Metal zirconium and method for preparing metal zirconium through molten salt electrolysis

Abstract

The invention provides a method for preparing metal zirconium through electrolysis of metal zirconium and molten salt, which comprises the following steps: uniformly mixing a zirconium carbide raw material and a proper amount of organic binder, granulating to form a granular material, and sintering in vacuum to obtain zirconium carbide particles; mixing alkali metal / alkaline earth metal chlorine salt with a small amount of zircon salt, pre-melting, and cooling to obtain molten salt electrolyte; adding zirconium carbide particles into the bottom of a graphite crucible in an electrolytic furnace, adding a molten salt electrolyte into the graphite crucible, sealing equipment, and carrying out electrolysis; after electrolysis is completed, sediment attached to the cathode is collected, and metal zirconium is extracted from the sediment; according to the preparation method provided by the invention, zirconium carbide is adopted as an anode material, so that the problem of equipment corrosion caused by a large amount of chlorine separated out from an anode when a high-temperature molten salt system is directly electrolyzed to prepare zirconium powder is avoided; besides, the production cost of zirconium carbide is relatively low, zirconium carbide can be obtained by taking zirconium oxide as a raw material through a carbon reduction method, and the cost is greatly saved compared with that of adopting sponge zirconium as an 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 as a fuel cladding material for nuclear reactors in the nuclear industry. It is also used in the chemical industry to manufacture chemical reaction vessels, heat exchangers, pumps, valves, pipelines, agitators and other equipment. Zirconium powder has good air absorption performance and can be used as a degassing agent in the manufacturing process of electronic devices to absorb residual gas inside the device and improve the vacuum degree of the device, thereby improving the performance and stability of the electronic device. Since zirconium metal has good biocompatibility and is not prone to rejection, it can be used to manufacture medical devices such as surgical instruments and dental instruments. The demand for zirconium powder for 3D printing is also gradually increasing. At present, there are three main processes for preparing zirconium powder: the first is the hydrogenation and dehydrogenation method. This process requires metal zirconium (sponge zirconium or zirconium chips) as raw material, hydrogenates metal zirconium to obtain zirconium hydride, and then dehydrogenates zirconium hydride to obtain zirconium powder after the zirconium hydride is crushed into powder. The process uses hydrogen, which has certain safety risks. Zirconium powder prepared by dehydrogenation of zirconium hydride is prone to spontaneous combustion and has safety production hazards. The second method is the calcium (calcium hydride) reduction method, which uses zirconium oxide and calcium (calcium hydride) as raw materials. This process can obtain finer zirconium powder, but the oxygen content of zirconium powder is high. If the process conditions are not well controlled, the zirconium oxide reduction will not be complete. At the same time, calcium and calcium hydride are also dangerous goods, which have certain safety hazards. The third method is the molten salt electrolysis method, which uses potassium zirconate or zirconium tetrachloride as the zirconium source. Under the action of the electric field, the metal zirconium powder is precipitated at the cathode by controlling the process conditions. This process uses the electric field to replace the dangerous goods reducing agent to ensure the safety of production.

[0003] The molten salt electrolysis method is to melt salts at high temperature to form a melt, and then pass direct current to make some ions in it undergo redox reactions on the electrodes, thereby achieving the purpose of preparing and refining metals or other substances. The existing process of preparing zirconium powder by molten salt electrolysis is to use potassium zirconium fluoride or zirconium tetrachloride as the raw material of zirconium, and add supporting electrolytes such as sodium chloride and potassium chloride for high-temperature molten salt electrolysis. Under the action of the electric field, metal zirconium is precipitated at the cathode, and metal zirconium is obtained after water washing.

[0004] However, during the direct electrolysis process, chlorine is precipitated at the anode. When the current density is too high or the concentration of zirconium ions is too low, an anode effect will occur, causing the electrolysis to be interrupted. The precipitation of chlorine causes severe corrosion to the equipment at high temperatures, and also leads to safety risks in the production process. In order to solve the problem of chlorine precipitation at the anode, the existing process is to add zirconium sponge to the anode as an anode material to avoid chlorine precipitation at the anode and as a source of zirconium. However, the production cost of zirconium sponge as a raw material is relatively high. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides a method for preparing metal 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: In a first aspect, the present invention provides a method for preparing metallic zirconium by molten salt electrolysis, comprising: The zirconium carbide raw material and an appropriate amount of organic binder are uniformly mixed, and then granulated to prepare 3-5 mm granular materials, and 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, the sediment attached to the cathode is collected, and the metal zirconium is extracted from the sediment; 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; The zirconium salt is selected from potassium fluorozirconate and / or zirconium tetrachloride.

[0007] 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.

[0008] Optionally, the electrolysis temperature is 750-850°C; The cathode current density of the electrolysis is 0.1 to 5 A / cm 2 .

[0009] Optionally, the mass ratio of the zirconium carbide raw material to the organic binder is 4:1 to 7:1; The organic binder is selected from one or a combination of polyvinyl acetate, polyvinyl alcohol, polyacrylate, polyurethane and phenolic resin; The vacuum sintering process has a pressure of 0.1 MPa to 0.5 MPa and a temperature of 1200° C. to 1500° C.

[0010] Optionally, the mass ratio of the zirconium salt to the alkali metal / alkaline earth metal chloride salt is 3:7 to 4:6.

[0011] Optionally, the mass ratio of the zirconium carbide particles to the molten salt electrolyte is 1:3 to 1:5.

[0012] Optionally, the particle size of the zirconium carbide raw material is +500 mesh to -300 mesh.

[0013] Optionally, before mixing the alkali metal / alkaline earth metal chloride salt with a small amount of zirconium salt, the method further comprises: Under the conditions of a temperature of 500-600° C. and a pressure of 0.1 MPa-0.5 MPa, vacuum dehydrating the alkali metal chloride salt; The potassium zirconate 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 subjected to vacuum dehydration at a temperature of 200-300° C. and a pressure of 0.1 MPa-0.5 MPa.

[0014] Optionally, extracting metallic zirconium from the sediment comprises: The cathode sediment is crushed into particles with a particle size of 1-3 mm, and placed in deionized water at 50° C. to 80° C. for stirring and washing, and after the mixed molten salt electrolyte is completely dissolved in the water, the coarse zirconium powder is filtered out; The crude zirconium powder is immersed in dilute hydrochloric acid for stirring and cleaning, and after sedimentation and filtration, it is washed with deionized water for 3 to 5 times, and dried at low temperature to obtain metal zirconium with low oxygen content.

[0015] 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.

[0016] Compared with the prior art, the present invention has the following advantages: The present invention provides a method for preparing metal 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 granular material of 3-5 mm, and performing vacuum sintering 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, adding the molten salt electrolyte to the graphite crucible, sealing the device, and performing electrolysis; after the electrolysis is completed, collecting the sediment attached to the cathode, and extracting the metal zirconium from the sediment; the oxygen content in the metal zirconium is 0.06%-0.08%.

[0017] In the preparation method provided by the present invention, zirconium carbide is used as the anode material, which avoids the problem of large amount of chlorine gas precipitated from the anode and causing equipment corrosion when zirconium powder is directly electrolyzed in a high-temperature molten salt system (without anode material); 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0019] Figure 1 A flow chart of a method for preparing metal zirconium by molten salt electrolysis provided in an embodiment of the present invention is shown; Figure 2 The metal zirconium prepared by molten salt electrolysis in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be described clearly and completely 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 identical or similar to the present invention 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 belong to the scope of protection of the present invention.

[0021] In the embodiment, no specific experimental steps or conditions are indicated, and the operation or conditions of the conventional experimental steps described in the prior art in this field can be carried out. The reagents used and other instruments that do not indicate the manufacturer are conventional reagent products that can be obtained commercially. In addition, the accompanying drawings are only schematic diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description 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.

[0022] Technologies, methods, and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the description of the present invention.

[0023] 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. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0024] 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.

[0025] Since the direct electrolysis of an electrolyte containing potassium zirconium fluoride or zirconium tetrachloride is used to prepare metallic zirconium, 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 induces a disproportionation reaction, resulting in a decrease in current efficiency. Therefore, the present invention uses zirconium carbide as an 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: In a first aspect, the present invention provides a method for preparing metal zirconium by molten salt electrolysis. Figure 1 The flow chart of the method for preparing metal zirconium by molten salt electrolysis provided in an embodiment of the present invention is shown as follows: Figure 1 As shown, the preparation method comprises the following steps: 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.

[0026] In specific implementation, before zirconium carbide is used for electrolytic preparation of metallic zirconium, the zirconium carbide is first granulated in this step, that is, the zirconium carbide is evenly mixed with an organic binder, put into a granulator, and prepared into particles with a particle size of 3-5 mm, and the particles are vacuum sintered to form zirconium carbide particles with uniform and stable shape. The vacuum sintering treatment pressure is 0.1MPa~0.5MPa, and the temperature is 1200℃~1500℃.

[0027] Compared with direct electrolysis with zirconium carbide powder, the specific surface area of ​​zirconium carbide particles formed by granulation is significantly increased, thereby increasing the contact area of ​​subsequent electrolysis reactions, promoting the reaction rate, and increasing the yield and efficiency of metallic zirconium; the granulated zirconium carbide has better fluidity and is easy to transport and load. 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.

[0028] In some embodiments, the mass ratio of the zirconium carbide raw material used for granulation to the organic binder is controlled at 4:1~7:1, and the organic binder is selected from one or a combination of polyvinyl acetate, polyvinyl alcohol, polyacrylate, polyurethane, and phenolic resin.

[0029] 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; In this step, a mixture of alkali metal / alkaline earth metal chloride and zirconium salt is used to form an electrolyte system. The presence of a small amount of zirconium salt in the electrolyte system helps to balance the zirconium ions during the electrolysis process. In addition, the addition of zirconium salt can lower the melting point of the electrolyte system as a whole, so that the molten salt can be fully melted at a lower temperature, reducing the energy consumption and operating temperature of the equipment.

[0030] 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 a 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.

[0031] 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; the zirconium salt is selected from potassium zirconate 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, LiCl-KCl-RbCl.

[0032] In some embodiments, before the alkali metal / alkaline earth metal chloride and zirconium salt participate in the pre-melting, the alkali metal / alkaline earth metal chloride and zirconium salt need to be vacuum dehydrated to remove interfering impurities in the raw materials. The alkali metal / alkaline earth metal chloride is vacuum dehydrated at a temperature of 500-600°C and 0.1MPa-0.5MPa; and the vacuum dehydration treatment procedure for the zirconium salt includes: vacuum dehydration of potassium zirconate at a temperature of 350-500°C and 0.1MPa-0.5MPa; and vacuum dehydration of zirconium tetrachloride at a temperature of 200-300°C and 0.1MPa-0.5MPa.

[0033] 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 treatment; In this step, a graphite crucible is used to hold zirconium carbide particles, which are spread flat on the bottom of the graphite crucible, and then a molten salt electrolyte is placed in the graphite crucible. After the equipment is sealed, the assembly of the electrolysis equipment is completed. The zirconium carbide particles that are in direct contact with the bottom of the graphite crucible serve as part of the anode. During the electrolysis process, the zirconium ions in the zirconium carbide, as the party that loses electrons, enter the electrolysis system, and finally precipitate metal zirconium at the cathode, replacing the original chloride ions that lose electrons, and avoiding the generation of chlorine gas.

[0034] 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 suspension losses caused by the difficulty of sedimentation of zirconium carbide powder materials, ensuring that more raw materials participate in the electrolysis reaction, thereby improving the utilization rate of materials.

[0035] In some embodiments, the mass ratio of the added zirconium carbide particles to the molten salt electrolyte is 1:3 to 1:5. After the electrolysis equipment is sealed, the heating furnace is started to heat 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 to 5 A / cm 2 .

[0036] S4. After the electrolysis is completed, the sediment attached to the cathode is collected, and metal zirconium is extracted from the sediment.

[0037] In specific implementation, after a certain period of electrolysis, the cathode electrode is lifted to the cooling chamber for cooling. After the electrode cools to room temperature, the deposit on the cathode is taken out. The deposit on the cathode is mainly mixed molten salt electrolyte and metal zirconium powder. The operation of extracting metal zirconium powder from the sediment includes: crushing the cathode sediment into particles with a particle size of 1-3mm, putting it into deionized water at 50℃~80℃, stirring and washing, and filtering to obtain zirconium powder after the mixed molten salt electrolyte is completely dissolved in water, and immersing the zirconium powder in a certain concentration of dilute hydrochloric acid for stirring and washing. After sedimentation and filtration, wash it with deionized water 3 to 5 times, and obtain electrolytic metal zirconium powder after low-temperature drying.

[0038] In the embodiment of the present invention, zirconium carbide is used as a raw material for electrolysis to prepare zirconium powder, which can replace the use of sponge zirconium prepared by the Kroll method (magnesium reduction of zirconium tetrachloride) as a raw material, thereby reducing costs and shortening the process flow. Because sponge zirconium needs to be prepared into zirconium tetrachloride by chlorination of zirconium oxide, and then the zirconium tetrachloride is purified, and then zirconium tetrachloride is reduced with metallic magnesium, and magnesium is distilled and separated, and zirconium sponge can be obtained after other processes, the process flow is long and the cost is high. Zirconium carbide can be obtained by carbon reduction with zirconium oxide as a raw material, which has a short process flow and low cost. If no anode material is added, the electrolyte containing potassium zirconium fluoride or zirconium tetrachloride is directly electrolyzed to prepare metallic zirconium, but the anode will produce chlorine gas, which will deteriorate the production environment. At the same time, the production of chlorine gas will seriously corrode the equipment and induce disproportionation reaction, resulting in a decrease in current efficiency. Therefore, electrolysis using zirconium carbide as a raw material is a new process for preparing zirconium powder with low oxygen content, which has good application value.

[0039] Furthermore, the method for preparing metallic zirconium by molten salt electrolysis provided by the present invention can realize continuous production of metallic zirconium by regularly adding zirconium carbide particles as required, thereby greatly improving production efficiency.

[0040] 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.

[0041] 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.

[0042] The following raw materials involved in electrolysis are pre-treated to remove moisture and volatile impurities: Alkali metal chloride pretreatment: vacuum dehydration at 500°C and 0.1MPa; Potassium fluoride zirconate pretreatment: vacuum dehydration pretreatment at 350°C and 0.1MPa; Zirconium tetrachloride pretreatment: vacuum dehydration at a temperature of 200°C and 0.1MPa for dehydration pretreatment.

[0043] Example 1 The zirconium carbide raw material (+500 mesh to -300 mesh) and the organic binder polyvinyl acetate in a mass ratio of 4:1 were mixed evenly, and prepared into 3-5 mm particles using a granulator, and then dehydrated under a vacuum of 0.1 MPa and sintered at 1500°C to form zirconium carbide particles; Sodium chloride and potassium chloride in equal molar ratios were ground for 30 min, added into a crucible and placed in a heating furnace. After evacuation, argon was filled into the crucible. 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. Mix 70% by weight of a sodium chloride and potassium chloride mixed salt in an equal molar ratio and 30% by weight of potassium fluoride zirconate, pre-melt and cool, and obtain a molten salt electrolyte NaCl-KCl-K2ZrF6 for use; 20% by weight of zirconium carbide particles are used as anode material and added to the bottom of the crucible in the electrolytic furnace. 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 taken out together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium. The cathode sediment was crushed into particles with a particle size of 1-3 mm, and then placed in deionized water at 50 °C for stirring and cleaning. After the mixed molten salt electrolyte was completely dissolved in water, the zirconium powder was filtered out and then immersed in a certain concentration of dilute hydrochloric acid for stirring and cleaning. After sedimentation and filtration, the powder was washed with deionized water for 3 to 5 times, and then dried at low temperature to obtain electrolytic metal zirconium powder; Figure 2 The metal zirconium prepared by molten salt electrolysis in an embodiment of the present invention is shown.

[0044] Table 1 shows the chemical composition analysis results of the metal zirconium provided in the 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%.

[0045] Table 1 Chemical composition analysis of metal zirconium

[0046] Embodiment 2: The zirconium carbide raw material (+500 mesh ~ -300 mesh) and the organic binder polyvinyl alcohol in a mass ratio of 5:1 are mixed evenly, and the particles with a particle size of 3-5 mm are prepared by a granulator, and then dehydrated and sintered under a vacuum of 0.5 MPa to form zirconium carbide particles as the raw material of electrolytic zirconium powder.

[0047] Sodium chloride and potassium chloride in equal molar ratios were ground for 30 min, added into a crucible and placed in a heating furnace. After evacuation, argon was filled into the crucible. 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. 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.

[0048] 20% by weight of zirconium carbide particles are used as anode material and added to the bottom of the crucible in the electrolytic furnace. 80% by weight of pre-melted and cooled NaCl-KCl-K2ZrCl6 molten salt electrolyte is added. After the electrolysis equipment is sealed, the heating furnace is started to heat 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 1.5 A / cm 2 After a certain period of electrolysis, the electrode is lifted to a cooling chamber for cooling. After the electrode cools to room temperature, the cathode and the deposits on the cathode are taken out together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium.

[0049] The cathode sediment is crushed into particles with a size of 1-3 mm, and then placed in deionized water at 80°C for stirring and cleaning. After all the mixed molten salt electrolyte is dissolved in water, the zirconium powder is filtered out, and then the zirconium powder is immersed in a certain concentration of dilute hydrochloric acid for stirring and cleaning. After sedimentation and filtration, it is washed with deionized water for 3 to 5 times, and then dried at low temperature to obtain electrolytic metal zirconium.

[0050] Table 2 shows the chemical composition analysis results of the metal zirconium provided in the 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%.

[0051] Table 2 Chemical composition analysis of metal zirconium

[0052] Example 3 The zirconium carbide raw material (+500 mesh to -300 mesh) and the organic binder polyacrylate in a mass ratio of 6:1 were mixed evenly, and the particles with a particle size of 3-5 mm were prepared by a granulator, and then dehydrated under a vacuum of 0.1 MPa and sintered at 1500°C to form zirconium carbide particles; After mixing sodium chloride and calcium chloride in equal molar ratio for 30 min, the mixture was added into a crucible and placed in a heating furnace. After vacuuming, the mixture was filled with argon gas. The mixture was heated to 700°C under a positive pressure of 0.1 MPa and kept at this temperature for 1 h. After cooling to room temperature, the NaCl-CaCl2 eutectic electrolyte was obtained. 60% by mass of NaCl-CaCl2 and 40% by mass of potassium fluoride zirconate are mixed, pre-melted and cooled to obtain a molten salt electrolyte NaCl-CaCl2-K2ZrF6 for standby use; 20% by weight of zirconium carbide particles are used as anode material and added to the bottom of the crucible in the electrolytic furnace. 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 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 taken out together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium. The cathode sediment is crushed into particles with a particle size of 1-3 mm, placed in deionized water at 50 °C, stirred and cleaned, and after the mixed molten salt electrolyte is completely dissolved in water, the zirconium powder is filtered out, and the zirconium powder is immersed in a certain concentration of dilute hydrochloric acid, stirred and cleaned. After sedimentation and filtration, it is washed with deionized water for 3 to 5 times, and electrolytic metal zirconium is obtained after low-temperature drying.

[0053] Table 3 shows the chemical composition analysis results of the metal zirconium provided in the 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%.

[0054] Table 3 Chemical composition analysis of metal zirconium

[0055] Example 4 The zirconium carbide raw material (+500 mesh to -300 mesh) and the organic binder phenolic resin in a mass ratio of 6:1 were mixed evenly, and particles with a particle size of 3-5 mm were prepared by a granulator, and then dehydrated under a vacuum of 0.1 MPa and sintered at 1500°C to form zirconium carbide particles; After grinding NaCl-KCl-CsCl in equal molar ratio for 30 min, the mixture was added into a crucible and placed in a heating furnace. After vacuuming, the mixture was filled with argon gas. The mixture was heated to 700°C under a positive pressure of 0.1 MPa and kept at this temperature for 1 h. After cooling to room temperature, the NaCl-KCl-CsCl eutectic electrolyte was obtained. Mix 65% of the mass of NaCl-KCl-CsCl and 35% of ZrCl4, pre-melt and cool, and obtain a molten salt electrolyte NaCl-KCl-Cs2ZrCl6 composite electrolyte for use; 20% by weight of zirconium carbide particles are used as anode material and added to the bottom of the crucible in the electrolytic furnace. 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 taken out together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium. The cathode sediment is crushed into particles with a particle size of 1-3 mm, placed in deionized water at 50 °C, stirred and washed, and after the mixed molten salt electrolyte is completely dissolved in water, the zirconium powder is filtered out, and the zirconium powder is immersed in a certain concentration of dilute hydrochloric acid, stirred and washed. After sedimentation and filtration, it is washed with deionized water for 3 to 5 times, and electrolytic metal zirconium is obtained after low-temperature drying.

[0056] Table 4 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 4 is as low as 0.065%.

[0057] Table 4 Chemical composition analysis of metal zirconium

[0058] Example 5 The zirconium carbide raw material (+500 mesh ~ -300 mesh) and the organic binder polyurethane in a mass ratio of 5:1 were mixed evenly, and the particles with a particle size of 3-5 mm were prepared by a granulator, and then dehydrated under a vacuum of 0.1 MPa and sintered at 1500°C to form zirconium carbide particles; After grinding NaCl-KCl-RbCl in equal molar ratio for 30 min, the mixture was added into a crucible and placed in a heating furnace. After vacuuming, the mixture was filled with argon gas. The mixture was heated to 700°C under a positive pressure of 0.1 MPa and kept at this temperature for 1 h. After cooling to room temperature, the NaCl-KCl-RbCl eutectic electrolyte was obtained. Mix 65% of the mass of NaCl-KCl-RbCl and 35% of ZrCl4, pre-melt and cool, and obtain a molten salt electrolyte NaCl-KCl-Rb2ZrCl6 composite electrolyte for use; 20% by weight of zirconium carbide particles are used as anode materials and added to the bottom of the crucible in the electrolytic furnace. 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 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 taken out together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium. The cathode sediment is crushed into particles with a particle size of 1-3 mm, placed in deionized water at 50 °C, stirred and washed, and after the mixed molten salt electrolyte is completely dissolved in water, the zirconium powder is filtered out, and the zirconium powder is immersed in a certain concentration of dilute hydrochloric acid, stirred and washed. After sedimentation and filtration, it is washed with deionized water for 3 to 5 times, and electrolytic metal zirconium is obtained after low-temperature drying.

[0059] 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%.

[0060] Table 5 Chemical composition analysis of metal zirconium

[0061] Example 6 The zirconium carbide raw material (+500 mesh to -300 mesh) and the organic binder polyvinyl alcohol in a mass ratio of 7:1 were mixed evenly, and particles with a particle size of 3-5 mm were prepared by a granulator, and then dehydrated under a vacuum of 0.1 MPa and sintered at 1500°C to form zirconium carbide particles; After mixing LiCl-KCl-CsCl in equal molar ratio for 30 min, the mixture was added into a crucible and placed in a heating furnace. After vacuuming, the mixture was filled with argon gas. The mixture was heated to 700°C under a positive pressure of 0.1 MPa and kept at this temperature for 1 h. After cooling to room temperature, the NaCl-KCl-CsCl eutectic electrolyte was obtained. 65% of the mass of LiCl-KCl-CsCl is mixed with 35% of ZrCl4, pre-melted and cooled, and a molten salt electrolyte LiCl-KCl-Cs2ZrCl6 composite electrolyte is obtained for use; 20% by weight of zirconium carbide particles are used as anode material and added to the bottom of the crucible in the electrolytic furnace. 80% by weight of pre-melted and cooled molten salt electrolyte is added. After the electrolysis equipment is sealed, the heating furnace is started to heat 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 taken out together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium. The cathode sediment is crushed into particles with a particle size of 1-3 mm, placed in deionized water at 50 °C, stirred and cleaned, and after the mixed molten salt electrolyte is completely dissolved in water, the zirconium powder is filtered out, and the zirconium powder is immersed in a certain concentration of dilute hydrochloric acid, stirred and cleaned. After sedimentation and filtration, it is washed with deionized water for 3 to 5 times, and electrolytic metal zirconium is obtained after low-temperature drying.

[0062] 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%.

[0063] Table 6 Chemical composition analysis of metal zirconium

[0064] Example 7 The zirconium carbide raw material (+500 mesh to -300 mesh) and the organic binder polyvinyl alcohol in a mass ratio of 4:1 were mixed evenly, and particles with a particle size of 3-5 mm were prepared by a granulator, and then dehydrated under a vacuum of 0.1 MPa and sintered at 1500°C to form zirconium carbide particles; After mixing and grinding LiCl-KCl-RbCl in equal molar ratio for 30 min, the mixture was added into a crucible and placed in a heating furnace. After vacuuming, the mixture was filled with argon gas. The mixture was heated to 700°C under a positive pressure of 0.1 MPa and kept at this temperature for 1 h. After cooling to room temperature, the LiCl-KCl-RbCl eutectic electrolyte was obtained. 65% of the mass of LiCl-KCl-RbCl is mixed with 35% of ZrCl4, pre-melted and cooled, and a molten salt electrolyte LiCl-KCl-Rb2ZrCl6 composite electrolyte is obtained for standby use; 20% by weight of zirconium carbide particles are used as anode material and added to the bottom of the crucible in the electrolytic furnace. 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 2After 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 taken out together. The deposits on the cathode are mainly mixed molten salt electrolyte and metal zirconium. The cathode sediment is crushed into particles with a particle size of 1-3 mm, placed in deionized water at 50 °C, stirred and washed, and after the mixed molten salt electrolyte is completely dissolved in water, the zirconium powder is filtered out, and the zirconium powder is immersed in a certain concentration of dilute hydrochloric acid, stirred and washed. After sedimentation and filtration, it is washed with deionized water for 3 to 5 times, and electrolytic metal zirconium is obtained after low-temperature drying.

[0065] 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%.

[0066] Table 7 Chemical composition analysis of metal zirconium

[0067] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means 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 may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0068] For the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily required by the present invention.

[0069] 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 idea 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 uniformly mixed, and then granulated to prepare 3-5 mm granular materials, and 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 then performing electrolysis; After the electrolysis is completed, the sediment attached to the cathode is collected, and the metal zirconium is extracted from the sediment; 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; The zirconium salt is selected from potassium fluorozirconate and / or zirconium tetrachloride.

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 to 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 carbide raw material to the organic binder is 4:1-7:1; The organic binder is selected from one or a combination of polyvinyl acetate, polyvinyl alcohol, polyacrylate, polyurethane and phenolic resin; The vacuum sintering process has a pressure of 0.1 MPa to 0.5 MPa and a temperature of 1200° C. to 1500° C.

5. 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 salt is 3:7 to 4:

6.

6. 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.

7. 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.

8. 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: Under the conditions of a temperature of 500-600° C. and a pressure of 0.1 MPa-0.5 MPa, vacuum dehydrating the alkali metal chloride salt; The potassium zirconate 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 subjected to vacuum dehydration at a temperature of 200-300° C. and a pressure of 0.1 MPa-0.5 MPa.

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

10. A metal zirconium, characterized in that: The metal zirconium is obtained by the method for preparing metal zirconium by molten salt electrolysis as described in any one of claims 1 to 9.

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