バナジウム

外観

銀灰色～緑黒色, 塊状

解説

バナジウム,V．原子番号23の元素．電子配置[Ar]3d34s2の周期表5族遷移金属元素．旧元素名バナジン．密度6.11 g cm－3(19 ℃)．融点1887 ℃，沸点3377 ℃．5.40 K 以下で超伝導を示す．通常の酸化数2～5．水，塩酸，アルカリ水溶液に不溶，硝酸，熱濃硫酸，王水，フッ化水素酸，過塩素酸に可溶．高温ではたいていの非金属と反応し，塩素とはVCl4，窒素とは侵入型化合物VNをつくる．As，C，Si，Bなどとも反応して，多くは侵入型，非化学量論的化合物をつくる．空気中で熱すると，灰色VⅡO，黒色VⅢ2O3，暗青色VⅣ2O4，橙赤色と順次変化し，VⅤ2O5まで酸化される．バナジウムを鉄鋼に添加するとすぐれた高抗張力性，耐熱性，靭性，耐摩耗性などを示すので，高抗張力鋼，構造用鋼，高速度鋼製造用に大量に使用される．

森北出版「化学辞典（第2版）

主な性質

1. バナジウムは常温で銀白色の金属光沢。酸化した状態では、異なった色調を発する。
2. バナジウムは塩酸や硫酸に侵されないが、硝酸には侵されやすい。
3. 金属バナジウムは柔らかく、延展性があり熱間や冷間で容易に加工が出来る。
4. バナジウムの強度は、共存する不純物の影響を受けやすい。
5. バナジウム鋼は、靭性、耐熱性、耐水性が優れる。
6. バナジウムは、電気及び熱の伝導性がチタンよりも大きい。
7. バナジウムとチタンの合金は軽く、強く、腐食しにくい性質を持つ（航空機部材として必須）。
8. バナジウムとカリウムの合金は現在、最も硬い超伝導体合金。
9. 酸化バナジウムなどは酸化触媒として使用される。

発見

1830年，スウェーデンのN.G.SefströmとJ. Berzelius(ベルセリウス)が同国産の鉄鉱石を分析して発見し，北欧神話の愛と美の女神Freyja Vanadisから命名したが，じつは1801年にメキシコのA.Manuel del Rioがすでに見いだしていたものであることがわかった．原子量50.9415(1)．天然には唯一の安定同位体．質量数51(99.750(4)％)と50(0.250(4)％)(半減期1.4×1017 y，β－，EC)が存在する．このほか，40～65の放射性同位体がある．バナジウムの地殻中の存在度は230 ppm で，堆積岩中にかなり広く分布しているが，単独の鉱床として存在することはまれである．主要鉱物はパトロン石(patronite，複雑な硫化物)，褐鉛鉱(vanadinite，Pb5(VO4)3Cl)，カルノー石(carnotite，K(UO2)VO4(3/2)H2O)などがある．

主な用途

2. バナジウム鋼（高張力鋼―橋梁、船舶、建造物、工具鋼）

4. バナジウム触媒（硫酸製造設備）

6. V入りチタン合金部品（航空機、ロケットなど機体、部品、ジェットエンジン）

8. V入りアルミ合金部品（ゴルフクラブ、航空機用耐熱鋳物部品、ヘリコプター）

10. その他（ガラス部品）

11. また工業触媒として石油の脱硝、アルコール の酸化、硫酸製造、プロピレン樹脂合成などに幅広く使用さ れている

使用上の注意

アルゴン封入

使用上の注意

不活性ガス封入

説明

Vanadium was discovered in 1830 in Mexico by Andreas Manuel del Rio. It is present at 0.01% in earth’s crust and found in about 65 different minerals. Vanadium is released naturally into the air through the formation of continental dust, marine aerosols, and volcanic emissions. The natural release of vanadium into water and soils occurs primarily as a result of weathering of rocks and soil erosion. Anthropogenic sources include the combustion of fossil fuels, particularly residual fuel oils, which constitute the single largest overall release of vanadium into the atmosphere. Deposition of atmospheric vanadium is also an important source both near and far from industrial plants burning residual fuel oils rich in vanadium. Other anthropogenic sources include leachates from mining tailings, vanadium-enriched slag heaps, municipal sewage sludge, and certain fertilizers. Natural releases to water and soil are far greater overall than anthropogenic releases to the atmosphere.

化学的特性

Vanadium is a soft, ductile, silver-gray metal. It has good resistance to corrosion by alkalis, sulfuric and hydrochloric acid, and salt water. Vanadium metal, sheet, strip, foil, bar, wire, and tubing are used in industries. It is used in high-temperature service, in the production of rust-resistant, high-speed tools, and is an important carbide stabilizer in making steels. In fact, most vanadium is used as an additive to improve steels. Vanadium steel is especially strong and hard, with improved resistance to shock. Vanadium pentoxide (V2O5) is perhaps vanadium’s most useful compound. It is used as a mordant—a material that permanently fi xes dyes to fabrics. Vanadium pentoxide is used as a catalyst in chemical reactions and in the manufacture of ceramics. Vanadium pentoxide can also be mixed with gallium to form superconductive magnets.

物理的性質

Vanadium is a silvery whitish-gray metal that is somewhat heavier than aluminum, butlighter than iron. It is ductile and can be worked into various shapes. It is like other transitionmetals in the way that some electrons from the next-to-outermost shell can bond with otherelements. Vanadium forms many complicated compounds as a result of variable valences. Thisattribute is responsible for the four oxidation states of its ions that enable it to combine withmost nonmetals and to at times even act as a nonmetal. Vanadium’s melting point is 1890°C,its boiling point is 3380°C, and its density is 6.11 g/cm³.

同位体

There are 27 isotopes of vanadium. Only vanadium-51 is stable and makes up99.75% of the total vanadium on Earth. The other 0.25% of the vanadium found onEarth is from the radioisotope vanadium-50, which has such a lon+17years that it is considered stable. The other radioactive isotopes have half-lives rangingfrom 150 nanoseconds to one year.

名前の由来

Named after the Scandinavian mythological goddess Vanadis because of the many colors exhibited by vanadium’s compounds.

天然物の起源

Vanadium is not found in its pure state. Small amounts of vanadium can be found inphosphate rocks and some iron ores. Most of it is recovered from two minerals: vanadinite,which is a compound of lead and chlorine plus some vanadium oxide, and carnotite, a mineral containing uranium, potassium, and an oxide of vanadium. Because of its four oxidationstates and its ability to act as both a metal and a nonmetal, vanadium is known to chemicallycombine with over 55 different elements.Vanadium’s principal ores are roscoelite, patronite, vanadinite, and carnotite, which arefound in the states of Idaho, Montana, Arkansas, and Arizona as well as in Mexico and Peru.It is also a by-product from the production of phosphate ores.

特性

Vanadium is an excellent alloy metal with iron that produces hard, strong, corrosion-resistant steel that resists most acids and alkali. It is even more resistant to seawater corrosion thanis stainless steel. Vanadium is difficult to prepare in a pure form in large amounts. Impureforms seem to work as well as a very pure form of the metal when used as an alloy. Whenworked as a metal, it must be heated in an inert atmosphere because it will readily oxidize.

使用

The major use of vanadium is as an alloying metal to make a strong and corrosion-resistant form of steel that is well suited for structures such as nuclear reactors. It does not absorbneutrons or become “stretched” by heat and stress, as does normal stainless steel, thus makingvanadium ideal for the construction of nuclear reactors.Some of its compounds, particularly the oxides, are used in chemical industries as catalyststo speed up organic chemical reactions. The yellow-brown vanadium pentoxide (V₂O₅) is usedas a catalyst to facilitate the production of sulfuric acid by the contact process. Vanadium pentoxide is also used as a photographic developer, to dye textiles, and in the production of artificialrubber. When combined with glass, it acts as a filter against ultraviolet rays from sunlight.

定義

A silvery transition element occurring in complex ores in small quantities. It is used in alloy steels. Vanadium forms compounds with oxidation states +5, +4, +3, and +2. It forms colored ions. Symbol: V; m.p. 1890°C; b.p. 3380°C; r.d. 6.1 (20°C); p.n. 23; r.a.m. 50.94.

空気と水の反応

Not oxidized by air and not appreciably affected by moisture at ordinary temperatures. Some hydrogen gas may be created however this would proceed slowly under ambient conditions. Insoluble in water.

反応プロフィール

VANADIUM is a reducing agent. Finely divided form favors rapid or explosive reactions with oxidizing agents such as air or oxygen. Reacts exothermically with compounds having active hydrogen atoms (such as acids and water) to form flammable hydrogen gas and caustic products. The reactions are much less vigorous than the similar reactions of alkali metals. Can catalyze polymerization reactions in several classes of organic compounds; these polymerizations sometimes proceed rapidly or even explosively. Vanadium is used as a catalyst in the production of synthetic rubber and sulfuric acid.

危険性

Vanadium powder, dust, and most of its oxide compounds are explosive when exposedto heat and air. They are also toxic when inhaled. Vanadium chloride compounds are strongirritants to the skin and poisonous when ingested.
Many of its compounds must be stored in a dry, oxygen-free atmosphere or in containersof inert gas. Protective clothing and goggles should be worn when handling vanadium, as wellas with most of the other transition elements.

健康ハザード

Exposures to high levels of vanadium cause harmful health effects. The major effects from breathing high levels of vanadium are on the lungs, throat, and eyes. Workers who breathe vanadium for short and long periods show lung irritation, coughing, wheezing, chest pain, runny nose, and sore throat. Prolonged period of exposures to respirable dusts and vanadium fume have caused potential symptoms of toxicity among occupational workers. The symptoms of poisoning include, but are not limited to, irritation of the eyes and throat, green tongue, metallic taste, sore throat, cough, drowsiness, wheezing, bronchitis, abdominal cramps, nausea, vomiting, diarrhea, respiratory distress, pulmonary edema, bronchial damage, epistaxis (bloody nose), eczema, conjunctivitis, headache, dry mouth, dizziness, nervousness, insomnia, and tremor. It is not classifi able as a human carcinogen. Vanadium is a natural component of fuel oil, and workers have developed vanadium poisoning during cleaning operations on oil-fi red furnaces.

农业用途

Vanadium (V) is a silvery-white, metallic, transition element of Group 5 of the Periodic Table and exhibits a range of valencies from +2 to +5. The ores containing vanadium include vanadite and carnotite. The pure metal, formed by the reduction of vanadium oxide with calcium, is generally used as an alloying element for steel and iron. Several vanadium compounds are used as oxidation catalysts. They are also used as coloring agents in the ceramic industry.
Vanadium comes under the category of beneficial elements which are non-essential but beneficial to plant growth. It is a very useful nutrient for the green alga Scenedesmus, but the exact amount of vanadium needed for the growth of higher plants is yet to be established.
Vanadium may replace molybdenum to some extent in nitrogen fixation by micro-organisms such as Azotobacter and Rhizobium. An increase in growth due to vanadium is seen in asparagus, rice, lettuce, barley and corn. It has also been speculated that vanadium may function in biological oxidation-reduction reactions.
Vanadium stimulates growth and nitrogenase activity in Anabaena variabilis in the absence of molybdenum. Low concentrations of vanadium are beneficial for the optimal growth of micro-organisms and higher plants. Generally, the concentration of vanadium in plants is about 1 ppm.

工業用途

Vanadium is a member of the d-block metals and belongs to group 5 of the periodic table of elements. Vanadium can be found in the earth s crust in numerous minerals and is isolated from ores mostly as a by-product. Its main application is in the steel industry, where it is used as an alloy in combination with iron. Vanadium pentaoxide is also being used as a catalyst for the production of sulfuric acid. The metal vanadium has very similar properties to titanium. Therefore, it is not surprising that its metallocene, vanadium dichloride, was also subjected to research as a potential anticancer agent. Vanadium is an essential trace metal in the human body, but still very little is known about its biological function. Vanadium is mainly found in its ionic state bound to proteins.

安全性プロファイル

An inhalation hazard. Poison by subcutaneous route. Questionable carcinogen with experimental tumorigenic data. Flammable in dust form from heat, flame, or sparks. Violent reaction with BrF3, Cl2, lithium, nitryl fluoride, oxidants. When heated to decomposition it emits toxic fumes of VOx. See also VANADIUM COMPOUNDS.

職業ばく露

Vanadium is used as a catalyst in the production of synthetic rubber and sulfuric acid. Most of the vanadium produced is used in ferrovanadium and of this the majority is used in high speed and other alloy steels with only small amounts in tool or structural steels. It is usually combined with chromium, nickel, manganese, boron, and tungsten in steel alloys.

特性

塩酸、アルカリ水溶液、希アルコー ルには溶けず、硝酸、濃硫酸、フッ 酸には溶ける

・銀白色の光沢を持ち、硬度が高い

・融点が高く、耐熱性に優れる

製法

バナジウムを含有する鉱物としては、クールソナイト（FeV2O4）、カルノー石（K2(UO2)2(VO4)2・3H2O）、デ グロワゾー石（Pb(Zn,Cu)VO4OH）、パトロナイト（VS4）、ロスコー雲母（K(V,Al,Mg)2AlSi3O10(OH)2）、褐鉛鉱 （Pb5(VO4)3Cl）があるが、主に、含バナジウムチタン磁鉄鉱を原料とする鉄鋼の副産物のスラグ（いわゆる バナジウムスラグ）からバナジウムが回収されている。また、原油（特に重質油）に硫黄とともにバナジウ ムが多く含まれることから、石油精製所の使用済脱硫触媒や火力発電所からの重油煤等から回収される。 鉱石を炭酸ナトリウムとともに焙焼し、水溶性のバナジン酸ナトリウムまで処理した後で、更に硫酸処 理して酸化バナジウムとする。酸化バナジウムをマグネシウム等で還元することにより、単体のバナジウ ムを得ることができる。

発がん性

The results of 2-year NTP inhalation study on F344/N rats (at concentrations of 0, 5, 1, or 2mg/m³) and B6C3F1 mice (at concentrations of 1, 2, or 4mg/m³)exposedfor6hperdayfor5daysperweekindicate clear evidence of carcinogenic activity of vanadium pentoxide based on the occurrence of alveolar/bronchiolar neoplasms. Exposure to V2O5 caused a spectrum of nonneoplastic lesions in the respiratory tract (nose, larynx, and lung), including alveolar and bronchiolar epithelium hyperplasia, in?ammation, ?brosis, and alveolar histiocytosis of the lung in male and female rats and mice, and an unusual squamous metaplasia of the lung in male and female rats. Hyperplasiaofthebronchiallymphnodesoccurredinfemale mice. In a 16-day inhalation study in rat, alveolar and bronchiolar epithelial hyperplasia was observed in most rats exposed to 2 or 4mg/m³ V2O5 on days 6 and 13.

環境運命予測

Vanadium is a gray metal with a body-centered cubic crystal system. Vanadium has oxidation states of +2, +3, +4, and +5. Vanadium is released naturally into the atmosphere by the formation of continental dust, marine aerosols, and volcanic emissions. Vanadium cannot be destroyed in the environment, but it can transform or change its form and attach or separate from airborne particulate, soil, water particulate, and sediment. Vanadium particles in the air settle to the ground or are washed out of the air by rain. Smaller particles, such as those emitted from oil-fueled power plants, may stay in the air for longer times and are more likely to be transported farther away from the site of release. The transport and partitioning of vanadium in water and soil is influenced by many factors, including acidity of the water or soil and the presence of particulates. Vanadium can either be dissolved in water as dissolved ions or may become adsorbed to particulate matter. As an element, vanadium cannot be degraded but can undergo various precipitation or ligand exchange reactions. Bioconcentration is insignificant.

輸送方法

UN3285 Vanadium compound, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required. This number includes vanadium fume or dust.

純化方法

Clean the metal by rapid exposure consecutively to HNO3, HCl, HF, de-ionised water and reagent grade acetone, then dry it in a vacuum desiccator. [Brauer in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol II pp 1252-1255 1965.]

不和合性

Dust may form explosive mixture with air. Dust, fume, and powders are a strong reducing agent; incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides, bromine trifluoride, lithium, nitryl fluoride, chlorine trifluoride.