy liquid. Aluminum oxide floats on the surface of the resulting alloy liquid. After cooling, the aluminum oxide and the metal alloy naturally separate, and the aluminum oxide is removed to obtain a vanadium-aluminum alloy. A calcium compound is used as a slagging agent to lower the primary crystallization temperature of the aluminum oxide, providing a longer floating time for impurities, thereby increasing the purity of the resulting vanadium-aluminum alloy. After obtaining the high-purity vanadium-aluminum alloy, the present invention extracts metallic vanadium from the vanadium-aluminum alloy by electrolysis and protects it with a protective gas (rare gas). The obtained metallic vanadium has high purity and a high recovery rate. The present invention uses vanadium oxide to smelt the vanadium-aluminum alloy, reducing the raw material cost. The present invention has simple steps and is easy to operate, making it suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 The invention discloses an electrolytic device for preparing high-purity metallic vanadium. DETAILED DESCRIPTION

[0031] The present invention provides a method for preparing high-purity metallic vanadium, comprising the following steps:

[0032] (1) mixing vanadium oxide, elemental aluminum and a calcium compound and performing an aluminothermic reduction reaction to obtain a vanadium aluminum alloy;

[0033] (2) heating and melting the chloride salt to obtain a chlorinated electrolyte;

[0034] (3) using the vanadium-aluminum alloy as an anode, adding the anode and cathode into the chlorinated electrolyte, introducing chlorine gas, sealing, and performing electrolysis under a protective atmosphere to obtain metallic vanadium;

[0035] (4) boiling the metallic vanadium in a hydrochloric acid solution to obtain high-purity metallic vanadium;

[0036] The purity of the high-purity vanadium metal is not less than 99.94 wt%;

[0037] There is no requirement for the time sequence of step (1) and step (2).

[0038] The present invention mixes vanadium oxide, elemental aluminum, and a calcium compound and performs an aluminothermic reduction reaction to obtain a vanadium-aluminum alloy. In the present invention, the vanadium oxide is preferably vanadium pentoxide or vanadium trioxide; the calcium compound preferably includes one or both of calcium fluoride and calcium oxide; the purity of the vanadium oxide, elemental aluminum, and calcium compound is preferably greater than 99.00%, more preferably greater than 99.50%; when the vanadium oxide is vanadium pentoxide, the mass ratio of the vanadium oxide to elemental aluminum is preferably 1.685 to 1.977:1, more preferably 1.8 to 1.9:1, and further preferably 1.83 to 1.87:1; the mass ratio of the elemental aluminum to the calcium compound is preferably 1: 1.142~1.158, more preferably 1:1.146~1.152, further preferably 1:1.148~1.150; when the vanadium oxide is vanadium trioxide, the mass ratio of the vanadium oxide to elemental aluminum is preferably 2.137~2.574:1, more preferably 2.2~2.5:1, further preferably 2.3~2.4:1; the mass ratio of the elemental aluminum to the calcium compound is preferably 1:0.835~0.974, more preferably 1:0.85~0.93, further preferably 1:0.88~0.90.

[0039] In the present invention, the temperature of the aluminothermic reduction reaction is preferably 1820-1920°C, more preferably 1860-1900°C, and the holding time is preferably 12-24 hours, more preferably 16-20 hours; the equipment for the aluminothermic reduction reaction is preferably an aluminothermic reduction furnace; the aluminothermic reduction reaction is preferably ignited by a magnesium ribbon; after the aluminothermic reduction reaction is completed, the resulting product is preferably cooled; the cooling is preferably natural cooling; in the present invention, after the aluminothermic reduction reaction product is naturally cooled, the aluminum oxide and the metal alloy are naturally separated into two upper and lower layers that are adhered together, and the aluminum oxide can be peeled off from the surface; the mass fraction of vanadium in the vanadium-aluminum alloy is preferably 85-98%, more preferably 93%.

[0040] The present invention heats and melts a chloride salt to obtain a chloride electrolyte. In the present invention, the chloride salt preferably comprises one or both of KCl and LiCl; the heating is preferably performed in a crucible; the heating device is preferably a resistance furnace; the heating temperature is preferably 650-700°C, more preferably 680°C; the temperature during electrolysis of the chloride electrolyte is preferably 650-700°C, more preferably 670-690°C; in a specific embodiment of the present invention, the chloride salt is preferably added gradually during the heating and melting process until the depth of the melt reaches 60-75%, more preferably 65-70%, of the crucible depth.

[0041] After obtaining the vanadium-aluminum alloy and the chlorinated electrolyte, the present invention uses the vanadium-aluminum alloy as an anode, adds the anode and cathode into the chlorinated electrolyte, introduces chlorine, seals, and performs electrolysis under a protective atmosphere to obtain metallic vanadium. In the present invention, before adding the anode to the chlorinated electrolyte, the vanadium-aluminum alloy is preferably crushed and shot blasted in sequence; the particle size of the aluminum-vanadium alloy obtained after the crushing is preferably 10 to 100 mm, more preferably 30 to 70 mm; the shot blasting equipment is preferably a shot blasting machine; the present invention removes the oxide layer and impurities on the surface of the vanadium-aluminum alloy by shot blasting until no foreign matter or film is visible to the naked eye; the anode and cathode are preferably added to the chlorinated electrolyte by placing the vanadium-aluminum alloy in a molybdenum wire mesh barrel, placing the molybdenum wire mesh barrel in a crucible, then adding a chloride salt to the crucible and heating to melt, then introducing chlorine gas, and then inserting the cathode into the obtained chlorinated electrolyte, and then continuously introducing a protective atmosphere until the crucible is full, and then sealing; the vanadium-aluminum alloy (anode) is preferably connected to the positive pole of the power supply via an anode wire; the cathode is preferably connected to the negative pole of the power supply via a cathode wire; the height of the molybdenum wire mesh barrel is preferably 50% of the height of the crucible; the cathode is preferably a molybdenum rod; and the cathode is preferably inserted at the center of the crucible. The present invention adopts a molybdenum wire mesh barrel as a container and a molybdenum rod as an electrode, which can avoid the introduction of impurities and is beneficial to improving the purity of metal vanadium.

[0042] In the present invention, the mass concentration of chlorine in the chlorinated electrolyte is preferably 5-6%, more preferably 5.2-5.8%, and even more preferably 5.5%; the chlorine is preferably introduced after the chloride salt is heated and melted, and is continued until the target concentration is reached; the device for introducing chlorine is preferably a porcelain tube; the protective atmosphere is preferably a noble gas; the noble gas is preferably argon; the sealed device is preferably evacuated before the noble gas is introduced; and the method for verifying the presence of the noble gas is preferably: placing an open flame at the exhaust port of the crucible; if the flame immediately extinguishes, it indicates that the crucible is full of the noble gas. Electrolysis under a protective atmosphere in the present invention can prevent the introduction of gaseous elements such as oxygen and nitrogen from contact between ions and air during the electrolysis process, thereby improving the purity of the metallic vanadium.

[0043] In the present invention, the power supply for the electrolysis is preferably direct current, the voltage of the electrolysis is preferably 0.35 to 3.5 V, more preferably 0.8 to 3.0 V, further preferably 1.4 to 2.2 V, the electrolysis time is preferably 2 to 20 hours, more preferably 8 to 16 hours, further preferably 12 hours; the voltage of the electrolysis is preferably adjusted by a voltage regulator; after the electrolysis is completed, the obtained electrolysis product is preferably washed and dried; the drying is preferably oven drying; in the electrolysis process of the present invention, the aluminum in the vanadium-aluminum alloy first obtains electrons to become Al 3+ Dissolved in the melt, metallic vanadium is deposited at the lower end of the cathode molybdenum rod.

[0044] The electrolysis device used in the present invention is as follows Figure 1 As shown. Figure 1 It can be seen that the electrolysis device of the present invention includes an anode, a cathode, a molybdenum wire mesh barrel, a crucible and an electrolyte. The equipment composition is relatively simple, the equipment requirements are low, and the investment cost of industrial production can be reduced.

[0045] After obtaining the vanadium metal, the present invention boils the vanadium metal in a hydrochloric acid solution to obtain high-purity vanadium metal. In the present invention, the concentration of the hydrochloric acid solution is preferably 24.6 to 25.4 wt%, more preferably 25 wt%. The boiling time is preferably 1 to 1.5 hours, more preferably 1.2 hours. After boiling, the resulting product is preferably washed with water; the water used for washing is preferably clean water.

[0046] In order to further illustrate the present invention, the scheme of the present invention is described in detail below with reference to the accompanying drawings and embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0047] Example 1

[0048] A method for preparing high-purity metallic vanadium comprises the following steps:

[0049] (1) 75.83 kg of vanadium pentoxide, 45.00 kg of elemental aluminum, and 6.40 kg of calcium fluoride were mixed uniformly using a mixer, and the mixture was placed in an aluminothermic reduction furnace, ignited by a magnesium bar, and the materials reacted to form a melt, which was cooled to obtain a vanadium-aluminum alloy. The obtained vanadium-aluminum alloy was crushed to a particle size of 10 to 100 mm and then cleaned using a shot blasting machine;

[0050] (2) adding the obtained vanadium-aluminum alloy into a molybdenum wire mesh bucket, which is placed in the middle of the crucible, and the adding height is 50% of the crucible height;

[0051] (3) Fill the crucible with KCl, heat the resistance furnace to melt the mixture, and control the furnace temperature at 650°C. As the material melts, gradually add KCl until the melt reaches 60% of the crucible depth;

[0052] (4) Add chlorine gas through a porcelain tube and stop adding chlorine when the concentration reaches 5%;

[0053] (5) Insert the cathode molybdenum rod, fill the crucible with argon gas until it is full, seal the crucible, and start electrolysis;

[0054] (6) Turn on the DC power supply, shake the voltage regulator, adjust the DC voltage to 0.35V, electrolyze for 2 hours, record the voltage and current every half hour, and keep the DC voltage at the normal control value. Stop the furnace when the anode alloy is about to be consumed by electrolysis;

[0055] (7) The cathode product was taken out to obtain metallic vanadium, which was boiled in 25 wt% dilute hydrochloric acid for 1 hour, then washed with clean water and dried to obtain high-purity metallic vanadium.

[0056] Through the above steps, 23.96 kg of high-purity metallic vanadium was obtained with a recovery rate of 93.96%. The obtained metallic vanadium had a clean appearance and, after analysis, a vanadium content of 99.94%.

[0057] Example 2

[0058] (1) 87.43 kg of vanadium pentoxide, 44.24 kg of elemental aluminum, and 7.00 kg of calcium fluoride were mixed uniformly using a mixer, and the mixture was placed in an aluminothermic reduction furnace, ignited by a magnesium bar, and the materials reacted to form a melt, which was cooled to obtain a vanadium-aluminum alloy. The obtained vanadium-aluminum alloy was crushed to a particle size of 10 to 100 mm and then cleaned using a shot blasting machine;

[0059] (2) adding the obtained vanadium-aluminum alloy into a molybdenum wire mesh bucket, which is placed in the middle of the crucible, and the adding height is 50% of the crucible height;

[0060] (3) Fill the crucible with LiCl, heat the resistance furnace to melt the mixture, and control the furnace temperature at 700°C. As the material melts, gradually add KCl until the melt reaches 75% of the crucible depth;

[0061] (4) Add chlorine gas through a porcelain tube and stop adding chlorine when the concentration reaches 6%;

[0062] (5) Insert the cathode molybdenum rod, fill the crucible with argon gas until it is full, seal the crucible, and start electrolysis;

[0063] (6) Connect the DC power supply, shake the voltage regulator, adjust the DC voltage to 3.5V, electrolyze for 20 hours, record the voltage and current every half hour, and keep the DC voltage at the normal control value. Stop the furnace when the anode alloy is about to be consumed by electrolysis;

[0064] (7) The cathode product was taken out to obtain metallic vanadium, which was boiled in 25 wt% dilute hydrochloric acid for 1.5 hours, then washed with clean water and dried to obtain high-purity metallic vanadium.

[0065] Through the above steps, 27.40 kg of high-purity metallic vanadium was obtained with a recovery rate of 93.20%. The obtained metallic vanadium had a clean appearance and, after analysis, a vanadium content of 99.97%.

[0066] Example 3

[0067] (1) 82.97 kg of vanadium pentoxide, 44.53 kg of elemental aluminum, and 6.80 kg of calcium fluoride were mixed uniformly using a mixer, and the mixture was placed in an aluminothermic reduction furnace, ignited by a magnesium bar, and the materials reacted to form a melt, which was cooled to obtain a vanadium-aluminum alloy. The obtained vanadium-aluminum alloy was crushed to a particle size of 10 to 100 mm and then cleaned using a shot blasting machine;

[0068] (2) adding the obtained vanadium-aluminum alloy into a molybdenum wire mesh bucket, which is placed in the middle of the crucible, and the adding height is 50% of the crucible height;

[0069] (3) Fill the crucible with a mixture of KCl and LiCl, heat the resistance furnace to melt the mixture, and control the furnace temperature at 680°C. As the material melts, gradually add more mixture until the melt reaches 70% of the crucible depth;

[0070] (4) Add chlorine gas through a porcelain tube and stop adding chlorine when the concentration reaches 5.5%;

[0071] (5) Insert the cathode molybdenum rod, fill the crucible with argon until it is full, seal the crucible, and start electrolysis;

[0072] (6) Turn on the DC power supply, shake the voltage regulator, adjust the DC voltage to 2V, and electrolyze for 12 hours. Record the voltage and current every half hour and keep the DC voltage at the normal control value. Stop the furnace when the anode alloy is about to be consumed by electrolysis.

[0073] (7) The cathode product was taken out to obtain metallic vanadium, which was boiled in 25 wt% dilute hydrochloric acid for 1.3 hours, then washed with clean water and dried to obtain high-purity metallic vanadium.

[0074] Through the above steps, 26.08 kg of metallic vanadium was obtained with a recovery rate of 93.50%. The obtained metallic vanadium had a clean appearance and, after analysis, a vanadium content of 99.96%.

[0075] It can be seen from the above examples that the method for preparing high-purity metallic vanadium provided by the present invention has high purity of high-purity metallic vanadium, which is above 99.94%, high recovery rate, which is above 93.20%, and low raw material cost.

[0076] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity metallic vanadium, characterized in that: The following steps are involved: (1) mixing vanadium oxide, elemental aluminum and a calcium compound and performing an aluminothermic reduction reaction to obtain a vanadium aluminum alloy; (2) heating and melting the chloride salt to obtain a chlorinated electrolyte; (3) using the vanadium-aluminum alloy as an anode, adding the anode and cathode into the chlorinated electrolyte, introducing chlorine gas, sealing, and performing electrolysis under a protective atmosphere to obtain metallic vanadium; (4) boiling the metallic vanadium in a hydrochloric acid solution to obtain high-purity metallic vanadium; The purity of the high-purity vanadium metal is not less than 99.94 wt%; There is no requirement for the time sequence of steps (1) and (2); The vanadium oxide is vanadium pentoxide or vanadium trioxide; When the vanadium oxide is vanadium pentoxide, the mass ratio of the vanadium oxide to elemental aluminum is 1.685-1.977:1, and the mass ratio of the elemental aluminum to the calcium compound is 1:1.142-1.158; When the vanadium oxide is vanadium trioxide, the mass ratio of the vanadium oxide to elemental aluminum is 2.137-2.574:1, and the mass ratio of the elemental aluminum to the calcium compound is 1:0.835-0.974; The mass concentration of chlorine in the chlorinated electrolyte is 5-6%; The boiling time is 1 to 1.5 hours; The concentration of the hydrochloric acid solution is 24.6-25.4 wt %; The chloride salt is one or both of KCl and LiCl; The temperature during electrolysis of the chlorinated electrolyte is 700°C; The power source for the electrolysis is direct current, the voltage is 0.35-3.5V, and the electrolysis time is 2-20 hours.

2. The method according to claim 1, characterized in that The calcium compound includes one or both of calcium fluoride and calcium oxide.

3. The method according to claim 1, characterized in that The temperature of the aluminothermic reduction reaction is 1820-1920°C.

4. The method according to claim 1, wherein Before adding the anode into the chlorinated electrolyte, the method further comprises crushing and shot blasting the vanadium-aluminum alloy in sequence; the particle size of the aluminum-vanadium alloy obtained after the crushing is 10 to 100 mm.

5. The method according to claim 1, wherein The cathode is a molybdenum rod.

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