Zirconium metal and method for preparing zirconium metal by molten salt electrolysis

Abstract

The present invention provides a method for preparing metallic zirconium by molten salt electrolysis, comprising: uniformly mixing a zirconium carbide raw material and an appropriate amount of an organic binder, granulating the mixture to form a granular material, and vacuum sintering the mixture to obtain zirconium carbide particles; mixing an alkali metal / alkaline earth metal chloride salt with a small amount of zirconium salt, pre-melting the mixture, and then cooling the mixture to obtain a molten salt electrolyte; adding the zirconium carbide particles to the bottom of a graphite crucible in an electrolytic furnace, then adding a molten salt electrolyte into the graphite crucible, sealing the equipment, and performing electrolysis; after the electrolysis is completed, collecting the sediment attached to the cathode, and extracting metallic zirconium from the sediment. In the preparation method provided by the present invention, zirconium carbide is used as the anode material, thereby avoiding the problem of large amounts of chlorine gas being precipitated from the anode and causing equipment corrosion when zirconium powder is directly electrolyzed in a high-temperature molten salt system. In addition, the production cost of zirconium carbide is relatively low, and it can be obtained by a carbon reduction method using zirconium oxide as a raw material, which greatly saves costs compared to using sponge zirconium as the anode material.

Description

Technical Field

[0001] The present invention relates to the field of metal zirconium and its preparation technology, and in particular to metal zirconium and a method for preparing metal zirconium by molten salt electrolysis. Background Art

[0002] Zirconium metal has a small thermal neutron capture cross-section and excellent corrosion resistance. It is used in the nuclear industry as a fuel cladding material for nuclear reactors and in the chemical industry to manufacture chemical reaction vessels, heat exchangers, pumps, valves, pipes, agitators, and other equipment. Zirconium powder has excellent gas-absorbing properties and can be used as a getter in electronic device manufacturing, absorbing residual gases within the device and increasing the vacuum level, thereby improving the performance and stability of the device. Zirconium metal is biocompatible and less susceptible to rejection, making it suitable for use in medical devices such as surgical and dental instruments. Demand for zirconium powder for 3D printing is also increasing. Currently, there are three main processes for preparing zirconium powder. The first is the hydrogenation-dehydrogenation method. This method uses zirconium metal (sponge or shavings) as the raw material, hydrogenates it to produce zirconium hydride, crushes it into a powder, and then dehydrogenates it to produce zirconium powder. This process uses hydrogen, which carries certain safety risks. Zirconium powder produced by dehydrogenation of zirconium hydride is prone to spontaneous combustion, posing a safety hazard. The second method is calcium (calcium hydride) reduction. This process uses zirconium oxide and calcium (calcium hydride) as raw materials. This process can produce finer zirconium powder, but the zirconium powder has a high oxygen content. If the process conditions are not properly controlled, the zirconium oxide reduction will not be complete. Calcium and calcium hydride are also hazardous substances, posing certain safety risks. The third method is molten salt electrolysis. This process uses potassium zirconium fluoride or zirconium tetrachloride as the zirconium source. Under the influence of an electric field, metallic zirconium powder is deposited at the cathode through controlled process conditions. This process uses an electric field instead of a hazardous reducing agent, ensuring production safety.

[0003] Molten salt electrolysis involves melting salts at high temperatures to form a melt. Direct current is then applied to the melt, causing certain ions in the melt to undergo redox reactions at electrodes, thereby producing and refining metals or other substances. The existing molten salt electrolysis process for zirconium powder production uses potassium fluorzirconate or zirconium tetrachloride as the zirconium raw material, along with supporting electrolytes such as sodium chloride or potassium chloride. High-temperature molten salt electrolysis is performed, and metallic zirconium is precipitated at the cathode under the action of an electric field. The resulting metal is then washed with water.

[0004] However, during direct electrolysis, chlorine gas is released at the anode. When the current density is too high or the zirconium ion concentration is too low, this can lead to an anode effect, interrupting the electrolysis. This chlorine release can cause severe corrosion to equipment at high temperatures, posing a safety risk during production. To address this issue, existing processes involve adding zirconium sponge to the anode as both an anode material and a source of zirconium. However, using zirconium sponge as a raw material is relatively expensive. Summary of the Invention

[0005] In response to the above-mentioned problems existing in the prior art, the present invention provides a method for preparing metallic zirconium by molten salt electrolysis, so as to solve the problem of chlorine precipitation at the anode when potassium zirconium fluoride or zirconium tetrachloride is directly electrolyzed as the zirconium source in the existing method, or the problem of high cost when sponge zirconium is used as the anode raw material.

[0006] The specific content of the invention is as follows:

[0007] In a first aspect, the present invention provides a method for preparing metallic zirconium by molten salt electrolysis, comprising:

[0008] The zirconium carbide raw material and an appropriate amount of organic binder are mixed evenly, and then granulated to prepare 3-5 mm granular materials, which are then vacuum sintered to obtain zirconium carbide particles;

[0009] Alkali metal / alkaline earth metal chloride salt is mixed with a small amount of zirconium salt, pre-melted and then cooled to obtain a molten salt electrolyte;

[0010] Adding the zirconium carbide particles to the bottom of a graphite crucible in an electrolytic furnace, then adding the molten salt electrolyte into the graphite crucible, sealing the equipment, and performing electrolysis;

[0011] After the electrolysis is completed, collecting the sediment attached to the cathode, and extracting the metal zirconium from the sediment;

[0012] Wherein, the alkali metal chloride salt is selected from one or more of sodium chloride, potassium chloride, lithium chloride, calcium chloride, rubidium chloride and cesium chloride, and the alkaline earth metal chloride salt is calcium chloride;

[0013] The zirconium salt is selected from potassium fluorozirconate and / or zirconium tetrachloride.

[0014] Optionally, the alkali metal / alkaline earth metal chloride salt is selected from NaCl-KCl, NaCl-CaCl2, NaCl-KCl-CsCl, NaCl-KCl-RbCl, LiCl-NaCl-KCl, LiCl-KCl-CsCl or LiCl-KCl-RbCl.

[0015] Optionally, the electrolysis temperature is 750-850°C;

[0016] The cathode current density of the electrolysis is 0.1 ~ 5 A / cm 2 .

[0017] Optionally, the mass ratio of the zirconium carbide raw material to the organic binder is 4:1 to 7:1;

[0018] The organic binder is selected from one or more of polyvinyl acetate, polyvinyl alcohol, polyacrylate, polyurethane and phenolic resin;

[0019] The vacuum sintering process is performed at a pressure of 0.1 MPa to 0.5 MPa and a temperature of 1200° C. to 1500° C.

[0020] Optionally, the mass ratio of the zirconium salt to the alkali metal / alkaline earth metal chloride salt is 3:7 to 4:6.

[0021] Optionally, the mass ratio of the zirconium carbide particles to the molten salt electrolyte is 1:3 to 1:5.

[0022] Optionally, the particle size of the zirconium carbide raw material is +500 mesh to -300 mesh.

[0023] Optionally, before mixing the alkali metal / alkaline earth metal chloride salt with a small amount of zirconium salt, the method further comprises:

[0024] The alkali metal chloride is subjected to vacuum dehydration at a temperature of 500-600° C. and a pressure of 0.1 MPa-0.5 MPa;

[0025] The potassium fluorozirconate is subjected to vacuum dehydration at a temperature of 350-500° C. and a pressure of 0.1 MPa-0.5 MPa;

[0026] The zirconium tetrachloride is vacuum dehydrated at a temperature of 200-300° C. and a pressure of 0.1 MPa-0.5 MPa.

[0027] Optionally, extracting metallic zirconium from the sediment comprises:

[0028] The cathode sediment is crushed into particles with a particle size of 1-3 mm, placed in deionized water at 50°C to 80°C, stirred and washed, and after the mixed molten salt electrolyte is completely dissolved in the water, filtered to obtain coarse zirconium powder;

[0029] The crude zirconium powder is immersed in dilute hydrochloric acid, stirred and washed, settled and filtered, and then washed with deionized water for 3 to 5 times. After low-temperature drying, low-oxygen content metal zirconium is obtained.

[0030] In a second aspect, the present invention provides metal zirconium obtained by the method for preparing metal zirconium by molten salt electrolysis described in the first aspect.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] The present invention provides a method for preparing metallic zirconium by molten salt electrolysis, comprising: uniformly mixing a zirconium carbide raw material and an appropriate amount of an organic binder, granulating the mixture to prepare a 3-5 mm granular material, and vacuum sintering the mixture to obtain zirconium carbide particles; mixing an alkali metal / alkaline earth metal chloride salt with a small amount of zirconium salt, pre-melting the mixture, and then cooling the mixture to obtain a molten salt electrolyte; adding the zirconium carbide particles to the bottom of a graphite crucible in an electrolytic furnace, then adding the molten salt electrolyte to the graphite crucible, sealing the device, and performing electrolysis; after the electrolysis is completed, collecting sediment attached to the cathode, and extracting the metallic zirconium from the sediment; the oxygen content in the metallic zirconium is 0.06% to 0.08%.

[0033] In the preparation method provided by the present invention, zirconium carbide is used as the anode material, which avoids the problem of large amounts of chlorine gas being precipitated from the anode and causing equipment corrosion when zirconium powder is directly electrolyzed in a high-temperature molten salt system (without an anode material). In addition, the production cost of zirconium carbide is relatively low. It can be obtained by a carbon reduction method using zirconium oxide as a raw material, which greatly saves costs compared to using sponge zirconium as the anode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] 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 or the description of the prior art. 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.

[0035] Figure 1 A flow chart of a method for preparing metallic zirconium by molten salt electrolysis provided in an embodiment of the present invention is shown;

[0036] Figure 2 The figure shows the metal zirconium prepared by molten salt electrolysis in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the present invention and its application or use. Based on the embodiments of the present invention, any product that is identical or similar to the present invention and is obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts falls within the scope of protection of the present invention. In addition, all other embodiments obtained by ordinary technicians in this field without carrying out creative work fall within the scope of protection of the present invention.

[0038] Where specific experimental steps or conditions are not specified in the examples, the conventional experimental steps or conditions described in the prior art in the art may be used. Reagents and other instruments used, for which the manufacturer is not specified, are commercially available conventional reagent products. Furthermore, the accompanying drawings are merely schematic illustrations of embodiments of the present invention and are not necessarily drawn to scale. Identical reference numerals in the figures denote identical or similar parts, and their repeated descriptions will be omitted. Some block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0039] Technologies, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies, methods, and equipment should be considered part of the description of the present invention.

[0040] In the description of the present invention, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0041] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] Since the preparation of metallic zirconium is carried out by direct electrolysis of an electrolyte containing potassium zirconium fluoride or zirconium tetrachloride, there is a problem that the anode will produce chlorine gas, which deteriorates the production environment. At the same time, the production of chlorine gas seriously corrodes the equipment and triggers a disproportionation reaction, resulting in a decrease in current efficiency. Therefore, the present invention uses zirconium carbide as the electrolytic anode material to provide a new method for preparing metallic zirconium by molten salt electrolysis, realizing a short process, low cost, environmentally friendly and safe method for preparing metallic zirconium powder. The specific implementation content is as follows:

[0043] In a first aspect, the present invention provides a method for preparing metallic zirconium by molten salt electrolysis. Figure 1The flow chart of the method for preparing metal zirconium by molten salt electrolysis provided by an embodiment of the present invention is shown as follows: Figure 1 As shown, the preparation method comprises the following steps:

[0044] S1. After uniformly mixing the zirconium carbide raw material and an appropriate amount of organic binder, granulation is performed to prepare 3-5 mm granular materials, and after vacuum sintering, zirconium carbide particles are obtained.

[0045] In practice, before using zirconium carbide for electrolytic zirconium metal production, it is first granulated in this step. Specifically, the zirconium carbide is uniformly mixed with an organic binder and placed in a granulator to produce granules with a size of 3-5 mm. The granules are then vacuum sintered to form uniform and stable zirconium carbide particles. The vacuum sintering process is performed at a pressure of 0.1 MPa to 0.5 MPa and a temperature of 1200°C to 1500°C.

[0046] Compared with direct electrolysis using zirconium carbide powder, the specific surface area of ​​the zirconium carbide particles formed by granulation is significantly increased, thereby increasing the contact area of ​​the subsequent electrolysis reaction, promoting the reaction rate, and improving the yield and efficiency of metallic zirconium; the granulated zirconium carbide has better fluidity, which is convenient for transportation and loading. At the same time, the granulated zirconium carbide can quickly sink to the bottom of the electrolyte anode after being added to the molten salt electrolyte, meeting the requirements of continuous electrolysis feeding.

[0047] In some embodiments, the mass ratio of the zirconium carbide raw material used for granulation to the organic binder is controlled at 4:1 to 7:1, and the organic binder is selected from one or more combinations of polyvinyl acetate, polyvinyl alcohol, polyacrylate, polyurethane, and phenolic resin.

[0048] S2. Mixing an alkali metal / alkaline earth metal chloride salt with a small amount of zirconium salt, pre-melting, and then cooling to obtain a molten salt electrolyte;

[0049] In this step, a mixture of alkali metal / alkaline earth metal chloride and zirconium salt forms the electrolyte system. The presence of a small amount of zirconium salt in the electrolyte system helps maintain the balance of zirconium ions during the electrolysis process. Furthermore, the addition of zirconium salt lowers the melting point of the electrolyte system, allowing the molten salt to fully melt at a lower temperature, reducing energy consumption and operating temperature of the equipment.

[0050] In this step, the alkali metal / alkaline earth metal chloride and the zirconium salt are pre-melted and cooled. The pre-melting allows the alkali metal / alkaline earth metal chloride and the zirconium salt to interact with each other to form a composite molten salt electrolyte with specific structure and properties. The ions in the composite molten salt electrolyte are evenly distributed, which improves the conductivity of the molten salt and makes it have better conductivity and chemical stability.

[0051] In some embodiments, the alkali metal chloride salt can be selected from one or more of sodium chloride, potassium chloride, lithium chloride, calcium chloride, rubidium chloride, and cesium chloride; the alkaline earth metal chloride salt is calcium chloride; and the zirconium salt is selected from potassium fluorzirconate and / or zirconium tetrachloride. The mass ratio of the added zirconium salt to the alkali metal / alkaline earth metal chloride salt is 3:7 to 4:6. When the alkali metal / alkaline earth metal chloride salt is a combination of two or more of the above salts, the alkali metal / alkaline earth metal chloride salt can specifically be NaCl-KCl, NaCl-CaCl2, NaCl-KCl-CsCl, NaCl-KCl-RbCl, LiCl-NaCl-KCl, LiCl-KCl-CsCl, or LiCl-KCl-RbCl.

[0052] In some embodiments, the alkali metal / alkaline earth metal chloride and zirconium salt are each subjected to vacuum dehydration prior to pre-melting to remove interfering impurities in the raw materials. The alkali metal / alkaline earth metal chloride and zirconium salt are vacuum dehydrated at a temperature of 500-600°C and a pressure of 0.1 MPa to 0.5 MPa. The vacuum dehydration process for the zirconium salt includes vacuum dehydration of potassium fluorozirconate at a temperature of 350-500°C and a pressure of 0.1 MPa to 0.5 MPa; and vacuum dehydration of zirconium tetrachloride at a temperature of 200-300°C and a pressure of 0.1 MPa to 0.5 MPa.

[0053] S3, adding the zirconium carbide particles to the bottom of a graphite crucible in an electrolytic furnace, then adding the molten salt electrolyte into the graphite crucible, sealing the equipment, and performing electrolysis;

[0054] In this step, zirconium carbide particles are placed in a graphite crucible, spread flat across the bottom. A molten salt electrolyte is then added to the crucible and sealed, completing the electrolysis equipment. The zirconium carbide particles, directly in contact with the crucible's bottom, serve as the anode. During the electrolysis process, the zirconium ions in the zirconium carbide lose electrons and enter the electrolysis system. Ultimately, metallic zirconium is deposited at the cathode, replacing the lost electrons of the chloride ions and preventing the production of chlorine gas.

[0055] The zirconium carbide granular material obtained by granulation is convenient for continuous feeding during the electrolysis process. After granulation, the added zirconium carbide particles can sink to the bottom, avoiding the suspension loss caused by the difficulty of sedimentation of the zirconium carbide powder material, ensuring that more raw materials participate in the electrolysis reaction, thereby improving the utilization rate of the material.

[0056] In some embodiments, the mass ratio of zirconium carbide particles to molten salt electrolyte is 1:3 to 1:5. After the electrolysis equipment is sealed, the heating furnace is started and heated to the set temperature and then kept warm. After the molten salt electrolyte melts, electrolysis begins. The electrolysis temperature is set at 750-850°C, and the cathode current density of the electrolysis is 0.1-5 A / cm 2 .

[0057] S4. After the electrolysis is completed, the sediment attached to the cathode is collected, and metal zirconium is extracted from the sediment.

[0058] In practice, after a certain period of electrolysis, the cathode electrode is removed from the cooling chamber to cool. Once the electrode cools to room temperature, the cathode deposit, which primarily consists of mixed molten salt electrolyte and metal zirconium powder, is removed. Extracting the metal zirconium powder from the deposit involves crushing the cathode deposit into particles of 1-3 mm in size, stirring and washing in deionized water at 50°C to 80°C, and filtering to obtain zirconium powder after the mixed molten salt electrolyte has completely dissolved in the water. The zirconium powder is then immersed in a certain concentration of dilute hydrochloric acid, stirred, and washed. After sedimentation and filtration, the powder is washed three to five times with deionized water and then dried at low temperature to obtain the electrolytic metal zirconium powder.

[0059] In the embodiments of the present invention, zirconium carbide is used as the raw material for electrolytic production of zirconium powder, replacing zirconium sponge prepared by the Kroll method (magnesium reduction of zirconium tetrachloride), thereby reducing costs and shortening the process. Zirconium sponge requires chlorination of zirconium oxide to produce zirconium tetrachloride, purification of the zirconium tetrachloride, reduction of the zirconium tetrachloride with metallic magnesium, and separation of the magnesium by distillation. This process is lengthy and expensive. Zirconium carbide can be obtained by carbon reduction using zirconium oxide as the raw material, shortening the process and reducing costs. While metallic zirconium can also be produced by direct electrolysis of an electrolyte containing potassium fluoride zirconate or zirconium tetrachloride without adding any anode material, the anode generates chlorine gas, which degrades the production environment. Furthermore, the chlorine gas produced can severely corrode equipment and induce disproportionation reactions, resulting in reduced current efficiency. Therefore, electrolysis using zirconium carbide as the raw material represents a novel process for producing low-oxygen zirconium powder with promising application value.

[0060] Furthermore, the method for preparing metallic zirconium by molten salt electrolysis provided by the present invention can achieve continuous production of metallic zirconium by regularly adding zirconium carbide particles as needed, thereby greatly improving production efficiency.

[0061] In a second aspect, the present invention provides metal zirconium obtained by the method for preparing metal zirconium by molten salt electrolysis described in the first aspect.

[0062] In order to enable those skilled in the art to more clearly understand the present invention, the metal zirconium and the method for preparing the metal zirconium by molten salt electrolysis according to the present invention are now described in detail through the following examples.

[0063] The following raw materials involved in electrolysis are pre-treated to remove moisture and volatile impurities:

[0064] Alkali metal chloride pretreatment: vacuum dehydration at 500°C and 0.1 MPa;

[0065] Potassium fluorozirconate pretreatment: vacuum dehydration pretreatment at 350°C and 0.1 MPa;

[0066] Zirconium tetrachloride pretreatment: vacuum dehydration at a temperature of 200°C and a pressure of 0.1 MPa for dehydration pretreatment.

[0067] Example 1

[0068] The zirconium carbide raw material (+500 mesh to -300 mesh) and the organic binder polyvinyl acetate were mixed uniformly in a mass ratio of 4:1, and granulated into 3-5 mm particles using a granulator. The particles were then dehydrated under a vacuum of 0.1 MPa and sintered at 1500°C to form zirconium carbide particles.

[0069] Sodium chloride and potassium chloride in equal molar ratios were ground together for 30 min, added to a crucible, and placed in a heating furnace. After evacuation, the crucible was filled with argon. The crucible was heated to 700°C at a pressure of 0.1 MPa, kept at this temperature for 1 h, and cooled to room temperature to obtain a NaCl-KCl eutectic electrolyte.

[0070] Mixing a mixed salt of sodium chloride and potassium chloride in an equal molar ratio of 70% by mass and potassium fluoride zirconate in an equal molar ratio of 30% by mass, pre-melting and cooling, to obtain a molten salt electrolyte NaCl-KCl-K2ZrF6 for use;

[0071] 20% by weight of zirconium carbide particles are added as anode material to the bottom of the crucible in the electrolysis furnace, and 80% by weight of pre-melted and cooled molten salt electrolyte is added. After the electrolysis equipment is sealed, the heating furnace is started and heated to the set temperature and then kept warm. After the molten salt electrolyte melts, electrolysis begins. The electrolysis temperature is set at 750°C, and the cathode current density of the electrolysis is 1 A / cm 2 After a certain period of electrolysis, the electrode is placed in a cooling chamber for cooling. After the electrode cools to room temperature, the cathode and the deposits on the cathode are removed together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium.

[0072] The cathode sediment is crushed into particles with a size of 1-3 mm and placed in 50°C deionized water for stirring and washing. After the impurities of the molten salt electrolyte are completely dissolved in the water, the zirconium powder is filtered and then immersed in a certain concentration of dilute hydrochloric acid for stirring and washing. After sedimentation and filtration, it is washed with deionized water 3-5 times and dried at low temperature to obtain electrolytic metal zirconium powder. Figure 2The figure shows the metal zirconium prepared by molten salt electrolysis in an embodiment of the present invention.

[0073] Table 1 shows the chemical composition analysis results of the metal zirconium provided in an embodiment of the present invention. As shown in Table 1, the oxygen content of the metal zirconium prepared by the molten salt electrolysis method provided in Example 1 is as low as 0.065%.

[0074] Table 1 Chemical composition analysis of metallic zirconium

[0075]

[0076] Example 2:

[0077] Zirconium carbide raw material (+500 mesh ~ -300 mesh) and organic binder polyvinyl alcohol are mixed evenly in a mass ratio of 5:1, and prepared into particles with a particle size of 3-5mm using a granulator. Then, the particles are dehydrated and sintered under a vacuum of 0.5MPa to form zirconium carbide particles, which are used as the raw material for electrolytic zirconium powder.

[0078] Sodium chloride and potassium chloride in equal molar ratios were ground together for 30 min, added to a crucible, and placed in a heating furnace. After evacuation, the crucible was filled with argon. The crucible was heated to 700°C at a pressure of 0.1 MPa, kept at this temperature for 1 h, and cooled to room temperature to obtain a NaCl-KCl eutectic electrolyte.

[0079] Mix 65% by mass of NaCl-KCl eutectic electrolyte and 35% by mass of zirconium tetrachloride, pre-melt and cool to obtain NaCl-KCl-K2ZrCl6 molten salt electrolyte for use.

[0080] 20% by weight of zirconium carbide particles were added as anode material to the bottom of the crucible in the electrolysis furnace, and 80% by weight of pre-melted and cooled NaCl-KCl-K2ZrCl6 molten salt electrolyte was added. After the electrolysis equipment was sealed, the heating furnace was started and heated to the set temperature and then kept warm. After the molten salt electrolyte melted, electrolysis began. The electrolysis temperature was set at 750°C, and the cathode current density of the electrolysis was 1.5 A / cm 2 After a certain period of electrolysis, the electrode is placed in a cooling chamber for cooling. After the electrode cools to room temperature, the cathode and the deposits on the cathode are removed together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium.

[0081] The cathode sediment is crushed into particles with a size of 1-3 mm, placed in 80°C deionized water, and stirred for cleaning. After the impurities of the molten salt electrolyte are completely dissolved in the water, the zirconium powder is filtered and then immersed in a certain concentration of dilute hydrochloric acid for stirring and cleaning. After sedimentation and filtration, the powder is washed with deionized water 3 to 5 times and then dried at low temperature to obtain electrolytic zirconium metal.

[0082] Table 2 shows the chemical composition analysis results of the metal zirconium provided in an embodiment of the present invention. As shown in Table 2, the oxygen content of the metal zirconium prepared by the molten salt electrolysis method provided in Example 2 is as low as 0.068%.

[0083] Table 2 Chemical composition analysis of metallic zirconium

[0084]

[0085] Example 3

[0086] The zirconium carbide raw material (+500 mesh to -300 mesh) and the organic binder polyacrylate were mixed uniformly in a mass ratio of 6:1, and granulated into particles with a particle size of 3-5 mm using a granulator. The particles were then dehydrated under a vacuum of 0.1 MPa and sintered at 1500°C to form zirconium carbide particles.

[0087] Sodium chloride and calcium chloride in equal molar ratios were ground for 30 min, added to a crucible and placed in a heating furnace. After evacuation, the crucible was filled with argon. The crucible was heated to 700°C under a positive pressure of 0.1 MPa, kept at this temperature for 1 h, and cooled to room temperature to obtain a NaCl-CaCl2 eutectic electrolyte.

[0088] 60% by mass of NaCl-CaCl2 and 40% by mass of potassium fluorzirconate are mixed, pre-melted and cooled to obtain a molten salt electrolyte NaCl-CaCl2-K2ZrF6 for standby use;

[0089] 20% by weight of zirconium carbide particles are added as anode material to the bottom of the crucible in the electrolysis furnace, and 80% by weight of pre-melted and cooled molten salt electrolyte is added. After the electrolysis equipment is sealed, the heating furnace is started and heated to the set temperature and then kept warm. After the molten salt electrolyte melts, electrolysis begins. The electrolysis temperature is set at 750°C, and the cathode current density of the molten salt electrolysis is 2 A / cm 2 After a certain period of electrolysis, the electrode is placed in a cooling chamber for cooling. After the electrode cools to room temperature, the cathode and the deposits on the cathode are removed together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium.

[0090] The cathode sediment is crushed into particles with a size of 1-3 mm and placed in 50°C deionized water for stirring and washing. After the impurities of the molten salt electrolyte are completely dissolved in the water, the zirconium powder is filtered and then immersed in a certain concentration of dilute hydrochloric acid for stirring and washing. After sedimentation and filtration, the powder is washed with deionized water three to five times and then dried at low temperature to obtain electrolytic zirconium metal.

[0091] Table 3 shows the chemical composition analysis results of the metal zirconium provided in an embodiment of the present invention. As shown in Table 3, the oxygen content of the metal zirconium prepared by the molten salt electrolysis method provided in Example 3 is as low as 0.070%.

[0092] Table 3 Chemical composition analysis of metallic zirconium

[0093]

[0094] Example 4

[0095] The zirconium carbide raw material (+500 mesh to -300 mesh) and the organic binder phenolic resin were mixed uniformly in a mass ratio of 6:1, and granulated into particles with a particle size of 3-5 mm using a granulator. The particles were then dehydrated under a vacuum of 0.1 MPa and sintered at 1500°C to form zirconium carbide particles.

[0096] After grinding NaCl-KCl-CsCl in equal molar ratio for 30 min, the mixture was added to a crucible and placed in a heating furnace. After evacuation, the crucible was filled with argon. The crucible was heated to 700°C under a positive pressure of 0.1 MPa, kept at this temperature for 1 h, and cooled to room temperature to obtain a NaCl-KCl-CsCl eutectic electrolyte.

[0097] Mix 65% of the mass of NaCl-KCl-CsCl and 35% of ZrCl4, pre-melt and cool to obtain a molten salt electrolyte NaCl-KCl-Cs2ZrCl6 composite electrolyte for use;

[0098] 20% by weight of zirconium carbide particles are added as anode material to the bottom of the crucible in the electrolysis furnace, and 80% by weight of pre-melted and cooled molten salt electrolyte is added. After the electrolysis equipment is sealed, the heating furnace is started and heated to the set temperature and then kept warm. After the molten salt electrolyte melts, electrolysis begins. The electrolysis temperature is set at 750°C, and the cathode current density of the electrolysis is 2.5A / cm 2 After a certain period of electrolysis, the electrode is placed in a cooling chamber for cooling. After the electrode cools to room temperature, the cathode and the deposits on the cathode are removed together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium.

[0099] The cathode sediment is crushed into particles with a size of 1-3 mm and placed in 50°C deionized water for stirring and washing. After the impurities of the molten salt electrolyte are completely dissolved in the water, the zirconium powder is filtered and then immersed in a certain concentration of dilute hydrochloric acid for stirring and washing. After sedimentation and filtration, the powder is washed with deionized water three to five times and then dried at low temperature to obtain electrolytic zirconium metal.

[0100] Table 4 shows the chemical composition analysis results of the metal zirconium provided in an embodiment of the present invention. As shown in Table 4, the oxygen content of the metal zirconium prepared by the molten salt electrolysis method provided in Example 4 is as low as 0.065%.

[0101] Table 4 Chemical composition analysis of metallic zirconium

[0102]

[0103] Example 5

[0104] The zirconium carbide raw material (+500 mesh to -300 mesh) and the organic binder polyurethane were mixed uniformly in a mass ratio of 5:1, and pelletized into particles with a particle size of 3-5 mm using a granulator. The particles were then dehydrated under a vacuum of 0.1 MPa and sintered at 1500°C to form zirconium carbide particles.

[0105] After grinding NaCl-KCl-RbCl in equal molar ratio for 30 min, the mixture was added to a crucible and placed in a heating furnace. After evacuation, the crucible was filled with argon. The crucible was heated to 700°C under a positive pressure of 0.1 MPa, kept at this temperature for 1 h, and cooled to room temperature to obtain the NaCl-KCl-RbCl eutectic electrolyte.

[0106] Mix 65% of the mass of NaCl-KCl-RbCl and 35% of ZrCl4, pre-melt and cool to obtain a molten salt electrolyte NaCl-KCl-Rb2ZrCl6 composite electrolyte for use;

[0107] 20% by weight of zirconium carbide particles are added as anode material to the bottom of the crucible in the electrolysis furnace, and 80% by weight of pre-melted and cooled molten salt electrolyte is added. After the electrolysis equipment is sealed, the heating furnace is started and heated to the set temperature and then kept warm. After the molten salt electrolyte melts, electrolysis begins. The electrolysis temperature is set at 750°C, and the cathode current density of the molten salt electrolysis is 3 A / cm 2 After a certain period of electrolysis, the electrode is placed in a cooling chamber for cooling. After the electrode cools to room temperature, the cathode and the deposits on the cathode are removed together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium.

[0108] The cathode sediment is crushed into particles with a size of 1-3 mm and placed in 50°C deionized water for stirring and washing. After the impurities of the molten salt electrolyte are completely dissolved in the water, the zirconium powder is filtered and then immersed in a certain concentration of dilute hydrochloric acid for stirring and washing. After sedimentation and filtration, the powder is washed with deionized water three to five times and then dried at low temperature to obtain electrolytic zirconium metal.

[0109] Table 5 shows the chemical composition analysis results of the metal zirconium provided in the embodiment of the present invention. As shown in Table 4, the oxygen content of the metal zirconium prepared by the molten salt electrolysis method provided in Example 5 is as low as 0.072%.

[0110] Table 5 Chemical composition analysis of metallic zirconium

[0111]

[0112] Example 6

[0113] The zirconium carbide raw material (+500 mesh to -300 mesh) and the organic binder polyvinyl alcohol were mixed uniformly in a mass ratio of 7:1, and granulated into particles with a particle size of 3-5 mm using a granulator. The particles were then dehydrated under a vacuum of 0.1 MPa and sintered at 1500°C to form zirconium carbide particles.

[0114] LiCl-KCl-CsCl in equal molar ratios were ground for 30 min, added to a crucible, and placed in a heating furnace. After evacuation, the crucible was filled with argon. The crucible was heated to 700°C under a positive pressure of 0.1 MPa, kept at this temperature for 1 h, and cooled to room temperature to obtain a NaCl-KCl-CsCl eutectic electrolyte.

[0115] 65% of the mass of LiCl-KCl-CsCl and 35% of ZrCl4 are mixed, pre-melted and cooled to obtain a molten salt electrolyte LiCl-KCl-Cs2ZrCl6 composite electrolyte for standby use;

[0116] 20% by weight of zirconium carbide particles are added as anode material to the bottom of the crucible in the electrolysis furnace, and 80% by weight of pre-melted and cooled molten salt electrolyte is added. After the electrolysis equipment is sealed, the heating furnace is started and heated to the set temperature and then kept warm. After the molten salt electrolyte melts, electrolysis begins. The electrolysis temperature is set at 750°C, and the cathode current density of the electrolysis is 3.5 A / cm 2 After a certain period of electrolysis, the electrode is placed in a cooling chamber for cooling. After the electrode cools to room temperature, the cathode and the deposits on the cathode are removed together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium.

[0117] The cathode sediment is crushed into particles with a size of 1-3 mm and placed in 50°C deionized water for stirring and washing. After the impurities of the molten salt electrolyte are completely dissolved in the water, the zirconium powder is filtered and then immersed in a certain concentration of dilute hydrochloric acid for stirring and washing. After sedimentation and filtration, the powder is washed with deionized water three to five times and then dried at low temperature to obtain electrolytic zirconium metal.

[0118] Table 6 shows the chemical composition analysis results of the metal zirconium provided in the embodiment of the present invention. As shown in Table 4, the oxygen content of the metal zirconium prepared by the molten salt electrolysis method provided in Example 6 is as low as 0.070%.

[0119] Table 6 Chemical composition analysis of metallic zirconium

[0120]

[0121] Example 7

[0122] The zirconium carbide raw material (+500 mesh to -300 mesh) and the organic binder polyvinyl alcohol were mixed uniformly in a mass ratio of 4:1, and granulated into particles with a particle size of 3-5 mm using a granulator. The particles were then dehydrated under a vacuum of 0.1 MPa and sintered at 1500°C to form zirconium carbide particles.

[0123] LiCl-KCl-RbCl in equal molar ratios were ground for 30 min, added to a crucible, and placed in a heating furnace. After evacuation, the crucible was filled with argon. The crucible was heated to 700°C under a positive pressure of 0.1 MPa, kept at this temperature for 1 h, and cooled to room temperature to obtain the LiCl-KCl-RbCl eutectic electrolyte.

[0124] 65% of the mass of LiCl-KCl-RbCl and 35% of ZrCl4 are mixed, pre-melted and cooled to obtain a molten salt electrolyte LiCl-KCl-Rb2ZrCl6 composite electrolyte for standby use;

[0125] 20% by weight of zirconium carbide particles are added as anode material to the bottom of the crucible in the electrolysis furnace, and 80% by weight of pre-melted and cooled molten salt electrolyte is added. After the electrolysis equipment is sealed, the heating furnace is started and heated to the set temperature and then kept warm. After the molten salt electrolyte melts, electrolysis begins. The electrolysis temperature is set at 750°C, and the cathode current density of the electrolysis is 5 A / cm 2 After a certain period of electrolysis, the electrode is placed in a cooling chamber for cooling. After the electrode cools to room temperature, the cathode and the deposits on the cathode are removed together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium.

[0126] The cathode sediment is crushed into particles with a size of 1-3 mm and placed in 50°C deionized water for stirring and washing. After the impurities of the molten salt electrolyte are completely dissolved in the water, the zirconium powder is filtered and then immersed in a certain concentration of dilute hydrochloric acid for stirring and washing. After sedimentation and filtration, the powder is washed with deionized water three to five times and then dried at low temperature to obtain electrolytic zirconium metal.

[0127] Table 7 shows the chemical composition analysis results of the metal zirconium provided in the embodiment of the present invention. As shown in Table 4, the oxygen content of the metal zirconium prepared by the molten salt electrolysis method provided in Example 7 is as low as 0.068%.

[0128] Table 7 Chemical composition analysis of metallic zirconium

[0129]

[0130] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification.

[0131] For simplicity of description, the method embodiments are described as a series of actions. However, those skilled in the art should be aware that the present invention is not limited by the order of the actions described, as certain steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also be aware that the embodiments described in this specification are preferred embodiments, and the actions and components involved are not necessarily required for the present invention.

[0132] The above is a detailed introduction to a metal zirconium and a method for preparing metal zirconium by molten salt electrolysis provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing metallic zirconium by molten salt electrolysis, characterized in that: include: The zirconium carbide raw material and an appropriate amount of organic binder are mixed evenly, and then granulated to prepare 3-5 mm granular materials, which are then vacuum sintered to obtain zirconium carbide particles; Alkali metal / alkaline earth metal chloride salt is mixed with a small amount of zirconium salt, pre-melted and then cooled to obtain a molten salt electrolyte; Adding the zirconium carbide particles to the bottom of a graphite crucible in an electrolytic furnace, then adding the molten salt electrolyte into the graphite crucible, sealing the equipment, and performing electrolysis; After the electrolysis is completed, collecting the sediment attached to the cathode, and extracting the metal zirconium from the sediment; Wherein, the alkali metal chloride salt is selected from one or more of sodium chloride, potassium chloride, lithium chloride, rubidium chloride and cesium chloride, and the alkaline earth metal chloride salt is calcium chloride; The zirconium salt is selected from potassium fluorozirconate and / or zirconium tetrachloride; The vacuum sintering process has a pressure of 0.1 MPa to 0.5 MPa and a temperature of 1200°C to 1500°C; the mass ratio of the zirconium carbide raw material to the organic binder is 4:1 to 7:1; and the organic binder is selected from one or a combination of polyvinyl acetate, polyvinyl alcohol, polyacrylate, polyurethane, and phenolic resin.

2. The method for preparing metallic zirconium by molten salt electrolysis according to claim 1, characterized in that: The alkali metal / alkaline earth metal chloride salt is selected from NaCl-KCl, NaCl-CaCl2, NaCl-KCl-CsCl, NaCl-KCl-RbCl, LiCl-NaCl-KCl, LiCl-KCl-CsCl or LiCl-KCl-RbCl.

3. The method for preparing metallic zirconium by molten salt electrolysis according to claim 1, characterized in that: The electrolysis temperature is 750-850°C; The cathode current density of the electrolysis is 0.1 ~ 5 A / cm 2 .

4. The method for preparing metallic zirconium by molten salt electrolysis according to claim 1, characterized in that: The mass ratio of the zirconium salt to the alkali metal / alkaline earth metal chloride is 3:7 to 4:

6.

5. The method for preparing metallic zirconium by molten salt electrolysis according to claim 1, characterized in that: The mass ratio of the zirconium carbide particles to the molten salt electrolyte is 1:3 to 1:

5.

6. The method for preparing metallic zirconium by molten salt electrolysis according to claim 1, characterized in that: The particle size of the zirconium carbide raw material is +500 mesh to -300 mesh.

7. The method for preparing metallic zirconium by molten salt electrolysis according to claim 1, characterized in that: Before mixing the alkali metal / alkaline earth metal chloride salt with a small amount of zirconium salt, the method further comprises: The alkali metal chloride is subjected to vacuum dehydration at a temperature of 500-600° C. and a pressure of 0.1 MPa-0.5 MPa; The potassium fluorozirconate is subjected to vacuum dehydration at a temperature of 350-500° C. and a pressure of 0.1 MPa-0.5 MPa; The zirconium tetrachloride is vacuum dehydrated at a temperature of 200-300° C. and a pressure of 0.1 MPa-0.5 MPa.

8. The method for preparing metallic zirconium by molten salt electrolysis according to claim 1, characterized in that: The step of extracting metallic zirconium from the sediment comprises: The cathode sediment is crushed into particles with a particle size of 1-3 mm, placed in deionized water at 50°C to 80°C, stirred and washed, and after the mixed molten salt electrolyte is completely dissolved in the water, filtered to obtain coarse zirconium powder; The crude zirconium powder is immersed in dilute hydrochloric acid, stirred and washed, settled and filtered, and then washed with deionized water for 3 to 5 times. After low-temperature drying, low-oxygen content metal zirconium is obtained.

Images