A method for refining beryllium by molten salt electrolysis

Abstract

The present invention relates to a method for molten salt electrolytic refining of beryllium, comprising first constructing an electrochemical system in which an anode chamber contains an anode molten salt electrolyte and a crude beryllium anode is inserted, and a cathode chamber contains a cathode molten salt electrolyte and a cathode is inserted. The anode molten salt electrolyte and the cathode molten salt electrolyte are not in contact with each other but are connected by a liquid alloy at the bottom of the electrolytic cell. By applying power to the electrolysis chamber, refined solid beryllium can be obtained at the cathode. The method of the present invention can effectively remove impurities from the crude beryllium, and the resulting metallic beryllium is of high purity. The preparation process does not require vacuuming or operation in an oxygen-free environment, and the reaction conditions are easy to achieve, thus providing a highly efficient method for refining beryllium.

Description

Technical Field

[0001] The invention belongs to the field of beryllium metallurgy, and in particular relates to a method for refining beryllium by molten salt electrolysis. Background Art

[0002] Beryllium is a widely used metal. Of all metals, it possesses the strongest X-ray penetration, earning it the nickname "metallic glass." It is an irreplaceable material for X-ray tube windows. Beryllium has a strong moderating effect on fast neutrons, enabling fission reactions to proceed continuously, making it an excellent neutron moderator in nuclear reactors. Beryllium dissolved in copper creates a beryllium-copper alloy, which can be used in conductive elastic elements and elastic-sensitive components.

[0003] Currently, beryllium is primarily produced through the beryllium fluoride magnesium thermal reduction method. The resulting metallic beryllium beads contain 96-97% beryllium, requiring further refining to obtain high-purity metallic beryllium. Industrially, beryllium is primarily refined through vacuum volatilization. However, the small amount of oxygen contained within the industrial volatilization furnace reacts with the exposed metallic beryllium to form beryllium oxide, which coats the surface of the metallic beryllium, making it difficult to volatilize impurities such as magnesium. Patent CN 109182786A discloses a method for producing high-purity metallic beryllium by oxygen-free impurity volatilization. This method follows the same principle as the industrial vacuum volatilization method for impurity removal, differing in that it purifies crude beryllium in an oxygen-free environment. However, this oxygen-free environment is difficult to achieve in practice, and therefore, this method is subject to the same drawbacks. Patent CN 109097602 A discloses a method for refining beryllium by thermal dissociation of beryllium iodide. This method first reacts crude beryllium powder with iodine at low temperature to produce beryllium iodide, and then decomposes the beryllium iodide at high temperature to produce high-purity beryllium powder. This method uses a thermal dissociation reactor to purify the crude beryllium powder, which is simple to operate. However, the reaction rate between iodine and beryllium is very slow, making it difficult to obtain beryllium iodide. Furthermore, this method requires vacuum and harsh reaction conditions. Patents US3278402 A and US3296107 A disclose a method for refining beryllium. This method first removes impurities less reactive than beryllium in a chloride molten salt through pre-electrolysis, and then produces metallic beryllium through electrolysis. This method can obtain high-purity beryllium, but beryllium precipitates during the pre-electrolysis process, resulting in partial beryllium loss. Furthermore, the electrolysis process produces chlorine gas. Summary of the Invention

[0004] The object of the present invention is to provide a method for efficiently refining beryllium by electrolysis based on the difference in metal redox potentials and by connecting an anode chamber and a cathode chamber using a liquid alloy. The method does not require vacuuming or operation in an oxygen-free environment, and the reaction conditions are easy to achieve without beryllium loss.

[0005] In order to achieve the above-mentioned purpose of the present invention, the present invention adopts the following technical solutions:

[0006] A method for refining beryllium by molten salt electrolysis comprises the following steps:

[0007] (1) Constructing an electrochemical system: the electrolytic cell is divided into an anode chamber and a cathode chamber, wherein the anode chamber contains an anode molten salt electrolyte and a coarse beryllium anode, and the cathode chamber contains a cathode molten salt electrolyte and a cathode, and the bottom of the electrolytic cell also contains a liquid alloy; the anode molten salt electrolyte and the cathode molten salt electrolyte do not contact each other but are connected by the liquid alloy at the bottom of the electrolytic cell;

[0008] (2) When power is applied for electrolysis, the metallic beryllium in the anode is oxidized into beryllium ions and enters the anode molten salt electrolyte. It is reduced to metallic beryllium at the interface between the anode molten salt electrolyte and the liquid alloy and dissolves into the liquid alloy. At the same time, the beryllium in the liquid alloy is oxidized into beryllium ions at the interface between the liquid alloy and the cathode molten salt electrolyte and enters the cathode molten salt electrolyte, and is reduced to metallic beryllium on the cathode surface.

[0009] Preferably, the cathode is a nickel, tungsten or molybdenum cathode.

[0010] Preferably, the liquid alloy is an alloy of one or more of copper, silver, gold, manganese and beryllium. Further preferably, the liquid alloy is an alloy of beryllium and copper in an atomic ratio of 28:72.

[0011] Preferably, the anode molten salt electrolyte and the cathode molten salt electrolyte are the same or different, and are both halide molten salts containing beryllium ions, preferably a mixture of one or more of lithium fluoride, sodium fluoride, potassium fluoride, magnesium fluoride, calcium fluoride and beryllium fluoride.

[0012] Preferably, under power-on conditions, the density of the anode molten salt electrolyte and the cathode molten salt electrolyte are both less than the density of the liquid alloy.

[0013] Preferably, the purity of the crude beryllium is not less than 90%.

[0014] Preferably, the anode current density is 0.1-1.5 A / cm 2 The electrolysis temperature is 600-1100 ° C. If the temperature is too low, the molten salt and alloy are difficult to melt, and if the temperature is too high, the molten salt will volatilize in large quantities.

[0015] The beneficial effects of the present invention are:

[0016] (1) The method for molten salt electrolysis refining of beryllium described in the present invention connects two electrolytic chambers through a liquid alloy. When the ions in the anode molten salt electrolyte are reduced to corresponding metals and enter the liquid alloy, the metals more active than beryllium enter the liquid alloy after the beryllium. Although the metals more inert than beryllium enter the liquid alloy before the beryllium, when the metals in the liquid alloy are oxidized to corresponding ions and enter the molten salt in the cathode chamber, the metals more inert than beryllium are oxidized after the beryllium. Therefore, the present invention can effectively remove impurities in crude beryllium.

[0017] (2) In the method for molten salt electrolysis refining of beryllium described in the present invention, the molten salt containing beryllium halide can isolate the air, preventing the generated metallic beryllium from coming into contact with the air. The reaction does not need to be carried out in an oxygen-free environment. At the same time, the present invention removes impurities based on the electrochemical differences of different ions, and the reaction does not require vacuuming.

[0018] (3) The method for molten salt electrolytic refining of beryllium described in the present invention does not require pre-electrolysis, and there will be no beryllium loss during the reaction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A diagram of an electrolysis device for the method of molten salt electrolysis refining beryllium according to the present invention;

[0020] Among them, 1-anode; 2-anode molten salt electrolyte; 3-liquid alloy; 4-cathode; 5-cathode molten salt electrolyte; 6-anode chamber; 7-cathode chamber. DETAILED DESCRIPTION

[0021] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise specified, the proportions referred to in the embodiments are all mass percentages.

[0022] Example 1

[0023] This embodiment provides a method for molten salt electrolytic refining of beryllium, comprising the following steps:

[0024] (1) Figure 1 As shown, a beryllium-containing alloy (21 at.% beryllium, 79 at.% gold) is added to the bottom of the electrolytic cell to ensure that the electrolytic device can be divided into an anode chamber and a cathode chamber after melting. A mixture of 30% lithium fluoride, 68% potassium fluoride, and 2% beryllium fluoride is added to the anode chamber and the cathode chamber as the anode molten salt electrolyte and the cathode molten salt electrolyte. The electrolytic cell is heated to 600° C., and an anode made of crude beryllium with a purity of 90% and a nickel cathode are immersed in the anode molten salt electrolyte and the cathode molten salt electrolyte, respectively.

[0025] (2) Power on for electrolysis, controlling the anode current density to 0.1 A / cm 2 , electrolysis for 24 hours, solid metallic beryllium is obtained at the cathode, and its purity is 99.90% after analysis.

[0026] Example 2

[0027] This embodiment provides a method for molten salt electrolytic refining of beryllium, comprising the following steps:

[0028] (1) Figure 1 As shown, a beryllium-containing alloy (28 at.% beryllium, 72 at.% copper) is added to the bottom of the electrolytic cell to ensure that the electrolytic device can be divided into an anode chamber and a cathode chamber after melting. A mixture of 95% lithium fluoride and 5% beryllium fluoride is added to the anode chamber as an anode molten salt electrolyte, and a mixture of 90% lithium fluoride and 10% beryllium fluoride is added to the cathode chamber as a cathode molten salt electrolyte. The electrolytic cell is heated to 900° C., and an anode made of crude beryllium with a purity of 92% and a molybdenum cathode are immersed in the anode molten salt electrolyte and the cathode molten salt electrolyte, respectively.

[0029] (2) Power on for electrolysis, controlling the anode current density to 0.2 A / cm 2 , electrolysis for 12 hours, solid metallic beryllium is obtained at the cathode, and its purity is 99.91% after analysis.

[0030] Example 3

[0031] This embodiment provides a method for molten salt electrolytic refining of beryllium, comprising the following steps:

[0032] (1) Figure 1 As shown, a beryllium-containing alloy (30 at.% beryllium, 35 at.% copper, 35 at.% silver) is added to the bottom of the electrolytic cell to ensure that the electrolytic device can be divided into an anode chamber and a cathode chamber after melting. A mixture of 35% magnesium fluoride, 45% calcium fluoride, and 20% beryllium fluoride is added to the anode chamber and the cathode chamber as an anode molten salt electrolyte and a cathode molten salt electrolyte. The electrolytic cell is heated to 1100° C., and an anode made of crude beryllium with a purity of 95% and a tungsten cathode are immersed in the anode molten salt electrolyte and the cathode molten salt electrolyte, respectively.

[0033] (2) Power on for electrolysis, controlling the anode current density to 0.5 A / cm 2 , electrolyzed for 6 hours, solid metallic beryllium was obtained at the cathode, and its purity was 99.95% after analysis.

[0034] Example 4

[0035] This embodiment provides a method for molten salt electrolytic refining of beryllium, comprising the following steps:

[0036] (1) Figure 1 As shown, a beryllium-containing alloy (30 at.% beryllium, 70 at.% copper) is added to the bottom of the electrolytic cell to ensure that the electrolytic device can be divided into an anode chamber and a cathode chamber after melting. A mixture of 50% potassium fluoride and 50% beryllium fluoride is added to the anode chamber and the cathode chamber as an anode molten salt electrolyte and a cathode molten salt electrolyte. The electrolytic cell is heated to 950° C., and an anode made of crude beryllium with a purity of 97% and a tungsten cathode are immersed in the anode molten salt electrolyte and the cathode molten salt electrolyte, respectively.

[0037] (2) Power on for electrolysis, controlling the anode current density to 1 A / cm 2 , electrolyzed for 3 hours, solid metallic beryllium was obtained at the cathode, and its purity was 99.96% after analysis.

[0038] Example 5

[0039] This embodiment provides a method for molten salt electrolytic refining of beryllium, comprising the following steps:

[0040] (1) Figure 1 As shown, a beryllium-containing alloy (30 at.% beryllium, 70 at.% manganese) is added to the bottom of the electrolytic cell to ensure that the electrolytic device can be divided into an anode chamber and a cathode chamber after melting. A mixture of 30% lithium fluoride and 70% beryllium fluoride is added to the anode chamber and the cathode chamber as an anode molten salt electrolyte and a cathode molten salt electrolyte. The electrolytic cell is heated to 950° C., and an anode made of crude beryllium with a purity of 99% and a tungsten cathode are immersed in the anode molten salt electrolyte and the cathode molten salt electrolyte, respectively.

[0041] (2) Power on for electrolysis, controlling the anode current density to 1.5 A / cm 2 , electrolyzed for 2 hours, solid metallic beryllium was obtained at the cathode, and its purity was 99.99% after analysis.

[0042] Example 6

[0043] This embodiment provides a method for molten salt electrolytic refining of beryllium, comprising the following steps:

[0044] (1) Figure 1 As shown, a beryllium-containing alloy (30 at.% beryllium, 35 at.% copper, 34 at.% silver, 1 at.% gold) is added to the bottom of the electrolytic cell to ensure that the electrolytic device can be divided into an anode chamber and a cathode chamber after melting. A mixture of 35% magnesium fluoride, 45% calcium fluoride, and 20% beryllium fluoride is added to the anode chamber and the cathode chamber as an anode molten salt electrolyte and a cathode molten salt electrolyte. The electrolytic cell is heated to 1100° C., and an anode made of crude beryllium with a purity of 95% and a tungsten cathode are immersed in the anode molten salt electrolyte and the cathode molten salt electrolyte, respectively.

[0045] (2) Power on for electrolysis, controlling the anode current density to 0.5 A / cm 2 , electrolyzed for 6 hours, solid metallic beryllium was obtained at the cathode, and its purity was 99.94% after analysis.

[0046] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for refining beryllium by molten salt electrolysis, characterized in that: The steps include: (1) Constructing an electrochemical system: The electrolytic cell is divided into an anode chamber and a cathode chamber. The anode chamber contains an anode molten salt electrolyte and a coarse beryllium anode, and the cathode chamber contains a cathode molten salt electrolyte and a cathode. The bottom of the electrolytic cell also contains a liquid alloy. The anode molten salt electrolyte and the cathode molten salt electrolyte do not contact each other but are connected by the liquid alloy at the bottom of the electrolytic cell. (2) When electricity is applied for electrolysis, the metallic beryllium in the anode is oxidized into beryllium ions and enters the anode molten salt electrolyte. It is reduced to metallic beryllium at the interface between the anode molten salt electrolyte and the liquid alloy and dissolves into the liquid alloy. At the same time, the beryllium in the liquid alloy is oxidized into beryllium ions at the interface between the liquid alloy and the cathode molten salt electrolyte and enters the cathode molten salt electrolyte, and is reduced to metallic beryllium on the cathode surface. Wherein: the liquid alloy is an alloy formed by one or more of copper, silver, gold, manganese and beryllium; The anode molten salt electrolyte and the cathode molten salt electrolyte are the same or different and are a mixture of one or more of lithium fluoride, sodium fluoride, potassium fluoride, magnesium fluoride, calcium fluoride and beryllium fluoride; Anode current density is 0.1-1.5A / cm 2 , the electrolysis temperature is 600-1100℃.

2. The method for molten salt electrolytic refining of beryllium according to claim 1, characterized in that: The cathode is a nickel, tungsten or molybdenum cathode.

3. The method for molten salt electrolytic refining of beryllium according to claim 1, characterized in that: The liquid alloy is an alloy composed of beryllium and copper in an atomic ratio of 28:

72.

4. The method for molten salt electrolytic refining of beryllium according to claim 1, characterized in that: The liquid alloy is an alloy composed of beryllium and gold in an atomic ratio of 21:

79.

5. The method for molten salt electrolytic refining of beryllium according to any one of claims 1, 3 and 4, characterized in that: Under power-on conditions, the densities of the anode molten salt electrolyte and the cathode molten salt electrolyte are both lower than the density of the liquid alloy.

6. The method for molten salt electrolytic refining of beryllium according to claim 1, characterized in that: The purity of the crude beryllium is not less than 90%.

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