Vanadium
The fourth period of the periodic table contains VB group elements, which are rare high melting point metals. Element symbol V, atomic number 23, relative atomic mass 50.9415, solid at room temperature, gray in powder form, and steel gray in dense form.
A Brief History
The vanadium industry in China started in the 1950s. In 1958, the vanadium extraction workshop of Jinzhou Ferroalloy Plant was restored and expanded, using Chengde Damiao vanadium containing iron concentrate as the raw material for vanadium extraction. After 1960, other vanadium extraction plants in China were successively built and put into operation. In the 1970s, Panzhihua Iron and Steel Company was built and put into operation, marking a new historical period for China's vanadium industry. By the 1980s, China had become one of the world's major vanadium producing countries, capable of producing various vanadium products. The promotion and application of vanadium have also developed rapidly.
nature
Vanadium has good plasticity and malleability, and can be made into sheets, drawn into wires, and processed into foils at room temperature. However, a small amount of impurities, especially interstitial elements such as carbon, hydrogen, oxygen, and nitrogen, can significantly affect the physical properties of vanadium. If vanadium contains 0.01% hydrogen, it will cause embrittlement and decrease plasticity; When the carbon content is 2.7%, its melting point increases to 2458K. Vanadium has a high melting point, high hardness, high electrical resistivity, weak paramagnetism, low coefficient of linear expansion, and similar elastic modulus and density to steel, making it suitable as a structural material.
Vanadium is a transition element with an outer electron layer configuration of [Ar] 3d34s2, and all 5 electrons can participate in bonding. Therefore, vanadium is a variable valence element, with a total of 8 valence states from -3 and -1 to+5. Among them, vanadium compounds with a+5 valence are the most stable. Positive pentavalent vanadium compounds have oxidizing properties, while low valent vanadium compounds have reducing properties. Vanadium compounds with lower valence states have stronger reducing properties, so V3+and V2+are strong reducing agents. Vanadium is prone to form complexes with many ligands.
Vanadium has 9 isotopes with mass numbers ranging from 46 to 54, and 51V is a stable natural isotope. Vanadium's corrosion resistance is second only to niobium and tantalum. At room temperature, vanadium does not react with air, water, and alkali, but can form compounds with most non-metallic elements such as carbon, silicon, nitrogen, oxygen, sulfur, chlorine, bromine, etc. at high temperatures. Vanadium is resistant to seawater corrosion, as well as corrosion from hydrochloric acid, dilute sulfuric acid, and alkaline solutions. Vanadium does not react with other halogenated hydrogen acids at room temperature, except for slow reactions with hydrofluoric acid. Vanadium reacts with oxygen-containing acids (concentrated sulfuric acid, hypochlorous acid, nitric acid, and aqua regia) to form vanadates.
Common vanadium compounds include oxides, halides, ammonium salts, sodium salts, and oxygen-containing salts. The properties of these compounds are often influenced by changes in the valence state of vanadium.
The oxides of vanadium mainly include V205, V02, V203, and V0.
The chemical stability of vanadium halides decreases with the increase of vanadium atomic valence; The chemical stability of vanadium halides with the same valence state gradually decreases from fluoride to iodide.
ammonium salt
There are mainly ammonium metavanadate (NH4VO3), ammonium vanadate [(NH4) 3V04 or 2 (NH4) 20·3V205· nH20], ammonium polyvanadate, among which ammonium metavanadate is the most important. Ammonium metavanadate is a white or light yellow crystal that begins to decompose when heated to 473K, with a density of 2304kg/m3. Ammonium metavanadate decomposes into NH3 and V205 in oxygen rich air at 523K temperature; Decompose into (NH4) 2O in air at temperatures of 523-613K?。3V205 and V204·5V205 decomposes into NH3 and V205 at temperatures of 693-713K; V205 was oxidized in a pure oxygen atmosphere at a temperature of 583-598K. Ammonium metavanadate heated to 473K in hydrogen gas to generate (NH4) 2O·3V205 generates (NH4) 2O at a temperature of 593K。 V204·5V205 generates V2013 and V203 at 673K, and V204 at 1273K. Ammonium metavanadate generates (NH4) 2O at 623K in CO2, N2, and Ar atmospheres。V204· 5V205 generates V6013 at temperatures of 673-773K. When water vapor is introduced and reaches a temperature of 498K, ammonium metavanadate generates (NH4) 2O·3V205.
sodium salt
The compounds in the phase diagram of the V205-Na20 binary system in vanadium sodium salts include NaV6015, Na8V24063, NaV03, Na4V207, and Na3V04. Common salts in the NaV03-V205 phase diagram include sodium metavanadate (NaV03), sodium pyrovanadate (Na4V2O7), sodium orthovanadate (Na3V04), and sodium polyvanadate.
Oxygenate salt
Vanadium oxide salts have low solubility, except for alkali and alkali earth metal vanadium salts which are easily soluble in water. The common oxygen-containing salts of vanadium include sodium salts, ammonium salts, calcium salts, iron salts, etc. According to the aggregation state of vanadium, it can be classified into orthovanadate (V043-), pyrovanadate (V2074-), metavanadate (V03-, V40124-), and polyvanadate (V40124-, V60162-, V100182-, V120312-), etc.
Vanadium alloy and additives
The commonly used vanadium alloys include vanadium iron, vanadium aluminum, molybdenum vanadium aluminum alloy, silicon manganese vanadium iron alloy, vanadium carbide, vanadium nitride and other specialized alloy additives. The standards for vanadium ferroalloys vary from country to country. There are usually six grades including 40% to 80% vanadium. There are four vanadium aluminum alloys with vanadium content of 55%, 65%, 75%, and 85%. Molybdenum vanadium aluminum alloys generally contain 23% to 25% vanadium, 24% to 26% molybdenum, and 48% to 53% aluminum. Silicon manganese vanadium iron generally contains vanadium>42%, silicon<7%, and manganese<4.5%. Vanadium carbide generally contains 82% to 86% vanadium and 10.5% to 14.5% carbon. Vanadium nitride contains 78% to 82% vanadium, 10% to 12% carbon, and over 6% nitrogen.
Toxicity
Vanadium and its compounds have certain toxicity, which generally increases with the increase of vanadium's valence state. Skin is prone to allergic reactions when exposed to vanadium. Industrial contact can easily cause respiratory diseases, including paroxysmal dry cough accompanied by hemoptysis and irritation to the eyes, nose, and throat. Hemoglobin and red blood cells temporarily increase and then decrease, leading to anemia. Sometimes conjunctivitis occurs, severe throat irritation occurs, stubborn dry cough, diffuse lung rales and bronchospasm, and sometimes skin itching occurs. Soluble vanadium enters the circulating blood, and the lethal dose for a healthy person weighing 70kg is only 30mg V205 (i.e., a woman's body weight of 0.43mg). The threshold limit values for some vanadium compounds are: V205 dust 0.5mg/m3, and smoke or ultrafine powder 0.1mg/m3. The effects of vanadium on animal neurophysiology, including central nervous system dysfunction and cardiovascular disease, cannot be ignored. Vanadium has no significant effect on animal metabolism, and the toxicity of certain vanadium salts in small amounts in the mouth and eyes is not significant. It can also reduce cholesterol in young people and animals; Intravenous injection is highly toxic. Acute exposure to and absorption of high concentrations of vanadium can cause vasoconstriction, leading to congestion and bleeding in certain parts of the body, which can damage the liver, kidneys, heart, and brain. Vanadium has been used in medicine to treat anemia, chlorosis, tuberculosis and diabetes. The maximum allowable vanadium content in drinking water is below 0.1mg/L.
application
Vanadium has excellent alloy and catalytic properties and is widely used in the steel and chemical industries. 90% of the world's vanadium is used in the steel industry, 5% is used in the chemical industry, and the rest is used in non-ferrous alloys and other aspects. Vanadium is added to steel to form vanadium carbide and nitride particles, which enhance the dispersion of steel and inhibit the growth of austenite grains, thereby improving the performance of the steel. The addition of vanadium O.05% to O.1% to steel can increase its strength by 10% to 20%, and improve its casting and welding properties, reducing the weight of components. High speed tool steel containing 1% to 5% vanadium not only has high wear resistance, but also good plasticity and toughness. Vanadium is mainly used in the chemical industry to manufacture various catalysts and ceramic pigments. The application of vanadium in non-ferrous metal alloys is mainly used to produce vanadium aluminum alloys. Vanadium aluminum alloy has high yield strength and impact strength, and is used as a material for aircraft and aerospace vehicles. The amount of vanadium used in this area is increasing year by year, with the United States currently accounting for 7% to 10% of the total consumption of vanadium. In addition, single crystal vanadium can be used as a material in the electronic industry.
Resources
Vanadium deposits can be classified into magmatic secretion deposits, vanadium containing hydrothermal deposits, weathering accumulation residual deposits, and sedimentary deposits based on their ore-forming reasons. The crustal abundance of vanadium is 136 10-4%, and seawater contains 1 10-7% vanadium. Vanadium in vanadium ore is mainly associated with iron, titanium, uranium, molybdenum, copper, lead, zinc, aluminum, or carbonaceous rock and phosphate ore. Recently, it has also been discovered that there are petroleum mines with high vanadium content.
Vanadium titanium magnetite is the main resource for producing vanadium, which can be comprehensively utilized for vanadium, iron, and titanium. The world's major vanadium deposits include vanadium titanium magnetite from Bushveld in central Transvaal, South Africa, with reserves of approximately 2 billion tons; The Urals and Kachkanar of the former Soviet Union; Otanmeki and Mustawala, Finland; Wyoming Iron Mountain in the United States; Vanadium titanium magnetite from Panzhihua, Sichuan, China and Chengde, Hebei.
Other vanadium resources include vanadium uranium ore, vanadate ore, phosphate rock, bitumen, petroleum, graphite ore containing vanadium mica, as well as abundant stone coal mines in provinces such as Sichuan, Hubei, Hunan, Jiangxi, Zhejiang, Guizhou, and Guangxi in the middle and lower reaches of the Yangtze River in China. At present, the world's proven vanadium resources are 4.36 million tons, with a prospective reserve of 16.62 million tons.
Extracting Metallurgy
The production of metallic vanadium from vanadium containing raw materials mainly includes two major steps: vanadium extraction and metallic vanadium production. Sometimes, in order to produce high-purity vanadium metal, it is necessary to add a vanadium refining process. Vanadium regeneration also belongs to the category of vanadium extraction metallurgy. The principle process of vanadium extraction metallurgy is shown in the figure. In the vanadium extraction metallurgical process, the vanadium extraction process is the most important. Vanadium extraction is the process of preparing vanadium compounds from vanadium containing raw materials. Due to the limited amount of vanadium concentrate, the main raw material for vanadium is vanadium titanium magnetite. Therefore, the process of extracting vanadium from vanadium containing iron produced by smelting vanadium titanium magnetite plays an important role in vanadium extraction metallurgy. This process involves vanadium titanium magnetite first entering the ironmaking blast furnace, where vanadium is reduced and enters the molten iron. Vanadium containing molten iron is then blown and refined to obtain vanadium slag; Then extract vanadium from vanadium slag. Vanadium slag and various vanadium containing materials are generally subjected to roasting, leaching, and solution purification to obtain relatively pure vanadium containing solutions. Prepare V205 and V203 from a relatively pure vanadium containing solution Vanadium compounds such as ammonium metavanadate, calcium vanadate, and iron vanadate. The vanadium compounds obtained from vanadium extraction are mostly sold as products, except for some V205 used as raw materials for the production of metallic vanadium. Reducing V205 with calcium, aluminum, or carbon to produce crude vanadium metal, which can then be refined to obtain pure vanadium metal. V205 is widely used as a raw material for the production of ferrovanadium, which is an important alloy additive in the production of alloy steel.