CN119433626A - Metal hafnium and method for preparing metal hafnium by molten salt electrolysis - Google Patents
Metal hafnium and method for preparing metal hafnium by molten salt electrolysis Download PDFInfo
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- CN119433626A CN119433626A CN202510032654.0A CN202510032654A CN119433626A CN 119433626 A CN119433626 A CN 119433626A CN 202510032654 A CN202510032654 A CN 202510032654A CN 119433626 A CN119433626 A CN 119433626A
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- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 title claims abstract description 145
- 238000005868 electrolysis reaction Methods 0.000 title claims abstract description 99
- 150000003839 salts Chemical class 0.000 title claims abstract description 99
- 229910052735 hafnium Inorganic materials 0.000 title claims abstract description 85
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 74
- 239000002184 metal Substances 0.000 title claims abstract description 74
- 238000000034 method Methods 0.000 title claims abstract description 56
- 239000003792 electrolyte Substances 0.000 claims abstract description 77
- WHJFNYXPKGDKBB-UHFFFAOYSA-N hafnium;methane Chemical compound C.[Hf] WHJFNYXPKGDKBB-UHFFFAOYSA-N 0.000 claims abstract description 65
- 239000002245 particle Substances 0.000 claims abstract description 60
- 238000001816 cooling Methods 0.000 claims abstract description 36
- 238000002156 mixing Methods 0.000 claims abstract description 31
- 239000002994 raw material Substances 0.000 claims abstract description 30
- 229910001514 alkali metal chloride Inorganic materials 0.000 claims abstract description 26
- 150000003841 chloride salts Chemical class 0.000 claims abstract description 26
- 229910001617 alkaline earth metal chloride Inorganic materials 0.000 claims abstract description 25
- 150000002362 hafnium Chemical class 0.000 claims abstract description 20
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 17
- 150000001340 alkali metals Chemical class 0.000 claims abstract description 16
- 238000005245 sintering Methods 0.000 claims abstract description 16
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 15
- 239000010439 graphite Substances 0.000 claims abstract description 15
- 239000000853 adhesive Substances 0.000 claims abstract description 13
- 230000001070 adhesive effect Effects 0.000 claims abstract description 13
- 238000007789 sealing Methods 0.000 claims abstract description 5
- 239000013049 sediment Substances 0.000 claims description 35
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 31
- 238000004140 cleaning Methods 0.000 claims description 20
- 239000008367 deionised water Substances 0.000 claims description 20
- 229910021641 deionized water Inorganic materials 0.000 claims description 20
- 238000001914 filtration Methods 0.000 claims description 20
- 238000003756 stirring Methods 0.000 claims description 20
- PDPJQWYGJJBYLF-UHFFFAOYSA-J hafnium tetrachloride Chemical compound Cl[Hf](Cl)(Cl)Cl PDPJQWYGJJBYLF-UHFFFAOYSA-J 0.000 claims description 17
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 16
- AIYUHDOJVYHVIT-UHFFFAOYSA-M caesium chloride Chemical compound [Cl-].[Cs+] AIYUHDOJVYHVIT-UHFFFAOYSA-M 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 15
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 14
- 239000001301 oxygen Substances 0.000 claims description 14
- 229910052760 oxygen Inorganic materials 0.000 claims description 14
- AKGXWNJHODZDIK-UHFFFAOYSA-I potassium hafnium(4+) pentafluoride Chemical group [F-].[Hf+4].[K+].[F-].[F-].[F-].[F-] AKGXWNJHODZDIK-UHFFFAOYSA-I 0.000 claims description 14
- 229910020595 KCl—RbCl Inorganic materials 0.000 claims description 12
- 230000018044 dehydration Effects 0.000 claims description 12
- 238000006297 dehydration reaction Methods 0.000 claims description 12
- 238000005406 washing Methods 0.000 claims description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 10
- 238000001035 drying Methods 0.000 claims description 10
- 239000008187 granular material Substances 0.000 claims description 10
- 239000003513 alkali Substances 0.000 claims description 8
- 239000011780 sodium chloride Substances 0.000 claims description 8
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 7
- 229910001628 calcium chloride Inorganic materials 0.000 claims description 7
- 239000001110 calcium chloride Substances 0.000 claims description 7
- 239000001103 potassium chloride Substances 0.000 claims description 7
- 235000011164 potassium chloride Nutrition 0.000 claims description 7
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 6
- 239000011230 binding agent Substances 0.000 claims description 6
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 claims description 6
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 6
- BUKHSQBUKZIMLB-UHFFFAOYSA-L potassium;sodium;dichloride Chemical compound [Na+].[Cl-].[Cl-].[K+] BUKHSQBUKZIMLB-UHFFFAOYSA-L 0.000 claims description 6
- FGDZQCVHDSGLHJ-UHFFFAOYSA-M rubidium chloride Chemical compound [Cl-].[Rb+] FGDZQCVHDSGLHJ-UHFFFAOYSA-M 0.000 claims description 6
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims description 4
- 229920001568 phenolic resin Polymers 0.000 claims description 4
- 239000005011 phenolic resin Substances 0.000 claims description 4
- 229920000058 polyacrylate Polymers 0.000 claims description 4
- 239000004814 polyurethane Substances 0.000 claims description 4
- 229920002689 polyvinyl acetate Polymers 0.000 claims description 4
- 239000011118 polyvinyl acetate Substances 0.000 claims description 4
- 229920005749 polyurethane resin Polymers 0.000 claims description 3
- 229940102127 rubidium chloride Drugs 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 description 22
- 239000000203 mixture Substances 0.000 description 21
- 239000010405 anode material Substances 0.000 description 18
- 239000000126 substance Substances 0.000 description 17
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 14
- 238000004458 analytical method Methods 0.000 description 14
- 239000000463 material Substances 0.000 description 10
- 238000004062 sedimentation Methods 0.000 description 9
- 230000005496 eutectics Effects 0.000 description 8
- 229910052786 argon Inorganic materials 0.000 description 7
- 239000000460 chlorine Substances 0.000 description 7
- 229910052801 chlorine Inorganic materials 0.000 description 7
- 239000002131 composite material Substances 0.000 description 7
- 238000011049 filling Methods 0.000 description 7
- 238000000227 grinding Methods 0.000 description 7
- 229910000449 hafnium oxide Inorganic materials 0.000 description 7
- WIHZLLGSGQNAGK-UHFFFAOYSA-N hafnium(4+);oxygen(2-) Chemical compound [O-2].[O-2].[Hf+4] WIHZLLGSGQNAGK-UHFFFAOYSA-N 0.000 description 7
- 238000002844 melting Methods 0.000 description 7
- 230000008018 melting Effects 0.000 description 7
- 238000010298 pulverizing process Methods 0.000 description 7
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 6
- -1 hafnium hydride Chemical compound 0.000 description 6
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000006722 reduction reaction Methods 0.000 description 4
- CSDQQAQKBAQLLE-UHFFFAOYSA-N 4-(4-chlorophenyl)-4,5,6,7-tetrahydrothieno[3,2-c]pyridine Chemical compound C1=CC(Cl)=CC=C1C1C(C=CS2)=C2CCN1 CSDQQAQKBAQLLE-UHFFFAOYSA-N 0.000 description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 3
- 229910052791 calcium Inorganic materials 0.000 description 3
- 239000011575 calcium Substances 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 230000005684 electric field Effects 0.000 description 3
- 238000005469 granulation Methods 0.000 description 3
- 230000003179 granulation Effects 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 239000011777 magnesium Substances 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000007323 disproportionation reaction Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000005984 hydrogenation reaction Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
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- 238000002360 preparation method Methods 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000005660 chlorination reaction Methods 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
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- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
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- 150000002739 metals Chemical class 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
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- 239000003115 supporting electrolyte Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
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- Electrolytic Production Of Metals (AREA)
Abstract
The invention provides a method for preparing metal hafnium by metal hafnium and molten salt electrolysis, which comprises the steps of uniformly mixing a hafnium carbide raw material and a proper amount of adhesive, granulating, carrying out vacuum sintering treatment to obtain hafnium carbide particles, mixing alkali metal/alkaline earth metal chloride salt with a small amount of hafnium salt, premelting and cooling to obtain molten salt electrolyte, adding the hafnium carbide particles into the bottom of a graphite crucible in an electrolytic furnace, adding the molten salt electrolyte into the graphite crucible, sealing equipment, and carrying out electrolysis.
Description
Technical Field
The invention relates to the technical field of metal hafnium and preparation, in particular to a method for preparing metal hafnium by metal hafnium and molten salt electrolysis.
Background
Hafnium is widely used in a variety of fields due to its unique physical and chemical properties. Hafnium has good neutron absorption characteristics, is commonly used in nuclear reactors as neutron absorption materials to help regulate and control nuclear reactions, is commonly used for manufacturing nickel-based and cobalt-based high-temperature alloys, is mainly used for engine components in the aerospace field to improve high-temperature resistance and oxidation resistance, and is an alloy formed by hafnium and other metals (such as tungsten, molybdenum and the like), has excellent physical and chemical characteristics, and is applied to some extreme working conditions. Hafnium oxide films prepared from metallic hafnium are used as capacitor materials in microelectronics and integrated circuits due to their excellent dielectric properties. Hafnium is widely applied in film technology, can be used as a coating material to enhance surface wear resistance and corrosion resistance, is used as a high-temperature oxidation resistant coating prepared from metal hafnium as a raw material, can be used for manufacturing high-performance optical materials due to high refractive index and excellent optical performance, can be used as a catalyst or a catalyst carrier in certain chemical reactions to promote reaction, plays an important role in development and research of new materials, and particularly has excellent performance in development of superconducting materials and novel ceramic materials, and is applied to the field of aerospace.
The first is hydrogenation dehydrogenation method, the process needs to hydrogenate metal hafnium (sponge hafnium or hafnium scraps) as raw material to obtain hafnium hydride, the hafnium hydride is crushed into powder and then dehydrogenated to obtain hafnium powder, the process uses hydrogen to have certain safety risk, and the hafnium powder prepared by hydrogenation of hafnium is easy to spontaneous combustion and has potential safety hazards in production. The second method is a calcium (calcium hydride) reduction method, the process takes hafnium oxide and calcium (calcium hydride) as raw materials, the process can obtain hafnium powder with finer granularity, but the oxygen content of the hafnium powder is higher, if the process conditions are not well controlled, the reduction of the hafnium oxide is incomplete, and meanwhile, the calcium and the calcium hydride are dangerous goods, so that certain potential safety hazards exist. The third method is a fused salt electrolysis method, which uses potassium hafnium fluoride or hafnium tetrachloride as a hafnium source, and under the action of an electric field, metal hafnium powder is precipitated at a cathode by controlling process conditions. The process adopts an electric field to replace dangerous goods reducing agent, thereby ensuring the safety of production.
The molten salt electrolysis method is to melt salt at high temperature to form melt, and then to introduce direct current to make some ions in the melt to produce oxidation-reduction reaction on the electrode, so as to realize the aim of producing and refining metal or other matters. The existing process for preparing hafnium powder by fused salt electrolysis uses potassium hafnium fluoride or hafnium tetrachloride as a raw material of hafnium, and adds supporting electrolyte sodium chloride and potassium chloride to carry out high-temperature fused salt electrolysis, and metal hafnium is separated out at a cathode under the action of an electric field, and then the metal hafnium powder is obtained through water washing treatment.
However, in the direct electrolysis process, chlorine gas is separated out from the anode, and when the current density is too high or the concentration of hafnium ions is too low, an anode effect is generated, so that the electrolysis is interrupted. The chlorine is seriously corroded by the chlorine at high temperature, and the safety risk exists in the production process, so that the problem of chlorine precipitation of the anode is solved, the existing technology is to add hafnium sponge to the anode as anode material to avoid chlorine precipitation of the anode, and the hafnium sponge is used as a source of the hafnium, but the production cost of the hafnium sponge is higher.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method for preparing metal hafnium by metal hafnium and molten salt electrolysis, which aims to solve the problem that in the prior art, potassium hafnium fluoride or hafnium tetrachloride is used as a hafnium source to directly electrolyze an anode to separate out chlorine, or the problem that the cost of using hafnium sponge as an anode raw material is high.
The specific invention comprises the following steps:
the invention provides a method for preparing metal hafnium by molten salt electrolysis, which comprises the following steps:
Uniformly mixing a hafnium carbide raw material and a proper amount of adhesive, granulating to prepare a 3-5mm granular material, and performing vacuum sintering to obtain hafnium carbide granules;
Mixing alkali metal/alkaline earth metal chloride salt with a small amount of hafnium salt, premelting and cooling to obtain molten salt electrolyte;
adding the hafnium carbide particles into the bottom of a graphite crucible in an electrolytic furnace, adding the molten salt electrolyte into the graphite crucible, and carrying out electrolysis after sealing equipment;
after the electrolysis is finished, collecting sediment attached to a cathode, and extracting the metal hafnium from the sediment;
Wherein the alkali/alkaline earth metal chloride salt is selected from one or more of sodium chloride, potassium chloride, lithium chloride, calcium chloride, rubidium chloride, cesium chloride and calcium chloride;
the hafnium salt is selected from potassium hafnium fluoride and/or hafnium tetrachloride;
The oxygen content in the metal hafnium is 0.06-0.08%.
Alternatively, the alkali/alkaline earth metal chloride salt is selected from NaCl-KCl, naCl-CaCl 2, naCl-KCl-CsCl, naCl-KCl-RbCl, liCl-NaCl-KCl, liCl-KCl-CsCl or LiCl-KCl-RbCl.
Optionally, the temperature of the electrolysis is 750-850 ℃;
The cathode current density of the electrolysis is 0.1-5A/cm 2.
Optionally, the mass ratio of the hafnium carbide raw material to the adhesive is 4:1-7:1;
The adhesive is one or a combination of more selected from polyvinyl acetate, polyvinyl alcohol, polyacrylate, polyurethane and phenolic resin;
the pressure of the vacuum sintering treatment is 0.1 MPa-0.5 MPa, and the temperature is 1200-1500 ℃.
Optionally, the mass ratio of the hafnium salt to the alkali metal/alkaline earth metal chloride salt is 3:7-4:6.
Optionally, the mass ratio of the hafnium carbide particles to the molten salt electrolyte is 1:3-1:5.
Optionally, the grain size of the hafnium carbide raw material is +500 meshes to-300 meshes.
Optionally, the method further comprises, prior to mixing the alkali/alkaline earth metal chloride salt with the minor amount of hafnium salt:
vacuum dehydrating the alkali metal/alkaline earth metal chloride salt at the temperature of 500-600 ℃ and under the condition of 0.1-0.5 MPa;
Vacuum dehydrating the potassium hafnium fluoride under the conditions that the temperature is 350-500 ℃ and 0.1-0.5 MPa;
and carrying out vacuum dehydration on the hafnium tetrachloride under the conditions that the temperature is 200-300 ℃ and 0.1-0.5 MPa.
Optionally, the extracting the hafnium metal from the deposit includes:
crushing the cathode sediment into particles with the granularity of 1-3mm, putting the particles into deionized water with the temperature of 50-80 ℃ for stirring and cleaning, and filtering after the mixed molten salt electrolyte is completely dissolved in water to obtain crude hafnium powder;
Immersing the crude hafnium powder into dilute hydrochloric acid, stirring and cleaning, settling and filtering, then washing with deionized water for 3-5 times, and drying at low temperature to obtain the metal hafnium powder with low oxygen content.
Alternatively, the present invention provides a hafnium metal obtained by the method of the first aspect.
Compared with the prior art, the invention has the following advantages:
the invention provides a method for preparing metal hafnium by molten salt electrolysis, which comprises the steps of uniformly mixing a hafnium carbide raw material and a proper amount of adhesive, granulating to prepare a granular material with the thickness of 3-5mm, vacuum sintering to obtain hafnium carbide granules, adding a proper amount of hafnium salt into electrolyte, premelting and cooling to obtain molten salt electrolyte, adding the hafnium carbide granules into the bottom of a graphite crucible in an electrolytic furnace, adding the molten salt electrolyte into the graphite crucible, sealing the graphite crucible, carrying out electrolytic treatment, collecting sediment attached to a cathode after the electrolytic treatment is finished, and extracting metal hafnium powder with low oxygen content from the sediment, wherein the oxygen content in the metal hafnium powder is 0.06-0.08%.
In addition, the production cost of the hafnium carbide is relatively low, and the hafnium carbide is obtained by a carbon reduction method by taking the hafnium oxide as a raw material, so that the cost is greatly saved compared with the case of taking the hafnium sponge as the anode material.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 shows a flow chart of a method for preparing metal hafnium by molten salt electrolysis provided by an embodiment of the invention;
FIG. 2 shows hafnium metal obtained by molten salt electrolysis in an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. Any product that is the same as or similar to the present invention, which anyone in the light of the present invention or combines the present invention with other prior art features, falls within the scope of the present invention based on the embodiments of the present invention. And all other embodiments that may be made by those of ordinary skill in the art without undue burden and without departing from the scope of the invention.
Specific experimental steps or conditions are not noted in the examples and may be performed in accordance with the operation or conditions of conventional experimental steps described in the prior art in the field. The reagents used, as well as other instruments, are conventional reagent products available commercially, without the manufacturer's knowledge. Furthermore, the drawings are merely schematic illustrations of embodiments of the invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus a repetitive description thereof will be omitted. Some of the block diagrams shown in the figures are functional entities and do not necessarily correspond to physically or logically separate entities.
Techniques, methods and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the present description where appropriate.
In the description of the present invention, it should be understood that the terms "first," "second," and the like are used for defining the components, and are merely for convenience in distinguishing the corresponding components, and the terms are not meant to have any special meaning unless otherwise indicated, so that the scope of the present invention is not to be construed as being limited.
In addition, the technical features of the different embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
The direct electrolysis of electrolyte containing hafnium potassium fluoride or hafnium tetrachloride produces metallic hafnium, which results in the generation of chlorine gas at the anode, which deteriorates the production environment, and the generation of chlorine gas causes serious corrosion to equipment, and causes disproportionation reaction, which results in reduced current efficiency. Therefore, the invention provides a novel method for preparing the metal hafnium by using the hafnium carbide as an electrolytic anode material through molten salt electrolysis, and the method for preparing the metal hafnium powder is short in process, low in cost, environment-friendly and high in safety. The specific implementation content is as follows:
In a first aspect, the present invention provides a method for preparing metal hafnium by molten salt electrolysis, fig. 1 shows a flowchart of a method for preparing metal hafnium by molten salt electrolysis provided by an embodiment of the present invention, and as shown in fig. 1, the preparation method includes the following steps:
S1, uniformly mixing a hafnium carbide raw material and a proper amount of adhesive, granulating to prepare a 3-5mm granular material, and performing vacuum sintering treatment to obtain hafnium carbide granules.
In the specific implementation, before the hafnium carbide is used for preparing the metal hafnium by electrolysis, granulating the hafnium carbide by the step, namely, uniformly mixing the hafnium carbide with an adhesive, putting the mixture into a granulator to prepare particles with the granularity of 3-5mm, and forming the hafnium carbide particles with uniform and stable shape after the particles are subjected to vacuum sintering treatment. Wherein the pressure of the vacuum sintering treatment is 0.1 MPa-0.5 MPa, and the temperature is 1200-1500 ℃.
Compared with the method of directly electrolyzing hafnium carbide powder, the specific surface area of the granulated hafnium carbide particles is obviously increased, so that the contact area of the subsequent electrolytic reaction is increased, the reaction rate is promoted, the yield and the efficiency of metal hafnium are improved, the granulated hafnium carbide has better fluidity, is convenient to convey and fill, and can quickly sink into the bottom of an electrolyte anode after being added with molten salt electrolyte, thereby meeting the requirement of continuous electrolytic charging.
In some embodiments, the mass ratio of the hafnium carbide raw material to the binder used for granulation is controlled to be 4:1-7:1, and the binder is selected from one or more of polyvinyl acetate, polyvinyl alcohol, polyacrylate, polyurethane and phenolic resin.
S2, mixing alkali metal/alkaline earth metal chloride salt with a small amount of hafnium salt, premelting and cooling to obtain molten salt electrolyte;
In this step, a mixture of alkali/alkaline earth metal chloride salts and hafnium salts is used together to form an electrolyte system, and the presence of a small amount of hafnium salts in the electrolyte system helps to assist in balancing the hafnium ions during electrolysis. In addition, the addition of hafnium salt can reduce the melting point of the whole electrolyte system, so that molten salt can be fully melted at a lower temperature, and the energy consumption and the working temperature of equipment are reduced.
In the step, the alkali metal/alkaline earth metal chloride salt and the hafnium salt are subjected to premelting and cooling treatment, and the premelting enables the alkali metal/alkaline earth metal chloride salt to interact with the hafnium salt to form the composite molten salt electrolyte with specific structure and property, the ions in the composite molten salt electrolyte are uniformly distributed, the conductivity of the molten salt is improved, and the composite molten salt electrolyte has better conductivity and chemical stability.
In some embodiments, the alkali metal chloride salt may 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 hafnium salt is selected from potassium hafnium fluoride and/or hafnium tetrachloride. The mass ratio of the added hafnium salt to the alkali metal/alkaline earth metal chloride salt is 3:7-4:6. When the alkali metal/alkaline earth metal chloride salt is a combination of two or more of the above, the alkali metal/alkaline earth metal chloride salt is mixed in equimolar, and the alkali metal/alkaline earth metal chloride salt may be specifically NaCl-KCl, naCl-CaCl 2, naCl-KCl-CsCl, naCl-KCl-RbCl, liCl-NaCl-KCl, liCl-KCl-CsCl, liCl-KCl-RbCl.
In some embodiments, the alkali/alkaline earth metal chloride salt and the hafnium salt are subjected to a vacuum dehydration treatment to remove interfering impurities from the feedstock, respectively, prior to participation in the premelting. The vacuum dehydration treatment procedure for the alkali metal/alkaline earth metal chloride salt comprises the steps of vacuum dehydration of the alkali metal/alkaline earth metal chloride salt at the temperature of 500-600 ℃ and the pressure of 0.1-0.5 MPa, and vacuum dehydration treatment procedure for the hafnium salt comprises the steps of vacuum dehydration of potassium hafnium fluoride at the temperature of 350-500 ℃ and the pressure of 0.1-0.5 MPa, and vacuum dehydration of hafnium tetrachloride at the temperature of 200-300 ℃ and the pressure of 0.1-0.5 MPa.
S3, adding the hafnium carbide particles into the bottom of a graphite crucible in an electrolytic furnace, adding the molten salt electrolyte into the graphite crucible, sealing equipment, and then carrying out electrolytic treatment;
In the step, a graphite crucible is adopted to contain hafnium carbide particles, the hafnium carbide particles are flatly paved at the bottom of the graphite crucible, then molten salt electrolyte is put into the graphite crucible, and after equipment is sealed, the assembly of electrolytic equipment is completed. Hafnium carbide particles which are in direct contact with the bottom of the graphite crucible are used as a part of an anode, hafnium ions in the hafnium carbide enter an electrolysis system as one side losing electrons in the electrolysis process, and finally metal hafnium is separated out from a cathode to replace the original chlorine ions to lose electrons, so that chlorine is prevented from being generated.
The hafnium carbide granular material obtained through granulation is convenient to continuously feed in the electrolysis process, and added hafnium carbide granules can be submerged in the bottom after granulation, so that suspension loss caused by difficult sedimentation of powdery hafnium carbide materials is avoided, more raw materials are ensured to participate in electrolysis reaction, and the utilization rate of the materials is improved.
In some embodiments, the mass ratio of added hafnium carbide particles to molten salt electrolyte is 1:3-1:5, preferably 1:4, after the electrolysis equipment is sealed, a heating furnace is started to heat to a set temperature, heat is preserved, and electrolysis is started after the molten salt electrolyte is melted. The electrolysis temperature is set at 750-850 ℃, and the cathode current density of electrolysis is 0.1-5A/cm 2.
S4, after the electrolysis is completed, collecting sediment attached to the cathode, and extracting metal hafnium from the sediment.
In the specific implementation, after electrolysis for a certain time, the cathode electrode is lifted to a cooling chamber for cooling, and after the electrode is cooled to room temperature, sediment on the cathode is taken out, wherein the sediment on the cathode is mainly mixed molten salt electrolyte and metal hafnium powder. The operation of extracting metal hafnium powder from sediment comprises the steps of crushing cathode sediment into particles with the granularity of 1-3mm, putting the particles into deionized water with the temperature of 50-80 ℃ for stirring and cleaning, filtering to obtain hafnium powder after molten salt electrolyte mixed with the particles is completely dissolved in water, and immersing the hafnium powder into dilute hydrochloric acid with a certain concentration for stirring and cleaning. And washing 3-5 times by using deionized water after sedimentation and filtration, and drying at a low temperature to obtain the electrolytic metal hafnium powder.
In the embodiment of the invention, hafnium carbide is used as a raw material for preparing hafnium powder by electrolysis, and hafnium sponge prepared by a Kroll method (magnesium reduction hafnium tetrachloride) can be used as a raw material instead, so that the cost is reduced and the process flow is shortened. Because the hafnium sponge needs to be prepared into hafnium tetrachloride through the chlorination of hafnium oxide, then the hafnium tetrachloride is purified, then the metal magnesium is used for reducing the hafnium tetrachloride, and the magnesium is distilled and separated, the hafnium sponge can be obtained after the working procedures of long working procedure and high cost. Hafnium carbide can be obtained by taking hafnium oxide as a raw material and reducing the hafnium oxide by carbon, and the process is short and the cost is low. If no anode material is added, the electrolyte containing hafnium potassium fluoride or hafnium tetrachloride can be directly electrolyzed to prepare metal hafnium, but the anode will generate chlorine gas, so that the production environment is deteriorated, and meanwhile, the corrosion of equipment caused by the generation of the chlorine gas is serious, and the disproportionation reaction is initiated to reduce the current efficiency. Therefore, the method adopts hafnium carbide as a raw material for electrolysis, is a novel process method for preparing hafnium powder with low oxygen content, and has good application value.
Furthermore, according to the method for preparing the metal hafnium by molten salt electrolysis, the mode of adding the hafnium carbide particles at fixed time can be adopted according to the requirement, so that the continuous production of the metal hafnium can be realized, and the production efficiency is greatly improved.
In a second aspect, the present invention provides a hafnium metal obtained by the method according to the first aspect.
In order to make the present invention more clearly understood by those skilled in the art, a detailed description will now be made of a method for producing metallic hafnium by molten salt electrolysis and metallic hafnium according to the present invention by the following examples.
The following raw materials participating in electrolysis are pretreated in advance to remove moisture and volatile impurities:
Alkali metal chloride pretreatment, namely vacuum dehydration is carried out at the temperature of 500 ℃ and the pressure of 0.1 MPa;
Pretreatment of potassium hafnium fluoride, namely vacuum dehydration pretreatment is carried out under the condition of the temperature of 350 ℃ and the pressure of 0.1 MPa;
hafnium tetrachloride pretreatment, namely vacuum dehydration at the temperature of 200 ℃ and 0.1MPa, and dehydration pretreatment.
Example 1
Uniformly mixing hafnium carbide raw materials (+ 500 meshes to-300 meshes) with binder polyvinyl acetate in a mass ratio of 4:1, preparing into particles of 3-5mm by using a granulator, dehydrating under vacuum of 0.1: 0.1 MPa, and sintering at 1500 ℃ to obtain hafnium carbide particles;
Mixing and grinding sodium chloride and potassium chloride in an equal molar ratio for 30min, adding the mixture into a crucible, placing the crucible in a heating furnace, vacuumizing, filling argon, heating to 700 ℃ under the pressure of 0.1 MPa, preserving heat for 1h, and cooling to room temperature to obtain NaCl-KCl eutectic electrolyte;
Mixing sodium chloride and potassium chloride mixed salt with the mass ratio of 70% and hafnium potassium fluoride with the mass ratio of 30%, and pre-melting and cooling to obtain molten salt electrolyte NaCl-KCl-K 2HfF6 for later use;
Taking 20% by mass of hafnium carbide particles as anode materials, adding the anode materials into the bottom of a crucible in an electrolytic furnace, and adding 80% by mass of premelted and cooled molten salt electrolyte. After the electrolysis equipment is sealed, a heating furnace is started to heat to a set temperature, heat is preserved, and electrolysis is started after molten salt electrolyte is melted. The electrolysis temperature was set at 750℃and the electrolysis cathode current density was 1A/cm 2. After electrolysis for a certain time, the electrode is lifted to a cooling chamber for cooling, and after the electrode is cooled to room temperature, the cathode and sediment on the cathode are taken out together, wherein the sediment on the cathode is mainly mixed molten salt electrolyte and metal hafnium powder;
Pulverizing cathode sediment into particles with granularity of 1-3 mm, placing into deionized water with temperature of 50 ℃ for stirring and cleaning, filtering to obtain hafnium powder after the molten salt electrolyte mixed with the particles is completely dissolved in water, and immersing the hafnium powder into dilute hydrochloric acid with a certain concentration for stirring and cleaning. Washing 3-5 times with deionized water after sedimentation and filtration, and drying at low temperature to obtain electrolytic metal hafnium powder, wherein FIG. 2 shows metal hafnium prepared by molten salt electrolysis in the embodiment of the invention.
Table 1 shows the results of analysis of the chemical composition of the metal hafnium provided in the examples of the present invention, and as shown in Table 1, the oxygen content in the metal hafnium prepared by the molten salt electrolysis method provided in example 1 was as low as 0.072%.
TABLE 1 chemical composition analysis of hafnium metal
Example 2:
Uniformly mixing hafnium carbide raw materials (+ 500 meshes to-300 meshes) with adhesive polyvinyl alcohol in a mass ratio of 4:1, preparing particles with the granularity of 3-5mm by using a granulator, and dehydrating and sintering the particles into hafnium carbide particles under the vacuum of 0.5MPa to serve as raw materials of electrolytic hafnium powder.
Mixing and grinding sodium chloride and potassium chloride in an equal molar ratio for 30min, adding the mixture into a crucible, placing the crucible in a heating furnace, vacuumizing, filling argon, heating to 700 ℃ under the pressure of 0.1 MPa, preserving heat for 1h, and cooling to room temperature to obtain NaCl-KCl eutectic electrolyte;
mixing NaCl-KCl eutectic electrolyte with the mass ratio of 65% and hafnium tetrachloride with the mass ratio of 35%, and pre-melting and cooling to obtain NaCl-KCl-K 2HfCl6 molten salt electrolyte for standby.
Taking 20% by mass of hafnium carbide particles as anode materials, adding the anode materials into the bottom of a crucible in an electrolytic furnace, and adding 80% by mass of premelted and cooled NaCl-KCl-K 2HfCl6 molten salt electrolyte. After the electrolysis equipment is sealed, a heating furnace is started to heat to a set temperature, heat is preserved, and electrolysis is started after molten salt electrolyte is melted. The electrolysis temperature was set at 750℃and the electrolysis cathode current density was 2A/cm 2. And after electrolysis for a certain time, the electrode is lifted to a cooling chamber for cooling, and after the electrode is cooled to room temperature, the cathode and the sediment on the cathode are taken out together, wherein the sediment on the cathode is mainly the mixed molten salt electrolyte and metal hafnium powder.
Pulverizing cathode sediment into particles with the granularity of 1-3mm, putting into deionized water with the temperature of 80 ℃ for stirring and cleaning, filtering to obtain hafnium powder after the molten salt electrolyte mixed with the particles is completely dissolved in water, and immersing the hafnium powder into dilute hydrochloric acid with a certain concentration for stirring and cleaning. And washing 3-5 times by using deionized water after sedimentation and filtration, and drying at a low temperature to obtain the electrolytic metal hafnium powder.
Table 2 shows the results of analysis of the chemical composition of the metal hafnium provided in the examples of the present invention, and as shown in Table 2, the oxygen content in the metal hafnium prepared by the molten salt electrolysis method provided in example 2 was as low as 0.068%.
TABLE 2 chemical composition analysis of hafnium metal
Example 3
Uniformly mixing hafnium carbide raw materials (+ 500 meshes to-300 meshes) with adhesive polyacrylate in a mass ratio of 4:1, preparing particles with the granularity of 3-5 mm by using a granulator, and then dehydrating under vacuum of 0.1: 0.1 MPa and sintering at 1500 ℃ to obtain hafnium carbide particles;
Mixing and grinding sodium chloride and calcium chloride with equal molar ratio for 30min, adding the mixture into a crucible, placing the crucible in a heating furnace, vacuumizing, filling argon, heating to 700 ℃ under positive pressure of 0.1 MPa, preserving heat for 1 h, and cooling to room temperature to obtain NaCl-CaCl 2 eutectic electrolyte;
Mixing 60% of NaCl-CaCl 2 and 40% of potassium hafnium fluoride, premelting and cooling to obtain molten salt electrolyte NaCl-CaCl 2-K2HfF6 for later use;
Taking 20% by mass of hafnium carbide particles as anode materials, adding the anode materials into the bottom of a crucible in an electrolytic furnace, and adding 80% by mass of premelted and cooled molten salt electrolyte. After the electrolysis equipment is sealed, a heating furnace is started to heat to a set temperature, heat is preserved, and electrolysis is started after molten salt electrolyte is melted. The electrolysis temperature was set at 750℃and the electrolysis cathode current density was 3A/cm 2. After electrolysis for a certain time, the electrode is lifted to a cooling chamber for cooling, and after the electrode is cooled to room temperature, the cathode and sediment on the cathode are taken out together, wherein the sediment on the cathode is mainly mixed molten salt electrolyte and metal hafnium powder;
Pulverizing cathode sediment into particles with granularity of 1-3 mm, placing into deionized water with temperature of 50 ℃ for stirring and cleaning, filtering to obtain hafnium powder after the molten salt electrolyte mixed with the particles is completely dissolved in water, and immersing the hafnium powder into dilute hydrochloric acid with a certain concentration for stirring and cleaning. And washing 3-5 times by using deionized water after sedimentation and filtration, and drying at a low temperature to obtain the electrolytic metal hafnium powder.
Table 3 shows the results of analysis of the chemical composition of the metal hafnium provided in the examples of the present invention, and as shown in Table 3, the oxygen content in the metal hafnium prepared by the molten salt electrolysis method provided in example 3 was as low as 0.065%.
TABLE 3 chemical composition analysis of hafnium metal
Example 4
Uniformly mixing a hafnium carbide raw material (+ 500 meshes to-300 meshes) with an adhesive phenolic resin in a mass ratio of 6:1, preparing particles with the granularity of 3-5 mm by using a granulator, and then dehydrating under vacuum of 0.1: 0.1MPa and sintering at 1500 ℃ to obtain hafnium carbide particles;
adding NaCl-KCl-CsCl mixed grinding with equal molar ratio into a crucible after 30 min, placing the crucible into a heating furnace, vacuumizing, filling argon, heating to 700 ℃ under positive pressure of 0.1 MPa, preserving heat 1h, and cooling to room temperature to obtain NaCl-KCl-CsCl eutectic electrolyte;
mixing the NaCl-KCl-CsCl with the mass of 65% and HfCl 4 with the mass of 35%, pre-melting and cooling to obtain molten salt electrolyte NaCl-KCl-Cs 2HfCl6 composite electrolyte for later use;
Taking 20% by mass of hafnium carbide particles as anode materials, adding the anode materials into the bottom of a crucible in an electrolytic furnace, and adding 80% by mass of premelted and cooled molten salt electrolyte. After the electrolysis equipment is sealed, a heating furnace is started to heat to a set temperature, heat is preserved, and electrolysis is started after molten salt electrolyte is melted. The electrolysis temperature was set at 750℃and the electrolysis cathode current density was 1.5A/cm 2. After electrolysis for a certain time, the electrode is lifted to a cooling chamber for cooling, and after the electrode is cooled to room temperature, the cathode and sediment on the cathode are taken out together, wherein the sediment on the cathode is mainly mixed molten salt electrolyte and metal hafnium powder;
Pulverizing cathode sediment into particles with granularity of 1-3 mm, placing into deionized water with temperature of 50 ℃ for stirring and cleaning, filtering to obtain hafnium powder after the molten salt electrolyte mixed with the particles is completely dissolved in water, and immersing the hafnium powder into dilute hydrochloric acid with a certain concentration for stirring and cleaning. And washing 3-5 times by using deionized water after sedimentation and filtration, and drying at a low temperature to obtain the electrolytic metal hafnium powder.
Table 4 shows the results of analysis of the chemical composition of the metallic hafnium provided in the examples of the present invention, and as shown in Table 4, the oxygen content in the metallic hafnium prepared by the molten salt electrolysis method provided in example 4 was as low as 0.06%.
TABLE 4 chemical composition analysis of hafnium metal
Example 5
Uniformly mixing a hafnium carbide raw material (+ 500 meshes to-300 meshes) and adhesive polyurethane in a mass ratio of 5:1, preparing particles with the granularity of 3-5 mm by using a granulator, dehydrating under vacuum of 0.1: 0.1 MPa, and sintering at 1500 ℃ to obtain hafnium carbide particles;
Adding NaCl-KCl-RbCl mixed grinding with equal molar ratio into a crucible after 30 min, placing the crucible into a heating furnace, vacuumizing, filling argon, heating to 700 ℃ under positive pressure of 0.1 MPa, preserving heat for 1h, and cooling to room temperature to obtain NaCl-KCl-RbCl eutectic electrolyte;
Mixing NaCl-KCl-RbCl with the mass of 65% with HfCl 4 with the mass of 35%, pre-melting and cooling to obtain molten salt electrolyte NaCl-KCl-Rb 2HfCl6 composite electrolyte for later use;
Taking 20% by mass of hafnium carbide particles as anode materials, adding the anode materials into the bottom of a crucible in an electrolytic furnace, and adding 80% by mass of premelted and cooled molten salt electrolyte. After the electrolysis equipment is sealed, a heating furnace is started to heat to a set temperature, heat is preserved, and electrolysis is started after molten salt electrolyte is melted. The electrolysis temperature was set at 750℃and the electrolysis cathode current density was 2.5A/cm 2. After electrolysis for a certain time, the electrode is lifted to a cooling chamber for cooling, and after the electrode is cooled to room temperature, the cathode and sediment on the cathode are taken out together, wherein the sediment on the cathode is mainly mixed molten salt electrolyte and metal hafnium powder;
Pulverizing cathode sediment into particles with granularity of 1-3 mm, placing into deionized water with temperature of 50 ℃ for stirring and cleaning, filtering to obtain hafnium powder after the molten salt electrolyte mixed with the particles is completely dissolved in water, and immersing the hafnium powder into dilute hydrochloric acid with a certain concentration for stirring and cleaning. And washing 3-5 times by using deionized water after sedimentation and filtration, and drying at a low temperature to obtain the electrolytic metal hafnium powder.
Table 5 shows the results of analysis of the chemical composition of the metallic hafnium provided in the examples of the present invention, and as shown in Table 5, the oxygen content in the metallic hafnium prepared by the molten salt electrolysis method provided in example 5 was as low as 0.06%.
TABLE 5 chemical composition analysis of hafnium metal
Example 6
Uniformly mixing a hafnium carbide raw material (+ 500 meshes to-300 meshes) with an organic binder polyvinyl alcohol in a mass ratio of 7:1, preparing particles with a granularity of 3-5 mm by using a granulator, dehydrating under a vacuum of 0.1: 0.1 MPa, and sintering at 1500 ℃ to obtain hafnium carbide particles;
Mixing and grinding LiCl-KCl-CsCl with equal molar ratio for 30 min, adding the mixture into a crucible, placing the crucible in a heating furnace, vacuumizing, filling argon, heating to 700 ℃ under positive pressure of 0.1 MPa, preserving heat for 1 h, and cooling to room temperature to obtain NaCl-KCl-CsCl eutectic electrolyte;
Mixing 65% of LiCl-KCl-CsCl mass with 35% of HfCl 4, pre-melting and cooling to obtain molten salt electrolyte LiCl-KCl-Cs 2HfCl6 composite electrolyte for later use;
Taking 20% by mass of hafnium carbide particles as anode materials, adding the anode materials into the bottom of a crucible in an electrolytic furnace, and adding 80% by mass of premelted and cooled molten salt electrolyte. After the electrolysis equipment is sealed, a heating furnace is started to heat to a set temperature, heat is preserved, and electrolysis is started after molten salt electrolyte is melted. The electrolysis temperature was set at 750℃and the electrolysis cathode current density was 3.5A/cm 2. After electrolysis for a certain time, the electrode is lifted to a cooling chamber for cooling, and after the electrode is cooled to room temperature, the cathode and sediment on the cathode are taken out together, wherein the sediment on the cathode is mainly mixed molten salt electrolyte and metal hafnium powder;
Pulverizing cathode sediment into particles with granularity of 1-3 mm, placing into deionized water with temperature of 50 ℃ for stirring and cleaning, filtering to obtain hafnium powder after the molten salt electrolyte mixed with the particles is completely dissolved in water, and immersing the hafnium powder into dilute hydrochloric acid with a certain concentration for stirring and cleaning. And washing 3-5 times by using deionized water after sedimentation and filtration, and drying at a low temperature to obtain the electrolytic metal hafnium powder.
Table 6 shows the results of analysis of the chemical composition of the metallic hafnium provided by the example of the present invention, and as shown in Table 6, the oxygen content in the metallic hafnium prepared by the molten salt electrolysis method provided by example 6 is as low as 0.061%.
TABLE 6 chemical composition analysis of hafnium metal
Example 7
Uniformly mixing a hafnium carbide raw material (+ 500 meshes to-300 meshes) with an organic binder polyvinyl alcohol in a mass ratio of 4:1, preparing particles with a granularity of 3-5 mm by using a granulator, dehydrating under a vacuum of 0.1 MPa, and sintering at 1500 ℃ to obtain hafnium carbide particles;
mixing and grinding LiCl-KCl-RbCl with equal molar ratio for 30 min, adding the mixture into a crucible, placing the crucible in a heating furnace, vacuumizing, filling argon, heating to 700 ℃ under positive pressure of 0.1 MPa, preserving heat for 1 h, and cooling to room temperature to obtain LiCl-KCl-RbCl eutectic electrolyte;
Mixing 65% of LiCl-KCl-RbCl and 35% of HfCl 4, and pre-melting and cooling to obtain a molten salt electrolyte LiCl-KCl-Rb 2HfCl6 composite electrolyte for later use;
taking 20% by mass of hafnium carbide particles as anode materials, adding the anode materials into the bottom of a crucible in an electrolytic furnace, and adding 80% by mass of premelted and cooled molten salt electrolyte. After the electrolysis equipment is sealed, a heating furnace is started to heat to a set temperature, heat is preserved, and electrolysis is started after molten salt electrolyte is melted. The electrolysis temperature was set at 750℃and the electrolysis cathode current density was 4A/cm 2. After electrolysis for a certain time, the electrode is lifted to a cooling chamber for cooling, and after the electrode is cooled to room temperature, the cathode and sediment on the cathode are taken out together, wherein the sediment on the cathode is mainly mixed molten salt electrolyte and metal hafnium powder;
Pulverizing cathode sediment into particles with granularity of 1-3 mm, placing into deionized water with temperature of 50 ℃ for stirring and cleaning, filtering to obtain hafnium powder after the molten salt electrolyte mixed with the particles is completely dissolved in water, and immersing the hafnium powder into dilute hydrochloric acid with a certain concentration for stirring and cleaning. And washing 3-5 times by using deionized water after sedimentation and filtration, and drying at a low temperature to obtain the electrolytic metal hafnium powder.
Table 7 shows the results of analysis of the chemical composition of the metallic hafnium provided in the examples of the present invention, and as shown in Table 7, the oxygen content in the metallic hafnium prepared by the molten salt electrolysis method provided in example 7 was as low as 0.062%.
TABLE 7 chemical composition analysis of hafnium metal
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, one skilled in the art can combine and combine the different embodiments or examples described in this specification.
For the purposes of simplicity of explanation, the methodologies are shown as a series of acts, but one of ordinary skill in the art will recognize that the present invention is not limited by the order of acts described, as some acts may, in accordance with the present invention, occur in other orders and concurrently. Further, those skilled in the art will recognize that the embodiments described in the specification are all of the preferred embodiments, and that the acts and components referred to are not necessarily required by the present invention.
The foregoing describes the metal hafnium and the method for preparing the metal hafnium by molten salt electrolysis, and specific examples are provided herein to illustrate the principles and embodiments of the present invention, but the above examples are only for aiding in understanding of the method and core ideas of the present invention, and meanwhile, the present disclosure should not be construed as limiting the invention to any extent in terms of the specific embodiments and applications, as will be apparent to those skilled in the art in light of the present invention.
Claims (10)
1. A method for preparing metal hafnium by molten salt electrolysis, which is characterized by comprising the following steps:
uniformly mixing a hafnium carbide raw material and a proper amount of adhesive, granulating to prepare a 3-5mm granular material, and performing vacuum sintering treatment to obtain hafnium carbide particles;
Mixing alkali metal/alkaline earth metal chloride salt with a small amount of hafnium salt, premelting and cooling to obtain molten salt electrolyte;
adding the hafnium carbide particles into the bottom of a graphite crucible in an electrolytic furnace, adding the molten salt electrolyte into the graphite crucible, and carrying out electrolysis after sealing equipment;
after the electrolysis is finished, collecting sediment attached to a cathode, and extracting the metal hafnium from the sediment;
Wherein the alkali/alkaline earth metal chloride salt is selected from one or more of sodium chloride, potassium chloride, lithium chloride, calcium chloride, rubidium chloride, cesium chloride and calcium chloride;
the hafnium salt is selected from potassium hafnium fluoride and/or hafnium tetrachloride.
2. The method for producing metallic hafnium by molten salt electrolysis according to claim 1, wherein the alkali/alkaline earth metal chloride salt is selected from the group consisting of NaCl-KCl, naCl-CaCl 2, naCl-KCl-CsCl, naCl-KCl-RbCl, liCl-NaCl-KCl, liCl-KCl-CsCl and LiCl-KCl-RbCl.
3. The method for preparing metal hafnium by molten salt electrolysis according to claim 1, wherein the temperature of the electrolysis is 750-850 ℃;
The cathode current density of the electrolysis is 0.1-5A/cm 2.
4. The method for preparing metal hafnium by molten salt electrolysis according to claim 1, wherein the mass ratio of the hafnium carbide raw material to the binder is 4:1-7:1;
The adhesive is one or a combination of more selected from polyvinyl acetate, polyvinyl alcohol, polyacrylate, polyurethane and phenolic resin;
The pressure of the vacuum sintering treatment is 0.1 MPa-0.5 MPa, and the temperature is 1200-1500 ℃.
5. The method for preparing metal hafnium by molten salt electrolysis according to claim 1, wherein the mass ratio of the hafnium salt to the alkali metal/alkaline earth metal chloride salt is 3:7-4:6.
6. The method for preparing metal hafnium by molten salt electrolysis according to claim 1, wherein the mass ratio of the hafnium carbide particles to the molten salt electrolyte is 1:3 to 1:5.
7. The method for preparing metal hafnium by molten salt electrolysis according to claim 1, wherein the grain size of the hafnium carbide raw material is +500 mesh to-300 mesh.
8. The method for producing metallic hafnium by molten salt electrolysis according to claim 1, wherein said method further comprises, before mixing the alkali/alkaline earth metal chloride salt with a small amount of hafnium salt:
vacuum dehydrating the alkali metal/alkaline earth metal chloride salt at the temperature of 500-600 ℃ and under the condition of 0.1-0.5 MPa;
Vacuum dehydrating the potassium hafnium fluoride under the conditions that the temperature is 350-500 ℃ and 0.1-0.5 MPa;
and carrying out vacuum dehydration on the hafnium tetrachloride under the conditions that the temperature is 200-300 ℃ and 0.1-0.5 MPa.
9. The method for producing metallic hafnium by molten salt electrolysis according to claim 1, wherein said extracting said metallic hafnium from said deposit comprises:
crushing the cathode sediment into particles with the granularity of 1-3mm, putting the particles into deionized water with the temperature of 50-80 ℃ for stirring and cleaning, and filtering after the mixed molten salt electrolyte is completely dissolved in water to obtain crude hafnium powder;
Immersing the crude hafnium powder into dilute hydrochloric acid, stirring and cleaning, settling and filtering, then washing with deionized water for 3-5 times, and drying at low temperature to obtain the metal hafnium powder with low oxygen content.
10. A metal hafnium, characterized in that it is obtained by a method for preparing metal hafnium by molten salt electrolysis according to any one of the preceding claims 1-9.
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| CN102225762A (en) * | 2011-05-25 | 2011-10-26 | 山东理工大学 | Preparation method of hafnium carbide powder |
| CN115305514A (en) * | 2021-05-08 | 2022-11-08 | 中南大学 | A kind of method for electrolytic refining of hafnium by molten salt |
| CN116265617A (en) * | 2021-12-17 | 2023-06-20 | 郑州大学 | A kind of method that molten salt electrolysis prepares metal hafnium |
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| CN102225762A (en) * | 2011-05-25 | 2011-10-26 | 山东理工大学 | Preparation method of hafnium carbide powder |
| CN115305514A (en) * | 2021-05-08 | 2022-11-08 | 中南大学 | A kind of method for electrolytic refining of hafnium by molten salt |
| CN116265617A (en) * | 2021-12-17 | 2023-06-20 | 郑州大学 | A kind of method that molten salt electrolysis prepares metal hafnium |
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