A method for preparing low-oxygen high-purity metal hafnium

Abstract

The present invention relates to the technical field of rare metals, and proposes a method for preparing low-oxygen high-purity metal hafnium, comprising the following steps: S1, mixing hafnium oxide, a deoxidizer and a flux, and performing a thermal reduction reaction in an inert gas atmosphere to obtain a solid mixture; S2, acid-washing, washing and drying the solid mixture to obtain metal hafnium powder; S3, heating and melting the metal hafnium powder in an inert gas atmosphere, and cold-pressing to obtain low-oxygen high-purity metal hafnium; the deoxidizer comprises the following components in parts by weight: 60-70 parts of Ca, 5-15 parts of Y, and 10-30 parts of Ba. Through the above technical scheme, the problem of high oxygen content in metal hafnium in the related art is solved.

Description

Technical Field

[0001] The invention relates to the technical field of rare metals, and in particular to a method for preparing low-oxygen high-purity metal hafnium. Background Art

[0002] Hafnium is a rare metal with an abundance of about 4.5ppm in the earth's crust, slightly higher than uranium, boron, tantalum and bromine. Most of the hafnium is dispersed in zirconium minerals and almost never forms independent minerals. Minerals that do not contain zirconium also do not contain hafnium. The content of hafnium in minerals is generally less than that of zirconium, while zirconium minerals are mainly zirconium silicates and oxides. Hafnium is a silvery white metal with plasticity, easy processing, high temperature resistance, and inactive chemical properties at room temperature. At high temperatures, it can react with hydrogen, halogens, oxygen, sulfur, nitrogen, carbon and other simple substances. It has strong corrosion resistance and is difficult to react with various acids. It is only easily soluble in aqua regia and hydrofluoric acid. The chemical properties of hafnium are very similar to those of zirconium. This similarity is the result of lanthanide contraction. Hafnium has a large thermal neutron capture cross section, good mechanical properties, resistance to hot water and steam corrosion, and radiation resistance. It is an ideal material for nuclear reactor control rods. Hafnium is mainly used as an alloy additive in the metallurgical industry to improve the strength and ductility of the alloy. However, oxygen impurities are easily introduced during the extraction of hafnium, resulting in a high oxygen content in hafnium, which makes metallic hafnium difficult to forge. Therefore, developing a method for preparing low-oxygen and high-purity metallic hafnium is of great significance to the application of metallic hafnium. Summary of the invention

[0003] The invention provides a method for preparing low-oxygen high-purity metal hafnium, which solves the problem of high oxygen content in the metal hafnium in the related art.

[0004] The technical solution of the present invention is as follows:

[0005] The present invention provides a method for preparing low-oxygen high-purity metal hafnium, comprising the following steps:

[0006] S1, mixing hafnium oxide, a deoxidizer and a flux, and performing a thermal reduction reaction under an inert gas atmosphere to obtain a solid mixture;

[0007] S2, pickling, washing and drying the solid mixture to obtain metal hafnium powder;

[0008] S3, heating and melting the metal hafnium powder in an inert gas atmosphere, and cold pressing to obtain low-oxygen high-purity metal hafnium;

[0009] The deoxidizer comprises the following components in parts by weight: 60-70 parts of Ca, 5-15 parts of Y, and 10-30 parts of Ba.

[0010] As a further technical solution, the purity of the hafnium oxide is 97wt%~98wt%.

[0011] As a further technical solution, the mass ratio of Y to Ba in the deoxidizer is 1:2~4.

[0012] In the present invention, the oxygen content of the metal hafnium is further reduced by limiting the mass ratio of Y to Ba in the deoxidizer to 1:2-4.

[0013] As a further technical solution, the mass ratio of Y to Ba in the deoxidizer is 1:3.

[0014] As a further technical solution, the flux includes one or more of potassium chloride, calcium chloride, strontium chloride, sodium chloride, and magnesium chloride.

[0015] As a further technical solution, when the flux is strontium chloride, calcium chloride and sodium chloride, the mass ratio of strontium chloride, calcium chloride and sodium chloride is 0.1~0.5:2:1.

[0016] In the present invention, the flux is composed of strontium chloride, calcium chloride and sodium chloride, and the mass ratio of strontium chloride, calcium chloride and sodium chloride is limited to 0.1-0.5:2:1, so as to further reduce the oxygen content in the metal hafnium.

[0017] As a further technical solution, the mass ratio of the deoxidizer to hafnium oxide is 5-8:1.

[0018] As a further technical solution, the mass ratio of the flux to hafnium oxide is 5-10:1.

[0019] As a further technical solution, in step S1 and step S3, the inert gas is independently argon or helium.

[0020] As a further technical solution, the temperature of the thermal reduction reaction is 1000-1500° C. and the time is 2-5 hours.

[0021] As a further technical solution, the pickling solvent is one or both of hydrochloric acid and sulfuric acid.

[0022] As a further technical solution, the concentration of the pickling solvent is 2-5 mol / L.

[0023] As a further technical solution, the washing solvent includes one or both of water and ethanol.

[0024] As a further technical solution, when the washing solvents are water and ethanol, the washing order is first washing with water and then washing with ethanol.

[0025] The working principle and beneficial effects of the present invention are:

[0026] In the present invention, hafnium oxide is used as a raw material, a deoxidizer including components of Ca, Y and Ba is added, and metal hafnium with a purity of more than 99wt% and an oxygen content of less than 700ppm is prepared under the action of a flux, thereby solving the problem of high oxygen content when preparing metal hafnium. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] In the following embodiments and comparative examples:

[0029] Hafnium oxide, purity: 97.5wt%, zirconium oxide content is 1.8wt%.

[0030] Example 1

[0031] A method for preparing low-oxygen high-purity metal hafnium comprises the following steps:

[0032] S1. After mixing 10 g of hafnium oxide, 50 g of a deoxidizer and 50 g of a flux, the mixture was heated to 1000° C. in an argon atmosphere for a thermal reduction reaction for 5 h to obtain a solid mixture.

[0033] S2, washing the solid mixture with 2 mol / L hydrochloric acid, then washing with deionized water and ethanol, and then drying to obtain metal hafnium powder;

[0034] S3, heating and melting the metal hafnium powder in an argon atmosphere, and cold pressing to obtain metal hafnium with a purity of 99.82 wt % and an oxygen content of 700 ppm;

[0035] The deoxidizer is obtained by mixing 65 parts of Ca, 15 parts of Y, and 15 parts of Ba;

[0036] The flux is obtained by mixing strontium chloride, calcium chloride and sodium chloride in a mass ratio of 1:2:1.

[0037] Example 2

[0038] S1. After mixing 10 g of hafnium oxide, 70 g of a deoxidizer and 80 g of a flux, heat to 1200° C. in an argon atmosphere for a thermal reduction reaction for 4 h.

[0039] S2, washing the solid mixture with 4 mol / L hydrochloric acid, then washing with deionized water and ethanol, and then drying to obtain metal hafnium powder;

[0040] S3, heating and melting the metal hafnium powder in an argon atmosphere, and cold pressing to obtain metal hafnium with a purity of 99.56 wt % and an oxygen content of 498 ppm;

[0041] The deoxidizer is obtained by mixing 60 parts of Ca, 10 parts of Y, and 10 parts of Ba;

[0042] The flux is obtained by mixing strontium chloride, calcium chloride and sodium chloride in a mass ratio of 1:2:1.

[0043] Example 3

[0044] S1. After mixing 10 g of hafnium oxide, 80 g of a deoxidizer and 100 g of a flux, heat to 1500° C. in a helium atmosphere for a thermal reduction reaction for 2 h.

[0045] S2, washing the solid mixture with 5 mol / L sulfuric acid, then washing with deionized water and ethanol, and then drying to obtain metal hafnium powder;

[0046] S3, heating and melting the metal hafnium powder in a helium atmosphere, and cold pressing to obtain metal hafnium with a purity of 99.31 wt % and an oxygen content of 412 ppm;

[0047] The deoxidizer is obtained by mixing 70 parts of Ca, 5 parts of Y, and 30 parts of Ba;

[0048] The flux is obtained by mixing strontium chloride, calcium chloride and sodium chloride in a mass ratio of 1:2:1.

[0049] Example 4

[0050] The difference between this embodiment and embodiment 1 is that the addition amount of Y is 5 parts and the addition amount of Ba is 25 parts.

[0051] Results: The purity of the hafnium metal was 99.84 wt % and the oxygen content was 622 ppm.

[0052] Example 5

[0053] The difference between this embodiment and embodiment 1 is that the addition amount of Y is 10 parts and the addition amount of Ba is 20 parts.

[0054] Results: The purity of the hafnium metal was 99.85 wt % and the oxygen content was 457 ppm.

[0055] Example 6

[0056] The difference between this embodiment and embodiment 1 is that the addition amount of Y is 7.5 parts and the addition amount of Ba is 22.5 parts.

[0057] Results: The purity of the hafnium metal was 99.86 wt % and the oxygen content was 249 ppm.

[0058] Example 7

[0059] The difference between this embodiment and embodiment 1 is that the addition amount of Y is 6 parts and the addition amount of Ba is 24 parts.

[0060] Results: The purity of the hafnium metal was 99.86 wt % and the oxygen content was 352 ppm.

[0061] Example 8

[0062] The only difference between this embodiment and embodiment 6 is that the flux is obtained by mixing strontium chloride, calcium chloride and sodium chloride in a mass ratio of 0.05:2:1.

[0063] Results: The purity of the hafnium metal was 99.72 wt % and the oxygen content was 194 ppm.

[0064] Example 9

[0065] The only difference between this embodiment and embodiment 6 is that the flux is obtained by mixing strontium chloride, calcium chloride and sodium chloride in a mass ratio of 0.1:2:1.

[0066] Results: The purity of the hafnium metal was 99.73 wt % and the oxygen content was 141 ppm.

[0067] Example 10

[0068] The only difference between this embodiment and embodiment 6 is that the flux is obtained by mixing strontium chloride, calcium chloride and sodium chloride in a mass ratio of 0.3:2:1.

[0069] Results: The purity of the hafnium metal was 99.73 wt % and the oxygen content was 105 ppm.

[0070] Embodiment 11

[0071] The only difference between this embodiment and embodiment 6 is that the flux is obtained by mixing strontium chloride, calcium chloride and sodium chloride in a mass ratio of 0.5:2:1.

[0072] Results: The purity of the hafnium metal was 99.74 wt % and the oxygen content was 102 ppm.

[0073] Comparative Example 1

[0074] The only difference between this comparative example and Example 1 is that Y is replaced by an equal amount of Ba.

[0075] Results: The purity of the hafnium metal was 98.87 wt % and the oxygen content was 1036 ppm.

[0076] Comparative Example 2

[0077] The only difference between this comparative example and Example 1 is that Ba is replaced by an equal amount of Y.

[0078] Results: The purity of the hafnium metal was 98.65 wt % and the oxygen content was 1210 ppm.

[0079] Comparative Example 3

[0080] The only difference between this comparative example and Example 1 is that it does not contain Y and Ba.

[0081] Results: The purity of the hafnium metal was 98.59 wt % and the oxygen content was 2048 ppm.

[0082] Compared with Example 1, the deoxidizer in Comparative Example 1 consists of Ca and Ba, the deoxidizer in Comparative Example 2 consists of Ca and Y, and the deoxidizer in Comparative Example 3 contains only Ca. As a result, the oxygen content of the metal hafnium prepared in Comparative Examples 1 to 3 is higher than that in Example 1, indicating that when the deoxidizer includes Ca, Y, and Ba, the oxygen content of the metal hafnium can be reduced.

[0083] Compared with Example 1, the mass ratio of Y and Ba was changed in Examples 4 to 7. As a result, the metal hafnium oxygen content obtained in Examples 5 to 7 was lower than that in Examples 1 and 4, indicating that when the mass ratio of Y and Ba in the deoxidizer was 1:2 to 4, the metal hafnium oxygen content could be further reduced. By comparing Examples 5 to 7, it was found that the metal hafnium oxygen content obtained in Example 6 was lower than that in Examples 5 and 7, indicating that when the mass ratio of Y and Ba in the deoxidizer was 1:3, the metal hafnium oxygen content obtained was the lowest.

[0084] Compared with Example 6, the mass ratio of strontium chloride, calcium chloride and sodium chloride in the flux was changed in Examples 8 to 11. As a result, the oxygen content of the metal hafnium obtained in Examples 9 to 11 was lower than that in Examples 6 and 8, indicating that when the mass ratio of strontium chloride, calcium chloride and sodium chloride in the flux is 0.1 to 0.5:2:1, the oxygen content of the metal hafnium can be further reduced.

[0085] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing low-oxygen high-purity metal hafnium, characterized in that: The following steps are involved: S1, mixing hafnium oxide, a deoxidizer and a flux, and performing a thermal reduction reaction under an inert gas atmosphere to obtain a solid mixture; S2, pickling, washing and drying the solid mixture to obtain metal hafnium powder; S3, heating and melting the metal hafnium powder in an inert gas atmosphere, and cold pressing to obtain low-oxygen high-purity metal hafnium; The deoxidizer comprises the following components in parts by weight: 60-70 parts of Ca, 5-15 parts of Y, and 10-30 parts of Ba; The flux includes one or more of potassium chloride, calcium chloride, strontium chloride, sodium chloride and magnesium chloride.

2. The method for preparing low-oxygen high-purity metal hafnium according to claim 1, characterized in that: The mass ratio of Y to Ba in the deoxidizer is 1:2-4.

3. The method for preparing low-oxygen high-purity metal hafnium according to claim 1, characterized in that: When the flux is strontium chloride, calcium chloride and sodium chloride, the mass ratio of strontium chloride, calcium chloride and sodium chloride is 0.1-0.5:2:

1.

4. The method for preparing low-oxygen high-purity metal hafnium according to claim 1, characterized in that: The mass ratio of the deoxidizer to hafnium oxide is 5-8:

1.

5. The method for preparing low-oxygen high-purity metal hafnium according to claim 1, characterized in that: The mass ratio of the flux to hafnium oxide is 5-10:

1.

6. The method for preparing low-oxygen high-purity metal hafnium according to claim 1, characterized in that: In step S1 and step S3, the inert gas is independently argon or helium.

7. The method for preparing low-oxygen high-purity metal hafnium according to claim 1, characterized in that: The temperature of the thermal reduction reaction is 1000-1500° C. and the time is 2-5 hours.

8. The method for preparing low-oxygen high-purity metal hafnium according to claim 1, characterized in that: The pickling solvent is one or both of hydrochloric acid and sulfuric acid.

9. The method for preparing low-oxygen high-purity metal hafnium according to claim 1, characterized in that: The washing solvent includes one or both of water and ethanol.