A simple substance zinc under normal conditions is a brittle transition metal of bluish-white color (it fades in the air, becoming covered with a thin layer of zinc oxide).
The alloy of zinc with copper - brass - was known in ancient Greece, Ancient Egypt, India (VII century), China (XI century). For a long time it was not possible to isolate pure zinc. In 1738, in England, William Champion patented a distillation method for producing zinc. On an industrial scale, zinc smelting also began in the XVIII century: in 1743, the first zinc plant, founded by William Champion, came into operation in Bristol, where zinc was obtained by distillation[4][5]:15. In 1746, A. S. Margraf in Germany has developed a similar method for obtaining pure zinc by calcining a mixture of its oxide with coal without air access in clay refractory retorts, followed by condensation of zinc vapor in refrigerators. Margraf described his method in all the details and thereby laid the foundations of the theory of zinc production. Therefore, he is often called the discoverer of zinc.
In 1805, Charles Hobson and Charles Sylvester from Sheffield patented a method for processing zinc - rolling at 100-150 °C[5]:28. The first zinc in Russia was obtained at the Alagir plant on January 1, 1905:86. The first plants where zinc was obtained by electrolytic method appeared in 1915 in Canada and the USA:82.
66 zinc minerals are known, in particular zinkite, sphalerite, willemite, calamine, smithsonite, franklinite. The most common mineral is sphalerite, or zinc blende. The main component of the mineral is zinc sulfide ZnS, and various impurities give this substance all kinds of colors. Due to the difficulty of determining this mineral, it is called a decoy (other-Greek. σφαλερός — deceptive). Zinc blende is considered the primary mineral from which other zinc minerals were formed [source not specified 43 days]: smithsonite ZnCO3, zincite ZnO, calamine 2ZnO * SiO2 · H2O. In Altai, it is not uncommon to find striped "chipmunk" ore - a mixture of zinc blende and brown spar. A piece of such ore from a distance really looks like a hidden striped animal [style].
The average zinc content in the earth's crust is 8.31010-3%, in the main igneous rocks it is slightly more (1.3⋅10-2%) than in acidic (61010-3%). Zinc is an energetic water migrant, its migration in thermal waters together with lead is especially characteristic. Zinc sulfides, which are of great industrial importance, are deposited from these waters. Zinc also migrates vigorously in surface and underground waters, hydrogen sulfide is the main precipitator for it, sorption by clays and other processes play a lesser role.
Zinc is an important biogenic element, living organisms contain an average of 5-10 - 4% zinc. But there are exceptions — the so-called concentrator organisms (for example, some violets).
Deposits
Zinc deposits are known in Iran, Australia, Bolivia, Kazakhstan[8]. In Russia, the largest producer of lead-zinc concentrates is OJSC MMC Dalpolymetal[9][non-authoritative source?On the territory of the Krasnoyarsk Territory in the Lower Angara region, a unique Gorevskoye polymetal deposit with zinc reserves of 1004.5 thousand tons in categories A + B + C1 and 798.4 thousand tons in category C2 is being developed. The deposit was discovered in 1956, operation began in 1975, but the first information about the presence of ores in the surrounding areas dates back to the 1770s. In 2012, zinc production amounted to 25.8 thousand tons. The field is being developed by a group of companies. The Partizanskoye and Harsh deposits in the west of the Taimyr Peninsula have also been explored. Forecasted zinc resources are 500 thousand tons.[
Receiving
Zinc is not found in nature as a native metal.
Zinc is extracted from polymetallic ores containing 1-4% Zn in the form of sulfide, as well as Cu, Pb, Ag, Au, Cd, Bi. Ores are enriched by selective flotation, obtaining zinc concentrates (50-60% Zn) and simultaneously lead, copper, and sometimes also pyrite concentrates. Zinc concentrates are fired in furnaces in a fluidized bed, converting zinc sulfide into ZnO oxide; the resulting sulfur dioxide SO2 is consumed for the production of sulfuric acid. Pure zinc from ZnO oxide is obtained in two ways. According to the pyrometallurgical (distillation) method, which has existed for a long time, the burnt concentrate is sintered to give granularity and gas permeability, and then restored with coal or coke at 1200-1300 ° C: ZnO + C → Zn + CO. The resulting metal vapors are condensed and poured into molds. At first, the restoration was carried out only in retorts made of baked clay, serviced manually, later vertical mechanized retorts made of carborundum were used, then mine and electric arc furnaces; zinc is obtained from lead-zinc concentrates in mine blast furnaces. Productivity gradually increased, but zinc contained up to 3% impurities, including valuable cadmium. Distilled zinc is purified by liquation (that is, by settling the liquid metal from iron and part of lead at 500 ° C), reaching a purity of 98.7%. The sometimes more complex and expensive purification by rectification gives the metal a purity of 99.995% and allows the extraction of cadmium.
The main method of obtaining zinc is electrolytic (hydrometallurgical). The burnt concentrates are treated with sulfuric acid; the resulting sulfate solution is purified from impurities (by depositing them with zinc dust) and subjected to electrolysis in baths densely lined with lead or vinyl plastic inside. Zinc is deposited on aluminum cathodes, from which it is removed daily (stripped off) and melted in induction furnaces. Usually, the purity of electrolytic zinc is 99.95%, the completeness of its extraction from the concentrate (taking into account waste processing) is 93-94%. Zinc sulfate, Pb, Cu, Cd, Au, Ag are obtained from production waste; sometimes also In, Ga, Ge, Tl.