Method for producing beryllium alloy by molten salt electrolytic oxidation of beryllium and electrolysis system

Abstract

The application discloses a method for preparing beryllium alloy by molten salt electrolytic oxidation of beryllia and an electrolysis system. The method comprises the following steps: mixing non-beryllium metal, beryllia, inert molten salt and electrolytic additives, and placing the mixture in an electrolysis tank for electrolytic smelting, wherein inert gas is introduced during the electrolytic smelting process to stir the molten pool. The application can produce high-quality beryllium alloy in one step, and has the advantages of simple method, low cost, low energy consumption, short process, clean and environmental protection, and the like. The problems existing in the traditional method, such as difficulty in reducing beryllia, difficulty in controlling the composition of beryllium alloy, prominent environmental risk and the like, are avoided.

Description

Technical Field

[0001] This invention relates to a method for preparing beryllium alloys, specifically a method for preparing beryllium alloys by molten salt electrolysis of beryllium oxide, and also to its electrolysis system, belonging to the field of non-ferrous metal metallurgy. Background Technology

[0002] Beryllium is primarily used in alloy form, with approximately 95% of the world's beryllium ultimately ending up in various beryllium alloys. Of these, beryllium copper alloys account for about 75%, and beryllium aluminum and other beryllium alloys account for about 20%. Beryllium copper and beryllium aluminum alloys are indispensable strategic materials in the defense, nuclear energy, and aerospace fields, and they demonstrate key value in emerging technologies such as artificial intelligence. For example, beryllium copper, with its excellent elasticity, electrical and thermal conductivity, and fatigue resistance, plays a crucial role in defense and aerospace, serving as a "precision joint" in signal switches, electrical connectors, relay springs, and electromagnetic shielding components for various advanced weapons, as well as in extreme conditions such as control rod drive mechanisms in nuclear reactors. Beryllium aluminum alloys, based on their lightweight, high specific stiffness, and neutron moderation properties, serve as a "lightweight structural skeleton" and "neutron control material," used in the manufacture of military aircraft structural components, missile instrument compartments, satellite mirrors, and inertial navigation components, and as neutron moderators and reflectors in nuclear reactors. In the booming field of artificial intelligence, beryllium copper, due to its property of not deforming after millions of elastic cycles, has become the core material for humanoid robot tactile sensors, precision connectors and flexible sensing structures; while beryllium aluminum alloy, with its dual advantages of lightweight and ultra-high thermal conductivity, is used as heat sink material for AI computing chips and semiconductor heat dissipation substrates.

[0003] However, current methods for preparing beryllium alloys still face numerous unresolved challenges. For instance, the main methods for preparing beryllium-copper master alloys include carbothermal reduction, metallothermal reduction, and eutectic melting. Carbothermal reduction is the mainstream process, typically involving the reduction and melting of beryllium oxide, carbon source, and copper scrap in an electric arc furnace at 1800–2100°C. This method suffers from long processes, high impurity content, high temperatures, and high energy consumption. Furthermore, the beryllium-containing fumes generated during the melting process are highly toxic, posing a serious challenge to environmental protection and occupational health. Meanwhile, the preparation of beryllium-aluminum alloys relies primarily on precision casting and powder metallurgy (such as hot isostatic pressing). However, due to the extremely low miscibility and significant difference in melting points between beryllium and aluminum, the alloy is essentially a two-phase composite, making its preparation extremely difficult. Casting methods are prone to defects such as deformation and hot cracking; while powder metallurgy can improve performance, it is complex and costly; and emerging additive manufacturing technologies face a series of unresolved problems, including unstable molten pools, porosity, compositional segregation, and residual stress. Currently, there is an urgent need to establish a clean and efficient beryllium master alloy preparation technology, such as beryllium copper and beryllium aluminum, to solve the industrial bottlenecks caused by existing preparation methods, such as highly toxic dust pollution, high energy consumption, and low yield. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing beryllium alloys by molten salt electrolysis of beryllium oxide. This method is simple, low-cost, highly efficient, and produces high-quality beryllium alloys.

[0005] A second objective of this invention is to provide an electrolytic system for preparing beryllium alloys by molten salt electrolysis of beryllium oxide. This system is fully compatible with the method of this invention.

[0006] To achieve the above-mentioned technical objectives, the present invention provides a method for preparing beryllium alloys by molten salt electrolysis of beryllium oxide. The method involves mixing non-beryllium metal, beryllium oxide, inert molten salt, and electrolytic additives in an electrolytic cell for electrolytic melting, wherein an inert gas is introduced during the electrolytic melting process to agitate the molten pool.

[0007] This invention enhances ion mass transfer in molten salt and improves electrolysis efficiency by blowing in an inert gas at a certain pressure into the molten salt electrolysis process. More importantly, it promotes the rapid capture of fine "beryllium particles" obtained by reduction at the interface between the molten liquid phase non-beryllium metal and the molten salt by the liquid phase metal, allowing them to enter the liquid phase non-beryllium metal to obtain a beryllium master alloy. This effectively avoids the problem of beryllium segregation that occurs in the preparation of beryllium alloys by traditional methods.

[0008] As a preferred embodiment, the inert gas is introduced from the bottom of the electrolytic cell. The inert gas can be blown in from any part of the electrolysis apparatus, as long as the blown inert gas can agitate the molten pool; however, blowing in the inert gas from the bottom of the electrolytic cell provides a better agitation effect.

[0009] As a preferred embodiment, the material distribution method in the electrolytic cell is as follows: inert molten salt and electrolytic additives are mixed and laid on top of beryllium oxide, and beryllium oxide is laid on top of non-beryllium metals.

[0010] As a preferred embodiment, the pressure of the inert gas introduced is 0.1~0.5 MPa. This pressure range used in the electrolytic cell improves electrolysis efficiency. If the inert gas pressure is too low, it will not have a stirring effect; if the pressure is too high, it will cause material to fly away, also affecting the electrolytic melting effect. In practice, the inert gas pressure can be adjusted according to the weight of the material being processed and the volume and morphology of the electrolytic cell. Due to variations in furnace size during implementation, the melt height will differ for the same weight of material in furnaces of different capacities, and the melt depth of the material layer may exceed the distance between the anode and cathode.

[0011] As a preferred embodiment, the temperature of the inert gas is 700~900℃. The inert gas includes at least one of argon and helium, with argon being more preferred. To prevent the introduced inert gas from affecting the reaction rate, the inert gas is preheated to shorten the reaction time.

[0012] As a preferred embodiment, the non-beryllium metal includes at least one of aluminum, copper, and antimony. These metals can form limited solid solutions, eutectic structures, or age-precipitated intermetallic compounds with beryllium, i.e., engineering-grade alloys, which can improve the problems of poor plasticity, high brittleness, and easy oxidation at high temperatures of elemental beryllium.

[0013] As a preferred embodiment, the mass ratio of the non-beryllium metal to beryllium oxide is 1 to 3:1.

[0014] As a preferred embodiment, the beryllium oxide purity is greater than 99.0 wt%, and the beryllium oxide addition amount is preferably 0.5 kg or more. This invention can process materials of any weight, but processing large-scale materials is more practically significant for production. Therefore, this invention preferably uses a beryllium oxide addition amount of 0.5 kg or more, and more preferably not less than 1 kg.

[0015] As a preferred embodiment, the mass ratio of beryllium oxide to inert molten salt is 1.2 to 10:1, and more preferably 2.5 to 6:1.

[0016] As a preferred embodiment, the inert molten salt comprises an alkaline earth metal chloride and an alkaline earth metal fluoride. The alkaline earth metal includes at least one of Ca and Ba. Using this combination of components in the inert molten salt can improve electrolysis efficiency.

[0017] As a preferred option, the alkaline earth metals in the alkaline earth metal chloride include Ca and Ba.

[0018] As a preferred option, the mass ratio of calcium chloride to barium chloride is 0.5 to 2:1.

[0019] As a preferred embodiment, the alkaline earth metal fluoride has a mass content of 1.5 to 4.5 wt% in the inert molten salt.

[0020] As a preferred embodiment, the mass of the electrolytic additive is 1-5 wt% of the inert molten salt. Controlling the electrolytic additive within a suitable range can improve the solubility of BeO in the inert molten salt, improve the fluidity of the molten salt, and suppress side reactions, which is beneficial to improving electrolysis efficiency. If the amount of additive is too low, the improvement effect is not obvious; if the amount of additive is too high, it can lead to a significant increase in the viscosity of the molten salt, poor fluidity, difficulty in bubble removal, and Ce and Sr in the additive are also prone to co-precipitate into the alloy and contaminate the alloy composition.

[0021] As a preferred embodiment, the electrolytic additive includes at least one of strontium oxide and cerium oxide, and at least one of strontium chloride and cerium chloride. This type of electrolytic additive can effectively regulate interfacial tension, inhibit secondary oxidation and agglomeration of beryllium, lower the melting point of molten salt, broaden the stable liquid phase range, increase BeO solubility, and alleviate cathode concentration polarization.

[0022] As a preferred embodiment, the molar ratio of oxide to chloride in the electrolytic additive is 0.9~1.1:0.9~1.1, more preferably 1:1.

[0023] As a preferred embodiment, the electrolytic melting conditions are: temperature of 700~1200℃, time of 30~200min, more preferably 60~150min, cell voltage of 2.0~3.5V, and cathode-cathode distance of 4~15cm, more preferably 4~8cm.

[0024] As a preferred approach, the gases generated during molten salt electrolysis at the anode are promptly discharged and collected for treatment. These gases include oxygen and carbon dioxide, which are then promptly transported by airflow to a dust collection bag for purification. This avoids the problem of easily re-oxidizing the newly generated beryllium in traditional molten salt electrolysis methods.

[0025] As a preferred embodiment, the beryllium content in the beryllium alloy is 4~15wt%.

[0026] This invention also provides an electrolysis system corresponding to the method of preparing beryllium alloy by molten salt electrolysis of beryllium oxide, which includes an electrolytic cell, a cathode rod, an anode rod, an inert anode, and a DC power supply. The bottom of the electrolytic cell is provided with a gas nozzle and a liquid outlet for discharging material, and the top is provided with a feed inlet and a slightly negative pressure flue gas outlet. The bottom of the electrolytic cell is lined with graphite. One end of the cathode rod is connected to the graphite lining at the bottom of the electrolytic cell, and the other end is connected to the negative terminal of the DC power supply through a wire. One end of the anode rod extends from the top of the furnace and is connected to the graphite anode inside the electrolytic cell, and the other end is connected to the positive terminal of the DC power supply through a wire. A resistance heating layer is provided outside the electrolytic cell.

[0027] As a preferred embodiment, the inert anode is a graphite anode (ash content < 0.15%) or a TiB2 and ceramic composite inert anode; both the anode rod and the cathode rod are copper conductive rods; and the gas jet pipe is made of silicon nitride ceramic tube or corundum ceramic tube.

[0028] As a preferred option, a screw feeder is used to replenish the beryllium oxide material. The sidewall material of the electrolytic cell is hot-pressed sintered silicon nitride ceramic, and the intermediate insulation layer is lightweight high-alumina refractory fiber brick or calcium silicate insulating brick.

[0029] As a preferred option, as molten salt electrolysis proceeds, liquid beryllium alloy (beryllium aluminum / beryllium copper / beryllium antimony master alloy) gradually accumulates in the lower layer of the device.

[0030] Compared with existing technologies, this invention can produce high-quality beryllium alloys (beryllium aluminum / beryllium copper / beryllium antimony master alloys) in a clean and efficient manner in one step. The preparation method is simple and low-cost, effectively solving the problems of high energy consumption, heavy pollution, low efficiency and low yield in the current traditional beryllium alloy preparation. The supporting electrolysis system is simple and practical, enabling continuous large-scale production of beryllium alloys. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the electrolytic system for preparing beryllium alloys by molten salt electrolysis of beryllium oxide according to the present invention, wherein: (1) molten salt electrolytic cell; (2) anode rod; (3) DC power supply; (4) discharge port; (5) inert gas nozzle; (6) flue gas outlet; (7) feed port; (8) molten salt layer; (9) mixed layer of beryllium oxide and additives; (10) beryllium alloy layer; (11) cathode rod; (12) graphite anode; (13) resistance heating layer. Specific Implementation

[0032] The following examples are intended to further illustrate the present invention, but are not intended to limit the invention.

[0033] The molten salt electrolysis device of the present invention includes a closed electrolytic cell (1), an anode rod (2), a cathode rod (11), a graphite anode (12), and a DC power supply (3); the bottom of the electrolytic cell is provided with a discharge port (4) and a gas nozzle (5) for discharging material, a resistance heating layer (13) is provided outside the electrolytic cell, and the top is provided with a feed port (7) with a one-way valve and a flue gas outlet (6). The bottom of the electrolytic cell is lined with graphite. One end of the cathode rod (11) is connected to the graphite lining at the bottom of the electrolytic cell (1), and the other end is connected to the negative terminal of the DC power supply (3) through a wire. One end of the anode rod (2) extends from the top of the electrolytic cell (1) and is connected to the graphite anode (12), and the other end is connected to the positive terminal of the DC power supply (3) through a wire. The flue gas outlet (6) receives dust bags and purifies the flue gas.

[0034] The above-described apparatus is used in all the following embodiments.

[0035] Example 1

[0036] Weigh 1 kg of copper block and place it at the bottom of the electrolytic cell. Spread 600 g of 99.5% pure beryllium oxide on top of the copper block. Then weigh out 150 g of a mixed molten salt of CaCl2, 144 g of BaCl2, and 6 g of CaF2, and 6 g of a mixture of CeO2 and SrCl2 (CeO2 / SrCl2 molar ratio = 1:1). Mix well and spread the mixture on top of the beryllium oxide layer. Cover the electrolytic cell and turn on the heating power to raise the temperature to 1100℃. Turn on the inert gas switch and blow preheated argon gas at 800℃ into the molten pool from the bottom to agitate the pool. The blown gas pressure is 0.3 MPa. Turn on the DC power to start molten salt electrolysis, controlling the cell voltage at 2.8V and the anode-cathode distance at 6 cm. After electrolysis for 90 min, stop the reaction, discharge the bottom alloy liquid from the discharge port, and after cooling, obtain a beryllium copper master alloy containing 4.8 wt.% beryllium.

[0037] Example 2

[0038] Weigh 1.5 kg of aluminum block and place it in the electrolytic cell. Spread 1 kg of 99.8% pure beryllium oxide on top of the aluminum block. Then weigh 140 g of CaCl2, 532 g of BaCl2 and 28 g of a mixed molten salt of BaF2, and 28 g of a mixture of SrO and CeCl3 (SrO / CeCl3 molar ratio = 1:1) and mix them thoroughly. Spread the mixed molten salt on top of the beryllium oxide layer. Then cover the electrolytic cell and turn on the heating power to raise the temperature to 980°C. Turn on the inert gas switch and blow preheated argon gas at 750°C into the molten pool from the bottom of the pool to stir it. The gas pressure is 0.2 MPa. Turn on the DC power to start molten salt electrolysis. Control the cell voltage at about 3.0V and the distance between the anode and cathode at 10 cm. After electrolysis for 120 min, stop the reaction and discharge the bottom alloy liquid from the discharge port. After cooling, a beryllium-aluminum master alloy containing 14.1% beryllium is obtained.

[0039] Example 3

[0040] Weigh 2.5 kg of antimony block and place it in the electrolytic cell. Place 900 g of beryllium oxide (99.5% purity) on top of the antimony block, then weigh 135 g of CaCl2... 250g of BaCl2 and 15g of CaF2 mixed molten salt, along with 8g of a mixture of CeO2 and SrCl2 (CeO2 / SrCl2 molar ratio = 1:1), were thoroughly mixed. This mixed molten salt was then spread over the beryllium oxide layer. The electrolytic cell lid was closed, and the heating power was turned on to raise the temperature to 1000℃. The inert gas switch was turned on, and preheated argon gas at 800℃ was blown into the molten pool from the bottom at a pressure of 0.3 MPa to agitate the molten pool. The DC power supply was then turned on to begin molten salt electrolysis, with the cell voltage controlled at approximately 2.2V and the anode-cathode distance at 8 cm. After electrolysis for 150 minutes, the reaction was stopped, and the bottom alloy liquid was discharged from the discharge port. After cooling, a beryllium-antimony master alloy containing 5.3% beryllium was obtained.

[0041] Comparative Example 1

[0042] The beryllium alloy was prepared using the method of Example 1, with the only difference being that argon gas was introduced into the electrolytic cell in accordance with conventional methods to maintain an inert gas atmosphere, i.e., the inert gas did not agitate the molten pool.

[0043] The results showed that after the released molten copper was cooled, the beryllium content was only 0.08 wt.%.

[0044] Comparative Example 2

[0045] Beryllium alloys were prepared using the method described in Example 1, with the only difference being that CaF2 was not added to the mixed molten salt.

[0046] The results showed that after the released molten copper was cooled, the beryllium content was only 0.11 wt.%.

[0047] Comparative Example 3

[0048] The beryllium alloy was prepared using the method of Example 1, with the only difference being that the amount of CaF2 added to the mixed molten salt was 40g (i.e., excess).

[0049] The results showed that after the released copper liquid was cooled, the beryllium content was only 0.27 wt.%.

[0050] Comparative Example 4

[0051] The beryllium alloy was prepared using the method of Example 1, except that CeO2 and SrCl2 were not added.

[0052] The results showed that after the released molten copper was cooled, the beryllium content was only 0.09 wt.%.

[0053] Comparative Example 5

[0054] The beryllium alloy was prepared using the method of Example 1, with the only difference being that the total amount of CeO2 and SrCl2 added was 20g (i.e., excess), and the molar ratio of CeO2 to SrCl2 was 1:1.

[0055] The results showed that after the released molten copper was cooled, the beryllium content was only 0.15 wt.%.

[0056] Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing beryllium alloys by molten salt electrolysis of beryllium oxide, characterized in that: Non-beryllium metal, beryllium oxide, inert molten salt, and electrolytic additives are mixed and placed in an electrolytic cell for electrolytic melting. During the electrolytic melting process, inert gas is introduced to agitate the molten pool.

2. The method for preparing beryllium alloys by molten salt electrolysis of beryllium oxide according to claim 1, characterized in that: The inert gas is introduced from the bottom of the electrolytic cell; The material distribution method in the electrolytic cell is as follows: inert molten salt and electrolytic additives are mixed and laid on top of beryllium oxide, and beryllium oxide is laid on top of non-beryllium metals.

3. The method for preparing beryllium alloys by molten salt electrolysis of beryllium oxide according to claim 1 or 2, characterized in that: The pressure of the inert gas introduced is 0.1~0.5 MPa; the temperature of the inert gas is 700~900℃.

4. The method for preparing beryllium alloys by molten salt electrolysis of beryllium oxide according to claim 1, characterized in that: The non-beryllium metal includes at least one of aluminum, copper, and antimony; The mass ratio of the non-beryllium metal to beryllium oxide is 1~3:

1.

5. The method for preparing beryllium alloys by molten salt electrolysis of beryllium oxide according to claim 1, characterized in that: The mass ratio of beryllium oxide to inert molten salt is 1.2 to 10:

1.

6. A method for preparing beryllium alloys by molten salt electrolysis of beryllium oxide according to claim 1 or 5, characterized in that: The inert molten salt includes alkaline earth metal chlorides and alkaline earth metal fluorides; the alkaline earth metal includes at least one of Ca and Ba. The alkaline earth metal fluoride has a mass content of 1.5~4.5 wt% in the inert molten salt.

7. The method for preparing beryllium alloys by molten salt electrolysis of beryllium oxide according to claim 1, characterized in that: The electrolytic additive is present in an amount of 1-5 wt% of the inert molten salt. The electrolytic additive includes at least one of strontium oxide and cerium oxide, and at least one of strontium chloride and cerium chloride, wherein the molar ratio of oxide to chloride in the electrolytic additive is 0.9~1.1:0.9~1.

1.

8. The method for preparing beryllium alloys by molten salt electrolysis of beryllium oxide according to claim 1, characterized in that: The conditions for electrolytic melting are: temperature of 700~1200℃, time of 30~200min, cell voltage of 2.0~3.5V, and anode-cathode distance of 4~15cm; the gas generated by the electrolysis of molten salt at the anode is discharged and collected and treated in a timely manner.

9. The method for preparing beryllium alloys by molten salt electrolysis of beryllium oxide according to claim 1, characterized in that: The beryllium content in the beryllium alloy is 4~15wt%.

10. The electrolysis system corresponding to the method for preparing beryllium alloys by molten salt electrolysis of beryllium oxide according to any one of claims 1 to 8, characterized in that: The system includes an electrolytic cell, a cathode rod, an anode rod, an inert anode, and a DC power supply. The bottom of the electrolytic cell is equipped with a gas nozzle and a liquid discharge port for material discharge, while the top is equipped with a feed inlet and a slightly negative pressure flue gas outlet. The bottom of the electrolytic cell is lined with graphite. One end of the cathode rod is connected to the graphite lining at the bottom of the electrolytic cell, and the other end is connected to the negative terminal of the DC power supply via a wire. One end of the anode rod extends from the top of the furnace and is connected to the graphite anode inside the electrolytic cell, while the other end is connected to the positive terminal of the DC power supply via a wire. A resistance heating layer is provided outside the electrolytic cell.

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