A molten salt and a method for synthesizing the same

Abstract

The application discloses a molten salt and a synthesis method thereof, and the synthesis method comprises the following steps: performing ball milling treatment on an inorganic salt mixture to obtain the molten salt; the inorganic salt mixture comprises a first inorganic salt and a second inorganic salt, the first inorganic salt is any one or more of a fluorine salt, a chlorine salt, a carbonate salt, a nitrate salt, a sulfate salt, a phosphate salt and a silicate salt, the second inorganic salt is any one or more of a carbonate salt, a fluorine salt, a nitrate salt, a chlorine salt, a sulfate salt, a phosphate salt and a silicate salt, the first inorganic salt and the second inorganic salt are different from each other, the molar content of any inorganic salt in the inorganic salt mixture is not more than 90%, and the rotating speed of ball milling is 200-800 rpm; the molten salt is synthesized by the ball milling method in one step, an additional heat source supply is not needed, and energy consumption is greatly reduced.

Description

Technical Field

[0001] This invention relates to a molten salt and a method for synthesizing the same. Background Technology

[0002] Molten salts are a class of inorganic salt mixtures that are liquid at high temperatures. They are typically solid at room temperature but transform into a liquid upon heating. These substances have attracted widespread attention due to their unique physicochemical properties, such as high heat capacity, excellent thermal conductivity, a wide liquidus temperature range, and good wetting properties for various metals. These advantages make molten salts indispensable materials in many industrial fields, such as energy storage systems, nuclear reactor cooling, metal processing and refining in metallurgical processes, and efficient heat transfer media in solar thermal power generation technology.

[0003] In particular, commonly used molten salt components of fluoride molten salts include lithium fluoride, beryllium fluoride, zirconium fluoride, thorium fluoride, sodium fluoride, and potassium fluoride. These components maintain stability and safety under extreme high-temperature environments, prompting their exploration for application in advanced nuclear energy systems—including fourth-generation fission reactors and future fusion reactors—as coolants or fuel carriers. Molten salt batteries commonly use components such as sodium chloride, potassium chloride, lithium chloride, calcium chloride, and magnesium chloride. The melting points of molten salts are typically between 300°C and 700°C, exhibiting high heat capacity and thermal conductivity. Molten salt batteries utilize these molten salts as electrolytes, achieving efficient energy storage and release, demonstrating great potential for large-scale power grid energy storage. Furthermore, the high-temperature heat transfer and storage properties of molten salts are widely used in solar thermal power generation. Currently, the molten salts widely used both domestically and internationally are generally nitrate molten salts, such as Solar salt (40% KNO3-60% NaNO3) and Hitec (40% NaNO2-7% NaNO3-53% KNO3). Carbonate molten salts, due to their good thermal stability below 850 °C, high specific heat capacity, and low viscosity, also show great promise for high-temperature heat transfer and storage. In conclusion, with the increasing global demand for clean energy solutions, the research and application areas of molten salts are expected to expand further, continuing to play a crucial role in modern industry and technological progress.

[0004] However, traditional molten salt preparation methods rely heavily on high-temperature heating and complex chemical synthesis steps, which not only increase costs but also burden the environment. Traditional processes are extremely energy-intensive, highly corrosive to containers and equipment, and increase construction and maintenance costs and complexity. Furthermore, the complex chemical processing steps not only raise technical requirements but may also lead to the generation of harmful byproducts, increasing process complexity and safety risks. Due to harsh operating conditions (such as high temperature and pressure) and the handling of hazardous chemicals, this process poses certain safety hazards. In addition, batch-to-batch quality variations are also a problem; different batches of products may have inconsistent quality, which is particularly detrimental to applications with extremely high safety requirements. Finally, traditional molten salt preparation is a time-consuming process, potentially taking weeks or even months from raw material preparation to finished product, hindering rapid response to market demands. Therefore, researchers are exploring more efficient and environmentally friendly methods to improve production processes, reduce energy consumption, minimize byproducts and waste, and improve production efficiency and product quality consistency. Summary of the Invention

[0005] The purpose of this invention is to address the problems of high energy consumption, low efficiency, and poor quality stability in existing molten salt synthesis methods, and to provide a molten salt and its synthesis method. This invention utilizes the vibration generated by a ball mill to provide continuous mechanical energy, thereby replacing traditional thermal energy as the reaction driving force.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0007] This invention provides a method for synthesizing molten salt, which includes the following steps:

[0008] The inorganic salt mixture was ball-milled to obtain molten salt;

[0009] The inorganic salt mixture includes a first inorganic salt and a second inorganic salt. The first inorganic salt is any one or more of fluoride, chloride, carbonate, nitrate, sulfate, phosphate and silicate. The second inorganic salt is any one or more of carbonate, fluoride, nitrate, chloride, sulfate, phosphate and silicate. The first inorganic salt and the second inorganic salt are not the same.

[0010] The molar percentage of any one inorganic salt in the inorganic salt mixture is no more than 90%, where % refers to the proportion of the molar percentage of any one inorganic salt to the total molar percentage of all inorganic salts in the inorganic salt mixture.

[0011] The ball mill rotates at a speed of 200-800 rpm.

[0012] This invention employs a mechanochemical ball milling synthesis strategy to prepare a reaction mixture of salts from various systems in a specific ratio. After homogenization, molten salts can be synthesized without the need for high-temperature melting or complex reaction conditions. This not only accelerates the reaction rate of molten salt synthesis but also increases the yield and reduces operational risks. The entire process does not require high-temperature treatment, reducing equipment requirements and mitigating safety hazards arising from harsh operating conditions.

[0013] In some embodiments of the present invention, the rotational speed is 400 to 720 rpm, for example 400 rpm, 600 rpm or 720 rpm.

[0014] Preferably, when the inorganic salt mixture contains fluoride salts, the rotation speed is 400-720 rpm; more preferably, when the inorganic salt mixture is LiF, NaF, and KF, the rotation speed is 350-450 rpm, for example, 400 rpm; even more preferably, when the inorganic salt mixture contains BeF2, ZrF4, RbF, or UF4, the rotation speed is 600-720 rpm.

[0015] Preferably, when the inorganic salt mixture contains chloride, nitrate, or carbonate, the rotation speed is 600-720 rpm. For example, when the inorganic salt mixture is a mixture of KCl and MgCl2, the rotation speed is 720 rpm; when the inorganic salt mixture is a mixture of NaNO3 and KNO3 or a mixture of NaNO3, NaNO2, and KNO3, the rotation speed is 720 rpm; when the inorganic salt mixture is a mixture of Na2CO3, Li2CO3, and K2CO3, the rotation speed is 600 rpm.

[0016] In some embodiments of the present invention, the weight ratio of the grinding balls in the ball milling process to the inorganic salt mixture is (1~200):1, preferably (1~100):1, for example 2.9:1, 4.17:1, 4.7:1, 5.2:1, 7.25:1, 7.5:1, 8.8:1, 9.8:1, 10.6:1, 11.7:1, 26.5:1, 32.8:1, 33.4:1, 36.5:1, 37.4:1, 42.7:1, 48.4:1, 72.9:1, 87.4:1 or 88:1.

[0017] In some embodiments of the present invention, the ball milling treatment time is 0.25 to 15 hours, for example, 0.25 hours, 2 hours, 3 hours, 6 hours, 8 hours, 10 hours, 12 hours or 15 hours.

[0018] In some embodiments of the present invention, the grinding balls used in the ball milling process are any one of polytetrafluoroethylene balls, zirconia balls, stainless steel balls, tungsten carbide balls, and agate balls, with polytetrafluoroethylene balls being preferred.

[0019] In some embodiments of the present invention, the grinding balls of the ball milling process have a particle size of 5 to 10 mm, for example, 5 mm, 8 mm or 10 mm; preferably, the grinding balls are composed of grinding balls of 5 mm, 8 mm and 10 mm, and more preferably, the weight ratio of grinding balls of 5 mm, 8 mm and 10 mm is 3:5:2.

[0020] In some embodiments of the present invention, the ball milling method includes the following steps: adding the inorganic salt mixture and grinding balls into a ball mill jar, and performing ball milling on a ball mill.

[0021] The grinding jar is conventional in the art. In some embodiments of the present invention, the grinding jar is any one of stainless steel jar, polytetrafluoroethylene jar, Hastelloy jar, nickel jar, and Teflon-lined jar, preferably a polytetrafluoroethylene jar.

[0022] The ball mill mentioned is conventional in the art, such as dry ball mill, wet ball mill, vertical ball mill, stirred ball mill, planetary ball mill, tube ball mill, rod ball mill, cement ball mill, ultrafine laminated mill, hand ball mill, horizontal ball mill, energy-saving ball mill, overflow ball mill, ceramic ball mill, grid ball mill, or cylindrical ball mill;

[0023] Preferably, the ball mill is a planetary ball mill, such as the YXQM-1L planetary ball mill from Changsha Miqi.

[0024] Preferably, the power of the ball mill is 30~50 Hz;

[0025] The volume of the ball mill jar is determined according to the material size. In some embodiments, the volume of the ball mill jar is 10 to 10,000 mL, for example, 100 mL.

[0026] In this invention, the ball milling process can be carried out in a gas, which can be a mixture of air, nitrogen, argon, helium, nitrogen and hydrogen fluoride, or a mixture of nitrogen and fluorine, and is generally air.

[0027] In this invention, the fluoride, chloride, carbonate, nitrate, sulfate, phosphate and silicate are conventional in the art.

[0028] In some embodiments of the present invention, the fluoride salt is an alkali metal fluoride salt, BeF2, CaF2, ZrF4, ThF4, or UF4, and the alkali metal fluoride salt is preferably LiF4. 7 LiF, NaF, KF, or RbF.

[0029] In some embodiments of the present invention, the chloride salt is an ionic chloride salt and / or a polymeric chloride salt, wherein the ionic chloride salt is preferably KCl, CaCl2, or MgCl2, and the polymeric chloride salt is preferably Zn. n Cl n Or Be n Cl n .

[0030] In some embodiments of the present invention, the carbonate is an alkali metal carbonate, preferably K2CO3 or Na2CO3.

[0031] In some embodiments of the present invention, the nitrate is an alkali metal nitrate, preferably NaNO3 or KNO3.

[0032] In some embodiments of the present invention, the sulfate is an alkali metal sulfate, preferably K2SO4.

[0033] In some embodiments of the present invention, the phosphate is an alkali metal phosphate, preferably Li2P2O7 or Na4P2O7.

[0034] In some embodiments of the present invention, the silicate is an alkali metal silicate, preferably Na2SiO3.

[0035] In a preferred embodiment of the present invention, the molar percentage of any one inorganic salt in the inorganic salt mixture is no more than 80%.

[0036] Preferably, when the inorganic salt mixture contains fluoride salts, the molar percentage of fluoride salts in the inorganic salt mixture is not greater than 80%.

[0037] More preferably, when the inorganic salt mixture contains BeF2, the molar percentage of BeF2 in the inorganic salt mixture is no more than 50%. More preferably, the molar percentage of BeF2 in the inorganic salt mixture is 10-50%, for example, 16.8%, 30%, 30.5%, 33%, 38%, or 43%.

[0038] More preferably, when the inorganic salt mixture contains ZrF4, the molar percentage of ZrF4 in the inorganic salt mixture is no more than 50%. More preferably, the molar percentage of ZrF4 in the inorganic salt mixture is 3-50%, for example, 5%, 29%, 40.5%, 42%, 43%, or 49%.

[0039] More preferably, when the inorganic salt mixture contains UF4, the molar percentage of UF4 in the inorganic salt mixture is 0.05~1%, for example 0.1% or 0.4%;

[0040] More preferably, when the inorganic salt mixture contains ThF4, the molar percentage of ThF4 in the inorganic salt mixture is 5-8%, for example, 6.8%.

[0041] Preferably, when the inorganic salt mixture contains chloride salts, the molar percentage of chloride salts in the inorganic salt mixture is no more than 85%. More preferably, the molar percentage of chloride salts in the inorganic salt mixture is 30-85%, for example, 32%, 68%, or 80%.

[0042] Preferably, when the inorganic salt mixture contains carbonates, the molar percentage of carbonates in the inorganic salt mixture is no more than 50%; more preferably, the molar percentage of carbonates in the inorganic salt mixture is 25-50%, for example, 30% or 40%.

[0043] Preferably, when the inorganic salt mixture contains nitrate, the molar percentage of nitrate in the inorganic salt mixture is no more than 60%. More preferably, the molar percentage of nitrate in the inorganic salt mixture is 5-60%, for example, 7%, 44%, 48%, 49% or 52%.

[0044] In some embodiments of the present invention, the inorganic salt mixture may be a mixture of 2 to 4 types of fluoride salts, a mixture of 2 types of chloride salts, a mixture of 2 to 3 types of nitrate salts, or a mixture of 3 types of carbonate salts.

[0045] In some embodiments of the present invention, the inorganic salt mixture is a mixture of LiF, NaF, and KF; a mixture of LiF and BeF2; a mixture of NaF and BeF2; a mixture of LiF, NaF, and BeF2; a mixture of NaF and ZrF4; a mixture of KF and ZrF4; a mixture of LiF and ZrF4; a mixture of LiF and RbF; a mixture of LiF, NaF, and RbF; a mixture of LiF, NaF, and ZrF4; a mixture of RbF and ZrF4; a mixture of LiF, BeF2, and ZrF4; or a mixture of NaF, RbF, and ZrF4. 7 A mixture of LiF, BeF2, ZrF4 and UF4 7 Any one of the following: a mixture of LiF, BeF2, ThF4 and UF4; a mixture of KCl and MgCl2; a mixture of NaNO3 and KNO3; a mixture of NaNO3, NaNO2 and KNO3; a mixture of Na2CO3, Li2CO3 and K2CO3; or a mixture of CaCl2 and CaF2.

[0046] When the inorganic salt mixture is a mixture of LiF, NaF and KF, preferably, the molar percentage of LiF is 40-60%, the molar percentage of NaF is 10-30%, and the molar percentage of KF is 30-50%; more preferably, the molar percentage of LiF is 46.5%, the molar percentage of NaF is 11.5%, and the molar percentage of KF is 42%.

[0047] When the inorganic salt mixture is a mixture of LiF and BeF2, preferably, the molar percentage of LiF is 50-70% and the molar percentage of BeF2 is 30-50%, more preferably, the molar percentage of LiF is 67% and the molar percentage of BeF2 is 33%.

[0048] When the inorganic salt mixture is a mixture of NaF and BeF2, preferably, the molar percentage of NaF is 57% and the molar percentage of BeF2 is 43%.

[0049] When the inorganic salt mixture is a mixture of LiF, NaF and BeF2, preferably, the molar percentage of LiF is 31%, the molar percentage of NaF is 31%, and the molar percentage of BeF2 is 38%.

[0050] When the inorganic salt mixture is a mixture of NaF and ZrF4, preferably, the molar percentage of NaF is 59.5% and the molar percentage of ZrF4 is 40.5%.

[0051] When the inorganic salt mixture is a mixture of KF and ZrF4, preferably, the molar percentage of KF is 58% and the molar percentage of ZrF4 is 42%.

[0052] When the inorganic salt mixture is a mixture of LiF and ZrF4, preferably, the molar percentage of LiF is 51% and the molar percentage of ZrF4 is 49%.

[0053] When the inorganic salt mixture is a mixture of LiF and RbF, preferably, the molar percentage of LiF is 44% and the molar percentage of RbF is 56%.

[0054] When the inorganic salt mixture is a mixture of LiF, NaF and RbF, preferably, the molar percentage of LiF is 42%, the molar percentage of NaF is 6%, and the molar percentage of RbF is 52%.

[0055] When the inorganic salt mixture is a mixture of LiF, NaF and ZrF4, preferably, the molar percentage of LiF is 42%, the molar percentage of NaF is 29%, and the molar percentage of ZrF4 is 29%.

[0056] When the inorganic salt mixture is a mixture of RbF and ZrF4, preferably, the molar percentage of RbF is 58% and the molar percentage of ZrF4 is 42%.

[0057] When the inorganic salt mixture is a mixture of LiF, BeF2 and ZrF4, preferably, the molar percentage of LiF is 64.5%, the molar percentage of BeF2 is 30.5%, and the molar percentage of ZrF4 is 5%.

[0058] When the inorganic salt mixture is a mixture of NaF, RbF and ZrF4, preferably, the molar percentage of NaF is 33%, the molar percentage of RbF is 24%, and the molar percentage of ZrF4 is 43%.

[0059] When the inorganic salt mixture is 7 When a mixture of LiF, BeF2, ZrF4 and UF4 is used, preferably, 7 The molar percentages of LiF are 65%, BeF2 is 30%, ZrF4 is 5%, and UF4 is 0.1%.

[0060] When the inorganic salt mixture is a mixture of LiF, BeF2, ThF4 and UF4, preferably, the molar percentage of LiF is 72%, the molar percentage of BeF2 is 16%, the molar percentage of ThF4 is 6.5%, and the molar percentage of UF4 is 0.4%.

[0061] When the inorganic salt mixture is a mixture of KCl and MgCl2, preferably, the molar percentage of KCl is 68% and the molar percentage of MgCl2 is 32%.

[0062] When the inorganic salt mixture is a mixture of NaNO3 and KNO3, preferably, the molar percentage of NaNO3 is 48% and the molar percentage of KNO3 is 52%.

[0063] When the inorganic salt mixture is a mixture of NaNO3, NaNO2 and KNO3, preferably, the molar percentage of NaNO3 is 7%, the molar percentage of NaNO2 is 49%, and the molar percentage of KNO3 is 44%.

[0064] When the inorganic salt mixture is a mixture of Na2CO3, Li2CO3 and K2CO3, preferably, the molar percentage of Na2CO3 is 30%, the molar percentage of Li2CO3 is 30%, and the molar percentage of K2CO3 is 40%.

[0065] When the inorganic salt mixture is a mixture of CaCl2 and CaF2, preferably, the molar percentage of CaCl2 is 80% and the molar percentage of CaF2 is 20%.

[0066] The present invention also provides a molten salt synthesized by the aforementioned method for synthesizing molten salt.

[0067] In some embodiments of the present invention, the extrapolated melting initiation temperature of the molten salt is 100~800℃, preferably 130~700℃, for example 142℃, 222℃, 319℃, 337℃, 390℃, 410℃, 420℃, 426℃, 428℃, 434℃, 435℃, 451℃, 453℃, 460℃, 470℃, 496℃, 497℃, 509℃ or 698℃.

[0068] In some embodiments of the present invention, the molten salt is LiF-NaF-KF, LiF-BeF2, NaF-BeF2, LiF-NaF-BeF2, NaF-ZrF4, KF-ZrF4, LiF-ZrF4, LiF-RbF, LiF-NaF-RbF, LiF-NaF-ZrF4, RbF-ZrF4, LiF-BeF2-ZrF4, NaF-RbF-ZrF4, 7 LiF-BeF2-ZrF4-UF4, 7 LiF-BeF2-ThF4-UF4, KCl-MgCl2, NaNO3-KNO3, NaNO3-NaNO2-KNO3, Na2CO3-Li2CO3-K2CO3 or CaCl2-CaF2.

[0069] The positive and progressive effects of this invention are as follows:

[0070] This invention synthesizes molten salt in one step using ball milling, eliminating the need for an additional heat source and significantly reducing energy consumption;

[0071] The method of this invention simplifies the production process, eliminates cumbersome chemical treatment steps, reduces waste emissions, and conforms to the principles of green chemistry.

[0072] The method of the present invention has mild reaction conditions, is easy to control, and is suitable for large-scale industrial applications;

[0073] The method of this invention can significantly shorten the production cycle. For example, the LiF-NaF-KF system can be synthesized in just 15 minutes, which greatly improves production efficiency.

[0074] Because the reaction process of this invention is stable and reliable, the consistency of product quality between different batches is guaranteed, making it suitable for application scenarios with extremely high requirements for safety and stability. Attached Figure Description

[0075] Figure 1 The XRD pattern of LiF-NaF-KF obtained in Example 1 of the present invention is shown.

[0076] Figure 2 The DSC diagram of LiF-NaF-KF obtained in Example 1 of the present invention is shown.

[0077] Figure 3 The XRD pattern of LiF-BeF2 obtained in Embodiment 2 of the present invention is shown.

[0078] Figure 4 The DSC diagram of LiF-BeF2 obtained in Embodiment 2 of the present invention is shown.

[0079] Figure 5 The XRD pattern of the product obtained in Comparative Example 1 of the present invention is shown.

[0080] Figure 6 The DSC diagram of the product obtained in Comparative Example 1 of the present invention is shown.

[0081] Figure 7 The XRD pattern of NaF-BeF2 obtained in Example 3 of the present invention is shown.

[0082] Figure 8 The DSC diagram of NaF-BeF2 obtained in Example 3 of the present invention is shown.

[0083] Figure 9 The XRD pattern of the product obtained in Comparative Example 2 of the present invention is shown.

[0084] Figure 10 The DSC diagram of the product obtained in Comparative Example 2 of the present invention is shown.

[0085] Figure 11 The XRD pattern of LiF-NaF-BeF2 obtained in Example 4 of the present invention is shown.

[0086] Figure 12 The DSC diagram of NaF-ZrF4 obtained in Example 5 of the present invention is shown.

[0087] Figure 13 The DSC diagram of KCl-MgCl2 obtained in Example 16 of the present invention is shown.

[0088] Figure 14 The DSC diagram of Na2CO3-Li2CO3-K2CO3 obtained in Example 19 of the present invention is shown. Detailed Implementation

[0089] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0090] All raw materials used in the examples were commercially available, and the ball mills used in the following examples were all YXQM-1L planetary ball mills from Changsha Miqi.

[0091] Example 1

[0092] Under air conditions, LiF (46.5 mmol, 1.21 g), NaF (11.5 mmol, 0.48 g), KF (42 mmol, 2.44 g), and PTFE balls were added to a PTFE ball mill jar with a ball-to-material ratio of 10.6:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The jar was placed in a planetary ball mill and ground at 400 rpm for 15 min to obtain the product.

[0093] The product was characterized by XRD and DSC, and the results are as follows: Figure 1 and Figure 2 As shown, the extrapolated melting initiation temperature of the product is 453℃, and the product prepared in this embodiment is LiF-NaF-KF (abbreviated as FLiNaK).

[0094] Example 2

[0095] Under air conditions, LiF (100 mmol, 2.59 g), BeF2 (50 mmol, 2.37 g), and PTFE balls were added to a PTFE ball mill jar with a ball-to-material ratio of 8.8:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The jar was placed in a planetary ball mill and ground at 600 rpm for 15 hours to obtain the product.

[0096] The product was characterized by XRD and DSC, and the results are as follows: Figure 3 and Figure 4 As shown in the PDF card for Li₂BeF₄, 2θ diffraction peaks of Li₂BeF₄ are observed at 22.73°, 26.81°, 33.01°, 35.72°, 38.29°, 40.70°, 47.36°, 49.41°, 57.11°, and 69.22°. Figure 3 As can be seen from the DSC, the product prepared in this embodiment is consistent with its characteristic diffraction peak. The extrapolated melting onset temperature of the molten salt prepared in this embodiment is 451℃. The product prepared in this embodiment is LiF-BeF2 (abbreviated as Li2BeF4).

[0097] Comparative Example 1

[0098] This comparative example is basically the same as Example 2, except that the ball milling speed in this comparative example is 400 rpm and the grinding time is 18 h.

[0099] The product was characterized by XRD and DSC, and the results are as follows: Figure 5 and Figure 6 As shown, Li2BeF4 was not obtained.

[0100] Example 3

[0101] Under air conditions, NaF (57 mmol, 2.39 g), BeF2 (43 mmol, 2.04 g), and PTFE balls were added to a PTFE ball mill jar at a ball-to-material ratio of 9.8:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The mixture was then placed in a planetary ball mill and ground at 600 rpm for 12 hours to obtain the product.

[0102] The product was characterized by XRD and DSC, and the results are as follows: Figure 6 and Figure 8 As shown in the diagram, according to the PDF card for NaBeF3, 2θ diffraction peaks of NaBeF3 are observed at 23.39°, 25.88°, 27.42°, 30.59°, 39.13°, 40.23°, 42.19°, 50.85°, 52.16°, and 54.76°. Figure 5 As can be seen from the data, the product prepared in this embodiment has the same characteristic diffraction peaks as NaBeF3, and the extrapolated melting onset temperature of the product is 337℃. The product prepared in this embodiment is NaF-BeF2 (abbreviated as NaBeF3).

[0103] Comparative Example 2

[0104] This comparative example is basically the same as Example 3, except that the ball milling speed in this comparative example is 400 rpm and the grinding time is 15 h.

[0105] The product was characterized by XRD and DSC. The results are as follows: Figure 9 and Figure 10 As shown, NaF-BeF2 could not be obtained.

[0106] Example 4

[0107] Under air conditions, LiF (15.5 mmol, 0.40 g), NaF (15.5 mmol, 2.44 g), BeF2 (19 mmol, 0.90 g), and PTFE balls were added to a PTFE ball mill jar with a ball-to-material ratio of 11.7:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The jar was placed in a planetary ball mill and ground at 720 rpm for 2 hours to obtain the product.

[0108] The product was characterized by DSC, and the results are as follows: Figure 11 As shown, the extrapolated melting initiation temperature of the product is 319℃, and the product is LiF-NaF-BeF2.

[0109] Example 5

[0110] Under air conditions, NaF (59.5 mmol, 2.50 g), ZrF4 (40.5 mmol, 6.77 g), and zirconia balls were added to a polytetrafluoroethylene ball mill jar with a ball-to-material ratio of 37.4:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The jar was placed in a planetary ball mill and ground at 720 rpm for 6 h to obtain the product.

[0111] The product was characterized by DSC, and the results are as follows: Figure 12 As shown, the extrapolated melting initiation temperature of the product is 496℃, and the product is NaF-ZrF4.

[0112] Example 6

[0113] Under air conditions, KF (58 mmol, 3.37 g), ZrF4 (42 mmol, 7.02 g), and zirconia balls were added to a polytetrafluoroethylene ball mill jar with a ball-to-material ratio of 33.4:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The jar was placed in a planetary ball mill and ground at 720 rpm for 6 hours to obtain the product.

[0114] The product was characterized by DSC, and the extrapolated melt onset temperature of the product was 390℃. The product was identified as KF-ZrF4.

[0115] Example 7

[0116] Under air conditions, LiF (51 mmol, 1.32 g), ZrF4 (49 mmol, 8.19 g), and zirconia balls were added to a polytetrafluoroethylene ball mill jar with a ball-to-material ratio of 36.5:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The jar was placed in a planetary ball mill and ground at 720 rpm for 6 hours to obtain the product.

[0117] The product was characterized by DSC, and the extrapolated melt onset temperature of the product was 509℃. The product was identified as LiF-ZrF4.

[0118] Example 8

[0119] Under air conditions, LiF (44 mmol, 1.14 g), RbF (56 mmol, 5.85 g), and agate balls were added to a polytetrafluoroethylene ball mill jar with a ball-to-material ratio of 7.25:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small grinding balls of 3:5:2. The jar was placed in a planetary ball mill and ground at 600 rpm for 10 hours to obtain the product.

[0120] The product was characterized by DSC, and the extrapolated melt onset temperature of the product was 470℃. The product was identified as LiF-RbF.

[0121] Example 9

[0122] Under air conditions, LiF (42 mmol, 1.09 g), NaF (6 mmol, 0.25 g), RbF (52 mmol, 5.43 g), and agate balls were added to a polytetrafluoroethylene ball mill jar with a ball-to-material ratio of 7.5:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small grinding balls of 3:5:2. The jar was placed in a planetary ball mill and ground at 600 rpm for 8 hours to obtain the product.

[0123] The product was characterized by DSC, and the extrapolated melt onset temperature of the product was 435℃. The product was identified as LiF-NaF-RbF.

[0124] Example 10

[0125] Under air conditions, LiF (42 mmol, 1.09 g), NaF (29 mmol, 1.22 g), ZrF4 (29 mmol, 4.85 g), and zirconia balls were added to a polytetrafluoroethylene ball mill jar with a ball-to-material ratio of 48.4:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The mixture was placed in a planetary ball mill and ground at 720 rpm for 8 hours to obtain the product.

[0126] The product was characterized by DSC, and the extrapolated melt onset temperature of the product was 460℃. The product was identified as LiF-NaF-ZrF4.

[0127] Example 11

[0128] Under air conditions, RbF (58 mmol, 6.06 g), ZrF4 (42 mmol, 7.02 g), and zirconia balls were added to a polytetrafluoroethylene ball mill jar with a ball-to-material ratio of 26.5:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The jar was placed in a planetary ball mill and ground at 720 rpm for 8 hours to obtain the product.

[0129] The product was characterized by DSC, and the extrapolated melt onset temperature of the product was 410℃. The product was identified as RbF-ZrF4.

[0130] Example 12

[0131] Under air conditions, LiF (64.5 mmol, 1.67 g), BeF2 (30.5 mmol, 1.43 g), ZrF4 (5 mmol, 0.84 g), and zirconia balls were added to a polytetrafluoroethylene ball mill jar with a ball-to-material ratio of 88:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The mixture was placed in a planetary ball mill and ground at 720 rpm for 12 hours to obtain the product.

[0132] The product was characterized by DSC, and the extrapolated melt onset temperature of the product was 428℃. The product was identified as LiF-BeF2-ZrF4.

[0133] Example 13

[0134] Under air conditions, NaF (33 mmol, 0.86 g), RbF (24 mmol, 2.51 g), ZrF4 (43 mmol, 7.19 g), and zirconia balls were added to a polytetrafluoroethylene ball mill jar with a ball-to-material ratio of 32.8:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The jar was placed in a planetary ball mill and ground at 720 rpm for 8 hours to obtain the product.

[0135] The product was characterized by DSC, and the extrapolated melt onset temperature of the product was 420℃. The product was identified as NaF-RbF-ZrF4.

[0136] Example 14

[0137] Add to the polytetrafluoroethylene ball mill jar under air conditions. 7LiF (65 mmol, 1.69 g), BeF2 (30 mmol, 1.41 g), ZrF4 (5 mmol, 0.84 g), UF4 (0.1 mmol, 0.03 g), and zirconia balls were prepared with a ball-to-material ratio of 87.4:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The mixture was placed in a planetary ball mill and ground at 600 rpm for 15 hours to obtain the product.

[0138] The product was characterized by DSC, and the extrapolated melt onset temperature was 434℃. The product was... 7 LiF-BeF2-ZrF4-UF4.

[0139] Example 15

[0140] Under air conditions, LiF (72 mmol, 1.87 g), BeF2 (16 mmol, 0.75 g), ThF4 (6.5 mmol, 2.01 g), UF4 (0.4 mmol, 0.13 g), and zirconia balls were added to a polytetrafluoroethylene ball mill jar with a ball-to-material ratio of 72.9:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small grinding balls of 3:5:2. The mixture was placed in a planetary ball mill and ground at 600 rpm for 15 hours to obtain the product.

[0141] The product was characterized by DSC. The extrapolated melting onset temperature of the molten salt was 497℃, and the product was identified as LiF-BeF2-ThF4-UF4.

[0142] Example 16

[0143] Under air conditions, KCl (68 mmol, 5.07 g), MgCl2 (32 mmol, 3.05 g), and zirconia balls were added to a polytetrafluoroethylene ball mill jar with a ball-to-material ratio of 42.7:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The jar was placed in a planetary ball mill and ground at 720 rpm for 3 hours to obtain the product.

[0144] The product was characterized by DSC, and the results are as follows: Figure 13 As shown, the extrapolated melting initiation temperature of the product is 426℃, and the product is KCl-MgCl2.

[0145] Example 17

[0146] Under air conditions, NaNO3 (48 mmol, 4.08 g), KNO3 (52 mmol, 5.26 g), and PTFE balls were added to a PTFE ball mill jar with a ball-to-material ratio of 4.7:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The jar was placed in a planetary ball mill and ground at 720 rpm for 3 hours to obtain the product.

[0147] The product was characterized by DSC, and the extrapolated melt onset temperature of the product was 222℃. The product was NaNO3-KNO3.

[0148] Example 18

[0149] Under air conditions, NaNO3 (7 mmol, 0.59 g), NaNO2 (49 mmol, 3.38 g), KNO3 (44 mmol, 4.45 g), and PTFE balls were added to a PTFE ball mill jar with a ball-to-material ratio of 5.2:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The jar was placed in a planetary ball mill and ground at 720 rpm for 3 hours to obtain the product.

[0150] The product was characterized by DSC, and the extrapolated melting onset temperature of the product was 142℃. The product was NaNO3-NaNO2-KNO3.

[0151] Example 19

[0152] Under air conditions, Na2CO3 (28 mmol, 3.00 g), Li2CO3 (41 mmol, 3.00 g), K2CO3 (29 mmol, 4.00 g), and PTFE balls were added to a PTFE ball mill jar with a ball-to-material ratio of 2.9:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm, with a weight ratio of large, medium, and small particles of 3:5:2. The jar was placed in a planetary ball mill and ground at 600 rpm for 2 hours to obtain the product.

[0153] The product was characterized by DSC, and the results are as follows: Figure 14 As shown, the extrapolated melting initiation temperature of the product is 390℃, and the product is Na2CO3-Li2CO3-K2CO3.

[0154] Example 20

[0155] Under air conditions, high-purity anhydrous CaCl2 (80 mmol, 8.88 g), high-purity anhydrous CaF2 (20 mmol, 1.56 g), and PTFE balls were added to a PTFE ball mill jar. The ball-to-material ratio was 4.17:1. The grinding balls included three particle sizes: 10 mm, 8 mm, and 5 mm. The weight ratio of the large, medium, and small grinding balls was 3:5:2. The jar was placed in a planetary ball mill and ground at 720 rpm for 3 hours to obtain the product.

[0156] The product was characterized by DSC, and the extrapolated melting onset temperature of the product was 698℃. The product was CaCl2-CaF2.

Claims

1. A method for synthesizing molten salt, characterized in that, It includes the following steps: The inorganic salt mixture was ball-milled to obtain molten salt; The inorganic salt mixture includes a first inorganic salt and a second inorganic salt. The first inorganic salt is any one or more of fluoride, chloride, carbonate, nitrate, sulfate, phosphate and silicate. The second inorganic salt is any one or more of carbonate, fluoride, nitrate, chloride, sulfate, phosphate and silicate. The first inorganic salt and the second inorganic salt are not the same. The molar percentage of any one inorganic salt in the inorganic salt mixture is no more than 90%, where % refers to the proportion of the molar percentage of any one inorganic salt to the total molar percentage of all inorganic salts in the inorganic salt mixture. The ball mill rotates at a speed of 200-800 rpm.

2. The method for synthesizing molten salt as described in claim 1, characterized in that, The method for synthesizing the molten salt satisfies one or more of the following conditions: (1) The rotational speed is 400~720 rpm, for example 400 rpm, 600 rpm or 720 rpm; Preferably, when the inorganic salt mixture contains fluoride salts, the rotation speed is 400-720 rpm; more preferably, when the inorganic salt mixture is LiF, NaF, and KF, the rotation speed is 350-450 rpm, for example, 400 rpm; even more preferably, when the inorganic salt mixture contains BeF2, ZrF4, RbF, or UF4, the rotation speed is 600-720 rpm. Preferably, when the inorganic salt mixture contains chlorides, nitrates, or carbonates, the rotation speed is 600-720 rpm. For example, when the inorganic salt mixture is a mixture of KCl and MgCl2, the rotation speed is 720 rpm; when the inorganic salt mixture is a mixture of NaNO3 and KNO3 or a mixture of NaNO3, NaNO2, and KNO3, the rotation speed is 720 rpm; when the inorganic salt mixture is a mixture of Na2CO3, Li2CO3, and K2CO3, the rotation speed is 600 rpm. (2) The weight ratio of the grinding balls in the ball milling process to the inorganic salt mixture is (1~200):1, preferably (1~100):1, for example 2.9:1, 4.17:1, 4.7:1, 5.2:1, 7.25:1, 7.5:1, 8.8:1, 9.8:1, 10.6:1, 11.7:1, 26.5:1, 32.8:1, 33.4:1, 36.5:1, 37.4:1, 42.7:1, 48.4:1, 72.9:1, 87.4:1 or 88:1; (3) The ball milling time is 0.25~15h, for example 0.25h, 2h, 3h, 6h, 8h, 10h, 12h or 15h.

3. The method for synthesizing molten salt as described in claim 1, characterized in that, The grinding balls used in the ball milling process are any one of polytetrafluoroethylene balls, zirconium oxide balls, stainless steel balls, tungsten carbide balls, and agate balls, with polytetrafluoroethylene balls being the preferred choice. And / or, the grinding balls in the ball milling process have a particle size of 5 to 10 mm, for example, 5 mm, 8 mm or 10 mm; preferably, the grinding balls are composed of grinding balls of 5 mm, 8 mm and 10 mm, and more preferably, the weight ratio of grinding balls of 5 mm, 8 mm and 10 mm is 3:5:

2.

4. The method for synthesizing molten salt as described in claim 1, characterized in that, The ball milling method includes the following steps: adding the inorganic salt mixture and grinding balls into a ball mill jar, and performing ball milling on a ball mill; Preferably, the grinding jar is any one of a stainless steel jar, a polytetrafluoroethylene jar, a Hastelloy jar, a nickel jar, and a jar lined with Teflon, and more preferably a polytetrafluoroethylene jar. Preferably, the power of the ball mill is 30~50 Hz; Preferably, the ball mill is a planetary ball mill; Preferably, the ball milling process is carried out in a gas, which may be a mixture of air, nitrogen, argon, helium, nitrogen and hydrogen fluoride, or a mixture of nitrogen and fluorine.

5. The method for synthesizing molten salt as described in claim 1, characterized in that, The method for synthesizing the molten salt satisfies one or more of the following conditions: (1) The fluoride salt is an alkali metal fluoride, BeF2, CaF2, ZrF4, ThF4, or UF4, and the alkali metal fluoride salt is preferably LiF, 7 LiF, NaF, KF, or RbF; (2) The chloride salt is an ionic chloride salt and / or a polymeric chloride salt, wherein the ionic chloride salt is preferably KCl, CaCl2 or MgCl2, and the polymeric chloride salt is preferably Zn. n Cl n Or Be n Cl n ; (3) The carbonate is an alkali metal carbonate, preferably K2CO3 or Na2CO3; (4) The nitrate is an alkali metal nitrate, preferably NaNO3 or KNO3; (5) The sulfate is an alkali metal sulfate, preferably K2SO4; (6) The phosphate is an alkali metal phosphate, preferably Li2P2O7 or Na4P2O7; (7) The silicate is an alkali metal silicate, and the alkali metal silicate is preferably Na2SiO3; (8) The inorganic salt mixture is a mixture of 2 to 4 types of fluoride salts, a mixture of 2 types of chloride salts, a mixture of 2 to 3 types of nitrate salts, or a mixture of 3 types of carbonate salts.

6. The method for synthesizing molten salt as described in claim 1, characterized in that, The molar percentage of any one inorganic salt in the inorganic salt mixture is no more than 80%. Preferably, when the inorganic salt mixture contains fluoride salts, the molar percentage of fluoride salts in the inorganic salt mixture is not greater than 80%. More preferably, when the inorganic salt mixture contains BeF2, the molar percentage of BeF2 in the inorganic salt mixture is no more than 50%. More preferably, the molar percentage of BeF2 in the inorganic salt mixture is 10-50%, for example, 16.8%, 30%, 30.5%, 33%, 38%, or 43%. More preferably, when the inorganic salt mixture contains ZrF4, the molar percentage of ZrF4 in the inorganic salt mixture is no more than 50%. More preferably, the molar percentage of ZrF4 in the inorganic salt mixture is 3-50%, for example, 5%, 29%, 40.5%, 42%, 43%, or 49%. More preferably, when the inorganic salt mixture contains UF4, the molar percentage of UF4 in the inorganic salt mixture is 0.05~1%, for example 0.1% or 0.4%; More preferably, when the inorganic salt mixture contains ThF4, the molar percentage of ThF4 in the inorganic salt mixture is 5-8%, for example, 6.8%; Preferably, when the inorganic salt mixture contains chloride salts, the molar percentage of chloride salts in the inorganic salt mixture is no more than 85%. More preferably, the molar percentage of chloride salts in the inorganic salt mixture is 30-85%, for example, 32%, 68%, or 80%. Preferably, when the inorganic salt mixture contains carbonates, the molar percentage of carbonates in the inorganic salt mixture is no more than 50%; more preferably, the molar percentage of carbonates in the inorganic salt mixture is 25-50%, for example, 30% or 40%. Preferably, when the inorganic salt mixture contains nitrate, the molar percentage of nitrate in the inorganic salt mixture is no more than 60%. More preferably, the molar percentage of nitrate in the inorganic salt mixture is 5-60%, for example, 7%, 44%, 48%, 49% or 52%.

7. The method for synthesizing molten salt as described in claim 1 or 6, characterized in that, The inorganic salt mixture is a mixture of LiF, NaF, and KF; a mixture of LiF and BeF2; a mixture of NaF and BeF2; a mixture of LiF, NaF, and BeF2; a mixture of NaF and ZrF4; a mixture of KF and ZrF4; a mixture of LiF and ZrF4; a mixture of LiF and RbF; a mixture of LiF, NaF, and RbF; a mixture of LiF, NaF, and ZrF4; a mixture of RbF and ZrF4; a mixture of LiF, BeF2, and ZrF4; or a mixture of NaF, RbF, and ZrF4. 7 A mixture of LiF, BeF2, ZrF4 and UF4 7 Any one of the following: a mixture of LiF, BeF2, ThF4 and UF4; a mixture of KCl and MgCl2; a mixture of NaNO3 and KNO3; a mixture of NaNO3, NaNO2 and KNO3; a mixture of Na2CO3, Li2CO3 and K2CO3; or a mixture of CaCl2 and CaF2. Preferably, when the inorganic salt mixture is a mixture of LiF, NaF and KF, the molar percentage of LiF is 40-60%, the molar percentage of NaF is 10-30%, and the molar percentage of KF is 30-50%. More preferably, the molar percentage of LiF is 46.5%, the molar percentage of NaF is 11.5%, and the molar percentage of KF is 42%. Preferably, when the inorganic salt mixture is a mixture of LiF and BeF2, the molar percentage of LiF is 50-70% and the molar percentage of BeF2 is 30-50%. More preferably, the molar percentage of LiF is 67% and the molar percentage of BeF2 is 33%. Preferably, when the inorganic salt mixture is a mixture of NaF and BeF2, the molar percentage of NaF is 57% and the molar percentage of BeF2 is 43%. Preferably, when the inorganic salt mixture is a mixture of LiF, NaF and BeF2, the molar percentage of LiF is 31%, the molar percentage of NaF is 31%, and the molar percentage of BeF2 is 38%. Preferably, when the inorganic salt mixture is a mixture of NaF and ZrF4, the molar percentage of NaF is 59.5% and the molar percentage of ZrF4 is 40.5%. Preferably, when the inorganic salt mixture is a mixture of KF and ZrF4, the molar percentage of KF is 58% and the molar percentage of ZrF4 is 42%. Preferably, when the inorganic salt mixture is a mixture of LiF and ZrF4, the molar percentage of LiF is 51% and the molar percentage of ZrF4 is 49%. Preferably, when the inorganic salt mixture is a mixture of LiF and RbF, the molar percentage of LiF is 44% and the molar percentage of RbF is 56%. Preferably, when the inorganic salt mixture is a mixture of LiF, NaF and RbF, the molar percentage of LiF is 42%, the molar percentage of NaF is 6%, and the molar percentage of RbF is 52%. Preferably, when the inorganic salt mixture is a mixture of LiF, NaF and ZrF4, the molar percentage of LiF is 42%, the molar percentage of NaF is 29%, and the molar percentage of ZrF4 is 29%. Preferably, when the inorganic salt mixture is a mixture of RbF and ZrF4, the molar percentage of RbF is 58% and the molar percentage of ZrF4 is 42%. Preferably, when the inorganic salt mixture is a mixture of LiF, BeF2 and ZrF4, the molar percentage of LiF is 64.5%, the molar percentage of BeF2 is 30.5%, and the molar percentage of ZrF4 is 5%. Preferably, when the inorganic salt mixture is a mixture of NaF, RbF and ZrF4, the molar percentage of NaF is 33%, the molar percentage of RbF is 24%, and the molar percentage of ZrF4 is 43%. Preferably, when the inorganic salt mixture is 7 When mixed with LiF, BeF2, ZrF4 and UF4, 7 The molar percentages of LiF are 65%, BeF2 is 30%, ZrF4 is 5%, and UF4 is 0.1%. Preferably, when the inorganic salt mixture is a mixture of LiF, BeF2, ThF4 and UF4, the molar percentage of LiF is 72%, the molar percentage of BeF2 is 16%, the molar percentage of ThF4 is 6.5%, and the molar percentage of UF4 is 0.4%. Preferably, when the inorganic salt mixture is a mixture of KCl and MgCl2, the molar percentage of KCl is 68% and the molar percentage of MgCl2 is 32%. Preferably, when the inorganic salt mixture is a mixture of NaNO3 and KNO3, the molar percentage of NaNO3 is 48% and the molar percentage of KNO3 is 52%. Preferably, when the inorganic salt mixture is a mixture of NaNO3, NaNO2 and KNO3, the molar percentage of NaNO3 is 7%, the molar percentage of NaNO2 is 49%, and the molar percentage of KNO3 is 44%. Preferably, when the inorganic salt mixture is a mixture of Na2CO3, Li2CO3 and K2CO3, the molar percentage of Na2CO3 is 30%, the molar percentage of Li2CO3 is 30%, and the molar percentage of K2CO3 is 40%. Preferably, when the inorganic salt mixture is a mixture of CaCl2 and CaF2, the molar percentage of CaCl2 is 80% and the molar percentage of CaF2 is 20%.

8. A molten salt synthesized by a method for synthesizing molten salt as described in any one of claims 1 to 7.

9. The molten salt as described in claim 8, characterized in that, The extrapolated melting initiation temperature of the molten salt is 100~800℃, preferably 130~700℃, for example 142℃, 222℃, 319℃, 337℃, 390℃, 410℃, 420℃, 426℃, 428℃, 434℃, 435℃, 451℃, 453℃, 460℃, 470℃, 496℃, 497℃, 509℃ or 698℃.

10. The molten salt as claimed in claim 8, characterized in that, The molten salt is LiF-NaF-KF, LiF-BeF2, NaF-BeF2, LiF-NaF-BeF2, NaF-ZrF4, KF-ZrF4, LiF-ZrF4, LiF-RbF, LiF-NaF-RbF, LiF-NaF-ZrF4, RbF-ZrF4, LiF-BeF2-ZrF4, NaF-RbF-ZrF4, 7 LiF-BeF2-ZrF4-UF4, 7 LiF-BeF2-ThF4-UF4, KCl-MgCl2, NaNO3-KNO3, NaNO3-NaNO2-KNO3, Na2CO3-Li2CO3-K2CO3 or CaCl2-CaF2.

Images