Process for the production of metallic rubidium

Abstract

The present application relates to the technical field of metal rubidium preparation, and particularly relates to a preparation method of metal rubidium. The present application provides a preparation method of metal rubidium, comprising the following steps: drying rubidium chloride to obtain dried rubidium chloride; mixing the dried rubidium chloride with calcium, and performing compression molding to obtain a molded material; performing vacuum thermal reduction and fractional condensation on the molded material to obtain metal rubidium; and performing fractional condensation on the metal rubidium at a condensation interval of 40-200 DEG C to obtain metal rubidium. The preparation method has high direct yield and product purity of the obtained metal rubidium.

Description

Technical Field

[0001] This invention relates to the field of rubidium metal preparation technology, and more particularly to a method for preparing rubidium metal. Background Technology

[0002] Due to its unique properties, metallic rubidium is widely used in aerospace, nuclear energy, bioengineering, genetic engineering, medicine, energy, and environmental science. In recent years, the demand for rubidium has been continuously increasing with the development of photovoltaic cells, atomic clocks, and laser technology. However, the extraction and purification of metallic rubidium continues to face numerous technical challenges.

[0003] Metallothermic reduction is currently the most important method for preparing metallic rubidium. It uses rubidium chloride, hydroxide, or carbonate as raw materials and active metals such as calcium, sodium, and magnesium as reducing agents to reduce rubidium under high-temperature conditions. The magnesium-thermal reduction method can be carried out at lower temperatures and is more suitable for processing rubidium carbonate (Rb₂CO₃). Reducing rubidium chloride with metallic calcium is the most common method for preparing metallic rubidium. Industrially, metallic calcium and anhydrous rubidium chloride are mixed uniformly in a stoichiometric ratio and placed in a dry stainless steel reactor. Under vacuum conditions, the temperature is slowly raised to about 700°C, where metallic calcium and rubidium chloride react as follows: Ca(s) + 2RbCl(s) = CaCl₂(s) + 2Rb(g). However, the direct yield of metallic rubidium using current metallothermic reduction methods is only below 80%, and the purity of rubidium needs further improvement. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for preparing metallic rubidium, wherein the method produces metallic rubidium with high direct yield and high product purity.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing metallic rubidium, comprising the following steps: Rubidium chloride was dried to obtain dried rubidium chloride; The dried rubidium chloride and calcium are mixed and pressed into shape to obtain the shaped material; The shaped material is subjected to vacuum thermal reduction and staged condensation to obtain metallic rubidium; the staged condensation is carried out in the condensation range of 40~200℃ to obtain metallic rubidium.

[0006] Preferably, the drying temperature is 250~300℃ and the time is 2~4h.

[0007] Preferably, the mixing and pressing are carried out in a protective atmosphere; The molar ratio of rubidium chloride to calcium is 1:(1.2~2).

[0008] Preferably, the vacuum thermal reduction temperature is 550~750℃ and the time is 6~15h.

[0009] Preferably, the heating rate to the temperature of the vacuum thermal reduction is 6~10℃ / min.

[0010] Preferably, the staged condensation is carried out in the condensation range of 250~350℃ to obtain volatile impurities.

[0011] This invention provides a method for preparing metallic rubidium, comprising the following steps: drying rubidium chloride to obtain dried rubidium chloride; mixing the dried rubidium chloride with calcium and pressing it into a molded material; subjecting the molded material to vacuum thermal reduction and staged condensation to obtain metallic rubidium; the staged condensation is performed in a condensation range of 40~200℃ to obtain metallic rubidium. Because rubidium chloride is hygroscopic, it may form RbCl·H2O upon contact with air moisture, while calcium may burn or even explode upon contact with water. Although the moisture is adsorbed onto RbCl, some moisture still remains. Simultaneously, during the heating reduction process, adsorbed water can be removed at 250℃, but due to the thickness of the material layer, some water may not completely leave the reaction zone or react directly with the metallic calcium powder. After the moisture is removed from the reduction zone, it may condense into a liquid in the condensation zone and react with rubidium vapor generated during the reduction process to form RbOH, thereby reducing the rubidium recovery rate. Therefore, this application first dries rubidium chloride to remove adsorbed water; mixing the dried rubidium chloride and calcium and pressing them together increases the heated surface area of ​​the material, accelerates the heat and mass transfer rate, improves the material utilization rate, and thus increases the direct recovery rate of metallic rubidium; simultaneously, the pressed material has good air permeability and high rubidium vapor volatilization efficiency. Controlling the condensation temperature within the above range can further improve the effective separation of the metal and increase the purity of metallic rubidium. The metallic rubidium prepared by the method of this invention can achieve a direct recovery rate of up to 92% and a purity of up to 99.9% (compliant with YS / T1246-2018Rb-3 standard). Furthermore, the preparation method is highly safe, simplifies the process flow, can produce high-purity metallic rubidium in one step, reduces production costs, and is easy to scale up and industrialize, providing technical support for the production of high-purity metallic rubidium resources and key process support for the industrial application of vacuum thermal reduction. Attached Figure Description

[0012] Figure 1 SEM and EDS images (a) of metallic rubidium in Example 1 and SEM and EDS images (b) of the condensed liquid impurities are shown. Figure 2 The image shows the XRD pattern of the residue after reduction in Example 1. Figure 3Here is a photograph of the rubidium metal prepared in Example 1; Figure 4 This is a schematic diagram of the preparation process of rubidium metal according to the present invention. Detailed Implementation

[0013] This invention provides a method for preparing metallic rubidium, comprising the following steps: Rubidium chloride was dried to obtain dried rubidium chloride; The dried rubidium chloride and calcium are mixed and pressed into shape to obtain the shaped material; The shaped material is subjected to vacuum thermal reduction and staged condensation to obtain metallic rubidium; the staged condensation is carried out in the condensation range of 40~200℃ to obtain metallic rubidium.

[0014] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0015] The present invention involves drying rubidium chloride to obtain dried rubidium chloride.

[0016] In this invention, the drying temperature is preferably 250~300℃, more preferably 250℃, 260℃, 270℃, 280℃, 290℃ or 300℃; the drying time is preferably 2~4h, more preferably 2h, 2.5h, 3h, 3.5h or 4h. In an embodiment of this invention, the drying temperature can be 250℃ and the drying time can be 3h.

[0017] In this invention, controlling the drying conditions within the aforementioned range further controls the adsorbed water content in rubidium chloride to ≤0.5wt%, while simultaneously removing impurities such as aluminum and silicon, thereby increasing the direct recovery rate of metallic rubidium and improving production safety. Furthermore, since the impurities of aluminum and silicon in rubidium chloride mainly exist in the form of chlorides, and aluminum chloride has a boiling point of 182.7℃ and silicon chloride has a boiling point of 57.6℃, both of which are volatile at 250℃, drying the material removes these impurities, preventing them from affecting the purity of rubidium during subsequent reduction processes.

[0018] In this invention, the drying apparatus is preferably an electromagnetic rotary kiln, a drying box, or a muffle furnace.

[0019] In this invention, the drying device abandons the traditional fuel combustion heating method, so that the exhaust gas contains only trace amounts of water vapor, eliminating the need for complex purification treatment and significantly reducing environmental protection costs and energy consumption.

[0020] After obtaining the dried rubidium chloride, the present invention mixes the dried rubidium chloride with calcium and presses it into shape to obtain the shaped material.

[0021] In this invention, the calcium is preferably calcium granules or calcium powder; this invention does not impose any special limitation on the particle size of the calcium granules and calcium powder, and any particle size known to those skilled in the art can be used.

[0022] In this invention, the mixing and pressing are preferably carried out in a protective atmosphere, preferably an argon atmosphere. In this invention, the molar ratio of rubidium chloride to calcium is preferably 1:(1.2~2), more preferably 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, or 1:2. In embodiments of this invention, the molar ratio of rubidium chloride to calcium can be 1:1.5 or 1:1.2.

[0023] The present invention does not impose any special limitations on the mixing process; any process known to those skilled in the art can be used.

[0024] In this invention, the pressing and molding process is preferably performed on spheres or blocks. This invention does not impose any special limitations on the specific conditions and parameters of the spheres or blocks used; conditions and parameters well-known to those skilled in the art are sufficient to ensure that the molding is not loose. In an embodiment of this invention, the pressing pressure is specifically 6T, and the holding time is specifically 15s.

[0025] In this invention, the pressing process increases the heated surface area of ​​the material by 30% (compared to a mixture without pressing), resulting in faster heat and mass transfer rates and higher material utilization. The pressed material also exhibits better air permeability and improved rubidium vapor volatilization efficiency.

[0026] The shaped material is obtained; the shaped material is subjected to vacuum thermal reduction and staged condensation to obtain metallic rubidium; the staged condensation is carried out at a temperature of 40~200℃ to obtain metallic rubidium.

[0027] In this invention, the vacuum degree of the vacuum thermal reduction is preferably below 1 Pa; the temperature of the vacuum thermal reduction is preferably 550~750℃, more preferably 550℃, 600℃, 650℃, 700℃ or 750℃; the time is preferably 6~15h, more preferably 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h or 15h; the heating rate to the vacuum thermal reduction temperature is preferably 6~10℃ / min, more preferably 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min. In an embodiment of this invention, the temperature of the vacuum thermal reduction can be 650℃, the time can be 6h or 15h, and the heating rate to the vacuum thermal reduction temperature can be 8℃ / min.

[0028] In this invention, the staged condensation is carried out in a condensation range of 40~200°C to obtain metallic rubidium; the staged condensation is preferably carried out in a condensation range of 250~350°C to obtain volatile impurities.

[0029] In an embodiment of the present invention, the staged condensation process is as follows: the product system generated by the vacuum thermal reduction is condensed through a first-stage condenser (condensation range of 250~350°C) to obtain solid impurities; rubidium vapor is condensed into liquid through a second-stage condenser (condensation range of 40~200°C) and collected in a metal rubidium storage tank, which is equipped with a liquid level detector.

[0030] After the staged condensation is completed, the present invention preferably further includes casting the rubidium metal obtained after staged condensation (condensed into a rubidium storage tank) into ampoules for storage in an argon glove box, and then sending it to a finished product warehouse protected by argon gas.

[0031] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0032] Example 1 like Figure 4 The process shown involves placing 99% pure rubidium chloride in a drying device (specifically a drying oven) and heating it at 250°C for 1 hour to obtain dried rubidium chloride (adsorbed water content ≤0.3wt%, RbOH content <0.05wt%, impurity silicon content reduced by 60% compared to undried rubidium chloride, and aluminum content reduced by 30% compared to undried rubidium chloride). In an argon protective atmosphere, the dried rubidium chloride and metallic calcium were mixed in a molar ratio of 1:1.5 and then briquetted (6T, 15s) to obtain the briquetted material. The compressed material is conveyed to a reaction crucible, which is then pushed into the reaction zone. After evacuating to below 1 Pa, the temperature is increased to 650°C at a rate of 8°C / min for vacuum thermal reduction for 6 hours. The resulting product system is then condensed in a primary condenser (condensation range of 250~350°C) to obtain solid impurities. Rubidium vapor is condensed into liquid in a secondary condenser (condensation range of 40~200°C) and collected in a metal rubidium storage tank equipped with a level detector. The metal rubidium in the storage tank (see actual image) is then... Figure 3 (As shown) It is cast into ampoules for storage and sent to a finished product warehouse with nitrogen protection (the direct recovery rate of rubidium metal is 92.10%, and the purity is 99.92%). Figure 1 The images show SEM and EDS images of the metal (a) and SEM and EDS images of the condensed liquid impurities (b). Figure 1 The SEM image of the condensed rubidium product shows a loose and porous morphology. This irregular porous structure indicates that the metal vapor underwent rapid condensation and aggregation at the cold end, without forming a dense sintered body. EDS analysis shows that Rb is evenly distributed and significantly enriched in the product, indicating that rubidium is the dominant volatile component. Simultaneously, O is present to some extent due to surface oxidation. The residue (the condensed liquid impurities) exhibits a blocky particle morphology with a relatively dense structure. EDS analysis shows that Ca and Cl are highly overlapping in the particle distribution and are significantly stronger than other elements, suggesting that the residue after the reaction is mainly composed of CaCl2, consistent with the XRD analysis results (e.g., ...). Figure 2 (As shown). The residue contained only a very small amount of unmigrated rubidium, indicating minimal residual loss; trace amounts of Al and Si were also detected, which may have originated from trace impurities in the raw materials, reactor contact materials, or trace contamination introduced during the sampling process.

[0033] Example 2 like Figure 4 The process shown involves placing 99% pure rubidium chloride in a drying device (specifically a drying oven) and heating it at 250°C for 1 hour to obtain dried rubidium chloride (adsorbed water content ≤0.3wt%, RbOH content <0.05wt%, impurity silicon content reduced by 60% compared to undried rubidium chloride, and aluminum content reduced by 30% compared to undried rubidium chloride). In an argon protective atmosphere, the dried rubidium chloride and metallic calcium were mixed in a molar ratio of 1:1.2 and then briquetted (6T, 15s) to obtain the briquetted material. The compressed material is conveyed to the reaction crucible, and after the reaction crucible is pushed to the reaction zone, a vacuum is drawn to below 1 Pa. The temperature is then increased to 650°C at a heating rate of 8°C / min for vacuum thermal reduction for 6 hours. The resulting product system is then condensed in a primary condenser (condensation range of 250~350°C) to obtain solid impurities. Rubidium vapor is condensed into liquid in a secondary condenser (condensation range of 40~200°C) and collected in a metal rubidium storage tank equipped with a liquid level detector. The metal rubidium in the storage tank is then cast into ampoules for storage and sent to a finished product warehouse under nitrogen protection (the direct recovery rate of metal rubidium is 91.10%, and the purity is 99.88%).

[0034] Example 3 like Figure 4The process shown involves placing 99% pure rubidium chloride in a drying device (specifically a drying oven) and heating it at 250°C for 1 hour to obtain dried rubidium chloride (adsorbed water content ≤0.3wt%, RbOH content <0.05wt%, impurity silicon content reduced by 60% compared to undried rubidium chloride, and aluminum content reduced by 30% compared to undried rubidium chloride). In an argon protective atmosphere, the dried rubidium chloride and metallic calcium were mixed in a molar ratio of 1:1.5 and then briquetted (6T, 15s) to obtain the briquetted material. The compressed material is conveyed to the reaction crucible, and after the reaction crucible is pushed to the reaction zone, a vacuum is drawn to below 1 Pa. The temperature is then increased to 650°C at a heating rate of 8°C / min for vacuum thermal reduction for 15 hours. The resulting product system is then condensed in a primary condenser (condensation range of 250~350°C) to obtain solid impurities. Rubidium vapor is condensed into liquid in a secondary condenser (condensation range of 40~200°C) and collected in a metal rubidium storage tank equipped with a liquid level detector. The metal rubidium in the storage tank is then cast into ampoules for storage and sent to a finished product warehouse under nitrogen protection (the direct recovery rate of metal rubidium is 92.13%, and the purity is 99.95%).

[0035] Comparative Example 1 Rubidium chloride with a purity of 99% was placed in a drying device (specifically a drying oven) and heated and dried at 250°C for 1 hour to obtain dried rubidium chloride (adsorbed water content ≤0.3wt%, RbOH content <0.05wt%, impurity silicon content reduced by 60% compared to undried rubidium chloride, and aluminum content reduced by 30% compared to undried rubidium chloride). In an argon protective atmosphere, the dried rubidium chloride and metallic calcium were mixed in a molar ratio of 1:1.5 to obtain a mixture. The mixture is fed into a reaction crucible, which is then pushed into the reaction zone. After evacuating to below 1 Pa, the temperature is increased to 650°C at a rate of 8°C / min for vacuum thermal reduction for 6 hours. The resulting product system is then condensed in a primary condenser (condensation zone of 250~350°C) to obtain solid impurities. Rubidium vapor is condensed into liquid in a secondary condenser (condensation zone of 40~200°C) and collected in a rubidium metal storage tank equipped with a liquid level detector. The rubidium metal in the storage tank is then cast into ampoules for storage and sent to a nitrogen-protected finished product warehouse (the direct recovery rate of rubidium metal is 71.28%, and the purity is 99.80%).

[0036] The content of each element in the raw materials, rubidium metal, and impurities described in Examples 1-3 and Comparative Example 1 is shown in Table 1: Table 1. Content of each element in the raw materials, rubidium metal, and impurities described in Examples 1-3 and Comparative Example 1.

[0037] Note: In Table 1, raw materials refer to undried rubidium chloride, HFW refers to the prepared metallic rubidium, and CLW refers to the residue after reduction.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing metallic rubidium, characterized in that, Includes the following steps: Rubidium chloride was dried to obtain dried rubidium chloride; The dried rubidium chloride and calcium are mixed and pressed into shape to obtain the shaped material; The shaped material is subjected to vacuum thermal reduction and staged condensation to obtain metallic rubidium; the staged condensation is carried out in the condensation range of 40~200℃ to obtain metallic rubidium.

2. The preparation method according to claim 1, characterized in that, The drying temperature is 250~300℃, and the time is 2~4h.

3. The preparation method according to claim 1, characterized in that, The mixing and pressing are carried out in a protective atmosphere; The molar ratio of rubidium chloride to calcium is 1:(1.2~2).

4. The preparation method according to claim 1, characterized in that, The vacuum thermal reduction is performed at a temperature of 550~750℃ for 6~15 hours.

5. The preparation method according to claim 4, characterized in that, The heating rate to the vacuum thermal reduction temperature is 6~10℃ / min.

6. The preparation method according to claim 1, characterized in that, The staged condensation is carried out in the condensation range of 250~350℃ to obtain volatile impurities.

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