Zinc,or spelter (which may also refer to zinc alloys)

Zinc,or spelter (which may also refer to zinc alloys), is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2.HP Pavilion DV4-1199EA Battery

Zinc is the 24th most abundant element in the Earth's crust and has five stable isotopes. The most common zinc ore issphalerite, a zinc sulfide. The largest mineable amounts are found in Australia, Asia, and the United States. Zinc production includes froth flotation of the ore, roasting, and final extraction using electricity (electrowinning).HP Pavilion DV4-1199EE Battery

Brass, which is an alloy of copper and zinc, has been used since at least the 10th century BC. Impure zinc metal was not produced in large scale until the 13th century in India, while the metal was unknown to Europe until the end of the 16th century. Alchemists burned zinc in air to form what they called "philosopher's wool" or "white snow".HP Pavilion DV4-1199EF Battery

The element was probably named by the alchemist Paracelsus after the German word Zinke. German chemist Andreas Sigismund Marggraf is normally given credit for discovering pure metallic zinc in 1746. Work by Luigi Galvani and Alessandro Voltauncovered the electrochemical properties of zinc by 1800.HP Pavilion DV4-1199EO Battery

Corrosion-resistant zinc plating of steel (hot-dip galvanizing) is the major application for zinc. Other applications are in batteries and alloys, such as brass. A variety of zinc compounds are commonly used, such as zinc carbonate and zinc gluconate (as dietary supplements), zinc chloride (in deodorants), zinc pyrithione (anti-dandruff shampoos), zinc sulfide (in luminescent paints), and zinc methyl or zinc diethyl in the organic laboratory.HP Pavilion DV4-1199EP Battery

Zinc is an essential mineral of "exceptional biologic and public health importance". Zinc deficiency affects about two billion people in the developing world and is associated with many diseases. In children it causes growth retardation, delayed sexual maturation, infection susceptibility, and diarrhea, contributing to the death of about 800,000 children worldwide per year.HP Pavilion DV4-1199ER Battery

Enzymes with a zinc atom in the reactive center are widespread in biochemistry, such as alcohol dehydrogenase in humans. Consumption of excess zinc can cause ataxia, lethargy and copper deficiency.

Physical properties

Zinc, also referred to in nonscientific contexts as spelter, is a bluish-white, lustrous, diamagnetic metal, though most common commercial grades of the metal have a dull finish.HP Pavilion DV4-1199ES Battery

It is somewhat less dense than iron and has a hexagonal crystal structure.

The metal is hard and brittle at most temperatures but becomes malleable between 100 and 150 °C. Above 210 °C, the metal becomes brittle again and can be pulverized by beating. Zinc is a fair conductor of electricity.HP Pavilion DV4-1199ET Battery

For a metal, zinc has relatively low melting (419.5 °C, 787.1 F) and boiling points (907 °C). Its melting point is the lowest of all thetransition metals aside from mercury and cadmium.

Many alloys contain zinc, including brass, an alloy of zinc and copper.HP Pavilion DV4-1200 CTO Battery

Other metals long known to form binary alloys with zinc are aluminium, antimony, bismuth, gold, iron, lead, mercury, silver, tin, magnesium, cobalt, nickel, tellurium andsodium. While neither zinc nor zirconium are ferromagnetic, their alloy ZrZn2 exhibits ferromagnetism below 35 K.HP Pavilion DV4-1200 Battery

Occurrence

Zinc makes up about 75 ppm (0.0075%) of the Earth's crust, making it the 24th most abundant element. Soil contains 5–770 ppm of zinc with an average of 64 ppm. Seawater has only 30 ppb zinc and the atmosphere contains 0.1–4 µg/m3.HP Pavilion DV4-1201AU Battery

The element is normally found in association with other base metals such as copper and lead inores.[11] Zinc is a chalcophile, meaning the element has a low affinity for oxides and prefers to bond with sulfides. Chalcophiles formed as the crust solidified under the reducing conditions of the early Earth's atmosphere.HP Pavilion DV4-1201TU Battery

Sphalerite, which is a form of zinc sulfide, is the most heavily mined zinc-containing ore because its concentrate contains 60–62% zinc.

Other minerals, from which zinc is extracted, include smithsonite (zinc carbonate), hemimorphite(zinc silicate), wurtzite (another zinc sulfide), and sometimes hydrozincite (basic zinc carbonate).HP Pavilion DV4-1201TX Battery

With the exception of wurtzite, all these other minerals were formed as a result of weathering processes on the primordial zinc sulfides.

Identified world zinc resources total about 1.9 billion tonnes.[14] Large deposits are in Australia, Canada and the United States with the largest reserves in Iran.HP Pavilion DV4-1202AU Battery

At the current rate of consumption, these reserves are estimated to be depleted sometime between 2027 and 2055. About 346 million tonnes have been extracted throughout history to 2002, and one estimate found that about 109 million tonnes of that remains in use.HP Pavilion DV4-1202TU Battery

Five isotopes of zinc occur in nature. 64Zn is the most abundant isotope (48.63% natural abundance). This isotope has such a long half-life, at 4.3×1018 a,that its radioactivity can be ignored. Similarly, 70Zn (0.6%), with a half-life of1.3×1016 a is not usually considered to be radioactive.HP Pavilion DV4-1202TX Battery

The other isotopes found in nature are 66Zn (28%), 67Zn (4%) and 68Zn(19%).

Several dozen radioisotopes have been characterized. 65Zn, which has a half-life of 243.66 days, is the most long-lived isotope, followed by 72Zn with a half-life of 46.5 hours.[20] Zinc has 10 nuclear isomers.HP Pavilion DV4-1203AU Battery

69mZn has the longest half-life, 13.76 h.[20] The superscript m indicates a metastable isotope. The nucleus of a metastable isotope is in an excited state and will return to the ground state by emitting a photon in the form of a gamma ray. 61Zn has three excited states and 73Zn has two.[23] The isotopes 65Zn, 71Zn, 77Zn and 78Zn each have only one excited state.HP Pavilion DV4-1203TU Battery

The most common decay mode of a radioisotope of zinc with a mass number lower than 66 is electron capture. The decay product resulting from electron capture is an isotope of copper.

The most common decay mode of a radioisotope of zinc with mass number higher than 66 is beta decay (?–), which produces an isotope of gallium.HP Pavilion DV4-1203TX Battery

Creation

Zinc is too large and heavy to form in stars using the silicon burning process. The stable form of zinc is created in supernovas via the r-process.

Reactivity

Zinc has an electron configuration of [Ar]3d104s2 and is a member of the group 12 of the periodic table.HP Pavilion DV4-1204AU Battery

It is a moderately reactive metal and strong reducing agent. The surface of the pure metal tarnishes quickly, eventually forming a protective passivating layer of the basic zinc carbonate, Zn5(OH)6(CO3)2, by reaction with atmospheric carbon dioxide.[25] This layer helps prevent further reaction with air and water.HP Pavilion DV4-1204TU Battery

Zinc burns in air with a bright bluish-green flame, giving off fumes of zinc oxide. Zinc reacts readily with acids, alkalis and other non-metals. Extremely pure zinc reacts only slowly at room temperature with acids. Strong acids, such as hydrochloric or sulfuric acid, can remove the passivating layer and subsequent reaction with water releases hydrogen gas.HP Pavilion DV4-1204TX Battery

The chemistry of zinc is dominated by the +2 oxidation state. When compounds in this oxidation state are formed the outer shell selectrons are lost, which yields a bare zinc ion with the electronic configuration [Ar]3d10.[28] This allows for the formation of four covalent bonds by accepting four electron pairs and thus obeying the octet rule.HP Pavilion DV4-1205AU Battery

The stereochemistry is therefore tetrahedral and the bonds may be described as being formed from sp3 hybrid orbitals on the zinc ion.[29] In aqueous solution an octahedral complex, [Zn(H2O)6]2+ is the predominant species.HP Pavilion DV4-1205TU Battery

The volatilization of zinc in combination with zinc chloride at temperatures above 285 °C indicates the formation of Zn2Cl2, a zinc compound with a +1 oxidation state.[26] No compounds of zinc in oxidation states other than +1 or +2 are known.[31]Calculations indicate that a zinc compound with the oxidation state of +4 is unlikely to exist.HP Pavilion DV4-1205TX Battery

Zinc chemistry is similar to the chemistry of the late first-row transition metals nickel and copper, though it has a filled d-shell, so its compounds arediamagnetic and mostly colorless. The ionic radii of zinc and magnesium happen to be nearly identical. Because of this some of their salts have the same crystal structure and in circumstances where ionic radius is a determining factor zinc and magnesium chemistries have much in common.HP Pavilion DV4-1206TU Battery

Otherwise there is little similarity. Zinc tends to form bonds with a greater degree of covalency and it forms much more stable complexes with N- and S- donors.[33] Complexes of zinc are mostly 4- or 6- coordinate although 5-coordinate complexes are known.HP Pavilion DV4-1206TX Battery

See also Clemmensen reduction.

Compounds

Binary compounds of zinc are known for most of the metalloids and all the nonmetals except the noble gases. The oxide ZnO is a white powder that is nearly insoluble in neutral aqueous solutions, but is amphoteric, dissolving in both strong basic and acidic solutions.HP Pavilion DV4-1207TU Battery

The other chalcogenides (ZnS, ZnSe, and ZnTe) have varied applications in electronics and optics.[35] Pnictogenides (Zn3N2, Zn3P2, Zn3As2 and Zn3Sb2), the peroxide (ZnO2), the hydride (ZnH2), and the carbide (ZnC2) are also known.HP Pavilion DV4-1207TX Battery

Of the four halides, ZnF2 has the most ionic character, whereas the others (ZnCl2, ZnBr2, and ZnI2) have relatively low melting points and are considered to have more covalent character.

In weak basic solutions containing Zn2+ ions, the hydroxide Zn(OH)2 forms as a white precipitate.HP Pavilion DV4-1208TU Battery

In stronger alkaline solutions, this hydroxide is dissolved to form zincates ([Zn(OH)4]2?).[26] The nitrate Zn(NO3)2, chlorate Zn(ClO3)2, sulfate ZnSO4, phosphate Zn3(PO4)2, molybdate ZnMoO4, cyanide Zn(CN)2, arsenite Zn(AsO2)2, arsenate Zn(AsO4)2·8H2O and the chromate ZnCrO4 (one of the few colored zinc compounds) are a few examples of other common inorganic compounds of zinc.HP Pavilion DV4-1208TX Battery

One of the simplest examples of an organic compound of zinc is the acetate (Zn(O2CCH3)2).

Organozinc compounds are those that contain zinc–carbon covalent bonds. Diethylzinc ((C2H5)2Zn) is a reagent in synthetic chemistry.HP Pavilion DV4-1209TU Battery

It was first reported in 1848 from the reaction of zinc and ethyl iodide, and was the first compound known to contain a metal–carbon sigma bond.[42] Decamethyldizincocene contains a strong zinc–zinc bond at room temperature.

Ancient use

Various isolated examples of the use of impure zinc in ancient times have been discovered.HP Pavilion DV4-1209TX Battery

A possibly prehistoric statuette containing 87.5% zinc was found in a Dacian archaeological site in Transylvania (modern Romania).[44] Ornaments made of alloys that contain 80–90% zinc with lead, iron, antimony, and other metals making up the remainder, have been found that are 2500 years old.HP Pavilion DV4-1210EA Battery

The Berne zinc tablet is a votive plaque dating to Roman Gaul made of an alloy that is mostly zinc.[45] Also, some ancient writings appear to mention zinc. The Greek historian Strabo, in a passage taken from an earlier writer of the 4th century BC, mentions "drops of false silver", which when mixed with copper make brass.HP Pavilion DV4-1210EF Battery

This may refer to small quantities of zinc by-product of smelting sulfide ores.[46] The Charaka Samhita, thought to have been written in 500 BC or before, mentions a metal which, when oxidized, produces pushpanjan, thought to be zinc oxide.HP Pavilion DV4-1210EO Battery

Zinc ores were used to make the zinc–copper alloy brass many centuries prior to the discovery of zinc as a separate element. Palestinian brass from the 14th to 10th centuries BC contains 23% zinc. The Book of Genesis, written between the 10th and 5th centuries BC, mentions (in the King James translation)HP Pavilion DV4-1210ER Battery

Tubal-cain as an "instructor in every artificer in brass and iron" (Genesis 4:22), but since the word nechosheth, translated as "brass", also means "copper", the significance of this is not clear. Knowledge of how to produce brass spread to Ancient Greece by the 7th century BC but few varieties were made.HP Pavilion DV4-1210TU Battery

The manufacture of brass was known to the Romans by about 30 BC.[51] They made brass by heating powdered calamine (zinc silicate or carbonate), charcoal and copper together in a crucible.[51] The resulting calamine brass was then either cast or hammered into shape and was used in weaponry.HP Pavilion DV4-1210TX Battery

Some coins struck by Romans in the Christian era are made of what is probably calamine brass. In the West, impure zinc was known from antiquity to exist in the remnants in melting ovens, but it was usually discarded, as it was thought to be worthless.HP Pavilion DV4-1211EA Battery

Zinc mines at Zawar, near Udaipur in India, have been active since the Mauryan period in the late 1st millennium BC. The smelting of metallic zinc here however appears to have begun around the 12th century AD. One estimate is that this location produced an estimated million tonnes of metallic zinc and zinc oxide from the 12th to 16th centuries.HP Pavilion DV4-1211TU Battery

Another estimate gives a total production of 60,000 tonnes of metallic zinc over this period.[55] The Rasaratna Samuccaya, written in approximately the 14th century AD, mentions two types of zinc-containing ores; one used for metal extraction and another used for medicinal purposes.HP Pavilion DV4-1211TX Battery

Early studies and naming

Zinc was distinctly recognized as a metal under the designation of Fasada in the medical Lexicon ascribed to the Hindu king Madanapala and written about the year 1374. Smelting and extraction of impure zinc by reducing calamine with wool and other organic substances was accomplished in the 13th century in India.HP Pavilion DV4-1212LA Battery

The Chinese did not learn of the technique until the 17th century.

Alchemists burned zinc metal in air and collected the resulting zinc oxide on a condenser. Some alchemists called this zinc oxidelana philosophica, Latin for "philosopher's wool", because it collected in wooly tufts while others thought it looked like white snow and named it nix album.HP Pavilion DV4-1212TU Battery

The name of the metal was probably first documented by Paracelsus, a Swiss-born German alchemist, who referred to the metal as "zincum" or "zinken" in his book Liber Mineralium II, in the 16th century. The word is probably derived from the Germanzinke, and supposedly meant "tooth-like, pointed or jagged" (metallic zinc crystals have a needle-like appearance).HP Pavilion DV4-1212TX Battery

Zink could also imply "tin-like" because of its relation to German zinn meaning tin. Yet another possibility is that the word is derived from the Persian word ??? seng meaning stone. The metal was also called Indian tin, tutanego, calamine, and spinter.HP Pavilion DV4-1213LA Battery

German metallurgist Andreas Libavius received a quantity of what he called "calay" of Malabar from a cargo ship captured from the Portuguese in 1596. Libavius described the properties of the sample, which may have been zinc. Zinc was regularly imported to Europe from the Orient in the 17th and early 18th centuries,[58] but was at times very expensive.HP Pavilion DV4-1213TU Battery

Isolation of the pure element

The isolation of metallic zinc in the West may have been achieved independently by several people. Postlewayt's Universal Dictionary, a contemporary source giving technological information in Europe, did not mention zinc before 1751 but the element was studied before then.HP Pavilion DV4-1213TX Battery

Flemish metallurgist P.M. de Respour reported that he extracted metallic zinc from zinc oxide in 1668.[13] By the turn of the century,Étienne François Geoffroy described how zinc oxide condenses as yellow crystals on bars of iron placed above zinc ore being smelted.HP Pavilion DV4-1214LA Battery

In Britain, John Lane is said to have carried out experiments to smelt zinc, probably at Landore, prior to his bankruptcy in 1726.

In 1738, William Champion patented in Great Britain a process to extract zinc from calamine in a vertical retort style smelter.HP Pavilion DV4-1214TU Battery

His technology was somewhat similar to that used at Zawar zinc mines in Rajasthan but there is no evidence that he visited the Orient. Champion's process was used through 1851.

German chemist Andreas Marggraf normally gets credit for discovering pure metallic zinc even though Swedish chemist Anton von Swab distilled zinc from calamine four years before.HP Pavilion DV4-1214TX Battery

In his 1746 experiment, Marggraf heated a mixture of calamine and charcoal in a closed vessel without copper to obtain a metal.This procedure became commercially practical by 1752.

Later work

William Champion's brother, John, patented a process in 1758 for calcining zinc sulfide into an oxide usable in the retort process.HP Pavilion DV4-1215EF Battery

Prior to this only calamine could be used to produce zinc. In 1798, Johann Christian Ruberg improved on the smelting process by building the first horizontal retort smelter. Jean-Jacques Daniel Dony built a different kind of horizontal zinc smelter in Belgium, which processed even more zinc.HP Pavilion DV4-1215TU Battery

Italian doctor Luigi Galvani discovered in 1780 that connecting the spinal cord of a freshly dissected frog to an iron rail attached by a brass hook caused the frog's leg to twitch. He incorrectly thought he had discovered an ability of nerves and muscles to create electricity and called the effect "animal electricity".HP Pavilion DV4-1215TX Battery

The galvanic cell and the process of galvanization were both named for Luigi Galvani and these discoveries paved the way for electrical batteries, galvanization and cathodic protection.

Galvani's friend, Alessandro Volta, continued researching this effect and invented the Voltaic pile in 1800.HP Pavilion DV4-1216TU Battery

The basic unit of Volta's pile was a simplified galvanic cell, which is made of a plate of copper and a plate of zinc connected to each other externally and separated by an electrolyte. These were stacked in series to make the Voltaic cell, which in turn produced electricity by directingelectrons from the zinc to the copper and allowing the zinc to corrode.HP Pavilion DV4-1216TX Battery

The non-magnetic character of zinc and its lack of color in solution delayed discovery of its importance to biochemistry and nutrition. This changed in 1940 when carbonic anhydrase, an enzyme that scrubs carbon dioxide from blood, was shown to have zinc in its active site.HP Pavilion DV4-1217LA Battery

The digestive enzyme carboxypeptidase became the second known zinc-containing enzyme in 1955.

Mining and processing

Zinc is the fourth most common metal in use, trailing only iron, aluminium, and copper with an annual production of about 12 million tonnes.HP Pavilion DV4-1217TX Battery

The world's largest zinc producer is Nyrstar, a merger of the Australian OZ Minerals and the BelgianUmicore. About 70% of the world's zinc originates from mining, while the remaining 30% comes from recycling secondary zinc. Commercially pure zinc is known as Special High Grade, often abbreviated SHG, and is 99.995% pure.HP Pavilion DV4-1218TX Battery

Worldwide, 95% of the zinc is mined from sulfidic ore deposits, in which sphalerite ZnS is nearly always mixed with the sulfides of copper, lead and iron. There are zinc mines throughout the world, with the main mining areas being China, Australia and Peru. China produced 29% of the global zinc output in 2010.HP Pavilion DV4-1219TX Battery

Zinc metal is produced using extractive metallurgy. After grinding the ore, froth flotation, which selectively separates minerals from gangue by taking advantage of differences in their hydrophobicity, is used to get an ore concentrate.HP Pavilion DV4-1220BR Battery

A final concentration of zinc of about 50% is reached by this process with the remainder of the concentrate being sulfur (32%), iron (13%), and SiO2 (5%).[79]

Roasting converts the zinc sulfide concentrate produced during processing to zinc oxide:HP Pavilion DV4-1220TX Battery

2 ZnS + 3 O2 ? 2 ZnO + 2 SO2

The sulfur dioxide is used for the production of sulfuric acid, which is necessary for the leaching process. If deposits of zinc carbonate, zinc silicate or zinc spinel, like the Skorpion Deposit in Namibia are used for zinc production the roasting can be omitted.HP Pavilion DV4-1220US Battery

For further processing two basic methods are used: pyrometallurgy or electrowinning. Pyrometallurgy processing reduces zinc oxide with carbon or carbon monoxide at 950 °C (1,740 °F) into the metal, which is distilled as zinc vapor.[81] The zinc vapor is collected in a condenser.HP Pavilion DV4-1221TX Battery

The below set of equations demonstrate this process:

2 ZnO + C ? 2 Zn + CO2

2 ZnO + 2 CO ? 2 Zn + 2 CO2

Electrowinning processing leaches zinc from the ore concentrate by sulfuric acid:HP Pavilion DV4-1222LA Battery

ZnO + H2SO4 ? ZnSO4 + H2O

After this step electrolysis is used to produce zinc metal.

2 ZnSO4 + 2 H2O ? 2 Zn + 2 H2SO4 + O2

The sulfuric acid regenerated is recycled to the leaching step.HP Pavilion DV4-1222NR Battery

Environmental impact

The production for sulfidic zinc ores produces large amounts of sulfur dioxide and cadmium vapor. Smelter slag and other residues of process also contain significant amounts of heavy metals.HP Pavilion DV4-1222TX Battery

About 1.1 million tonnes of metallic zinc and 130 thousand tonnes of lead were mined and smelted in the Belgian towns of La Calamine andPlombières between 1806 and 1882. The dumps of the past mining operations leach significant amounts of zinc and cadmium, and, as a result, the sediments of theGeul River contain significant amounts of heavy metals.HP Pavilion DV4-1223LA Battery

About two thousand years ago emissions of zinc from mining and smelting totaled 10 thousand tonnes a year. After increasing 10-fold from 1850, zinc emissions peaked at 3.4 million tonnes per year in the 1980s and declined to 2.7 million tonnes in the 1990s, although a 2005 study of the Arctic troposphere found that the concentrations there did not reflect the decline.HP Pavilion DV4-1223TX Battery

Anthropogenic and natural emissions occur at a ratio of 20 to 1.

Levels of zinc in rivers flowing through industrial or mining areas can be as high as 20 ppm. Effective sewage treatment greatly reduces this; treatment along the Rhine, for example, has decreased zinc levels to 50 ppb.HP Pavilion DV4-1224LA Battery

Concentrations of zinc as low as 2 ppm adversely affects the amount of oxygen that fish can carry in their blood.

Soils contaminated with zinc through the mining of zinc-containing ores, refining, or where zinc-containing sludge is used as fertilizer, can contain several grams of zinc per kilogram of dry soil.HP Pavilion DV4-1224TX Battery

Levels of zinc in excess of 500 ppm in soil interfere with the ability of plants to absorb other essential metals, such as iron andmanganese. Zinc levels of 2000 ppm to 180,000 ppm (18%) have been recorded in some soil samples.HP Pavilion DV4-1225DX Battery

Anti-corrosion and batteries

The metal is most commonly used as an anti-corrosion agent. Galvanization, which is the coating of iron or steel to protect the metals against corrosion, is the most familiar form of using zinc in this way. In 2009 in the United States, 55% or 893 thousand tonnes of the zinc metal was used for galvanization.HP Pavilion DV4-1225EE Battery

Zinc is more reactive than iron or steel and thus will attract almost all local oxidation until it completely corrodes away. A protective surface layer of oxide and carbonate (Zn5(OH)6(CO3)2) forms as the zinc corrodes. This protection lasts even after the zinc layer is scratched but degrades through time as the zinc corrodes away.HP Pavilion DV4-1225LA Battery

The zinc is applied electrochemically or as molten zinc by hot-dip galvanizing or spraying. Galvanization is used on chain-link fencing, guard rails, suspension bridges, lightposts, metal roofs, heat exchangers, and car bodies.

The relative reactivity of zinc and its ability to attract oxidation to itself makes it an efficient sacrificial anode incathodic protection (CP).HP Pavilion DV4-1225TX Battery

For example, cathodic protection of a buried pipeline can be achieved by connecting anodes made from zinc to the pipe. Zinc acts as the anode (negative terminus) by slowly corroding away as it passes electric current to the steel pipeline. Zinc is also used to cathodically protect metals that are exposed to sea water from corrosion.HP Pavilion DV4-1226TX Battery

A zinc disc attached to a ship's iron rudder will slowly corrode while the rudder stays unattacked. Other similar uses include a plug of zinc attached to a propeller or the metal protective guard for the keel of the ship.

With a standard electrode potential (SEP) of ?0.76 volts, zinc is used as an anode material for batteries.HP Pavilion DV4-1227LA Battery

(More reactive lithium (SEP ?3.04 V) is used for anodes in lithium batteries ). Powdered zinc is used in this way in alkaline batteries and sheets of zinc metal form the cases for and act as anodes in zinc–carbon batteries.[94][95] Zinc is used as the anode or fuel of the zinc-air battery/fuel cell.HP Pavilion DV4-1227TX Battery

Alloys

A widely used alloy which contains zinc is brass, in which copper is alloyed with anywhere from 3% to 45% zinc, depending upon the type of brass. Brass is generally more ductile and stronger than copper and has superior corrosion resistance. These properties make it useful in communication equipment, hardware, musical instruments, and water valves.HP Pavilion DV4-1227US Battery

Other widely used alloys that contain zinc include nickel silver, typewriter metal, soft and aluminium solder, and commercialbronze.[4] Zinc is also used in contemporary pipe organs as a substitute for the traditional lead/tin alloy in pipes.HP Pavilion DV4-1228CA Battery

Alloys of 85–88% zinc, 4–10% copper, and 2–8% aluminium find limited use in certain types of machine bearings. Zinc is the primary metal used in making American one cent coins since 1982.[100] The zinc core is coated with a thin layer of copper to give the impression of a copper coin.HP Pavilion DV4-1228LA Battery

In 1994, 33,200 tonnes (36,600 short tons) of zinc were used to produce 13.6 billion pennies in the United States.

Alloys of primarily zinc with small amounts of copper, aluminium, and magnesium are useful in die casting as well as spin casting, especially in the automotive, electrical, and hardware industries.HP Pavilion DV4-1228TX Battery

These alloys are marketed under the nameZamak. An example of this is zinc aluminium. The low melting point together with the low viscosity of the alloy makes the production of small and intricate shapes possible. The low working temperature leads to rapid cooling of the cast products and therefore fast assembly is possible.HP Pavilion DV4-1229LA Battery

Another alloy, marketed under the brand name Prestal, contains 78% zinc and 22% aluminium and is reported to be nearly as strong as steel but as malleable as plastic. This superplasticity of the alloy allows it to be molded using die casts made of ceramics and cement.HP Pavilion DV4-1229TX Battery

Similar alloys with the addition of a small amount of lead can be cold-rolled into sheets. An alloy of 96% zinc and 4% aluminium is used to make stamping dies for low production run applications for which ferrous metal dies would be too expensive.HP Pavilion DV4-1230BR Battery

In building facades, roofs or other applications in which zinc is used assheet metal and for methods such as deep drawing, roll forming or bending, zinc alloys with titanium and copper are used.[106] Unalloyed zinc is too brittle for these kinds of manufacturing processes.HP Pavilion DV4-1230TX Battery

As a dense, inexpensive, easily-worked material, zinc is used as a lead replacement. In the wake of lead concerns, zinc appears in lab weights, tire weights, and flywheels.

Cadmium zinc telluride (CZT) is a semiconductive alloy that can be divided into an array of small sensing devices.HP Pavilion DV4-1231TX Battery

These devices are similar to an integrated circuit and can detect the energy of incoming gamma ray photons.[109] When placed behind an absorbing mask, the CZT sensor array can also be used to determine the direction of the rays.[109]

Other industrial uses

Roughly one quarter of all zinc output, in the United States (2009), is consumed in the form of zinc compounds;HP Pavilion DV4-1232TX Battery

a variety of which are used industrially. Zinc oxide is widely used as a white pigment in paints, and as a catalyst in the manufacture of rubber. It is also used as a heat disperser for the rubber and acts to protect its polymers from ultraviolet radiation (the same UV protection is conferred to plastics containing zinc oxide).HP Pavilion DV4-1233TX Battery

The semiconductor properties of zinc oxide make it useful invaristors and photocopying products.[110] The zinc zinc-oxide cycle is a two step thermochemical process based on zinc and zinc oxide for hydrogen production.[111]

Zinc chloride is often added to lumber as a fire retardant[112] and can be used as a wood preservative.HP Pavilion DV4-1234TX Battery

It is also used to make other chemicals.[112] Zinc methyl (Zn(CH3)2) is used in a number of organic syntheses.[114] Zinc sulfide (ZnS) is used inluminescent pigments such as on the hands of clocks, X-ray and television screens, and luminous paints.[115] Crystals of ZnS are used in lasers that operate in the mid-infrared part of the spectrum.[HP Pavilion DV4-1235EE Battery

Zinc sulfate is a chemical in dyes and pigments.[112]Zinc pyrithione is used in antifouling paints.[117]

Zinc powder is sometimes used as a propellant in model rockets.[118] When a compressed mixture of 70% zinc and 30% sulfur powder is ignited there is a violent chemical reaction.[118] This produces zinc sulfide, together with large amounts of hot gas, heat, and light.[118] Zinc sheet metal is used to make zinc bars.HP Pavilion DV4-1235EI Battery

Zinc has been proposed as a salting material for nuclear weapons (cobalt is another, better-known salting material). A jacket of isotopically enriched 64Zn, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope 65Zn with a half-life of 244 days and produce massive gamma radiationHP Pavilion DV4-1235TX Battery

, significantly increasing the radioactivity of the weapon's fallout for several days.[120] Such a weapon is not known to have ever been built, tested, or used.[120] 65Zn is also used as a tracer to study how alloys that contain zinc wear out, or the path and the role of zinc in organisms.HP Pavilion DV4-1236TX Battery

Zinc dithiocarbamate complexes are used as agricultural fungicides; these include Zineb, Metiram, Propineb and Ziram.[122] Zinc naphthenate is used as wood preservative.[123] Zinc, in the form of ZDDP, is also used as an anti-wear additive for metal parts in engine oil.HP Pavilion DV4-1237TX Battery

Dietary supplement

Zinc is included in most single tablet over-the-counter daily vitamin and mineral supplements. Preparations include zinc oxide, zinc acetate, and zinc gluconate. It is believed to possess antioxidant properties, which may protect against accelerated aging of the skin and muscles of the body; studies differ as to its effectiveness.HP Pavilion DV4-1238TX Battery

Zinc also helps speed up the healing process after an injury.

The efficacy of zinc compounds when used to reduce the duration or severity of cold symptoms is controversial. A 2011 systematic review concludes that supplementation yields a mild decrease in duration and severity of cold symptoms.HP Pavilion DV4-1239TX Battery

Zinc preparations can protect against sunburn in the summer and windburn in the winter. Applied thinly to a baby's diaper area (perineum) with each diaper change, it can protect against diaper rash.

The Age-Related Eye Disease Study determined that zinc can be part of an effective treatment forage-related macular degeneration.HP Pavilion DV4-1240TX Battery

Zinc supplementation is an effective treatment foracrodermatitis enteropathica, a genetic disorder affecting zinc absorption that was previously fatal to babies born with it.

Zinc lactate is used in toothpaste to prevent halitosis. Zinc pyrithione is widely applied in shampoos because of its anti-dandruff function.HP Pavilion DV4-1241TX Battery

Zinc ions are effective antimicrobial agents even at low concentrations. Gastroenteritis is strongly attenuated by ingestion of zinc, and this effect could be due to direct antimicrobial action of the zinc ions in the gastrointestinal tract, or to the absorption of the zinc and re-release from immune cells (all granulocytes secrete zinc), or both.HP Pavilion DV4-1242TX Battery

In 2011, researchers at John Jay College of Criminal Justice reported that dietary zinc supplements can mask the presence of drugs in urine. Similar claims have been made in web forums on that topic.

Although not yet tested as a therapy in humans, a growing body of evidence indicates that zinc may preferentially kill prostate cancer cells.HP Pavilion DV4-1243TX Battery

Because zinc naturally homes to the prostate and because the prostate is accessible with relatively non-invasive procedures, its potential as a chemotherapeutic agent in this type of cancer has shown promise. However, other studies have demonstrated that chronic use of zinc supplements in excess of the recommended dosage may actually increase the chance of developing prostate cancer, also likely due to the natural buildup of this heavy metal in the prostate.HP Pavilion DV4-1244TX Battery

Use in Organic chemistry

There are many important organozinc compounds. Organozinc chemistry is the science of organozinc compounds describing their physical properties, synthesis and reactions. HP Pavilion DV4-1245BR Battery

Among important applications is the Frankland-Duppa Reaction in which an oxalate ester(ROCOCOOR) reacts with an alkyl halide R'X, zinc and hydrochloric acid to the ?-hydroxycarboxylic esters RR'COHCOOR , the Reformatskii reaction which converts ?-halo-esters and aldehydes to ?-hydroxy-esters,HP Pavilion DV4-1245TX Battery

the Simmons-Smith reaction in which the carbenoid (iodomethyl)zinc iodide reacts with alkene(or alkyne) and converts them to cyclopropane, the Addition reaction of organozinc compounds to carbonyl compounds. The Barbier reaction (1899) which is the zinc equivalent of the magnesium Grignard reaction and is better of the two.HP Pavilion DV4-1246TX Battery

In presence of just about any water the formation of the organomagnesium halide will fail whereas the Barbier reaction can even take place in water. On the downside organozincs are much less nucleophilic than Grignards, are expensive and difficult to handle.HP Pavilion DV4-1247TX Battery

Commercially available diorganozinc compounds are dimethylzinc,diethylzinc and diphenylzinc. In one study the active organozinc compound is obtained from much cheaper organobromine precursors:

The Negishi coupling is also an important reaction for the formation of new carbon carbon bonds between unsaturated carbon atoms in alkenes, arenes and alkynes.HP Pavilion DV4-1248TX Battery

The catalysts are nickel and palladium. A key step in the catalytic cycle is a transmetalation in which a zinc halide exchanges its organic substituent for another halogen with the palladium (nickel) metal center. The Fukuyama coupling is another coupling reaction but this one with a thioester as reactant forming a ketone.HP Pavilion DV4-1249TX Battery

Organozinc compounds usually contain zinc in +2 oxidation state, but compound in +1 state are also known such as decamethyldizincocene.

Biological role

Zinc is an essential trace element, necessary for plants,[84] animals,[145] and microorganisms.HP Pavilion DV4-1250TX Battery

Zinc is found in nearly 100 specific enzymes (other sources say 300), serves as structural ions in transcription factors and is stored and transferred in metallothioneins.[148] It is "typically the second most abundant transition metal in organisms" after iron and it is the only metal which appears in all enzyme classes.HP Pavilion DV4-1251TX Battery

In proteins, Zn ions are often coordinated to the amino acid side chains of aspartic acid, glutamic acid, cysteine and histidine.[149]The theoretical and computational description of this zinc binding in proteins (as well as that of other transition metals) is difficult.HP Pavilion DV4-1252TX Battery

There are 2–4 grams of zinc[150] distributed throughout the human body. Most zinc is in the brain, muscle, bones, kidney, and liver, with the highest concentrations in the prostate and parts of the eye.[151] Semen is particularly rich in zinc, which is a key factor in prostate gland function and reproductive organ growth.HP Pavilion DV4-1253TX Battery

In humans, zinc plays "ubiquitous biological roles".[1] It interacts with "a wide range of organic ligands",[1] and has roles in the metabolism of RNA and DNA,signal transduction, and gene expression. It also regulates apoptosis. A 2006 study estimated that about 10% of human proteins (2800) potentially bind zinc,HP Pavilion DV4-1254TX Battery

in addition to hundreds which transport and traffic zinc; a similar in silico study in the plant Arabidopsis thaliana found 2367 zinc-related proteins.[84]

In the brain, zinc is stored in specific synaptic vesicles by glutamatergic neurons[153] and can "modulate brain excitability".[1] It plays a key role in synaptic plasticity and so in learning.HP Pavilion DV4-1255TX Battery

However it has been called "the brain's dark horse"[153] since it also can be a neurotoxin, suggesting zinc homeostasis plays a critical role in normal functioning of the brain and central nervous system.[153]

Enzymes

Zinc is an efficient Lewis acid, making it a useful catalytic agent in hydroxylation and other enzymatic reactions.HP Pavilion DV4-1256TX Battery

The metal also has a flexible coordination geometry, which allows proteins using it to rapidly shift conformations to perform biological reactions. Two examples of zinc-containing enzymes are carbonic anhydrase and carboxypeptidase, which are vital to the processes of carbon dioxide (CO2) regulation and digestion of proteins, respectively.HP Pavilion DV4-1257TX Battery

In vertebrate blood, carbonic anhydrase converts CO2 into bicarbonate and the same enzyme transforms the bicarbonate back into CO2 for exhalation through the lungs. Without this enzyme, this conversion would occur about one million times slower at the normal blood pHof 7 or would require a pH of 10 or more.HP Pavilion DV4-1258TX Battery

The non-related ?-carbonic anhydrase is required in plants for leaf formation, the synthesis of indole acetic acid (auxin) andanaerobic respiration (alcoholic fermentation).

Carboxypeptidase cleaves peptide linkages during digestion of proteins.HP Pavilion DV4-1259TX Battery

A coordinate covalent bond is formed between the terminal peptide and a C=O group attached to zinc, which gives the carbon a positive charge. This helps to create a hydrophobic pocket on the enzyme near the zinc, which attracts the non-polar part of the protein being digested.HP Pavilion DV4-1260TX Battery

Other proteins

Zinc serves a purely structural role in zinc fingers, twists and clusters. Zinc fingers form parts of some transcription factors, which are proteins that recognize DNA base sequences during the replication and transcription of DNA.HP Pavilion DV4-1265DX Battery

Each of the nine or ten Zn2+ ions in a zinc finger helps maintain the finger's structure by coordinately binding to four amino acids in the transcription factor.[158] The transcription factor wraps around the DNA helix and uses its fingers to accurately bind to the DNA sequence.HP Pavilion DV4-1272CM Battery

In blood plasma, zinc is bound to and transported by albumin (60%, low-affinity) and transferrin (10%).[150] Since transferrin also transports iron, excessive iron reduces zinc absorption, and vice-versa. A similar reaction occurs with copper.[162] The concentration of zinc in blood plasma stays relatively constant regardless of zinc intake.HP Pavilion DV4-1275MX Battery

Cells in the salivary gland, prostate, immune system and intestine use zinc signaling as one way to communicate with other cells.

Zinc may be held in metallothionein reserves within microorganisms or in the intestines or liver of animals. Metallothionein in intestinal cells is capable of adjusting absorption of zinc by 15–40%.HP Pavilion DV4-1280US Battery

However, inadequate or excessive zinc intake can be harmful; excess zinc particularly impairs copper absorption because metallothionein absorbs both metals.

Dietary intake

In the U.S., the Recommended Dietary Allowance (RDA) is 8 mg/day for women and 11 mg/day for men.HP Pavilion DV4-1281US Battery

Median intake in the U.S. around 2000 was 9 mg/day for women and 14 mg/day in men.[169] Oysters, lobster [170] and red meats, especially beef, lamb and liver have some of the highest concentrations of zinc in food.[152]

The concentration of zinc in plants varies based on levels of the element in soil.HP Pavilion DV4-1282CM Battery

When there is adequate zinc in the soil, the food plants that contain the most zinc are wheat (germ and bran) and various seeds (sesame, poppy, alfalfa, celery, mustard).[171] Zinc is also found in beans, nuts, almonds, whole grains, pumpkin seeds, sunflower seeds and blackcurrant.HP Pavilion DV4-1283CL Battery

Other sources include fortified food and dietary supplements, which come in various forms. A 1998 review concluded that zinc oxide, one of the most common supplements in the United States, and zinc carbonate are nearly insoluble and poorly absorbed in the body.HP Pavilion DV4-1287CL Battery

This review cited studies which found low plasma zinc concentrations after zinc oxide and zinc carbonate were consumed compared with those seen after consumption of zinc acetate and sulfate salts. However, harmful excessive supplementation is a problem among the relatively affluent,HP Pavilion DV4-1290BR Battery

and should probably not exceed 20 mg/day in healthy people,[174] although the U.S. National Research Council set a Tolerable Upper Intake of 40 mg/day.

For fortification, however, a 2003 review recommended zinc oxide in cereals as cheap, stable, and as easily absorbed as more expensive forms.HP Pavilion DV4-1290EL Battery

A 2005 study found that various compounds of zinc, including oxide and sulfate, did not show statistically significant differences in absorption when added as fortificants to maize tortillas. A 1987 study found that zinc picolinate was better absorbed than zinc gluconate or zinc citrate.HP Pavilion DV4-1292CM Battery

However, a study published in 2008 determined that zinc glycinate is the best absorbed of the four dietary supplement types available.

Deficiency

Zinc deficiency is usually due to insufficient dietary intake, but can be associated with malabsorption,HP Pavilion DV4-1299EE Battery

acrodermatitis enteropathica, chronic liver disease, chronic renal disease, sickle cell disease, diabetes, malignancy, and other chronic illnesses. Symptoms of mild zinc deficiency are diverse. Clinical outcomes include depressed growth, diarrhea, impotence and delayed sexual maturation,HP Pavilion DV4-1300 CTO Battery

alopecia, eye and skin lesions, impaired appetite, altered cognition, impaired host defense properties, defects in carbohydrate utilization, and reproductive teratogenesis.[163] Mild zinc deficiency depresses immunity,[180] although excessive zinc does also.HP Pavilion DV4-1301TU Battery

Animals with a diet deficient in zinc require twice as much food in order to attain the same weight gain as animals given sufficient zinc.[115]

Groups at risk for zinc deficiency include the elderly, and those with renal insufficiency. The zinc chelator phytate, found in seeds and cereal bran, can contribute to zinc malabsorption.HP Pavilion DV4-1301TX Battery

Despite some concerns,[181] western vegetarians and vegans have not been found to suffer from overt zinc deficiencies any more than meat-eaters.[182] Major plant sources of zinc include cooked dried beans, sea vegetables, fortified cereals, soyfoods, nuts, peas, and seeds.HP Pavilion DV4-1302TU Battery

However, phytates in many whole-grains and fiber in many foods may interfere with zinc absorption and marginal zinc intake has poorly understood effects. There is some evidence to suggest that more than the US RDA (15 mg) of zinc daily may be needed in those whose diet is high in phytates, such as some vegetarians.HP Pavilion DV4-1302TX Battery

These considerations must be balanced against the fact that there is a paucity of adequate zinc biomarkers, and the most widely used indicator, plasma zinc, has poor sensitivity and specificity.[183] Diagnosing zinc deficiency is a persistent challenge.[1]

Nearly two billion people in the developing world are deficient in zinc.HP Pavilion DV4-1303TU Battery

In children it causes an increase in infection and diarrhea, contributing to the death of about 800,000 children worldwide per year.[1] The World Health Organization advocates zinc supplementation for severe malnutrition and diarrhea.HP Pavilion DV4-1303TX Battery

Zinc supplements help prevent disease and reduce mortality, especially among children with low birth weight or stunted growth.[184] However, zinc supplements should not be administered alone, since many in the developing world have several deficiencies, and zinc interacts with other micronutrients.HP Pavilion DV4-1304TU Battery

Zinc deficiency is crop plants' most common micronutrient deficiency; it is particularly common in high-pH soils. Zinc-deficient soil is cultivated in the cropland of about half of Turkey and India, a third of China, and most of Western Australia, and substantial responses to zinc fertilization have been reported in these areas.HP Pavilion DV4-1304TX Battery

Plants that grow in soils that are zinc-deficient are more susceptible to disease. Zinc is primarily added to the soil through the weathering of rocks, but humans have added zinc through fossil fuel combustion, mine waste, phosphate fertilizers, limestone, manure, sewage sludge, and particles from galvanized surfaces.HP Pavilion DV4-1305TU Battery

Excess zinc is toxic to plants, although zinc toxicity is far less widespread.

Toxicity

Although zinc is an essential requirement for good health, excess zinc can be harmful. Excessive absorption of zinc suppresses copper and iron absorption.HP Pavilion DV4-1305TX Battery

The free zinc ion in solution is highly toxic to plants, invertebrates, and even vertebrate fish.[186] The Free Ion Activity Model is well-established in the literature, and shows that just micromolar amounts of the free ion kills some organisms. A recent example showed 6 micromolar killing 93% of all Daphnia in water.HP Pavilion DV4-1306TU Battery

The free zinc ion is a powerful Lewis acid up to the point of being corrosive. Stomach acid contains hydrochloric acid, in which metallic zinc dissolves readily to give corrosive zinc chloride. Swallowing a post-1982 American one cent piece (97.5% zinc) can cause damage to the stomach lining due to the high solubility of the zinc ion in the acidic stomach.HP Pavilion DV4-1306TX Battery

There is evidence of induced copper deficiency at low intakes of 100–300 mg Zn/day; a recent trial had higher hospitalizations for urinary complications compared to placebo among elderly men taking 80 mg/day.[189] The USDA RDA is 11 and 8 mg Zn/day for men and women, respectively.HP Pavilion DV4-1307TU Battery

Even lower levels, closer to the RDA, may interfere with the utilization of copper and iron or adversely affect cholesterol.[167]Levels of zinc in excess of 500 ppm in soil interfere with the ability of plants to absorb other essential metals, such as iron and manganese.HP Pavilion DV4-1307TX Battery

There is also a condition called the zinc shakes or "zinc chills" that can be induced by the inhalation of freshly formed zinc oxide formed during the welding of galvanized materials.

The U.S. Food and Drug Administration (FDA) has stated that zinc damages nerve receptors in the nose, which can cause anosmia.HP Pavilion DV4-1308TU Battery

Reports of anosmia were also observed in the 1930s when zinc preparations were used in a failed attempt to prevent polio infections.On June 16, 2009, the FDA said that consumers should stop using zinc-based intranasal cold products and ordered their removal from store shelves.HP Pavilion DV4-1308TX Battery

The FDA said the loss of smell can be life-threatening because people with impaired smell cannot detect leaking gas or smoke and cannot tell if food has spoiled before they eat it. Recent research suggests that the topical antimicrobial zinc pyrithione is a potent heat shock response inducer that may impair genomic integrity with induction of PARP-dependent energy crisis in cultured human keratinocytesand melanocytes.HP Pavilion DV4-1309TU Battery

Poisoning

In 1982, the United States Mint began minting pennies coated in copper but made primarily of zinc. With the new zinc pennies, there is the potential for zinc toxicosis, which can be fatal.HP Pavilion DV4-1309TX Battery

One reported case of chronic ingestion of 425 pennies (over 1 kg of zinc) resulted in death due to gastrointestinal bacterial and fungal sepsis, while another patient, who ingested 12 grams of zinc, only showed lethargy and ataxia (gross lack of coordination of muscle movements).HP Pavilion DV4-1310TU Battery

Several other cases have been reported of humans suffering zinc intoxication by the ingestion of zinc coins.

Pennies and other small coins are sometimes ingested by dogs, resulting in the need for medical treatment to remove the foreign body.HP Pavilion DV4-1310TX Battery

The zinc content of some coins can cause zinc toxicity, which is commonly fatal in dogs, where it causes a severe hemolytic anemia, and also liver or kidney damage; vomiting and diarrhea are possible symptoms.[196] Zinc is highly toxic in parrots and poisoning can often be fatal.HP Pavilion DV4-1311TU Battery

The consumption of fruit juices stored in galvanized cans has resulted in mass parrot poisonings with zinc.

Zinc smelting is the process of converting zinc concentrates (ores that contain zinc) into pure zinc.HP Pavilion DV4-1311TX Battery

The most common zinc concentrate processed is zinc sulfide,[1] which is obtained by concentratingsphalerite using the froth flotation method. Secondary (recycled) zinc material, such as zinc oxide, is also processed with the zinc sulfide.[2] Approximately 30% of all zinc produced is from recycled sources.HP Pavilion DV4-1312TU Battery

There are two methods of smelting zinc: the pyrometallurgical process and the electrolysis process.[2]Both methods are still used.[2][4] Both of these processes share the same first step: roasting.

Roasting is a process of oxidizing zinc sulfide concentrates at high temperatures into an impure zinc oxide, called "Zinc Calcine". The chemical reactions taking place during the process are:HP Pavilion DV4-1312TX Battery

Approximately 90% of zinc in concentrates are oxidized to zinc oxide, but at the roasting temperatures around 10% of the zinc reacts with the iron impurities of the zinc sulfide concentrates to form zinc ferrite. A byproduct of roasting is sulfur dioxide, which is further processed into sulfuric acid, a commodity.HP Pavilion DV4-1313DX Battery

The linked refinery flow sheet shows a schematic of Noranda's eastern Canadian zinc roasting operation[5]

The process of roasting varies based on the type of roaster used. There are three types of roasters: multiple-hearth, suspension, and fluidized-bed.HP Pavilion DV4-1313TU Battery

Multiple-hearth roaster

In a multiple-hearth roaster, the concentrate drops through a series of 9 or more hearths stacked inside a brick-lined cylindrical column. As the feed concentrate drops through the furnace, it is first dried by the hot gases passing through the hearths and then oxidized to produce calcine.HP Pavilion DV4-1313TX Battery

The reactions are slow and can be sustained only by the addition of fuel. Multiple hearth roasters are unpressurized and operate at about 690 °C (1,270 °F). Operating time depends upon the composition of concentrate and the amount of the sulfur removal required. Multiple hearth roasters have the capability of producing a high-purity calcine.HP Pavilion DV4-1314TU Battery

Suspension roaster

In a suspension roaster, the concentrates are blown into a combustion chamber very similar to that of a pulverized coal furnace. The roaster consists of a refractory-lined cylindrical steel shell, with a large combustion space at the top and 2 to 4 hearths in the lower portion, similar to those of a multiple hearth furnace.HP Pavilion DV4-1314TX Battery

Additional grinding, beyond that required for a multiple hearth furnace, is normally required to ensure that heat transfer to the material is sufficiently rapid for the desulfurization and oxidation reactions to occur in the furnace chamber. Suspension roasters are unpressurized and operate at about 980 °C(1,800 °F).HP Pavilion DV4-1315TU Battery

Fluidized-bed roaster

In a fluidized-bed roaster, finely ground sulfide concentrates are suspended and oxidized in a feedstock bed supported on an air column. As in the suspension roaster, the reaction rates for desulfurization are more rapid than in the older multiple-hearth processes.HP Pavilion DV4-1315TX Battery

Fluidized-bed roasters operate under a pressure slightly lower than atmospheric and at temperatures averaging 1,000 °C (1,830 °F). In the fluidized-bed process, no additional fuel is required after ignition has been achieved. The major advantages of this roaster are greater throughput capacities, greater sulfur removal capabilities, and lower maintenance.HP Pavilion DV4-1316TU Battery

Electrolysis process

The electrolysis process, also known as the hydrometallurgical process, Roast-Leach-Electrowin (RLE) process, or electrolytic process, is more widely used than the pyrometallurgical processes.

The electrolysis process consists of 4 steps: leaching, purification, electrolysis, and melting and casting.HP Pavilion DV4-1316TX Battery

Leaching

The basic leaching chemical formula that drives this process is:

This is achieved in practice though a process called double leaching. The calcine is first leached in a neutral or slightly acidic solution (of sulfuric acid) in order to leach the zinc out of the zinc oxide. The remaining calcine is then leached in strong sulfuric acid to leach the rest of the zinc out of the zinc oxide and zinc ferrite.HP Pavilion DV4-1317TU Battery

The result of this process is a solid and a liquid; the liquid contains the zinc and is often called leach product; the solid is called leach residue and contains precious metals (usually lead and silver) which are sold as a by-product. There is also iron in the leach product from the strong acid leach, which is removed in an intermediate step, in the form of goethite, jarosite, and haematite.HP Pavilion DV4-1317TX Battery

There is still cadmium, copper, arsenic, antimony, cobalt, germanium, nickel, andthallium in the leach product. Therefore it needs to be purified.

Purification

The purification process utilizes the cementation process to further purify the zinc. It uses zinc dust and steam to remove copper, cadmium, cobalt, and nickel, which would interfere with the electrolysis process.HP Pavilion DV4-1318TU Battery

After purification, concentrations of these impurities are limited to less than 0.05 milligram per liter (4×10?7 pound per U.S. gallon). Purification is usually conducted in large agitated tanks. The process takes place at temperatures ranging from 40 to 85 °C (104 to 185 °F), and pressures ranging from atmospheric to 2.4 atm (240 kPa) (absolute scale). The by-products are sold for further refining.HP Pavilion DV4-1318TX Battery

The zinc sulfate solution must be very pure for electrowinning to be at all efficient. Impurities can change the decomposition voltage enough to where the electrolysis cell produces largely hydrogen gas rather than zinc metal.

Electrolysis

Zinc is extracted from the purified zinc sulfate solution by electrowinning, which is a specialized form of electrolysis.HP Pavilion DV4-1319TU Battery

The process works by passing an electric current through the solution in a series of cells. This causes the zinc to deposits on the cathodes (aluminium sheets) and oxygen to form at the anodes. Sulfuric acid is also formed in the process and reused in the leaching process.HP Pavilion DV4-1319TX Battery

Every 24 to 48 hours, each cell is shut down, the zinc-coated cathodes are removed and rinsed, and the zinc is mechanically stripped from the aluminium plates.

Electrolytic zinc smelters contain as many as several hundred cells. A portion of the electrical energy is converted into heat, which increases the temperature of the electrolyte.HP Pavilion DV4-1320CA Battery

Electrolytic cells operate at temperature ranges from 30 to 35 °C (86 to 95 °F) and at atmospheric pressure. A portion of the electrolyte is continuously circulated through the cooling towers both to cool and concentrate the electrolyte through evaporation of water. The cooled and concentrated electrolyte is then recycled to the cells.HP Pavilion DV4-1320TX Battery

This process accounts for approximately one-third of all the energy usage when smelting zinc.

There are two common processes for electrowinning the metal: the low current density process, and the Tainton high current density process. The former uses a 10% sulfuric acid solution as the electrolyte, with current density of 270–325 amperes per square meter.HP Pavilion DV4-1321TX Battery

The latter uses 22–28% sulfuric acid solution as the electrolyte with a current density of about 1,000 amperes per square metre. The latter gives better purity and has higher production capacity per volume of electrolyte, but has the disadvantage of running hotter and being more corrosive to the vessel in which it is done.HP Pavilion DV4-1322TX Battery

In either of the electrolytic processes, each metric ton of zinc production expends about 3,900 kW·h (14 GJ) of electric power.

Melting and casting

The final step is to melt the cathodes in an induction furnace. It is then either cast into pure zinc (99.995% pure) ingots or alloyed and cast into ingots.HP Pavilion DV4-1322US Battery

Pyrometallurgical processes

There are also several pyrometallurgical processes that reduce zinc oxide using carbon, then distil the metallic zinc from the resulting mix in an atmosphere of carbon monoxide. The major downfall of any of the pyrometallurgical process is that it is only 98% pure; a standard composition is 1.3% lead, 0.2% cadmium, 0.03% iron, and 98.5% zinc.HP Pavilion DV4-1323TX Battery

This may be pure enough for galvanization, but not enough for die casting alloys, which requires special high-grade zinc (99.995% pure).[7]In order to reach this purity the zinc must be refined.HP Pavilion DV4-1324TX Battery

The four types of commercial pyrometallurgical processes are the Belgian-type horizontal retort process, the New Jersey Zinc continuous vertical-retort process, theblast furnace process and the St. Joseph Minerals Corporation's (electrothermic) process.HP Pavilion DV4-1325TX Battery

St. Joseph Mineral Company (electrothermic) process

This process was developed by the St. Joseph Mineral Company in 1930, and is the only pyrometallurgical process still used in the US to smelt zinc. The advantage of this system is that it is able to smelt a wide variety of zinc-bearing materials, including electric arc furnace dust.HP Pavilion DV4-1326TX Battery

The disadvantage of this process is that it is less efficient than the electrolysis process.

The process begins with a downdraft sintering operation. The sinter, which is a mixture of roaster calcine and EAF calcine, is loaded onto a gate type conveyor and then combustions gases are pumped through the sinter.HP Pavilion DV4-1327TX Battery

The carbon in the combustion gases react with some the impurities, such as lead, cadmium, and halides. These impurities are driven off into filtration bags. The sinter after this process, called product sinter, usually has a composition of 48% zinc, 8% iron, 5% aluminium, 4% silicon, 2.5% calcium, and smaller quantities of magnesium, lead, and other metals.HP Pavilion DV4-1328TX Battery

The sinter product is then charged with coke into an electric retort furnace. A pair of graphite electrodes from the top and bottom furnace produce current flow through the mixture. The coke provides electrical resistance to the mixture in order to heat the mixture to 1,400 °C (2,550 °F) and produce carbon monoxide.HP Pavilion DV4-1329TX Battery

These conditions allow for the following chemical reaction to occur:

The zinc vapour and carbon dioxide pass to a vacuum condenser, where zinc is recovered by bubbling through a molten zinc bath. Over 95% of the zinc vapour leaving the retort is condensed to liquid zinc. The carbon dioxide is regenerated with carbon, and the carbon monoxide is recycled back to the retort furnace.HP Pavilion DV4-1330TX Battery

Blast furnace process

This process was developed by the Imperial Smelting Corporation at Avonmouth, England, in order to increase production, increase efficiency, and decrease labour and maintenance costs. L. J. Derham proposed using a spray of molten lead droplets to rapidly chill and absorb the zinc vapour, despite the high concentration of carbon dioxide.HP Pavilion DV4-1331TX Battery

The mixture is then cooled, where the zinc separates from the lead. The first plant using this design opened up in 1950. One of the advantages of this process is that it can co-produce lead bullion and copper dross. In 1990, it accounted for 12% of the world's zinc production.HP Pavilion DV4-1332TX Battery

The process starts by charging solid sinter and heated coke into the top of the blast furnace. Preheated air at 190 to 1,050 °C (370 to 1,920 °F) is blown into the bottom of the furnace. Zinc vapour and sulfides leave through the top and enter the condenser. Slag and lead collect at the bottom of the furnace and are tapped off regularly.HP Pavilion DV4-1365DX Battery

The zinc is scrubbed from the vapour in the condenser via liquid lead. The liquid zinc is separated from the lead in the cooling circuit. Approximately 5,000 metric tons (5,500 short tons) of lead are required each year for this process, however this process recovers 25% more lead from the starting ores than other processes.HP Pavilion DV4-1400 CTO Battery

New Jersey Zinc continuous vertical retort

The New Jersey Zinc process is no longer used to produce primary zinc in the U.S., Europe and Japan, however it still is used to treat secondary operations. This processes peaked in 1960, when 5% of the world production was done by this process. A modified version of this process is still used at Huludao, China, which produced 65,000 metric tons per year.HP Pavilion DV4-1404TX Battery

This process begins by roasting concentrates that are mixed with coal and briquetted in two stages. The briquettes are then heated in an autogenous coker at 700 °C(1,292 °F) and then charged into the retort. There are three reasons to briquette the calcine: to ensure free downward movement of the charge; to permit heat transfer across a practical size cross-section;HP Pavilion DV4-1405TX Battery

to allow adequate porosity for the passage of reduced zinc vapour to the top of the retort. The reduced zinc vapour that is collected at the top of the retort is then condensed to a liquid.

Overpelt improved upon this design by using only one large condensation chamber, instead of many small ones, as it was originally designed. This allowed for the carbon monoxide to be recirculated into the furnaces for heating the retorts.HP Pavilion DV4-1406TX Battery

This process was licensed to the Imperial Smelting Company (ISC), in Avonmouth, England, which had a large vertical retort (VR) plant in production for many years. It was used until the mid 1970s when it was superseded by the company's Imperial Smelting Furnace (ISF) plant. The VR plant was demolished in 1975.HP Pavilion DV4-1407TX Battery

Belgian-type horizontal retort process

This process was the main process used in Britain from the mid-19th century until 1951. The process was very inefficient as it was designed as a small scale batch operation. Each retort only produced 40 kilograms (88 lb) so companies would put them together in banks and used one large gas burner to heat all of them.HP Pavilion DV4-1408TX Battery

The Belgian process requires redistillation to remove impurities of lead, cadmium, iron, copper, and arsenic.

Although some zinc artifacts appear to have been made during classical antiquity in Europe,[9] the first production of zinc in quantity seems to have been in Indiaand China.HP Pavilion DV4-1409TX Battery

In India, zinc was produced at Zawar from the 12th to the 18th centuries. The sphalerite ore found here was presumably converted to zinc oxide via roasting, although no archaeological evidence of this has been found. Smelting is thought to have been done in sealed cylindrical clay retorts which were packed with a mixture of roasted ore,HP Pavilion DV4-1413LA Battery

dolomite, and an organic material, perhaps cow dung, and then placed vertically in a furnace and heated to around 1100 °C. Carbon monoxideproduced by the charring of the organic material would have reduced the zinc oxide to zinc vapour, which then liquefied in a conical clay condenser at the bottom of the retort, dripping down into a collection vessel.HP Pavilion DV4-1414LA Battery

Over the period 1400–1800, production is estimated to have been about 200 kg/day.[11] Zinc was also smelted in China from the mid-sixteenth century on.[12]

Large-scale zinc production in Europe began with William Champion, who patented a zinc distillation process in 1738.HP Pavilion DV4-1416LA Battery

In Champion's process, zinc ore (in this case, the carbonate, ZnCO3) was sealed in large reduction pots with charcoal and heated in a furnace. The zinc vapor then descended through an iron condensing pipe until reaching a water-filled vessel at the bottom.HP Pavilion DV4-1425LA Battery

Champion set up his first zinc works in Bristol, England, but soon expanded to Warmley and by 1754 had built four zinc furnaces there.[15] Although Champion succeeded in producing about 200 tons of zinc,[15] his business plans were not successful and he was bankrupt by 1769.[14] However, zinc smelting continued in this area until 1880.[HP Pavilion DV4T Battery

Early European zinc production also took place in Silesia, in Carinthia, and in Liège, Belgium. In the Carinthian process, used in works established in 1798 by Bergrath Dillinger, a wood-fueled furnace heated a large number of small vertical retorts,[18] and zinc vapor then dropped through a ceramic pipe into a common condensation chamber below.HP Pavilion DV4T-1000 CTO Battery

This process was out of use by 1840. The Belgian and Silesian processes both used horizontal retorts.[19] In Silesia, Johann Ruhberg built a furnace to distill zinc in 1799, at first using pots but later changing to flat-bottomed retorts called "muffles", attached to horizontal tubes bent downwards in which the zinc condensed.HP Pavilion DV4T-1100 CTO Battery

The Silesian process eventually merged with the Belgian process. This process, developed by Jean-Jacques Daniel Dony, was introduced 1805–1810, and used retorts with a cylindrical cross-section. Condensers were horizontal clay tubes extending from the ends of the retorts.HP Pavilion DV4T-1200 CTO Battery

The merged "Belgo-Silesian" horizontal retort process was widely adopted in Europe by the third quarter of the 19th century, and later in the United States.

Experimental attempts to extract zinc via electrolysis begun in the 19th century, but the only commercially successful application before 1913 was a process, used inGreat Britain and Austria,HP Pavilion DV4T-1200SE CTO Battery

where zinc and chlorine were co-produced by electrolysis of an aqueous zinc chloride solution.[21] The Anaconda Copper Company, atAnaconda, Montana, and the Consolidated Mining and Smelting Company, at Trail, British Columbia, both built successful electrolytic plants in 1915 using the currently used zinc sulfate process.HP Pavilion DV4T-1300 CTO Battery

This method has continued to grow in importance and in 1975 accounted for 68% of world zinc production.

The continuous vertical retort process was introduced in 1929 by the New Jersey Zinc Company. This process used a retort with silicon carbide walls, around 9 meters high and with a cross section of 2 by 0.3 meters.HP Pavilion DV4T-1300SE CTO Battery

The walls of the retort were heated to 1300 °C and briquettes consisting of sintered zinc ore, coke, coal, and recycled material were fed into the top of the retort. Gaseous zinc was drawn off from the top of the column and, after a 20-hour journey through the retort, spent briquettes were removed from the bottom.HP Pavilion DV4T-1400 CTO Battery

To condense the gaseous zinc, the company first used a simple brick chamber with carborundum baffles, but efficiency was poor. During the 1940s a condenser was developed which condensed the zinc vapor on a spray of liquid zinc droplets, thrown up by an electrical impeller.HP Pavilion DV4Z Battery

The electrothermic process, developed by the St. Joseph's Lead Company, was somewhat similar. The first commercial plant using this process was built in 1930 at the present site of Josephtown, Pennsylvania. The electrothermic furnace was a steel cylinder around 15 meters high and 2 meters in diameter, lined with firebrick.HP Pavilion DV4Z-1000 CTO Battery

A mixture of sintered ore and coke was fed into the top of the furnace, and a current of 10,000–20,000 amperes, at a potential difference of 240 volts, was applied between carbon electrodes in the furnace, raising the temperature to 1200–1400 °C. An efficient condenser was devised for this process from 1931–1936;HP Pavilion DV4Z-1100 CTO Battery

it consisted of a bath of liquid zinc which the exhaust gases were drawn through by suction. The zinc content of the gas stream was absorbed into the liquid bath.

The blast-furnace process was developed starting in 1943 at Avonmouth, England by the Imperial Smelting Corporation. It uses a spray of molten lead droplets to condense the zinc vapor.HP Pavilion DV4Z-1200 CTO Battery

Zinc deficiency is insufficient zinc to meet the needs of biological organisms. It can occur in both plants and animals. Zinc deficient soil is soil in which there is insufficient zinc to allow plants to grow normally.

Prevalence

In fact, one-third of the world population is at risk of zinc deficiency, ranging from 4 to 73% depending on the country.HP Pavilion DV4 Battery

Zinc deficiency is the fifth leading risk factor for disease in the developing world. Providing micronutrients, including zinc, to humans is one of the four quick-win solutions to major global problems identified in the Copenhagen Consensus from an international panel of distinguished economists.HP Pavilion DV4-1000 Battery

Conservative estimates suggest that 25% of the world's population is at risk of zinc deficiency.

Causes

Hypozincemia is usually a nutritional deficiency, but can also be associated with malabsorption, diarrhea, acrodermatitis enteropathica, chronic liver disease, chronic renal disease, sickle-cell disease, diabetes, malignancy, and other chronic illnesses.HP Pavilion DV4-1000EA Battery

It can also occur after bariatric surgery.

Zinc deficiency is typically the result of inadequate dietary intake of zinc, disease states that promote zinc losses, or physiological states that require increased zinc. Populations that consume primarily plant based diets that are low in bioavailable zinc often have zinc deficiencies.HP Pavilion DV4-1000ET Battery

Diseases or conditions that involve intestinal malabsorption promote zinc losses. Fecal losses of zinc caused by diarrhea are one contributing factor, often common in developing countries. Changes in intestinal tract absorbability and permeability due, in part, to viral, protozoal, and bacteria pathogens may also encourage fecal losses of zinc.HP Pavilion DV4-1001 Battery

Physiological states that require increased zinc include periods of growth in infants and children as well as in mothers during pregnancy.

Signs and symptoms

Signs of zinc deficiency include hair loss, skin lesions, diarrhea, and wasting of body tissues. A lack of zinc can contribute to acne.HP Pavilion DV4-1001AX Battery

Eyesight, taste, smell and memory are also connected with zinc. A deficiency in zinc can cause malfunctions of these organs and functions. Congenital abnormalities causing zinc deficiency may lead to a disease called acrodermatitis enteropathica.

One easily recognized sign which may be caused by zinc deficiency is white spots, bands, or lines on fingernails (leukonychia).HP Pavilion DV4-1001TU Battery

An occasional white spot is usually evidence that the immune system overcame a bacterial or some other systemic infection, and is a positive, not negative sign. Some women may have multiple parallel white bands or lines on the fingernails marking menstrual cycles when marginal zinc deficiency was present.HP Pavilion DV4-1001TX Battery

Anorexia

Zinc deficiency may cause a decrease in appetite which can degenerate into anorexia or anorexia nervosa. Appetite disorders, in turn, causemalnutrition and, notably, inadequate zinc intake. Anorexia itself is a cause of zinc deficiency, thus leading to a vicious cycle: the worsening of anorexia worsens the zinc deficiency.HP Pavilion DV4-1002 Battery

The use of zinc in the treatment of anorexia has been advocated since 1979 by Bakan. At least 15 trials showed that zinc improved weight gain in anorexia. A 1994 randomized, double-blind, placebo-controlled trial showed that zinc (14 mg per day) doubled the rate of body mass increase in the treatment of anorexia nervosa (AN).HP Pavilion DV4-1002AX Battery

Deficiency of other nutrients such as tyrosine and tryptophan (precursors of the monoamine neurotransmitters norepinephrine and serotonin, respectively), as well as vitamin B1 (thiamine) could contribute to this phenomenon of malnutrition-induced malnutrition.HP Pavilion DV4-1002TU Battery

Cognitive and motor function impairment

Cognitive and motor function may also be impaired in zinc deficient children. Zinc deficiency can interfere with many organ systems especially when it occurs during a time of rapid growth and development when nutritional needs are high, such as during infancy.HP Pavilion DV4-1002TX Battery

In animal studies, rats who were deprived of zinc during early fetal development exhibited increased emotionality, poor memory, and abnormal response to stress which interfered with performance in learning situations. Zinc deprivation in monkeys showed that zinc deficient animals were emotionally less mature, and also had cognitive deficits indicated by their difficulty in retaining previously learned problems and in learning new problems.HP Pavilion DV4-1003AX Battery

Human observational studies show weaker results. Low maternal zinc status has been associated with less attention during the neonatal period and worse motor functioning.In some studies, supplementation has been associated with motor development in very low birth weight infants and more vigorous and functional activity in infants and toddlers.HP Pavilion DV4-1003TU Battery

Diarrhea and pneumonia

Zinc deficiency contributes to an increased incidence and severity of diarrhea and pneumonia. Studies have shown that zinc treatment results in a 25 percent reduction in duration of acute diarrhea and a 40 percent reduction in treatment failure or death in persistent diarrhea.HP Pavilion DV4-1003TX Battery

The studies determined that a ten-day therapy of zinc treatment can considerably reduce the duration and severity of diarrheal episodes, decrease stool output, and lessen the need for hospitalization. Zinc may also prevent future diarrhea episodes for up to three months.HP Pavilion DV4-1004AX Battery

The current World Health Organization recommendation for diarrhea control includes the use of 20 mg per day of zinc supplementation for 10 to 14 days (10 mg per day for infants under the age of six months).[21] A zinc taste test may have potential for diagnosing deficiency.HP Pavilion DV4-1004TU Battery

High dose of zinc, 30 mg 1-3 times a day, prevents dysmenorrhea.

Zinc deficiency during pregnancy can negatively affect both the mother and fetus. Animal studies indicate that maternal zinc deficiency can upset both the sequencing and efficiency of the birth process.HP Pavilion DV4-1004TX Battery

An increased incidence of difficult and prolonged labor, hemorrhage, uterine dystocia and placental abruption has been documented in zinc deficient animals. These effects may be mediated by the defective functioning of estrogen via the estrogen receptor, which contains a zinc finger protein.HP Pavilion DV4-1005TX Battery

A review of pregnancy outcomes in women with acrodermatitis enteropathica, reported that out of every seven pregnancies, there was one abortion and two malfunctions, suggesting the human fetus is also susceptible to the teratogenic effects of severe zinc deficiency.HP Pavilion DV4-1006TX Battery

However, a review on zinc supplementation trials during pregnancy did not report a significant effect of zinc supplementation on neonatal survival.

Vitamins A and D

Plasma zinc levels have been found to be dependent upon vitamins A and D.HP Pavilion DV4-1007TX Battery

This suggests that a Vitamin A or D deficiency could cause a secondary zinc deficiency and that for treatment of zinc deficiency one should ensure adequate vitamin A and D intake.

Hunger

The influence of zinc on hunger is complex and likely depends upon the status of other nutrients, the developmental stage of the animal, and percentage body fat.HP Pavilion DV4-1008TX Battery

Some research groups have argued for a role of zinc deficiency decreasing appetite, while others have shown zinc ingestion can reduce feelings of hunger by increasing leptin levels. There is evidence that the way zinc influences hunger depends on the sodium/osmotic status of the organism,HP Pavilion DV4-1009TX Battery

with low sodium/low zinc levels increasing hunger and high sodium/low zinc levels decreasing it. An organism with a low level of zinc has an increased susceptibility to hypoosmotic stress and cell rupture. Thus if the osmotic pressure is too low the organism may be inclined to eat to raise osmolality and prevent osmotic shock.HP Pavilion DV4-1010TX Battery

It should be noted that zinc is known to affect osmolality by increasing sodium retention.

In rats, the "first visible sign" of zinc deficiency is a decreased appetite.

Treatment

Zinc supplementation has been shown to reduce diarrhea prevalence and mortality in children younger than 5 years of age.HP Pavilion DV4-1011TX Battery

To combat zinc deficiency, five intervention strategies can be used:

• Supplementation using medicines
• Food fortification through the incorporation of zinc additives in food
• Dietary modification/diversificationHP Pavilion DV4-1012TX Battery

• Genetic biofortification through plant breeding
• Agronomic biofortification through zinc fertilization.

These five intervention strategies may be used individually or in combination, depending on the setting, target group and degree of zinc deficiency.HP Pavilion DV4-1013TX Battery

The amount of zinc absorbed by the human body is a function of dietary intake of both zinc and phytate (a phosphate storage compound that chelates zinc), because the ratio between these two substances affects the bioavailability of zinc. Meeting the needs for absorbed zinc requires an increase in the zinc content and/or a decrease in the phytate content.HP Pavilion DV4-1014NR Battery

Plants, crops, and soils

Zinc is an essential micronutrient needed not only by people but also by crops. Almost half of the world’s cereal crops are deficient in zinc, leading to poor crop yields.Many agricultural countries around the world are affected by zinc deficiencies.HP Pavilion DV4-1014TX Battery

In China, zinc deficiency occurs on around half of the agricultural soils, affecting mainly rice and maize.

In India, zinc-deficient soils occupy almost 50% of the agricultural area and are a critical constraint on yield, but crops are highly responsive to zinc fertilization.HP Pavilion DV4-1015TX Battery

In Turkey, major yield and quality benefits in wheat have been obtained with the widespread use of zinc fertilizers, where half of the cereal growing land is zinc-deficient.

Research has shown that areas with zinc-deficient soils are often regions with widespread zinc deficiency in humans.HP Pavilion DV4-1015TX Battery

A basic knowledge of the dynamics of Zn in soils, understanding of the uptake and transport of Zn in plant systems and characterizing the response of plants to Zn deficiency are essential steps in achieving sustainable solutions to the problem of Zn deficiency in plants and humans (Zinc in soils and crop nutrition), International Fertilizer Industry Association (IFA)and International Zinc Association (IZA).)HP Pavilion DV4-1016TX Battery

Fertilization

Experiments show that soil and foliar application of zinc fertilizer can effectively reduce the phytate:zinc ratio in grain. People who eat bread prepared from zinc enriched wheat show a significant increase in serum zinc, suggesting that the zinc fertilizer strategy may be a viable commercial approach to address zinc deficiencies in humans.HP Pavilion DV4-1017TX Battery

Where zinc deficiency is a limiting factor, zinc fertilization can increase crop yields. Balanced crop nutrition supplying all essential nutrients, including zinc, is a cost effective management strategy. Even with zinc-efficient varieties, zinc fertilizers are needed when the available zinc in the topsoil becomes depleted.HP Pavilion DV4-1018TX Battery

Plant breeding, including modern biotechnology, can improve:

Zinc uptake capacity of plants under soil conditions with low chemical availability of zinc; Zinc translocation, thus elevating zinc content in edible crop parts rather than the rest of the plant; Zinc bioavailability.HP Pavilion DV4-1019TX Battery

For optimal efficiency, zinc-efficient genotypes should be associated with complementary soil crop management (including fertilization) to ensure adequate zinc uptake by roots and thus enhance zinc nutrition of crops and humans

Turkey

Central Anatolia, in Turkey, was a region with zinc-deficient soils and widespread zinc deficiency in humans.HP Pavilion DV4-1020TX Battery

In 1993, a research project found that yields could be increased by 6 to 8-fold and children nutrition dramatically increased through zinc fertilization.

Through a partnership with Cukurova University, the State and the private company TOROS Agri Industry Group, zinc was added to fertilizers.HP Pavilion DV4-1020US Battery

While the product was initially made available at the same cost, the results were so convincing that Turkish farmers significantly increased the use of the zinc-fortified fertilizer (1 per cent of zinc) within a few short years, despite the repricing of the products to reflect the added value of the content.HP Pavilion DV4-1021TX Battery

Today, nearly 10 years after the identification of the zinc deficiency problem, the total amount of zinc-containing compound fertilizers produced and applied in Turkey reached a record level of 300,000 tonnes per annum.HP Pavilion DV4-1022TX Battery

It is estimated that the economic benefits associated with the application of Zn-fertilizers on Zn deficient soils in Turkey is around US$ 100 million per year. Zinc deficiency in children has been dramatically reduced.HP Pavilion DV4-1023TX Battery

Such a policy could be easily replicated around the world in the many zinc-deficient countries.HP Pavilion DV4-1024TX Battery,HP Pavilion DV4-1025TX Battery,HP Pavilion DV4-1026TX Battery,HP Pavilion DV4-1027TX Battery,HP Pavilion DV4-1028TX Battery,HP Pavilion DV4-1028US Battery,HP Pavilion DV4-1029TX Battery,HP Pavilion DV4-1030EE Battery,HP Pavilion DV4-1030EI Battery