Method for preparing metal samarium through vacuum distillation
Through the method of calcium thermal reduction combined with vacuum distillation, the problem of efficient preparation of high-purity metal samarium is solved, and high-purity and low-cost preparation effects are achieved.
Patent Information
- Application Number
- CN202510663961.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-22
- Publication Date
- 2025-08-01
AI Technical Summary
The prior art is difficult to efficiently prepare high-purity metal samarium, and it is susceptible to oxidation and contamination during the preparation process.
The method of calcium thermal reduction combined with vacuum distillation is used to react samarium fluoride with metal calcium in a high vacuum environment, and then smelting and refining to ensure that the reaction is carried out under high purity conditions.
It significantly improves the purity and production efficiency of metal samarium, reduces processing costs, and meets the needs of high-end and sophisticated fields.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of metal preparation, and in particular to a method for preparing metallic samarium by vacuum distillation. Background Art
[0002] Samarium is an important light rare earth element with an atomic mass of 62 and a relative atomic mass of 150.4. It has special physical and chemical properties and a density of 7.54 g / cm 3 , boiling point 1794 ° C, melting point 1074 ° C, has very good ductility and is easy to process. The outer electron configuration of samarium is 4 f 6 5 s 2 5 p 6 6 s 2 It easily loses electrons and becomes ions with a valence of +2 or +3. In chloride melts, the valence of +2 is the stable valence. It has very active chemical properties and, under certain conditions, easily reacts with gases such as nitrogen, oxygen, and gas to form compounds. It can also react with acids and bases to form different salts. The compounds and alloys of samarium metal have strong practical and economic value. Samarium metal can be used to manufacture laser materials, microwave and infrared equipment, and is also of great use in the atomic energy industry. It can also be used in the electronics and ceramics industries. Samarium is easily magnetized but difficult to demagnetize, which means it will have important applications in solid-state devices and superconducting technology in the future. Currently, rare earth samarium in my country is mainly used to make luminescent materials and permanent magnetic materials, with sales accounting for more than 85% of the total domestic sales.
[0003] Samarium is a variable valence element with a moderate melting point and high vapor pressure. It can be prepared by reducing rare earth halides using calcium thermal reduction. The present invention provides a method for preparing high-purity, low-oxygen samarium metal by combining calcium thermal reduction with vacuum distillation. Summary of the Invention
[0004] The purpose of the present invention is to provide a method for preparing metallic samarium, which can prepare high-purity low-oxygen metallic samarium by calcium thermal reduction combined with vacuum distillation, thereby significantly improving the purity of the prepared metallic samarium.
[0005] In order to achieve the above object, the present invention provides a method for preparing metallic samarium by vacuum distillation, comprising the following steps: S1. Fluorinating the samarium metal oxide raw material to obtain samarium fluoride; S2. Place the obtained samarium fluoride and metallic calcium into a vacuum furnace and mix them evenly. Cover with calcium powder and evacuate the furnace. Then heat the vacuum furnace to promote the reduction reaction. After the reaction is completed, a crude samarium metallic product is obtained. S3. Put the obtained crude samarium metal into a tungsten crucible and repeat melting to obtain a metal liquid. Evacuate to evaporate and remove calcium metal in the metal liquid, and then cool to obtain high-purity samarium metal.
[0006] Preferably, the fluorination in the above method S1 is carried out as follows: dissolve samarium oxide by heating in hydrochloric acid, maintain stirring and add NH4HCO3 solution. After precipitation, add hydrofluoric acid, let it stand, remove the supernatant, and then dry to constant weight.
[0007] More preferably, the hydrochloric acid in the above method is 5N, NH4HCO3 is 0.16 g / mL, and the concentration of the hydrofluoric acid solution is 45%; the molar ratio of samarium oxide to hydrochloric acid is 1:6 - 8, the molar ratio of samarium chloride to NH4HCO3 is 1:3 - 5, and the molar ratio of samarium oxide to HF is 1:6 - 8; the drying is carried out at 150 °C to constant weight.
[0008] Preferably, the mass ratio of samarium fluoride to calcium metal in the above method S2 is 1:1.8, and the evacuation is to 10 -2 Pa.
[0009] Preferably, the heating to promote the reduction reaction in the above method S2 is specifically: heating to 1000 °C and reacting for 45 min.
[0010] Preferably, the melting temperature in the above method S3 is 1500 °C, and the evacuation is to 10 -2 Pa.
[0011] The present invention also provides a more preferable method for preparing samarium metal, which further includes, after the evacuation in the above step S3, filling an inert gas such as argon into the vacuum furnace, which can effectively prevent calcium metal from absorbing moisture to generate Ca(OH)2 or calcium metal from being oxidized by air to generate CaO.
[0012] The present invention also provides a more preferable method for preparing samarium metal, which further includes post-treatment of the high-purity samarium metal, including: removing calcium metal or oxides on the surface of the high-purity samarium metal until the surface is bright, cleaning with absolute ethanol and ultrasonic cleaning, and then drying at 100 °C for 20 - 30 minutes.
[0013] The present invention has the following advantages: The present invention provides a method for preparing high-purity samarium metal. By adopting a calciothermic reduction reaction combined with vacuum distillation to prepare high-purity samarium metal, the prepared samarium metal, due to the raw materials having a purity of 99.9% and the entire calciothermic reduction reaction being carried out in a high-vacuum environment, effectively avoids problems such as oxidation and pollution that may occur in the traditional preparation process, ensures the purity of the prepared samarium metal, and has a simple preparation process, low processing cost, and low energy consumption. Detailed Embodiments
[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0015] Note: The experimental methods in the following embodiments are all conventional methods unless otherwise specified, and are carried out according to the technologies or conditions described in the literature in this field or according to the product specifications. The materials, reagents, etc. used in the following embodiments can be obtained from commercial channels unless otherwise specified.
[0016] The present invention provides a method for preparing metallic samarium by calciothermic reduction, comprising the following steps: S1. Weigh a certain amount of samarium oxide, heat it in 5N HCl, filter it, and prepare a raw material solution. Heat it until the samarium oxide is completely dissolved. Add the obtained solution to an NH4HCO3 solution under stirring, control the addition rate of the solution and the stirring rate, so that the samarium ions in the solution react fully with ammonium bicarbonate, wait for precipitation to occur, then add an appropriate amount of HF to further adjust the pH of the solution, continue stirring and add water to make the solution neutral. After standing, remove the supernatant and dry it to constant weight to obtain samarium fluoride. S2. Mix samarium fluoride and metallic calcium powder. Cut the metallic Ca into pieces of a certain length to increase its specific surface area and improve the reaction activity, and put them into a ball mill in a weight ratio of 1.8:1 with samarium fluoride and mix evenly. S3. Put the mixed raw materials into the crucible of a vacuum reaction furnace, and evenly spread a layer of metallic calcium powder on its surface to ensure sufficient contact between calcium and samarium fluoride during the reaction. Pump the reaction furnace crucible to a vacuum of 10 -2 Pa to avoid interference of impurities such as oxygen on the reduction reaction. Under a high-vacuum environment, heat the crucible. According to the preset heating program, slowly heat it up until the metallic calcium starts to melt. At this time, the metallic calcium comes into contact with samarium fluoride and a reduction reaction occurs, releasing a large amount of heat. Set the reduction temperature to 1000 °C and the reaction time to 45 min. After the reaction ends, wait for the furnace body to cool down and then open the furnace to take out the mold, and knock off the calcium slag on the upper layer of the metallic samarium to obtain the crude product of metallic samarium.
[0017] S4. Put the obtained crude product of metallic samarium into a tungsten crucible, repeat the above melting and heating process, heat the crucible to 1500 °C until it melts, then start the vacuum unit to evaporate and extract the residual metallic calcium in the metal liquid. When the vacuum rises to 10 -2 Pa, turn off the vacuum unit and let the crucible cool naturally to room temperature. After cooling, open the reaction furnace, take out the mold, and obtain the high-purity refined product of metallic samarium.
[0018] The present invention also provides a better method for treating samarium metal. Specifically, on the basis of the above step S4, a surface treatment step is carried out on the samarium metal, including removing part of the metallic calcium, calcium oxide powder and samarium oxide on the surface of the samarium metal. These impurities may remain on the surface of the samarium metal during the preparation process, affecting its purity and subsequent application performance. Then, the surface is polished with sandpaper to make it shiny, washed with absolute ethanol and then ultrasonically cleaned; the surface-treated samarium metal is placed in a vacuum drying oven and dried at 100 °C for 20 - 30 minutes.
[0019] By optimizing the process parameters of each step such as raw material preparation, mixing, reduction reaction and smelting refinement, the present invention realizes the efficient preparation of samarium metal, improves the production efficiency and yield of samarium metal; adopting a high-vacuum environment for reduction reaction and smelting refinement effectively avoids the interference of impurities such as oxygen, significantly improves the purity of samarium metal, and enables it to meet the requirements for high-purity samarium metal in high-precision fields.
[0020] The specific implementation mode is as follows: Example 1 This example provides a method for preparing samarium metal by calcium thermal reduction combined with vacuum distillation, including the following steps: Step S1: Heat samarium oxide in 5N HCl, filter it and prepare a raw material solution. Add the obtained raw material solution to a 0.16 g / mL NH4HCO3 solution under stirring, wait for precipitation to occur, then add an appropriate amount of 45% HF, continue stirring and add water to make the solution neutral; after standing, remove the supernatant and then dry it at 150 °C to constant weight to obtain samarium fluoride powder. The specific reaction formula is as follows; among them, the molar ratio of samarium oxide to hydrochloric acid is 1:6 - 8, the molar ratio of samarium chloride to NH4HCO3 is 1:3 - 5, and the molar ratio of samarium oxide to HF is 1:6 - 8: Sm2O3 + 6HCl → 2SmCl3 + 3H2O 2SmCl3 + 6NH4HCO3 → Sm2(CO3)3 + 6NH4Cl + 3CO2 + 3H2O Sm2(CO3)3 + 6HF → 2SmF3 + 3CO2 + 3H2O Step S2: Weigh the reaction raw materials, including 180 g of metallic calcium powder and 100 g of samarium fluoride powder. The purity of the powders used is 99.9%. Use a planetary ball mill to mix the raw materials. The rotation speed of the ball mill is 100 r / min, the ball-to-material ratio is 1:3, and the ball milling time is 2 h. Change the rotation direction of the ball mill every 1 h to ensure uniform mixing of the raw materials.
[0021] Step S3: First, put the mixed raw materials into a crucible, lay calcium powder on it, and evacuate to 10 -2Pa, heat the crucible in a high-vacuum environment. When the temperature rises to 800 °C, metallic Ca starts to melt and comes into contact with samarium fluoride, and a reduction reaction occurs, releasing a large amount of heat simultaneously. Set the reduction temperature at 1000 °C and the reaction time at 45 min. After the reaction ends, tilt the crucible to pour the eutectic of metallic samarium and CaF2 into a mold and let it stand for layering. After the furnace body cools down, open the furnace to take out the mold, and knock off the calcium slag on the upper layer of metallic samarium to obtain the crude product of metallic samarium; among them, the mass of calcium powder used is more than twice the mass of the samarium fluoride raw material and covers the sample.
[0022] Step S4: Put the obtained crude product of metallic samarium into a tungsten crucible, repeat the above melting and heating process, heat the crucible to 1500 °C until it melts, then turn on the vacuum unit to evaporate and extract the residual metallic calcium in the metal liquid. When the vacuum degree rises to 10 -2 Pa, the calcium is basically removed completely. Tilt the crucible to pour the gadolinium metal liquid into a mold for cooling and forming. After cooling, open the furnace to take out the mold to obtain the refined product of metallic samarium. Put the surface-treated metallic samarium into a vacuum drying oven and dry it at 100 °C for 20 - 30 minutes.
[0023] Example 2 A better method for preparing metallic samarium. Compared with Example 1, in the process of Step S4 above, after the metallic calcium is evaporated and extracted, an inert gas such as argon is filled into the vacuum furnace for protection, which can effectively prevent the metallic calcium from absorbing moisture to generate Ca(OH)2 or being oxidized by air to generate CaO.
[0024] Use ICP-MS, oxygen-nitrogen-hydrogen analyzer, and carbon-sulfur analyzer to test the element content of the metallic samarium prepared in Example 2. The test results are shown in Table 1. It can be seen that the yield of the prepared high-purity metallic samarium > 95%, the oxygen content ≤ 200 ppm, the rare earth purity ≥ 99.5%, among which the purity of metallic samarium ≥ 99.99%, effectively reducing the impurity content in metallic samarium and improving the purity of samarium.
[0025] Table Ⅰ Test Results of Element Content of Prepared Metallic Samarium
[0026] Comparative Example 1 Step S1: Heat samarium oxide in 5N HCl and filter it to prepare a raw material solution. Add the obtained solution to a 0.16 g / mL NH4HCO3 solution under stirring, wait for precipitation to occur, then add an appropriate amount of 45% HF, continue stirring and add water to make the solution neutral. After standing, remove the supernatant and then dry it at 150 °C to constant weight.
[0027] Step S2: Weigh the reaction raw materials, including 180 g of calcium metal powder and 100 g of samarium fluoride powder. The purity of the powders used is 99.9%. Use a planetary ball mill to mix the raw materials. The rotation speed of the ball mill is 100 r / min, the ball-to-material ratio is 1:3, and the ball milling time is 2 h. Change the rotation direction of the ball mill every 1 h to ensure uniform mixing of the raw materials.
[0028] Step S3: First, put the mixed raw materials into a crucible and cover them with calcium powder. Heat the crucible. When the temperature rises to 800 °C, the metal Ca starts to melt and comes into contact with samarium fluoride, and a reduction reaction occurs, releasing a large amount of heat at the same time. Set the reduction temperature to 1000 °C and the reaction time to 45 min. After the reaction ends, tilt the crucible to pour the eutectic mixture of samarium metal and CaF2 into a mold and let it stand for layering. After the furnace body cools down, open the furnace to take out the mold, and knock off the calcium slag on the upper layer of the samarium metal to obtain the crude samarium metal. Step S4: Put the obtained crude samarium metal into a tungsten crucible, repeat the above melting and heating process, heat the crucible to 1100 °C until it melts, then turn on the air pump to evaporate and extract the residual calcium metal in the metal liquid. Tilt the crucible to pour the gadolinium metal liquid into a mold for cooling and forming. After cooling, open the furnace to take out the mold to obtain the refined samarium metal. Put the surface-treated samarium metal into a vacuum drying oven and dry it at 100 °C for 20 - 30 minutes.
[0029] Measure the samarium metal product prepared in the comparative example. It is known that the yield of high-purity samarium metal is less than 90%, the oxygen content is greater than 1000 ppm, and the rare earth purity is less than 95%. Among them, the purity of samarium metal is only 99.5%.
[0030] In summary, the present invention provides a method for preparing samarium metal by calcium thermal reduction combined with vacuum distillation. The prepared samarium metal has high purity, greatly reducing the impurities in the finished samarium metal, and providing high-purity samarium metal for subsequent vacuum refining and electron beam remelting.
[0031] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and substitutions of the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.
Claims
1. A method for preparing samarium metal by vacuum distillation, characterized in that, It includes the following steps: S1. Fluorinate the samarium oxide raw material to obtain samarium fluoride; S2. Put the obtained samarium fluoride and metallic calcium into a vacuum furnace, mix them evenly, spread calcium powder on it and evacuate the air, then heat the vacuum furnace to promote the reduction reaction. After the reaction ends, obtain the crude samarium metal; S3. Put the obtained crude samarium metal into a tungsten crucible and repeat melting it into a metal liquid. Evacuate the air to evaporate and extract the metallic calcium in the metal liquid. After cooling, obtain the high-quality samarium metal.
2. The method for preparing samarium metal according to claim 1, wherein, The fluorination in S1 is carried out as follows: Heat and dissolve the samarium oxide in hydrochloric acid, maintain stirring and add NH4HCO3 solution. After precipitates are formed, add hydrofluoric acid. After standing and removing the supernatant, dry it to a constant weight.
3. The method for preparing samarium metal according to claim 2, wherein The hydrochloric acid is 5N, NH4HCO3 is 0.16 g / mL, and the concentration of the hydrofluoric acid solution is 45%; the molar ratio of samarium oxide to hydrochloric acid is 1:6 - 8, the molar ratio of samarium chloride to NH4HCO3 is 1:3 - 5, and the molar ratio of samarium oxide to HF is 1:6 - 8; the drying is drying to a constant weight at 150°C.
4. The method for preparing samarium metal according to claim 1, characterized in that, In S2, the mass ratio of samarium fluoride to calcium metal is 1:1.8, and the evacuation is to 10 -2 Pa.
5. The method for preparing samarium metal according to claim 1, characterized in that, The heating to promote the reduction reaction in S2 is specifically: Heat to 1000°C and react for 45 minutes.
6. The method for preparing samarium metal according to claim 1, characterized in that, The melting temperature in S3 is 1500 °C, and the vacuum pumping is to pump to 10 -2 Pa.
7. The method for preparing samarium metal according to any one of claims 1-6, characterized in that, It also includes filling an inert gas into the vacuum furnace after evacuating the air in step S3.
8. The method for preparing samarium metal according to claim 7, characterized in that, The inert gas is selected from argon.
9. The method for preparing samarium metal according to claim 7, wherein, It also includes post-treating the high-quality samarium metal, including: removing the metallic calcium or oxide on the surface of the high-quality samarium metal until the surface is bright. After cleaning with absolute ethanol and ultrasonic cleaning, dry it at 100°C for 20 - 30 minutes.