An aluminum-thorium alloy, its preparation method and application

Abstract

The present invention provides an aluminum-thorium alloy, a preparation method thereof and an application. The preparation method comprises the following steps: (1) mixing aluminum oxide, thorium oxide and an electrolyte to obtain a mixed molten salt; (2) electrolyzing the mixed molten salt after heating and melting in a protective gas to obtain the aluminum-thorium alloy. The present invention prepares the aluminum-thorium alloy by a molten salt electrolysis method. Compared with the traditional preparation method of aluminum-thorium alloy, the process is short, the equipment is simple, the cost is low, and the reaction conditions are easy to control. The preparation method of the present invention can be used in the existing aluminum electrolysis system. By adding thorium fluoride and thorium oxide at a certain concentration to the existing 200-500 KA aluminum electrolysis cell, the continuous production of aluminum-thorium alloy can be realized without changing the structure and facilities of the existing aluminum electrolysis cell, and it is easy to realize industrial popularization and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-ferrous metal electrolysis, relates to an alloy, and particularly relates to an aluminum-thorium alloy, a preparation method thereof, and an application thereof. Background Art

[0002] Aluminum alloys have the advantages of low density, high specific strength, excellent electrical and thermal conductivity, good workability, etc., and are widely used in the fields of aerospace industry, electric power industry, automobile manufacturing industry, construction industry, food industry, marine shipbuilding industry, etc. Aluminum alloys have a low density, but relatively high strength, approaching or exceeding high-quality steel, with good plasticity, can be processed into various profiles, and have excellent electrical conductivity, thermal conductivity, and corrosion resistance. They are widely used in industry, and the usage amount is second only to steel. However, the existing aluminum alloys still need to be improved in terms of hardness, toughness, and heat resistance. China's thorium resource reserves are about 280,000 tons, and its abundance in the earth's crust is about half that of lead and 3 to 4 times that of uranium. Thorium can be used to manufacture alloys to improve the strength and heat resistance of metals. If the aluminum-thorium alloy is obtained by smelting pure thorium metal and pure aluminum metal in a certain proportion according to the traditional preparation process, if this method is adopted, pure thorium and pure aluminum need to be prepared first, and the secondary smelting loss is large, and the process is complex. The prices of thorium oxide and aluminum oxide are relatively low. Preparing aluminum-thorium alloy by molten salt electrolysis of thorium oxide and aluminum oxide is a good direction. However, the melting point of thorium oxide is 3220 °C, and the melting point of thorium is 1842 °C, which results in high preparation cost of aluminum-thorium alloy and high requirements for experimental conditions.

[0003] CN1936085A discloses a method for preparing aluminum and aluminum alloys by low-temperature molten salt electrolysis, using metal chloride or a mixture of metal chlorides as the electrolyte, requiring the melting point of the electrolyte ≤ 800 °C, using graphite carbon material or inert electrode as the anode, and the process of solid-state cathode electrolysis is intermittent electrolysis. The cathode is placed at the bottom of the graphite electrolytic cell, the electrolyte is placed above the cathode, and after being heated by electricity and the electrolyte melts, the anode is inserted into the molten salt. Molten salt electrolysis is carried out under the conditions that the voltage is greater than the decomposition voltage of Al2O3 and less than the decomposition voltage of the electrolyte, the electrode spacing ≥ 0.1 cm, and the temperature is 600 °C. When the current is lower than 1.0 ampere, the cathode is taken out and put into the melting furnace, and the aluminum is melted at ≥ 660 °C and then ingoted; the electrolysis with a mixture of liquid aluminum and Al2O3 as the cathode is continuous electrolysis, the temperature ≥ 660 °C, and aluminum is taken out from the cathode regularly and Al2O3 is added, and the electrolysis process is carried out continuously. However, the hardness and heat resistance of the aluminum alloy prepared by this method are poor, and aluminum-thorium alloy cannot be prepared.

[0004] CN104694974A discloses a uranium-aluminum alloy and a method for preparing the same by molten salt electrolysis. The composition of the uranium-aluminum alloy is: Al, Al4U, Al3U, and Al2U, where the Al content is 24-70%; U, 30-76%. The present invention also provides a method for preparing a uranium-aluminum alloy by molten salt electrolysis. The LiCl-KCl molten salt is heated to melting; UO2 powder and AlCl3 powder are simultaneously added to the molten salt to chlorinate UO2 to form UCl4; an aluminum sheet is used as the cathode, graphite is used as the anode, and Ag(I) / Ag is used as the reference electrode. The uranium-aluminum alloy is deposited on the cathode by potentiostatic electrolysis. However, the content of uranium in the crust is scarce and the price is expensive, so the uranium-aluminum alloy is not suitable for popularization and use.

[0005] CN105238942A discloses a thorium-doped aluminum alloy and a method for preparing the same. The thorium-doped aluminum alloy of the present invention is composed of the following components by weight: 150 parts by weight of aluminum, 5 parts by weight of magnesium hydride, 5 parts by weight of nickel, 1-2 parts by weight of thorium, and 0.6 parts by weight of sodium fluotitanate. When preparing, the following steps are included: 1) Add 150 parts by weight of aluminum to the melting furnace and heat it to complete melting to form aluminum liquid; 2) Add 5 parts by weight of magnesium hydride, 5 parts by weight of nickel, 1-2 parts by weight of thorium, and 0.6 parts by weight of sodium fluotitanate to the aluminum liquid in step 1) in sequence, heat it to complete melting, and mix well to obtain a mixed liquid; 3) Let the mixed liquid obtained in step 2) stand for 11 hours at 560 °C, and then transfer it to the casting mold of the casting for casting. However, the preparation of pure thorium metal is difficult and the preparation cost is also high, so the thorium-doped aluminum alloy cannot be popularized and used on a large scale.

[0006] Currently, the disclosed aluminum alloys all have certain defects, such as the problems of low hardness and heat resistance, and the preparation cost of the thorium alloy prepared by doping thorium is high, and the experimental conditions are demanding. Therefore, it is crucial to develop a preparation method with low cost and simple experimental conditions to prepare an aluminum-thorium alloy with high hardness and strong heat resistance. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide an aluminum-thorium alloy, a preparation method and an application thereof. The present invention uses molten salt electrolysis to prepare the aluminum-thorium alloy. Compared with the traditional preparation method of the aluminum-thorium alloy, the process is short, the equipment is simple, the cost is low, and the reaction conditions are easy to control; the preparation method of the present invention can be used in the existing aluminum electrolysis system. By adding thorium oxide and electrolyte at a certain concentration to the existing 200-500KA aluminum electrolysis cell, the aluminum-thorium alloy can be continuously produced without changing the structure and facilities of the existing aluminum electrolysis cell, and it is easy to realize industrial popularization and application.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing an aluminum-thorium alloy, and the preparation method includes the following steps:

[0010] (1) Mix alumina, thorium oxide and an electrolyte to obtain a mixed molten salt;

[0011] (2) Electrolyze the mixed molten salt after heating and melting it in a protective gas to obtain an aluminum-thorium alloy.

[0012] The present invention provides a method for preparing an aluminum-thorium alloy. The preparation method uses a molten salt electrolysis method to prepare the aluminum-thorium alloy. Compared with the traditional method for preparing an aluminum-thorium alloy, it has a short process, simple equipment, low cost, and easy control of reaction conditions. The preparation method of the present invention can be used in the existing aluminum electrolysis system. By adding thorium oxide and an electrolyte at a certain concentration to the existing aluminum electrolysis cells with a capacity of 200 - 500 KA, the continuous production of aluminum-thorium alloy can be achieved without changing the structure and facilities of the existing aluminum electrolysis cells, and it is easy to realize industrial promotion and application.

[0013] Preferably, the electrolyte includes sodium hexafluoroaluminate and a fluoride salt.

[0014] Preferably, the fluoride salt includes a combination of at least two of aluminum fluoride, thorium fluoride, calcium fluoride, magnesium fluoride or lithium fluoride. For example, it can be a combination of aluminum fluoride and thorium fluoride, a combination of thorium fluoride and calcium fluoride, a combination of calcium fluoride and magnesium fluoride, a combination of magnesium fluoride and lithium fluoride, a combination of aluminum fluoride, thorium fluoride and calcium fluoride, or a combination of aluminum fluoride, thorium fluoride, calcium fluoride and magnesium fluoride.

[0015] Preferably, the fluoride salt includes thorium fluoride and at least one of aluminum fluoride, calcium fluoride, magnesium fluoride or lithium fluoride. For example, it can be a combination of thorium fluoride and aluminum fluoride, a combination of thorium fluoride and calcium fluoride, a combination of thorium fluoride and magnesium fluoride, a combination of thorium fluoride and lithium fluoride, or a combination of thorium fluoride, aluminum fluoride and calcium fluoride.

[0016] Preferably, by weight, the mixed molten salt includes:

[0017]

[0018] In the present invention, the content of alumina in the mixed molten salt is limited to 2 - 15 parts by weight. For example, it can be 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts or 15 parts, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable. When the content of alumina is too low, the content of aluminum ions in the mixed molten salt is low, which will make it difficult to reduce aluminum ions and reduce the cathode current efficiency. When the content of alumina is too high, the content of aluminum ions in the mixed molten salt is too high, and it is difficult for thorium ions to deposit, which will result in too low content of thorium ions in the aluminum-thorium alloy, thus affecting the performance of the aluminum-thorium alloy.

[0019] In the present invention, the content of thorium oxide in the mixed molten salt is limited to 2-15 parts. For example, it can be 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts or 15 parts, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable. When the content of thorium oxide is too low, the content of thorium ions in the mixed molten salt is low, which will result in too low content of thorium in the aluminum-thorium metal, thus affecting the performance of the aluminum-thorium metal. When the content of thorium oxide is too high, it will lead to a decrease in the cathode current efficiency.

[0020] In the present invention, the content of sodium hexafluoroaluminate in the mixed molten salt is limited to 60-85 parts. For example, it can be 60 parts, 65 parts, 70 parts, 75 parts, 80 parts or 85 parts, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0021] In the present invention, the content of fluoride salt in the mixed molten salt is limited to 4-40 parts. For example, it can be 4 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts or 40 parts, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable. When the content of fluoride salt is too low, the content of electrolyte in the mixed molten salt is low, which is not conducive to the transport of ions during electrolysis, resulting in a decrease in the cathode current efficiency. When the content of fluoride salt is too high, the content of alumina and thorium oxide in the mixed molten salt is low, which is not conducive to the deposition of aluminum-thorium metal.

[0022] Preferably, the mixed molten salt obtained in step (1) is dried before being heated and melted.

[0023] Preferably, the temperature of the drying is 100-600 °C and the time is 1-20 h.

[0024] In the present invention, the temperature of the drying is limited to 100-600 °C. For example, it can be 100 °C, 200 °C, 300 °C, 400 °C, 500 °C or 600 °C, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0025] In the present invention, the time of the drying is limited to 1-20 h. For example, it can be 1 h, 3 h, 5 h, 7 h, 9 h, 10 h, 12 h, 14 h, 16 h, 18 h or 20 h, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0026] Preferably, the heating and melting in step (2) includes heating and heat preservation processes carried out in sequence.

[0027] Preferably, the heating rate is 1-10 °C / min. For example, it can be 1 °C / min, 2 °C / min, 3 °C / min, 5 °C / min, 7 °C / min, 9 °C / min or 10 °C / min, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0028] Preferably, the final temperature of the heating is 900-1000 °C. For example, it can be 900 °C, 910 °C, 920 °C, 930 °C, 940 °C, 950 °C, 960 °C, 970 °C, 980 °C, 990 °C or 1000 °C, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0029] Preferably, the temperature of the heat preservation treatment is the final temperature of the heating.

[0030] Preferably, the time of the heat preservation treatment is 1-20 h. For example, it can be 1 h, 3 h, 5 h, 7 h, 9 h, 10 h, 12 h, 14 h, 16 h, 18 h or 20 h, but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0031] Preferably, the protective gas includes nitrogen and / or inert gas.

[0032] Preferably, the cathode of the electrolysis includes any one of tungsten, molybdenum or graphite.

[0033] Preferably, the anode of the electrolysis includes an inert electrode.

[0034] Preferably, the inert electrode includes graphite.

[0035] Preferably, the electrolysis uses a DC power supply.

[0036] Preferably, the current density of the electrolysis is 0.5-5 A / cm 2 , for example, it can be 0.5 A / cm 2 , 0.8 A / cm 2 , 1 A / cm 2 , 2 A / cm 2 , 3 A / cm 2 , 4 A / cm 2 or 5 A / cm 2 , but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0037] In the present invention, the current density of the electrolysis is defined as 0.5-5 A / cm 2, when the current density of electrolysis is too high, the cathode overpotential increases, the cathode polarization increases, the cathode current efficiency decreases, the energy consumption is serious, and the edge effect is likely to occur, resulting in poor performance of the aluminum-thorium alloy; when the current density of electrolysis is too low, the cathode overpotential decreases, the cathode polarization is small, the electrolysis speed is slow, the crystallization of the aluminum-thorium alloy is coarse, the alloy performance is poor, and even the electrolysis process cannot proceed.

[0038] Preferably, the temperature of the electrolysis is 900 - 1000 °C. For example, it can be 900 °C, 910 °C, 920 °C, 930 °C, 940 °C, 950 °C, 960 °C, 970 °C, 980 °C, 990 °C or 1000 °C, but it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0039] In the present invention, the temperature of the electrolysis is limited to 900 - 1000 °C. When the temperature of the electrolysis is too high, the cathode overpotential becomes smaller, the cathode polarization decreases, which is not conducive to the precipitation of the aluminum-thorium alloy, and the energy consumption is relatively high, not meeting the requirements of energy conservation and environmental protection; when the temperature of the electrolysis is too low, the cathode overpotential becomes larger, the cathode polarization becomes larger, but a too low temperature is not conducive to the ion transport in the mixed molten salt, which will lead to a decrease in current efficiency, and the composition of the aluminum-thorium alloy is uneven. If the temperature of the electrolysis is not sufficient to turn the mixed molten salt into an ionic state, the electrolysis current is extremely low, and even the electrolysis cannot proceed.

[0040] Preferably, the electrolysis time is 5 - 30 h. For example, it can be 5 h, 10 h, 15 h, 20 h, 25 h or 30 h, but it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0041] Preferably, as a preferred technical solution of the preparation method described in the first aspect, the preparation method includes the following steps:

[0042] (1) Mix alumina, thorium oxide and electrolyte according to the formula amounts to obtain a mixed molten salt;

[0043] (2) In a protective gas, the mixed molten salt is kept at 100 - 600 °C for 1 - 20 h, heated at a heating rate of 1 - 10 °C / min to 900 - 1000 °C and kept for 1 - 20 h. Using tungsten, molybdenum or graphite as the cathode and graphite as the anode, direct current power supply is used for electrolysis. The temperature of the electrolysis is 900 - 1000 °C, the current density of the electrolysis is 0.5 - 5 A / cm 2 , and the electrolysis time is 5 - 30 h to obtain an aluminum-thorium alloy.

[0044] In the second aspect, the present invention provides an aluminum-thorium alloy, which is obtained by the preparation method described in the first aspect.

[0045] In a third aspect, the present invention provides an application of the aluminum-thorium alloy described in the second aspect, and the aluminum-thorium alloy is used in the aviation industry, marine industry or chemical industry.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] The present invention prepares the aluminum-thorium alloy by the molten salt electrolysis method. Compared with the traditional preparation method of aluminum-thorium alloy, the process is short, the equipment is simple, the cost is low, and the reaction conditions are easy to control; the preparation method of the present invention can be used in the existing aluminum electrolysis system. By adding thorium oxide and electrolyte at a certain concentration to the existing aluminum electrolysis cell with a capacity of 200 - 500 KA, the continuous production of aluminum-thorium alloy can be realized without changing the structure and facilities of the existing aluminum electrolysis cell, which is easy to realize industrial popularization and application. Specific Embodiments

[0048] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0049] To facilitate the understanding of the technical solution provided by the present invention by those skilled in the art, the present invention exemplarily provides a device applicable to the preparation method of aluminum-thorium alloy. The device includes a molten salt electrolysis furnace;

[0050] A cathode, an anode, a heating device and an atmosphere protection device are arranged in the molten salt electrolysis furnace;

[0051] There is a mixed molten salt in the molten salt electrolysis furnace; the cathode and the anode are electrically conductive through the mixed molten salt;

[0052] A feeding port is arranged at the upper part of the molten salt electrolysis furnace;

[0053] During the electrolysis of the mixed molten salt, direct current is connected, and electrolysis raw materials are added into the electrolysis molten salt through the feeding port at the upper part of the electrolysis cell. Under the action of direct current, an electrochemical reaction occurs, and aluminum-thorium alloy is obtained at the cathode, and CO and CO2 gases are generated at the anode.

[0054] Example 1

[0055] This example provides a preparation method of aluminum-thorium alloy, and the preparation method includes the following steps:

[0056] (1) Mix aluminum oxide, thorium oxide, sodium hexafluoroaluminate, aluminum fluoride, thorium fluoride, calcium fluoride and magnesium fluoride according to the formula amounts to obtain a mixed molten salt. The mixed molten salt includes: 6 parts of aluminum oxide, 6 parts of thorium oxide, 70 parts of sodium hexafluoroaluminate, 4 parts of aluminum fluoride, 2 parts of thorium fluoride, 5 parts of calcium fluoride, and 3 parts of magnesium fluoride;

[0057] (2) In an argon atmosphere, the mixed molten salt is held at 350 °C for 5 h, then heated to 950 °C and held for 15 h. Using tungsten as the cathode and graphite as the anode, electrolysis is carried out with a DC power supply. The electrolysis temperature is 950 °C and the current density is 2 A / cm 2 , and the electrolysis time is 15 h to obtain an aluminum-thorium alloy.

[0058] Example 2

[0059] This example provides a method for preparing an aluminum-thorium alloy, and the preparation method includes the following steps:

[0060] (1) Mix aluminum oxide, thorium oxide, sodium hexafluoroaluminate, aluminum fluoride, calcium fluoride, thorium fluoride and lithium fluoride according to the formula amounts to obtain a mixed molten salt. The mixed molten salt includes: 6 parts of aluminum oxide, 8 parts of thorium oxide, 75 parts of sodium hexafluoroaluminate, 2 parts of aluminum fluoride, 8 parts of calcium fluoride, 3 parts of thorium fluoride, and 4 parts of lithium fluoride;

[0061] (2) In a nitrogen atmosphere, the mixed molten salt is held at 250 °C for 10 h, then heated to 975 °C and held for 5 h. Using molybdenum as the cathode and graphite as the anode, electrolysis is carried out with a DC power supply. The electrolysis temperature is 975 °C and the current density is 4 A / cm 2 , and the electrolysis time is 10 h to obtain an aluminum-thorium alloy.

[0062] Example 3

[0063] This example provides a method for preparing an aluminum-thorium alloy, and the preparation method includes the following steps:

[0064] (1) Mix aluminum oxide, thorium oxide, sodium hexafluoroaluminate, thorium fluoride, calcium fluoride and magnesium fluoride according to the formula amounts to obtain a mixed molten salt. The mixed molten salt includes: 3 parts of aluminum oxide, 6 parts of thorium oxide, 65 parts of sodium hexafluoroaluminate, 5 parts of thorium fluoride, 2 parts of calcium fluoride, and 6 parts of magnesium fluoride;

[0065] (2) In a nitrogen atmosphere, the mixed molten salt is held at 500 °C for 15 h, then heated to 1000 °C and held for 1 h. Using graphite as the cathode and graphite as the anode, electrolysis is carried out with a DC power supply. The electrolysis temperature is 975 °C and the current density is 5 A / cm 2 , and the electrolysis time is 5 h to obtain an aluminum-thorium alloy.

[0066] Example 4

[0067] This example provides a method for preparing an aluminum-thorium alloy, and the preparation method includes the following steps:

[0068] (1) Mix alumina, thorium oxide, sodium hexafluoroaluminate, calcium fluoride, magnesium fluoride, thorium fluoride and lithium fluoride according to the formula amounts to obtain a mixed molten salt. The mixed molten salt includes: 4 parts of alumina, 6 parts of thorium oxide, 85 parts of sodium hexafluoroaluminate, 2 parts of calcium fluoride, 2 parts of magnesium fluoride, 4 parts of thorium fluoride, and 6 parts of lithium fluoride;

[0069] (2) In an argon atmosphere, the mixed molten salt is kept at 600 °C for 1 h, then heated to 950 °C and kept for 20 h. Using tungsten as the cathode and graphite as the anode, electrolysis is carried out with a DC power supply. The electrolysis temperature is 950 °C, and the electrolysis current density is 3 A / cm 2 , and the electrolysis time is 30 h to obtain an aluminum-thorium alloy.

[0070] Example 5

[0071] This example provides a method for preparing an aluminum-thorium alloy. The preparation method includes the following steps:

[0072] (1) Mix alumina, thorium oxide, sodium hexafluoroaluminate, aluminum fluoride and thorium fluoride according to the formula amounts to obtain a mixed molten salt. The mixed molten salt includes: 12 parts of alumina, 6 parts of thorium oxide, 70 parts of sodium hexafluoroaluminate, 4 parts of aluminum fluoride, and 2 parts of thorium fluoride;

[0073] (2) In an argon atmosphere, the mixed molten salt is kept at 100 °C for 20 h, then heated to 950 °C and kept for 10 h. Using molybdenum as the cathode and graphite as the anode, electrolysis is carried out with a DC power supply. The electrolysis temperature is 1000 °C, and the electrolysis current density is 0.5 A / cm 2 , and the electrolysis time is 25 h to obtain an aluminum-thorium alloy.

[0074] Example 6

[0075] This example provides a method for preparing an aluminum-thorium alloy. Except that the weight part of alumina in the mixed molten salt is 1 part, the rest are the same as in Example 1.

[0076] Example 7

[0077] This example provides a method for preparing an aluminum-thorium alloy. Except that the weight part of alumina in the mixed molten salt is 17 parts, the rest are the same as in Example 1.

[0078] Example 8

[0079] This example provides a method for preparing an aluminum-thorium alloy. Except that the weight part of thorium oxide in the mixed molten salt is 1 part, the rest are the same as in Example 1.

[0080] Example 9

[0081] This example provides a method for preparing an aluminum-thorium alloy. Except that the weight part of thorium oxide in the mixed molten salt is 17 parts, the rest are the same as in Example 1.

[0082] Example 10

[0083] This example provides a method for preparing an aluminum-thorium alloy. Except that the current density of electrolysis is 0.2 A / cm 2 the rest are the same as in Example 1.

[0084] Example 11

[0085] This example provides a method for preparing an aluminum-thorium alloy. Except that the current density of electrolysis is 6 A / cm 2 the rest are the same as in Example 1.

[0086] Example 12

[0087] This example provides a method for preparing an aluminum-thorium alloy. Except that the electrolysis temperature is 700 °C, the rest are the same as in Example 1.

[0088] Example 13

[0089] This example provides a method for preparing an aluminum-thorium alloy. Except that the electrolysis temperature is 1100 °C, the rest are the same as in Example 1.

[0090] The aluminum-thorium alloy obtained by the preparation methods in Examples 1-13 was tested. The test methods are as follows:

[0091] (1) Element mass ratio: The element mass ratio of aluminum and thorium in the aluminum-thorium alloy was obtained by X-ray fluorescence spectroscopy analysis;

[0092] (2) Electrolysis current efficiency: Calculate the current efficiency of aluminum and thorium respectively, and calculate the sum of the current efficiencies of aluminum and thorium;

[0093] The mass of the actual metal = the mass of the product × the element mass ratio in the alloy;

[0094] The current efficiency of the metal = (the mass of the actual metal / the mass of the metal obtained according to Faraday's law) × 100%;

[0095] The mass of the metal obtained according to Faraday's law = the current intensity × the energization time × the electrochemical equivalent of the metal;

[0096] The electrochemical equivalent refers to the mass of the metal produced by 1 Coulomb of electric charge.

[0097] The obtained results are shown in Table 1:

[0098] Table 1

[0099]

[0100]

[0101] It can be obtained from the data in Table 1 that:

[0102] (1) The thorium content of the aluminum-thorium alloy obtained by the preparation method of the aluminum-thorium alloy in Examples 1-5 is relatively high, and the current efficiency is relatively high. Using the molten salt electrolysis method to prepare the aluminum-thorium alloy, compared with the traditional preparation method of the aluminum-thorium alloy, the process is short, the equipment is simple, the cost is low, and the reaction conditions are easy to control.

[0103] (2) By comparing Example 1 with Examples 6 and 7, it can be seen that the content of alumina in the mixed molten salt will affect the contents of aluminum and thorium in the aluminum-thorium alloy, and will also affect the electrolysis current efficiency. When the content of alumina is too low, the content of aluminum ions in the mixed molten salt is relatively low, which will make it difficult for the reduction of aluminum ions and reduce the cathode current efficiency; when the content of alumina is too high, the content of aluminum ions in the mixed molten salt is too high, and it is difficult for thorium ions to deposit, which will lead to too low content of thorium ions in the aluminum-thorium alloy, thus affecting the performance of the aluminum-thorium alloy.

[0104] (3) By comparing Example 1 with Examples 8 and 9, it can be seen that the content of thorium oxide in the mixed molten salt will affect the contents of aluminum and thorium in the aluminum-thorium alloy, and will also affect the electrolysis current efficiency. When the content of thorium oxide is too low, the content of thorium ions in the mixed molten salt is relatively low, which will lead to too low content of thorium in the aluminum-thorium metal, thus affecting the performance of the aluminum-thorium metal; when the content of thorium oxide is too high, it will lead to a decrease in the cathode current efficiency.

[0105] (4) By comparing Example 1 with Examples 10 and 11, it can be seen that the current density of electrolysis will affect the contents of aluminum and thorium in the aluminum-thorium alloy, and will also affect the electrolysis current efficiency. When the current density of electrolysis is too large, the cathode overpotential increases, the cathode polarization increases, the cathode current efficiency decreases, the energy consumption is serious, and the edge effect is easy to occur, resulting in poor performance of the aluminum-thorium alloy; when the current density of electrolysis is too small, the cathode overpotential decreases, the cathode polarization is smaller, the electrolysis speed is slower, the crystallization of the aluminum-thorium alloy is coarser, the alloy performance is poor, and even the electrolysis process cannot proceed.

[0106] (5) By comparing Example 1 with Examples 12 and 13, it can be seen that in the present invention, the electrolysis temperature is limited to 900-1000 °C. When the electrolysis temperature is too high, the cathode overpotential becomes smaller, the cathode polarization decreases, which is not conducive to the precipitation of the aluminum-thorium alloy, and the energy consumption is relatively high, not meeting the requirements of energy conservation and environmental protection; when the electrolysis temperature is too low, the cathode overpotential becomes larger, the cathode polarization becomes larger, but too low temperature is not conducive to the transmission of ions in the mixed molten salt, which will lead to a decrease in the current efficiency, and the composition of the aluminum-thorium alloy is uneven. If the electrolysis temperature is not enough to make the mixed molten salt become ionic state, the electrolysis current is extremely low, and even the electrolysis cannot proceed.

[0107] In summary, the present invention uses the molten salt electrolysis method to prepare aluminum-thorium alloy. Compared with the traditional methods for preparing aluminum-thorium alloy, it has a shorter process, simpler equipment, lower cost, and the reaction conditions are easy to control. The preparation method described in the present invention can be used in the existing aluminum electrolysis system. By using the existing aluminum electrolysis cells with a capacity of 200 - 500 KA and adding thorium oxide and electrolyte at a certain concentration, aluminum-thorium alloy can be continuously produced without changing the structure and facilities of the existing aluminum electrolysis cells, and it is easy to realize industrial popularization and application.

[0108] In the specific embodiments described above, the purpose, technical solutions, and beneficial effects of the present invention have been further elaborated in detail. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of an aluminum-thorium alloy, characterized in that, The preparation method includes the following steps: (1) Mix alumina, thorium oxide and electrolyte to obtain a mixed molten salt; (2) Electrolyze the mixed molten salt after heating and melting in a protective gas to obtain an aluminum-thorium alloy; The electrolyte includes sodium hexafluoroaluminate and fluoride salt.

2. The preparation method according to claim 1, wherein The fluoride salt includes a combination of at least two of aluminum fluoride, thorium fluoride, calcium fluoride, magnesium fluoride or lithium fluoride.

3. The preparation method according to claim 1, characterized in that, The fluoride salt includes thorium fluoride and at least one of aluminum fluoride, calcium fluoride, magnesium fluoride or lithium fluoride.

4. The preparation method according to claim 2, wherein By weight, the mixed molten salt includes:

5. The preparation method according to claim 1, wherein The mixed molten salt obtained in step (1) is dried before heating and melting.

6. The preparation method according to claim 5, wherein The drying temperature is 100 - 600 °C and the time is 1 - 20 h.

7. The preparation method according to claim 1, characterized in that, The heating and melting in step (2) includes a heating process and a heat preservation process carried out in sequence.

8. The preparation method according to claim 7, characterized in that The heating rate is 1 - 10 °C / min.

9. The preparation method according to claim 7, characterized in that, The final temperature of the heating is 900 - 1000 °C.

10. The preparation method according to claim 7, characterized in that, The temperature of the heat preservation process is the final temperature of the heating.

11. The preparation method according to claim 7, wherein The time of the heat preservation process is 1 - 20 h.

12. The preparation method according to claim 1, wherein, The protective gas includes nitrogen and / or inert gas.

13. The preparation method according to claim 1, characterized in that, The cathode of the electrolysis includes any one of tungsten, molybdenum or graphite.

14. The preparation method according to claim 1, characterized in that, The anode of the electrolysis includes an inert electrode.

15. The preparation method according to claim 14, characterized in that, The inert electrode includes graphite.

16. The preparation method according to claim 1, characterized in that, The electrolysis uses a DC power supply.

17. The preparation method according to claim 1, wherein The current density of the electrolysis is 0.5 - 5 A / cm 2 .

18. The preparation method according to claim 1, characterized in that, The temperature of the electrolysis is 900 - 1000 °C.

19. The preparation method according to claim 1, characterized in that, The time of the electrolysis is 5 - 30 h.

20. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Mix alumina, thorium oxide and electrolyte according to the formula amount to obtain a mixed molten salt; (2) In a protective gas, the mixed molten salt is held at 100 - 600 °C for 1 - 20 h, heated to 900 - 1000 °C at a heating rate of 1 - 10 °C / min and held for 1 - 20 h. Using tungsten, molybdenum or graphite as the cathode and graphite as the anode, electrolysis is carried out with a DC power supply. The electrolysis temperature is 900 - 1000 °C and the electrolysis current density is 0.5 - 5 A / cm 2 , and the electrolysis time is 5 - 30 h to obtain an aluminum-thorium alloy.

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