亜鉛 (粉末)

外観

銀白色〜灰色, 粒状

定義

本品は、金属元素 Zn である。

溶解性

塩酸、硝酸、硫酸及び水酸化ナトリウム溶液と反応して水素を発生する。

主な性質

1. 単体亜鉛は青白色の金属で、酸化物及び水酸化物は両性化合物で酸にもアルカリにも溶ける
2. 鉄に比べて亜鉛の方がイオン化傾向が大きいため、電解中であっても鉄の代わりに亜鉛が溶け出す性質がある（鉄鋼の犠牲防食用メッキ材として必需品）
3. 〔トタン〕は鉄板に亜鉛メッキしたもの
4. 融点が比較的低いので銅との合金（快削材料の真ちゅう）の成分に多用される
5. 鋳造性がよく、ダイス寿命が長く、寸法精度も高いのでダイカスト材に好適
6. 亜鉛華（ＺｎＯ）は塗料、顔料の添加剤に用いられている
7. 硫化亜鉛に電子線を当てると黄緑色の蛍光を発する性質からブラウン管の蛍光剤として銅と併せて使用している

解説

元素記号はZn。原子番号30，原子量65.38。融点419.527℃，沸点907℃。青みをおびた銀白色の金属。空気中では塩基性炭酸亜鉛の被膜をつくり，内部を保護する。高温に熱すると緑白色の炎をあげて燃え，酸化物となる。イオン化傾向は大きく，希酸には水素を発生して溶ける。濃アルカリ溶液でも水素を発生し，亜鉛酸塩となる。遊離して存在しないが，地球上広く分布。主要鉱石はセン亜鉛鉱，リョウ亜鉛鉱で，浮遊選鉱により鉛精鉱と分離，Zn約60％の亜鉛精鉱は焙焼して酸化物とする。製錬は酸化物をレトルト，電気炉などに装入，炭素で還元しつつ蒸留する乾式法，酸化物を硫酸で処理した硫酸塩を電気分解する湿式法，鉛・亜鉛同時製錬のISP法もある（1958年操業開始）。亜鉛の主要産出国は米国，オーストラリア，カナダなど。トタン板（亜鉛鉄板）など鉄鋼製品のめっき，黄銅その他の合金，ダイカスト，印刷版などに使用。生体必須元素で，多くの亜鉛含有酵素が知られている。→関連項目非鉄金属
株式会社平凡社 百科事典マイペディアについて　情報

用途

窒素酸化物測定用還元剤。

用途

ひ素分析(グートツァイト法)用。

用途

一般分析、亜鉛化合物製造原料、合金材料。

用途

めっき、薄鋼板、合金の原料

用途

高純度金属材料。

用途

一般分析、亜鉛化合物合成原料、合金材料。

化粧品の成分用途

酸化防止剤

主な用途

1. 亜鉛メッキ鋼板（自動車部材、建材構造物、電気機器部材）
2. 伸銅品（黄銅板、管、棒製品、電子部品）
3. ダイカスト（自動車部品、機械部品、モーター、おもちゃ、ヘリコプター）
4. 無機薬品（亜鉛華など／ゴム、塗料）
5. その他（積層乾電池）

使用上の注意

湿った空気中では自然発火することがある。

説明

Zinc (Zn) is a metallic element discovered by a German chemist, Andreas Marggraf, in 1746. It is environmentally ubiquitous and essential for life. It exhibits a strong tendency to react with both organic and inorganic compounds. Zinc is the 24th most abundant element, constitutes 0.027% bw of the Earth’s crust, and has five stable isotopes. The largest mineable amounts are found in Australia, Asia, and the United States. A recent estimate suggests that approximately 20% of the world’s population is at risk of Zn deficiency. However, free access to uncontrolled amounts of Zn in nutritional supplements is the most common cause of Zn excess. Both Zn deficiency and Zn excess contribute to human Zn toxicity.

化学的特性

Zinc is a soft silvery colored metal; the dust is odorless and gray. It is one of the most common elements in the earth's crust. Metal zinc was first produced in India and China during the middle ages. Industrially important compounds of zinc are zinc chloride (ZnCl2), zinc oxide (ZnO), zinc stearate (Zn(C16H35O2)2), and zinc sulfide (Sphalerite, ZnS) found in hazardous waste sites. It is found in air, soil, and water, and is present in all foods.

Pure zinc is a bluish-white shiny metal. Zinc has many commercial uses as coatings to prevent rust, in dry-cell batteries, and mixed with other metals to make alloys like brass and bronze. Zinc combines with other elements to form zinc compounds. Zinc compounds are widely used in industry to make paint, rubber, dye, wood preservatives, and ointments.

物理的性質

Zinc is a whitish metal with a bluish hue. As an electropositive metal, it readily gives up itstwo outer electrons located in the N shell as it combines with nonmetal elements. Zinc foilwill ignite in moist air, and zinc shavings and powder react violently with acids. Zinc’s meltingpoint is 419.58°C, its boiling point is 907°C, and its density is 7.14 g/cm³.Note: Zinc is not always included as one of the metals in the first series of the transitionelements, but it is the first element in group 12 (IIB).

同位体

There are 38 isotopes of zinc, ranging in atomic weights from Zn-54 to Zn-83.Just four of these are stable, and those four, plus one naturally radioactive isotope (Zn-70) that has a very long half-life (5×10⁺¹⁴ years), make up the element’s existence onEarth. Their proportional contributions to the natural existence of zinc on Earth are assuch: Zn-64 = 48.63%, Zn-66 = 27.90%, Zn-67 = 4.10%, Zn- 68 = 18.75%, and Zn-70 = 0.62%. All the other isotopes are radioactive and artificially produced.

名前の由来

Although ancients used zinc compounds, the name “zinc” is assumed to be derived from the German word zinn, which was related to tin.

天然物の起源

Zinc is the 24th most abundant on Earth, which means it makes up only about 0.007%of the Earth’s crust. Even so, humans have found many uses for it over the past thousands ofyears.It is not found in its pure metallic form in nature but is refined from the mineral (compound) zinc sulfide (ZnSO₄) known as the ores sphalerite and zincblende. It is also recoveredfrom minerals and ores known as willemite, hydrozincite, smithsonite, wurtzite, zincite, andFranklinite. Zinc ores are found in Canada, Mexico, Australia, and Belgium, as well as in theUnited States. Valuable grades of zinc ores are mined in Colorado and New Jersey.

特性

Zinc is malleable and can be machined, rolled, die-cast, molded into various forms similarto plastic molding, and formed into rods, tubing, wires, and sheets. It is not magnetic, butit does resist corrosion by forming a hard oxide coating that prevents it from reacting anyfurther with air. When used to coat iron, it protects iron by a process called “galvanic protection,” also known as “sacrificial protection.” This protective characteristic occurs because theair will react with the zinc metal coating, which is a more electropositive (reactive) metal thanis the coated iron or steel, which is less electropositive than zinc. In other words, the zinc isoxidized instead of the underlying metal. (See the section under “Common Uses of Zinc” formore on galvanization.

使用

zinc is described as an oligo element, trace element, or micro nutrient. Zinc is believed to accelerate wound healing. It is also considered an anti-oxidant, offering protection against uV radiation. It appears to favor the sulfur uptake in sulfurated amino acids and facilitates the incorporation of cysteine, an amino acid, into the skin. It also has a synergistic effect with vitamins A and e. Zinc is a component of more than 70 metal enzymes. It promotes collagen synthesis in the dermis and keratinization of the corneum layer. Zinc is useful for acne treatments because it lowers sebaceous secretion, and is also used in the treatment of psoriasis.

定義

zinc: Symbol Zn. A blue-white metallicelement; a.n. 30; r.a.m. 65.38; r.d.7.1; m.p. 419.88°C; b.p. 907°C. It occursin sphalerite (or zinc blende,ZnS), which is found associated withthe lead sulphide, and in smithsonite(ZnCO₃). Ores are roasted to give theoxide and this is reduced with carbon(coke) at high temperature, the zincvapour being condensed. Alternatively,the oxide is dissolved in sulphuricacid and the zinc obtained byelectrolysis. There are five stable isotopes(mass numbers 64, 66, 67, 68,and 70) and six radioactive isotopesare known. The metal is used in galvanizingand in a number of alloys(brass, bronze, etc.). Chemically it is areactive metal, combining with oxygenand other nonmetals and reactingwith dilute acids to releasehydrogen. It also dissolves in alkalis to give zincates. Most of its compoundscontain the Zn²⁺ ion.

調製方法

Zinc is widely distributed in nature, constituting 20–200 ppm of the Earth’s crust.The principal zinc ore is in the form of sulfides, such as sphalerite and wurtzite (cubic and hexagonal ZnS) and willemite (Zn2SiO4). To obtain metallic zinc, the zinc ores that are relatively low in zinc content are concentrated. Zinc smelting is gradually being replaced by the electrolytic processes. During smelting there are often large emissions of zinc, and other heavy metals contained in the zinc ore such as lead and cadmium, into the air.

反応性

Zinc exhibits a valence of +2 in all its compounds. It also is a highly electropositive metal. It replaces less electropositive metals from their aqueous salt solutions or melts. For example, a zinc metal bar put into Cu2+ solution acquires a brown-black crust of copper metal deposited on it. At the same time the blue color of the solution fades. Zinc reduces Cu2+ ions to copper metal. The overall reaction is:
Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s)
This spontaneous reaction was used first in 1830 to make a voltaic cell. The metal is attacked by mineral acids. Reactions with sulfuric and hydrochloric acids produce hydrogen. With nitric acid, no hydrogen is evolved but the pentavalent nitrogen is reduced to nitrogen at lower valence states. Zinc is attacked by moist air at room temperature. Dry air has no action at ambient temperatures but the metal combines with dry oxygen rapidly above 225°C. Zinc reacts with carbon dioxide in the presence of moisture at ordinary temperatures forming a hydrated basic carbonate. The metal, on heating with dry halogen gases, yields zinc halides. However, in the presence of moisture the reaction occurs rapidly at ambient temperatures. The metal dissolves in hot solutions of caustic alkalis to form zincates and evolves hydrogen:
Zn + 2NaOH → Na2ZnO2 + H2

一般的な説明

A grayish powder. Insoluble in water. May produce toxic zinc oxide fumes when heated to very high temperatures or when burned. Used in paints, bleaches and to make other chemicals.

空気と水の反応

Can evolve gaseous hydrogen in contact with water or damp air. The heat of the reaction may be sufficient to ignite the hydrogen produced [Haz. Chem. Data 1966. p. 171]. Flammable. May form an explosive mixture with air [Hawley].

反応プロフィール

ZINC METAL is a reducing agent. Reacts violently with oxidants causing fire and explosion hazards [Handling Chemicals Safely 1980. p. 966]. In the presence of carbon, the combination of chlorine trifluoride with zinc results in a violent reaction [Mellor 2, Supp. 1: 1956]. Sodium peroxide oxidizes zinc with incandescence [Mellor 2:490-93 1946-47]. Zinc powder or dust in contact with acids forms hydrogen. The heat generated by the reaction is sufficient to ignite the hydrogen evolved [Lab. Govt. Chemist 1965]. A mixture of powdered zinc and an oxidizing agent such as potassium chlorate or powdered sulfur can be exploded by percussion. Zinc burns in moist chlorine. A mixture of zinc and carbon disulfide reacts with incandescence. Zinc powder reacts explosively when heated with manganese chloride. The reaction between zinc and selenium or tellurium is accompanied by incandescence [Mellor 4:476-480 1946-47]. When zinc and ammonium nitrate are mixed and wetted with a minimum of water, a violent reaction occurs with evolution of steam and zinc oxide. When hydrazine mononitrate is heated in contact with zinc a flaming decomposition occurs at temperatures a little above its melting point. Hydroxylamine is reduced when heated with ZINC, unpredictably ZINC may either ignite and burn or explode [Mellor 8 1946-47].

危険性

As mentioned, zinc dust and powder are very explosive. When zinc shavings are placedin acid or strong alkaline solutions, hydrogen gas is produced, which may explode. Many ofzinc’s compounds are toxic if inhaled or ingested.
A deficiency of zinc in humans will retard growth, both physically and mentally, andcontribute to anemia. It is present in many foods, particularly proteins (meat). A balanceddiet provides an adequate amount of zinc. Not more than 50 milligrams per day of dietaryzinc supplement should be taken, given that high levels of zinc in the body are toxic. Humanbodies contain about two grams of zinc. A deficiency of zinc can cause a lack of taste and candelay growth as well as cause retardation in children.
Zinc intoxication can occur both from inhaling zinc fumes and particles, mainly in industrialprocesses, and from orally ingesting an excess of zinc in dietary supplements. Zinc intoxicationcan cause stomach pains, vomiting, and bleeding. Excess zinc also can cause prematurebirth in pregnant women.

健康ハザード

Zinc and its compounds are relatively non-toxic, but very large doses can produce an acute gastroenteritis characterized by nausea, vomiting, and diarrhea. The recommended dietary allowance (RDA) for zinc is 15 mg/day for men, 12 mg/day for women, 10 mg/day for children, and 5 mg/day for infants. Insuffi cient zinc in the diet can result in a loss of appetite, a decreased sense of taste and smell, slow wound healing and skin sores, or a damaged immune system. Pregnant women with low zinc intake have babies with growth retardation. Exposure to zinc in excess, however, can also be damaging to health. Harmful health effects generally begin at levels from 10–15 times the RDA (in the 100–250 mg/day range). Eating large amounts of zinc, even for a short time, can cause stomach cramps, nausea, and vomiting. Chronic exposures to zinc chloride fumes cause irritation, pulmonary edema, bronchopneumonia, pulmonary fi brosis, and cyanosis. It also causes anemia, pancreas damage, and lower levels of high-density lipoprotein cholesterol. Breathing large amounts of zinc (as dust or fumes) can cause a specifi c short-term disease, called metal fume fever, including disturbances in the adrenal secretion. Information on the possible toxicological effects following prolonged period of exposures to high concentrations of zinc is not known.

火災危険

Produce flammable gases on contact with water. May ignite on contact with water or moist air. Some react vigorously or explosively on contact with water. May be ignited by heat, sparks or flames. May re-ignite after fire is extinguished. Some are transported in highly flammable liquids. Runoff may create fire or explosion hazard.

応用例（製薬）

The average human body contains around 2 g of Zn2+. Therefore, zinc (after iron) is the second most abundant d-block metal in the human body. Zinc occurs in the human body as Zn2+ (closed d10 shell configuration), which forms diamagnetic and mainly colourless complexes. In biological systems, zinc ions are often found as the active centre of enzymes, which can catalyse metabolism or degradation processes, and are known to be essential for stabilising certain protein structures that are important for a variety of biological processes.
Already from ancient times, Zn2+ was known to have important biological properties. Zinc-based ointments were traditionally used for wound healing. Low Zn2+ concentrations can lead to a variety of health-related problems especially in connection with biological systems of high Zn2+ demand such as the reproductive system. The daily requirement for Zn2+ is between 3 and 25 mg, depending on the age and circumstances.
The enzymatic function of Zn2+ is based on its Lewis acid activity, which are electron-deficient species. In the following chapters, examples will be shown to further explain this. Carboanhydrase (CA),carboxypeptidase and superoxide dismutase are some examples for well-studied zinc-containing enzymes. The so-called zinc fingers have been discovered because of the crucial role of Zn2+ in the growth of organisms. Within the zinc finger, Zn2+ stabilises the protein structure and therefore enables its biological function.

农业用途

Zinc (Zn) is a bluish-white metal belonging to the 12th Group of the Periodic Table. It occurs naturally as sphalerite, smithsonite, hemimorphite and wurzite, and is extracted by roasting the oxide and reducing with carbon. It is used for galvanizing,

工業用途

Hot-dipped or galvanized zinc coatings havebeen popular for many years for protecting ferrousproducts because of their ideal combinationof high corrosion protection and low cost.Their corrosion protection stems from threeimportant factors:zinc has a slower rate ofcorrosion than iron,zinc corrosion productsare white and nonstaining, and zinc affordselectrolytic protection to iron.
The amount of protection against corrosiondepends largely upon coating weight — theheavier the coating, the longer the life of the base metal. For example, a coating 0.04 mmthick is expected to have a life of 25 years inrural atmospheres, whereas a 0.88-mm coatingwill last 50 years. The life of zinc coatings maybe five to ten times greater in rural atmospheresthan in industrial atmospheres containing sulfurand acid gases. Nevertheless, the coatings arestill popular for industrial use because of theirlow cost.Hot dipping is particularly valuable for zinccoating parts that cannot conveniently be madeof galvanized sheet. Thus, it is quite popular forstructural parts, castings, bolts, nuts, nails, polelinehardware, heater and condenser coils,windlasses, and many other products.

安全性プロファイル

Human systemic effects by ingestion: cough, dyspnea, and sweating. A human skin irritant. Pure zinc powder, dust, and fume are relatively nontoxic to humans by inhalation. The dfficulty arises from oxidation of zinc fumes immedately prior to inhalation or presence of impurities such as Cd, Sb, As, Pb. Inhalation may cause sweet taste, throat dryness, cough, weakness, generalized aches, chills, fever, nausea, vomiting. Flammable in the form of dust when exposed to heat or flame. May i p t e spontaneously in air when dry. Explosive in the form of dust when reacted with acids. Incompatible with NH4NO3, BaO2, Ba(NO3)2, Cd, CS2, chlorates, Cl2, ClF3, CrO3, (ethyl acetoacetate + tribromoneo- pentyl alcohol), F2, hydrazine mononitrate, hydroxylamine, Pb(N3)2, (Mg + Ba(NO3)2 + BaO2), MnCl2, HNO3, performic acid, KCLO3, KNO3, K2O2, Se, NaClO3, Na2O2, S, Te, H2O2 (NH4)2S, As2O3, CS2, CaCl2, NaOH, chlorinated rubber, catalytic metals, halocarbons, o-nitroanisole, nitrobenzene, nonmetals, oxidants, paint primer base, pentacarbonyliron, transition metal halides, seleninyl bromide. To fight fire, use special mixtures of dry chemical. When heated to decomposition it emits toxic fumes of ZnO. See also ZINC COMPOUNDS.

職業ばく露

Zinc is used most commonly as a protective coating of other metals. In addition, it is used in alloys, such as bronze and brass, for electrical apparatus in many common goods; and in organic chemical extractions and reductions. Zinc chloride is a primary ingredient in smoke bombs used by military for screening purposes, crowd dispersal and occasionally in firefighting exercises by both military and civilian communities. In pharmaceuticals, salts of zinc are used as solubilizing agents in many drugs, including insulin.

用途

亜鉛の最大の用途は鉄鋼の防食用である。金属亜鉛は鉄に対する犠牲防食作用が強いので、鉄 鋼の防食（亜鉛めっき）には欠くことのできない金属である。鉄板に亜鉛めっきしたものは「トタン」と呼 ばれる。亜鉛めっきの種類には溶融亜鉛めっきと電気亜鉛めっきがある。溶融亜鉛めっきは高温で溶 かした亜鉛に鋼材を浸し、鋼材の表面に被膜をつくる処理法で、電気亜鉛めっきは、めっき槽に鉄をつ け、電気を介して亜鉛をめっきする方法である。亜鉛めっき鋼板は大型建築・戸建建築の屋根や外壁、 スチールハウスや鉄骨プレハブの骨材として、土木関係ではガードレール、標識、防音壁等に、自動 車用途ではドア、フェンダー、タンク等に、そのほか洗濯機や冷蔵庫等の電気製品、パソコン等の OA 機器、物置や車庫、また店舗、車庫、倉庫、工場等のシャッターにも使われている。防食用のめっきの ほか、船舶、橋梁、ドックなどの水に常に接する鉄の構造物への耐食用部材（めっきでなく亜鉛ブロッ クで覆う）としても利用されている。
防食用の塗料にも亜鉛が用いられる。亜鉛粉末とごくわずかなバインダーからなるジンクリッチ塗料 は鉄面に塗装することで、亜鉛粉末の電気防食作用により、鋼構造材の耐久性が向上する。
また、鉄、アルミニウム、銅より融点が低く加工しやすいメリットから、広くダイカスト用合金や鋳造品 としても使われる。合金では、真鍮（銅との合金、黄銅の別名）、ダイカスト用亜鉛合金として利用され、 自動車、家電製品、通信機器などの精密部品や工業製品から玩具、ドアノブなどの日用品へ広く用い られている。鋳造品としては、自動車の部品の金型などに使用されている。また、酸化亜鉛、塩化亜鉛 などとしてゴム製品（タイヤの加硫促進剤）、フェライト用原料、バリスタ、塗装（塗膜強化剤）、陶磁器 （上薬）、乾電池、農薬、医薬品等無機薬品用途としても幅広く活用されている。
さらに、亜鉛は乾電池用の材料としても用いられ、マンガン乾電池の場合、亜鉛粒として使用される。 酸化亜鉛、塩化亜鉛はゴム製品（タイヤの加硫促進剤）、フェライト用原料、塗装、医薬品等無機薬品 として幅広く活用されている。
亜鉛の新規用途は、非常用電池としてのニッケル亜鉛電池等がある。

発がん性

Repeated intratesticular injections of zinc chloride to chickens and rats have been reported to produce testicular sarcomas. There is no evidence that zinc compounds are carcinogenic after administration by any other route. Zinc oxide, zinc chloride, and zinc stearate have been classified by the U.S. EPAas belonging to group D.

製造方法

亜鉛鉱石から選鉱により不純物が取り除かれた亜鉛精鉱から乾式法（蒸留法）もしくは湿式法（電気 分解法）により亜鉛が製造される。乾式法は亜鉛の低い沸点（907℃）を利用し、亜鉛だけを蒸発させる 方法である。まず、精鉱を焙焼し酸化亜鉛焼結鉱を造り、この酸化亜鉛焼結鉱とコークスを混合加熱 することで、酸化亜鉛中の亜鉛分を蒸発させる。蒸発した亜鉛を鉛に吸収させた後に、亜鉛を分離す る。乾式で製造された蒸留亜鉛には鉛の含有量が高く、その特性を活かして溶融亜鉛めっき等に利用 されている。湿式法は電気分解によって金属亜鉛を得る方法である。まず、精鉱を焙焼し酸化亜鉛焼 鉱を造り、硫酸に溶解させ硫酸亜鉛溶液を造る。その後、この溶液を電気分解して電極に付着したも のを回収し電気亜鉛（亜鉛純分 99.99％）を得る。湿式法は乾式法よりも短い工程でより高純度の亜鉛 地金を製造できるため、世界的に最も多く取り入れられている製造方法である。
また、各種廃棄物や鉄鋼ダストも酸化亜鉛にてリサイクルされ原料となる。
亜鉛地金は、その製造工程によって電気亜鉛、蒸留亜鉛、精留亜鉛の 3 種類に分かれる。先述の 湿式法で作られたものを電気亜鉛（品位 4N）と呼び、乾式法で作られたものを蒸留亜鉛（品位 98.5％） と呼ぶ。精留亜鉛（品位 4N）は、蒸留亜鉛を、精留塔で融点の異なる不純物を除去して高純度化した ものである。

輸送方法

UN1436 Zinc powder or zinc dust, Hazard Class: 4.3; Labels: 4.3-Dangerous when wet material, 4.2-Spontaneously combustible material.

純化方法

Commercial zinc dust (1.2kg) is stirred with 2% HCl (3L) for 1minute, then the acid is removed by filtration, and washed in a 4L beaker with a 3L portion of 2% HCl, three 1L portions of distilled water, two 2L portions of 95% EtOH, and finally with 2L of absolute Et2O. (The wash solutions were removed each time by filtration.) The material is then dried thoroughly, and if necessary, any lumps are broken up in a mortar. [Wagenknecht & Juza Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol II p 1067 1965.]

不和合性

Dust is pyrophoric and may self-ignite in air. A strong reducing agent. Violent reaction with oxidizers, chromic anhydride; manganese chloride; chlorates, chlorine and magnesium. Reacts with water and reacts violently with acids, alkali hydroxides; and bases forming highly flammable hydrogen gas. Reacts violently with sulfur, halogenated hydrocarbons and many other substances, causing fire and explosion hazard.

廃棄物の処理

Zinc powder should be reclaimed. Unsalvageable waste may be buried in an approved landfill. Leachate should be monitored for zinc content.