Scandium
Scandium atomic absorption standard solution
CAS: 7440-20-2
Molecular Formula: Sc
Scandium - Names and Identifiers
Scandium - Physico-chemical Properties
| Molecular Formula | Sc |
| Molar Mass | 44.96 |
| Density | 2.99 g/mL at 25 °C (lit.) |
| Melting Point | 1540 °C (lit.) |
| Boling Point | 2836 °C (lit.) |
| Water Solubility | Reacts with water. |
| Solubility | Slowly dissolve in dilute acids. |
| Appearance | powder |
| Specific Gravity | 3 |
| Color | Silver-gray |
| Exposure Limit | ACGIH: TWA 2 ppm; STEL 4 ppmOSHA: TWA 2 ppm(5 mg/m3)NIOSH: IDLH 25 ppm; TWA 2 ppm(5 mg/m3); STEL 4 ppm(10 mg/m3) |
| Merck | 13,8468 |
| Sensitive | air sensitive |
| Physical and Chemical Properties | Pure metal scandium is silver white and microstrip yellow, with metallic luster, quite soft without annealing and rolling into thin, metal scandium is a very active metal, it is easy to interact with acid, it is easy to combine with oxygen, carbon dioxide and water in the air, and soon lose the luster like lead, but the erosion with water is slow. Scandium oxide (Sc2O3) is the most common compound of scandium, the appearance of white powder, after high temperature burning of scandium oxide is not soluble in dilute acid, but soluble in boiling concentrated nitric acid, scandium fluoride (ScF3) white powder, insoluble in water, is an important compound in the preparation of metal scandium. |
Scandium - Risk and Safety
| Risk Codes | R5 - Heating may cause an explosion R11 - Highly Flammable R34 - Causes burns R23/24/25 - Toxic by inhalation, in contact with skin and if swallowed. R36/37/38 - Irritating to eyes, respiratory system and skin. R36/38 - Irritating to eyes and skin. |
| Safety Description | S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S28 - After contact with skin, wash immediately with plenty of soap-suds. S36/37 - Wear suitable protective clothing and gloves. S7/9 - S36/37/39 - Wear suitable protective clothing, gloves and eye/face protection. S16 - Keep away from sources of ignition. S43 - In case of fire use ... (there follows the type of fire-fighting equipment to be used.) S45 - In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) S27 - Take off immediately all contaminated clothing. |
| UN IDs | UN 3089 4.1/PG 2 |
| WGK Germany | 1 |
| TSCA | Yes |
| Hazard Class | 8 |
| Packing Group | III |
Scandium - Reference Information
| resistivity (resistivity) | 50.5 μΩ-cm, 0°C |
| EPA chemical information | Information provided by: ofmpub.epa.gov (external link) |
| introduction | scandium (SC, Scandium) is in the third subgroup of the fourth period of the periodic table, with an atomic number of 21 and an atomic weight of 44.956. The atomic radius of scandium is small (1.6641 × 10-10 m), there are no 4 f electrons, and its lanthanide shrinkage fails to reduce the atomic size to the corresponding size, resulting in a significant difference in the properties of scandium and rare earth elements. This difference can hardly make scandium enter the rare earth family, but because it is associated with rare earth elements in nature and has some similar properties, it is customary to include scandium as a rare earth element. Because scandium was first discovered in minerals in the Scandinavian (Scandinavia) Peninsula, it was named scandium (Scandium). There are 28 isotopes of scandium, ranging from scandium 36 to to to 57. Scandium 45 is the only stable isotope, and its content accounts for about 100% of the natural resources in the earth's crust. The remaining isotopes are radioactive and have half-lives ranging from nanoseconds to minutes to hours to days, so they are naturally not found in the earth's crust. Radioisotopes of scandium are produced through nuclear reactors. |
| Discovery history | According to the periodic table system, Mendeleev predicted the existence of Yekaporone, and its atomic weight was between calcium 40 and titanium 48. In 1878 Nilson discovered scandium in hematoxylin and gabbro minerals, except in Scandinavia, it was not found anywhere else. By treating 10kg of hematoxylin and other rare earth mineral residues, Nielsen was able to prepare about 2g of high-purity scandium oxide. Cliff later pointed out that Nelson's scandium is the same as Mendeleev's Yekabinlong. |
| Source | Scandium is obviously a more abundant element on the sun and some stars than on the earth. It is the 2 3rd most abundant element in the sun and the 50th most abundant element on earth. It is widely distributed on the earth and exists in a very small amount in more than 800 minerals. The blue color of beryl (aquamarine variety) is said to be caused by scandium. It is the main component in the rare mineral Suite found in Scandinavia and Madagascar. Scandium has also been found in residues remaining after tungsten extraction from Sinwald wolframite, as well as in wiikite and bazzite. Most scandium is currently recovered from cycad mines or by-products extracted from uranium plant tailings. Scandium is a typical scattered lithophile element with an average abundance of 36 ppm in the earth's crust. There are more than 800 kinds of minerals known to contain scandium. At present, large-scale scandium-rich deposits have been discovered in rare earth mines in Jiangxi Province of China. Scandium is widely distributed in other minerals, such as ilmenite, zirconite, zircon, bauxite, rare earth ore, titanium pyroxene, vanadium titanium magnetite, tungsten ore, tin ore, uranium ore and coal. The reserves of scandium in the world are about 2 million t, and the countries with more scandium resources are China, the United States and Russia. Scandium is mainly in the form of homomorphic and exists in other minerals. |
| application | scandium is mainly used in ceramics, lasers, phosphors and crystals. Scandium oxide is suitable for high refractive index components of UV,AR and bandpass coatings due to its high refractive index value, transparency and layer hardness. Therefore, the combination of silicon oxide with silicon fluoride or magnesium fluoride has been reported to have a high damage threshold in AR. Scandium metal is used in various superalloys, which have light metal properties. The main application of scandium by weight is scandium aluminum alloy for aerospace small parts. They are used in Russian military aircraft, especially MiG-21 and MiG-29. Some sports equipment is made of high-performance materials and is made of scandium aluminum alloy. |
| preparation | in the 1980 s, with the soaring price of scandium in the world market, a research upsurge on scandium separation was set off in China. extraction mainly focused on titanium-containing raw materials-sulfuric acid waste liquid for titanium dioxide production, chlorinated soot in titanium production process and titanium tailings. The principle flow of scandium extraction from titanium white hydrolysis mother liquor is shown in fig. 1. fig. 1 shows the process of extracting scandium from titanium dioxide hydrolysis mother liquor. the methods of recovering scandium from red mud are: ① reduction smelting method to treat red mud. (2) sulfation roasting to treat red mud. (3) Leaching of waste acid wash solution to treat red mud. ④ Leach with sodium carbonate solution. ⑤ Direct leaching with sulfuric acid with 50% concentration. ⑥ Leach with concentrated hydrochloric acid. The principle flow of scandium recovery from red mud is shown in Figure 2. fig. 2 shows the process of recovering scandium from red mud. The method of beneficiation can be used to enrich the scandium in the raw materials to improve the grade of scandium, and then use leaching, extraction, oxalic acid precipitation, ignition purification and other hydrometallurgical processes to obtain Sc2O3. At present, Professor Zhang Zonghua of Kunming University of Science and Technology has studied more in this area. The more successful projects include scandium extraction from Panzhihua tailings and scandium extraction from the sludge of the Three Gorges of the Yangtze River. The process flow of extracting scandium from silt in the Three Gorges of the Yangtze River is shown in Figure 3. fig. 3 shows the process flow of scandium extraction from silt in the Three Gorges of the Yangtze River. |
| prospect of extraction technology | with the rapid development of electronic technology, the demand for high-performance electronic components is increasing. in addition, with the wide application of high-performance scandium alloy, the demand for scandium will be increasing, so the market prospect of scandium will be more and more broad. At present, the problem of scandium extraction technology is that the cost is too high and the recovery rate is low. Solving the cost problem is the key to scandium extraction technology. The key to solving the cost problem is to find an efficient and cheap extraction process. The key to making a breakthrough from the current hydrometallurgical process is to find efficient extractants and improve the recovery and purity of scandium. my country has the advantages of scandium resources and production. It can be predicted that with the development of high technology, the application market of scandium will continue to expand, the demand will gradually increase, and the competition among scandium importing countries is bound to intensify. China's rare earth industry should seize the favorable opportunity to transform scandium resources into economic advantages and create more economic benefits. |
| use | scandium and its compounds have many excellent properties. Scandium is widely used in national defense, metallurgy, chemical industry, glass, aerospace, nuclear technology, laser, electronics, computer power supply, superconductivity and medical science. High purity scandium oxide can be used in electron emission materials, superconducting materials, solar cell materials, etc. Western countries such as the United States and Japan are mostly used as sports equipment, such as baseball bats, softball bats, bicycle beams, and also used in new light source scandium lamps. The research on scandium and scandium-containing alloys in Russia began in the 2060s. At that time, the United States and the Soviet Union were engaged in a nuclear arms race. Under the planned economic system, the Soviet Union produced a large amount of uranium, and conducted military development and research on its by-product scandium. As far as aluminum scandium alloy is concerned, Russia has always been in the leading position, |
| Hazardous | Like other metals, transition metals and many of their compounds are toxic and should not be inhaled or inhaled in their powder or gaseous form. In addition, all but one of the isotopes of scandium are radioactive and should be handled by experienced personnel. |
| references | [1] Dong Fang, Gao Likun, Chen Long, Wang Peng, Ma Fangtong. Development Status of Scandium Resources and Recovery and Extraction Technology [J]. Comprehensive Utilization of Minerals, 2016,(04):21-26. [2] Yang Haiqiong, Dong Haigang, Zhao Jiachun, Li Bojie, Fan Xingxiang, wu Yuedong, Wu Xiaofeng, Tong Weifeng. Research Progress on Scandium Recovery Technology [J]. Non-ferrous Metals (Smelting Part),2014,(03):29-33. [3] Zhang Zhongbao, Zhang Zonghua. Scandium Resources and Extraction Technology [J]. Yunnan Metallurgy, 2006,(05): 23-2542. |
| Production method | 1. The main compounds are oxides (scandium oxide), halides (scandium fluoride, scandium chloride, etc.), coordination compounds [hexafluoroscandium ion)(ScF 6 3-), cesium trichloroscandium (CsScCl 3], etc. The main mineral is scandium yttrium. Scandium is much more abundant in the sun and other stars than in the earth's crust. Metal scandium can be prepared by reducing scandium fluoride with metal calcium. 2. Under the protection of atmospheric argon, ScCl3 and metal Ca are heated in a tantalum crucible with a high-frequency electric furnace, and the reaction is started at 700~800 ℃. The reaction is the most intense at 850 ℃. After the reaction is completed, it is under the protection of argon. Cooling, then mechanically separating slag CaCl2, and then sublimating and purifying in a vacuum of 10-3 ~ 10-4Pa at 1500~1600 ℃ to prepare metal scandium with a purity of about 99%. |
Last Update：2024-04-09 20:49:11
