Zinc

The zinc is a chemical element, of symbol Zn and Atomic number 30.

Origin of the discovery

Old which knew the Calamine (the carbonated ore of zinc) do not appear to have used zinc as a metal isolated, although zinc bracelets were discovered in Greece, in the mines from Camaros. The first industrialization of the production is achieved by William Champion which patents in 1738 a process of reduction of the Calamine.

Lexicology

The name derives from the word Zinke as former German who means “sharp-edged point” or “tooth”, related to the appearance of the zinc cooled in Récipient of cast (effect due to the formation of Dendrite S).
The academic pronunciation zɛ̃ɡ (“zingu'”) is found in zincate (zɛ̃ɡat, “zingat'”) and explains the derivatives zinking, zinc works, zinc worker.

Notable characteristics

Zinc is a Métal, fairly reagent, which combines with the Oxygène and others non-metals, and which reacts with Acide S diluted while releasing from the Hydrogène.
The state of the most common oxidation of zinc is +II (called ion zincic).

Exposed to the air, it forms a thin impermeable oxide coating, sometimes called white Rouille.

Current chemical reactions

Zinc metal Zn reacts by oxydoreduction with the ion coppers II, according to the equation:

$Zn + Cu^ \left\{2+\right\} \ rightarrow Zn^ \left\{2+\right\} + Cu$

Trace element essential to the man

Zinc is contained primarily in the red meat and it does not seem to exist of the shape of storage of this metal in the human organism. A zinc deficiency is noted in nearly a third of the world population, especially in connection with problems of malnutrition.

It is present in several hundreds of Enzyme S, takes part in carbonic the oxygen-gas exchanges by the red globules.

According to a study carried out by a team of American nutritionnists in 1975, the deficiency out of zinc would make the rats more aggressive and less intelligent. It can be avoided by a food rich in Noix, Noisette S, Pissenlit, Ail, Lait, Viande S, egg S, Poisson S and Légume S.

Zinc also seems to intervene in the immunological processes . The supplementation in this Oligo-élément decreases significantly occurred of certain infections (primarily pneumonia and diarrhea) in the natives in the process of development, which can be translated into term of profit in life.

Uses

The principal use of zinc is the Galvanisation Acier S: the deposit of a thin layer of zinc on the surface of steel protects it from corrosion. Galvanization consumes 47% of the zinc exploited in the world. Galvanized steel is used in the car, the construction industry, the electric household appliances, the industrial plants, etc The Brass - alloy of Copper and zinc - and the Bronze - alloy of Copper and tin, to which one adds sometimes zinc - consume 19% of zinc.

Zinc alloys, the such Zamac, for castings (Automobile, domestic equipment, industrial parts…) 14% of its consumption represent, the chemicals, 9%, and the other applications (of which plates and parts for Toit RUE), 11%.

It is also used in Agriculture, like contribution of Oligo-élément, primarily in zone of grounds strongly Calcaire S.

The culture most sensitive to the deficiency or insufficiency out of zinc is probably the Maïs.

Symptoms of insufficiency also appear on the majority of the Fruit trees, more rarely on the Vigne. The vegetables are less sensitive, except the Asperge S, the Eggplant S, the Oignon S and the Potatoes.

The contributions, preventive or curative, are done on the ground - and it is then necessary to take care of the duration of the availability for the plants - or by foliar pulverization.

For example, the annual needs for the Maïs are around 300 to 500 grams of zinc per hectare.

Zinc ores

The ore more used is the Sulfure of zinc called sphalerite or Sphalérite (ZnS). The word sphalerite, from now on abandoned in the mineralogical literature , comes from the German word blenden : “to dazzle, mislead”. This sulfide - most widespread in the Lithosphere - crystallizes in the cubic system. It can contain metal impurities, such of iron (dark sphalerites): the Marmatite, (Zn, Fe) S, contains until 14% of Fer. In nature, sphalerite is associated with other sulfides, like the Galène (sulfide of Plomb: PbS).

The Wurtzite with the same chemical composition but crystallizes in the hexagonal system: it is the polymorphic of high Température of ZnS.

Under the old term of calamine one finds the Smithsonite (Carbonate of zinc: ZnCO3) and the Hémimorphite (Silicate of zinc: Zn4Si2O7 (OH) 2, H2O). Both mineral can be associated. So historically calamine was used at the beginning of the industrial development of this Métal, it is exploited now little.

Other rarer minerals:

Production of zinc

The production of zinc starting from ore (sphalerite) is carried out in two distinct technologogic dies:

• pyrometallurgy;
• the hydrometallurgy followed by an electrolysis.

The operations of the pyrometallurgical process are:

• netting of zinc sulfide (ZnS) to obtain a zinc oxide (ZnO);
• reduction of oxide to obtain metal zinc (Zn);
• refining of zinc by liquation and distillation to remove the impurities like lead or iron.

The operations of the hydrometallurgic process are:

• netting of zinc sulfide (ZnS) to obtain a zinc oxide (ZnO) and to remove certain impurities (Iron);
• leaching to solubilize zinc in the form of zinc sulfate (ZnSO4);
• cementing to eliminate the impurities: Cobalt, Nickel, Cadmium and Copper of the zinc sulfate solution;
• electrolysis to transform zinc sulfate into zinc metal.

These two processes are detailed in the article extractive Métallurgie of zinc.

Some economic situation

The zinc worldwide consumption in 2004 was about 10 million tons:

• Asia 5.057 kt (kt = thousands of tons)
• Europe 2.840 kt
• Americas 2.113 kt
• Oceania 263 kt
• Africa 193 kt
Total 10.466 kt

The production of metal in 2004 was distributed in the following way:

• Asia 4.729 kt
• Europe 2.715 kt
• Americas 1.993 kt
• Oceania 474 kt
• Africa 256 kt
Total 10.167 kt

The mining production (in zinc kt contained in the concentrate) was into 2004 of:

• Asia 3.340 kt
• Europe 1.037 kt
• Americas 3.606 kt
• Oceania 1.298 kt
• Africa 353 kt
Total 9.634 kt

Zinc is one of the non-ferrous metals with dimensions to the purse of metals of London. Its price the cash, expressed into \$, is cyclic: between 1994 and 2005, it varied between 725 \$/t and 1.760 \$/t. In 2006, it exceeded the 3.000 \$/t.

Expressions

• In the popular speech the zinc indicates the counter of a bar, although it was never used for this purpose. They were manufactured with an alloy of Plomb and tin;
• the zinc is a nickname to indicate a Avion;
• the plumber-tinsmith indicates a Plombier;
• “You have zinc in the head”: to be painful;
• To dezinc : to kill.

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