Zinc is a chemical element with atomic number 30 and symbol Zn. When oxidation is removed, zinc turns into a shiny grayish metal that is slightly brittle at normal temperature. It is the first element in group 12 (IIB) of the periodic table. Zinc and magnesium share several chemical properties, including a single normal oxidation state (+2) and similarly sized Zn2+ and Mg2+ ions. Zinc, the 24th most common element in the earth's crust, has five stable isotopes. Sphalerite, a zinc sulfide mineral, is the most typical zinc ore.
Australia, Asia and the United States have the largest working veins. The ore is refined using foam flotation, roasting and electrically driven final extraction to produce zinc.
Zinc is a trace element essential for the pre- and postnatal development of humans, animals, plants and microbes. It is the only metal found in all types of enzymes and is the second most common trace metal in humans after iron. An important cofactor for many enzymes, zinc is also a very important vitamin for coral growth.
Two billion people in the poor world suffer from zinc deficiency, which is linked to numerous ailments. Deficiency in children results in slow growth, delayed sexual maturation, increased susceptibility to infection, and diarrhea. Many biochemical enzymes, such as human alcohol dehydrogenase, have a zinc atom in their reactive center. Ataxia, fatigue, and copper deficiency can result from too much zinc consumption.
In the Aegean region, which includes Iraq, United Arab Emirates, Kalmykia, Turkmenistan and Georgia today, brass, which is an alloy of copper and zinc in varying amounts, dates back to the XNUMXth century BC. It was used in the early third millennium BC. The present-day locations of western India, Uzbekistan, Iran, Syria, Iraq, and Israel were using rice in the second millennium BC.
Although known to the ancient Romans and Greeks, zinc metal was not produced on a large scale in India until the 12th century. Rajasthani mines have provided conclusive evidence of zinc production dating back to the 6th century BC. The earliest documented use of pure zinc was in Zawar, Rajasthan, in the ninth century AD, when it was produced by distillation. Alchemists burned zinc in air to create what they called "philosopher's wool" or "white snow."
The element was most likely given the German name Zinke by the alchemist Paracelsus. (fork, tooth). In 1746, German chemist Andreas Sigismund Marggraf discovered pure metallic zinc. By 1800, the researches of Luigi Galvani and Alessandro Volta revealed the electrochemical properties of zinc. The primary use of zinc is hot-dip galvanizing, which coats the iron with corrosion-resistant zinc. Other uses include small non-structural castings, electric batteries, and alloys such as brass. There are many different types of zinc compounds commonly used, including zinc gluconate and carbonate (as a nutritional supplement), zinc chloride (in deodorants), zinc pyrithione (in anti-dandruff shampoos), zinc sulfide (in gloss paints), and dimethyl zinc or diethyl zinc in the organic lab.
Physical Properties of Zinc
Zinc is a bluish-white, shiny, diamagnetic metal; however, most of their commercial grades have a dull appearance. It has a hexagonal crystal structure, a slightly deformed version of the hexagonal close packing, and is slightly less dense than iron. Each atom has six nearest neighbors in its plane (at 265,9 pm) and six more at a further distance of 290,6 pm. The metal is brittle and hard at most temperatures, but becomes pliable between 100 and 150 °C. Above 210 °C the metal becomes brittle again and can be hammered. A good conductor of electricity is zinc. Zinc has a relatively low melting point (419,5 °C) and boiling point (907 °C) for a metal.
Except for mercury and cadmium, the d-block metals have the lowest melting point; therefore, zinc, cadmium, and mercury, among others, are generally not considered transition metals like other d-block metals.
Brass is an alloy containing zinc. Aluminum, antimony, bismuth, gold, iron, lead, mercury, silver, tin, magnesium, cobalt, nickel, tellurium, and sodium are additional metals that have long been known to combine with zinc to make binary alloys.
Although neither zirconium nor zinc are ferromagnetic, their alloy ZrZn2 , below 35K does this.
How Did Zinc Occur?
Zinc, the 24th most abundant metal, makes up about 75 ppm (0,0075%) of the earth's crust. Zinc is typically around 1 g/mXNUMX in the atmosphere.3It is found at background levels of not more than 300 mg/kg in soil, 100 mg/kg in plants, 20 g/L in fresh water and no more than 5 g/L in sea water. The element is typically found in ores along with other base metals such as copper and lead. As a chalcophyll, zinc is more likely to be found in minerals containing sulfur and other heavy chalcogens than oxygen, which is a light chalcogen, or other non-electronegative elements such as halogens. Sulfurs developed as the crust consolidated in the declining atmosphere of the early Earth.
Sphalerite, a type of zinc sulfide, is the most commonly mined zinc-containing ore, as its concentrate contains 60-62% zinc.
Smithsonite (zinc carbonate), hemimorphite (zinc silicate), wurtzite (another zinc sulfide), and sometimes hydrozincite are other sources of zinc. (basic zinc carbonate). All these additional minerals, with the exception of wurtzite, were formed by weathering of the oldest zinc sulfides.
Global zinc deposits are estimated to be between 1,9 and 2,8 billion tons. Iran has the largest reserves, followed by Australia, Canada and the United States. The latest estimate of the zinc reserve base, which meets the minimum physical requirements for current mining and production techniques, was made in 2009 and was estimated to be around 480 Mt.
On the other hand, zinc reserves are geologically defined ore deposits and their suitability for recovery depends on economic factors (location, grade, quality and quantity) at the time they are identified. The amount of zinc reserves is not a fixed number because exploration and mineral development are ongoing processes, and the sustainability of the zinc ore supply cannot be determined simply by estimating the total mine life of existing zinc mines. United States Geological Survey (USGS) data provide strong support for this idea, showing that although refined zinc production increased by 1990% between 2010 and 80, the zinc reserve lifetime remained constant. By 2002, 346 million tons were mined and today between 109 and 305 million tons are thought to be in use.
Source: Wikipedia
Günceleme: 01/04/2023 12:17