Zinc price, occurrence, extraction and use

Zinc is a chemical element with the element symbol Zn and the atomic number 30. Zinc is one of the transition metals, but it occupies a special position in it, because it is more similar to the alkaline earth metals due to the completed d-shell in its properties. After the outdated count, the zinc group is called 2. Subgroup called (analogous to the alkaline earth metals as 2 main group), according to the current IUPAC nomenclature zinc forms the group 12 with cadmium, mercury and the exclusively in the research relevant Copernicium. It is a bluish-white brittle metal and is used among other things for galvanizing iron and steel parts and for gutters. Zinc is essential for all living beings and is a component of important enzymes. The name zinc comes from prong, Zind ("tooth, spike"), since zinc solidifies like a jagged.

History

Already in ancient times, zinc was used as an alloy component of brass. As an independent metal, however, zinc was first in the 14. Century in India and brass from the 17. Century discovered and processed. In the 1679 built Messinghof in Kassel Galmei was smelted. In 1743, a first zinc smelter was commissioned in Bristol. More created in 19. Century in Upper Silesia, z. B. Georg von Giesche or its successor, in the Aachen-Liège region as well as in Upper Saxony and in Westphalia. The first smelters 1845 in Mülheim an der Ruhr and 1847 in Borbeck (today Essen) were built in the Ruhr area.

occurrence

Zinc is a relatively abundant element on Earth, containing 0,0076% (or 76 ppm) of earth's crust. If you sort the elements by frequency, it is 24. Location. It is more common than copper or lead. Although zinc is rare, it is usually recognized as a mineral. So far, 30 registered sites for solid zinc are known.

Mostly zinc is bound in ores. The most common and most important for the production of zinc ores are zinc sulfide ores. These are naturally either sphalerite or wurtzite and contain about 65% zinc. Another zinc ore is Galmei, which refers to both Smithsonite (also zincspar) ZnCO3 (about 52% zinc) and Willemite Zn2 [SiO4]. In addition, there are even rarer zinc minerals such as zincite (also red zinc ore) ZnO (about 73% zinc), hemimorphite Zn4 (OH) 2 [Si2O7] (54% zinc), adamine Zn2 (AsO4) (OH) (about 45% Zinc), minrecordite CaZn [CO3] 2 (about 29% zinc) and franklinite (Zn, Fe, Mn) (Fe2Mn2) O4 (16% zinc). Altogether (2010) are currently known about 300 zinc minerals.

Large deposits exist in North America (United States, Canada), Australia, the People's Republic of China and Kazakhstan. There were also zinc ore deposits in Germany, for example in Brilon, in the Eschweiler-Stolberg area in the Rhineland, on the Rammelsberg in the Harz, Freiberg or in Ramsbeck in the Sauerland. Above ground, one can find in these areas rare plants that grow particularly well on zinc-rich soils, such as the yellow galmei, which is named after the old name for the zinc ore Smithsonite (Galmei).

 

The states with the largest promotion worldwide (2015)

Rank	Country	Flow rates in ts. t per year
1	People's Republic of China	4.900
2	Australia	1.580
3	Peru	1.370
4	United States	850
5	India	830
6	Mexico	660
7	Bolivia	430
8	Kazakhstan	340
9	Canada	300
10	Ireland	230
	Rest of the world	1.870

Zinc ores are mainly produced in the People's Republic of China, Australia, Peru, India, the United States, Mexico and Canada. In Europe some zinc mines are still active in Ireland, Poland, Finland, Bulgaria and Sweden. 2015's total zinc production amounted to 13,4 million tons and another 14 million tons was recovered from recycling. The most important company for the production of zinc is the Swiss company Nyrstar.

Extraction and presentation

Zinc is predominantly obtained from zinc sulfide ores. To use these, they must first be converted to zinc oxide. This is done by roasting in the air. In addition to the zinc oxide, large quantities of sulfur dioxide are formed, which can be further processed to sulfuric acid.

Smithsonite is used as a raw material, this can be done by burning with elimination of carbon dioxide.

The further processing can be done by two possible methods. These are the wet and dry procedures. The dry process nowadays produces only about 10% of the world's produced zinc. The zinc oxide is mixed with finely ground coal and heated to 1100-1300 ° C in an Imperial Smelting furnace. This initially forms carbon monoxide. This then reduces the zinc oxide to metallic zinc. From the resulting carbon dioxide is formed after the Boudouard equilibrium again carbon monoxide.

Reduction of zinc

Boudouard equilibrium

Since temperatures above the boiling point of zinc prevail in the furnace, the zinc escapes as steam at the top of the furnace. Lead is now sprayed there and the zinc is condensed out.

The resulting crude zinc contains large amounts of impurities, especially lead, iron and cadmium. By fractional distillation, the crude zinc can be further purified. In a first stage, the crude product is heated so that only zinc and cadmium evaporate, leaving behind iron and lead. Cadmium and zinc can be separated by condensation. Zinc condenses at higher temperatures, forming 99,99% pure fine zinc. Cadmium is more volatile and is collected elsewhere than cadmium dust. The by-product of the distillation is fine-powdered zinc, the so-called zinc dust.

The wet process is used when cheap electric power is available. For the process, the crude zinc oxide is dissolved in dilute sulfuric acid. Impurities of nobler metals such as cadmium are precipitated by zinc powder. Subsequently, the solution is electrolyzed using lead anodes and aluminum cathodes. As with the dry process, 99,99% pure electrolysis zinc is produced at the cathode.

Physical Properties

Zinc is a bluish white, base metal which is fairly brittle at room temperature and above 200 ° C. Between 100 and 200 ° C, however, it is quite ductile and easily deformed. His break is silvery white. Zinc crystallizes in a hexagonal close-packed sphere. However, this is stretched perpendicular to the spherical layers, the distances between the zinc atoms differ slightly (in one layer 264,4 pm, between the layers 291,2 pm).
Chemical properties

In the air, zinc forms a weather-resistant protective coating of zinc oxide and carbonate (Zn5 (OH) 6 (CO3) 2). Therefore, it is used despite its base character as corrosion protection (galvanizing iron). Zinc dissolves in acids to form zinc (II) salts and in alkalis to form zincates, [Zn (OH) 4] 2-. An exception is zinc with very high purity (99,999%), which does not react with acids. Zinc is in its compounds almost without exception in the oxidation state + II.

Chemically, zinc is one of the base metals (redox potential -0,763 volts). This can be exploited, for example, to precipitate elemental metals from their salts by reduction elementary, as shown here by the example of the implementation of a copper salt:

In powder form, zinc is a self-ignitable (pyrophoric) solid. It can heat at room temperature in the air without energy supply and finally ignite. Among other things, the ignition readiness depends very much on the particle size and the degree of distribution. Zinc powder forms flammable gases on contact with water that may ignite spontaneously.

isotope

Of zinc, 31 isotopes from 54Zn to 85Zn and a further eleven core isomers are known. Of these, five, the isotopes 64Zn, 66Zn, 67Zn, 68Zn and 70Zn are stable and natural. There are no radioactive natural isotopes. The most common isotope is 64Zn with 48,63% share of the natural isotope ratio. This is followed by 66Zn with 27,90%, 68Zn with 18,75%, 67Zn with 4,10%, and the rarest natural isotope 70Zn with a share of 0,62%. The most stable artificial isotope is the beta and gamma emitter (K ​​/ β + decay) 65Zn with a half-life of 244 days. This and the core isomer 69m serve as tracers. As the only natural isotope, 67Zn can be detected by NMR spectroscopy.

iso- top	half-life time	decay energy (MeV)	Spin / parity	Decay (s) (%)	NH (%)	Mass (U)
54Zn	1,59 ms	1,491	0	2p = 92		53,992 04 (75 #)
55Zn	19,8 ms	16,711 (ε), 17,012 (εp)	5 / 2-	ε = 9, εp = 91		54,983 98 (75 #)
56Zn	30 ms	12,659 (ε), 12,467 (εp)	0+	ε = 14, εp = 86		55,972 54 (54 #)
57Zn	38 ms	14,762 (β+), 14,072 (εp)	7 / 2-	β+ = 35, εp = 65		56,965 06 (22 #)
58Zn	86 ms	9,369 (ε), 6,496 (β+p)	0+	ε = 97, β+p = 3		57,954 591(54)
59Zn	182 ms	9,143 (ε), 5,724 (εp)	3 / 2-	ε = 99,9, εp = 0,1		58,949 312 66 (89)
60Zn	2,38 min	4,171	0+	ε		59,941 842 10 (69)
61Zn	89,1 s	5,635	3 / 2-	ε		60,939 507(17)
61m1Zn	400 ms	0,09177	1 / 2-	IT		60,939 605 52
61m2Zn	140 ms	0,42146	3 / 2-	IT		60,939 959 46
61m3Zn	100 ms	0,75937	5 / 2-	IT		60,940 322 22
62Zn	9,186 hours	1,62	0+	ε		61,934 333 97 (73)
63Zn	38,47 min	3,366	3 / 2-	ε		62,933 2115(17)
64Zn	stable 2e	1,095	0+	2e	49,17	63,929 142 01 (71)
65Zn	243,93 d	1,352	5 / 2-	ε		64,929 240 77 (71)
65m1Zn	1,6 μs	0,0541	1 / 2-	IT		64,929 298 85
66Zn	stable		0+		27,73	65,926 033 81 (94)
67Zn	stable		5 / 2-		4,04	66,927 127 75 (96)
68Zn	stable		0+		18,45	67,924 844 55 (98)
69Zn	56,4 min	0,91026	1 / 2-	β-		68,926 5507(10)
69m1Zn	13,76 hours	0,43818 (IT), 1,348 (β-)	9 / 2 +	IT = 99,997, β- = 0,003		68,927 021 11
70Zn	stable 2b	0,99712	0+	2b	0,61	69,925 3192(21)
71Zn	2,45 min	2,81	1 / 2-	β-		70,927 7196(28)
71m1Zn	3,96 hours	2,97 (β-), 0,15986 (IT)	9 / 2 +	β- = 99,95, IT = 0,05		70,927 891 22
72Zn	46,5 hours	0,44277	0+	β-		71,926 8428(23)
73Zn	23,5 s	4,106	1 / 2-	β-		72,929 5826(20)
73m1Zn	5,8 s	4,527 (β-), 0,42069 (IT)	7 / 2 +	β- =?, IT =?		72,930 034 23
73m2Zn	13 ms	0,37859	5 / 2 +	IT		72,929 989 03
74Zn	95,6 s	2,293	0+	β-		73,929 4073(27)
75Zn	10,2 s	5,906	7 / 2 +	β-		74,932 8402(21)
76Zn	5,7 s	3,994	0+	β-		75,933 1150(16)
77Zn	2,08 s	7,203	7 / 2 +	β-		76,936 8872(21)
77m1Zn	1,05 s	0,8393 (IT), 8,043 (β-)	1 / 2-	IT> 50, β- <50		76,937 788 22
78Zn	1,47 s	6,228	0+	β-		77,938 2892(21)
79Zn	995 ms	9,115 (β-), 2,202 (β-n)	9 / 2 +	β- = 98,7, β-n = 1,3		78,942 6381(24)
80Zn	0,54 s	7,575 (β-), 2,828 (β-n)	0+	β- = 99, β-n = 1		79,944 5529(28)
81Zn	304 ms	11,428 (β-), 4,953 (β-n)	5 / 2 +	β- = 92,5, β-n = 7,5		80,950 4026(54)
82Zn	228 ms	10,324	0+	β- = 100?		81,954 26 (32 #)
83Zn	117 ms	12,519 (β-), 8,121 (β-n)	5 / 2 +	β- =?, β-n =?		82,960 56 (54 #)
84Zn	> 633 ns	11,877 (β-), 8,779 (β-n), 4,381 (β-2n)	0+	β- =?, β-n =?, β-2n =?		83,965 21 (64 #)
85Zn	> 637 ns	14,224		β- = 100?		84,972 26 (75

Usage

2006 consumed over 11 million tonnes of zinc. Of these, 47% was used for corrosion protection of iron and steel products by galvanizing. The most important field of application according to consumption quantities are its alloys, preferably those with copper, such as brass, or with aluminum, either as AlZn alloy or with significantly higher zinc contents than Alzen, which is used for parts produced in sand casting and chill casting. Zinc is also contained in the standardized magnesium alloys with up to 5%. Equally important are the standardized fine-zinc casting alloys, which are cast predominantly in die-casting, but also in sand and mold. Zinc alloys are also processed into rolled material such as zinc sheets.

Corrosion Protection

Zinc has long been used as corrosion protection (rust protection) for steel and iron parts, by galvanizing them, ie coated with a metallic coating of zinc. The zinc actively and passively protects against corrosion, ie it forms a barrier on the one hand and protects on the other hand also exposed adjacent iron surfaces as well as layer defects against corrosion by acting like a sacrificial anode.

The galvanizing can be done in different ways. Methods include hot dip galvanizing, electrogalvanizing, mechanical coatings, spray galvanizing and zinc flake coatings. They differ in the manner of applying the zinc layer, the thickness and thus the durability.

The oldest galvanizing method is the discontinuous hot-dip galvanizing (piece galvanizing). Pre-treated and prefabricated steel components (eg balcony railings) are immersed in a bath of liquid zinc. In the 1930 years, as a process variant, continuous hot-dip galvanizing (strip galvanizing) was used for the first time, in which steel strip is galvanized in a continuous process as a semi-finished product and then further processed. Zinc coating produces zinc layers, which are usually between 50 and 150 μm and protect against corrosion for decades, depending on the atmospheric conditions. Strip-galvanized sheets have very thin zinc layer thicknesses between 7 and 25 μm and therefore only achieve significantly shorter protection periods. The protection duration of hot-dip galvanized steel can be further increased by an additional coating (duplex system).

In the galvanic process, the zinc layer is applied electrolytically. For this purpose, the workpiece is dipped together with a piece of pure zinc in an acidic or basic solution of a zinc salt. Thereafter, DC voltage is applied, the workpiece forming the cathode, the piece of zinc forming the anode. Zinc is formed on the workpiece by reduction of zinc ions. At the same time, the pure zinc of the anode is oxidized, the anode dissolves. The result is a dense layer of zinc, which in practice 2,5 up to 25 microns. is thus significantly lower than in the discontinuous hot-dip galvanizing. The zinc layer could theoretically be brought to the thickness of a hot-dip galvanized layer during the galvanic process. However, this would not be economical due to the duration (about 0,5 microns in one minute) and energy costs.

In the case of spray galvanizing, the zinc is melted and then sprayed onto the workpiece using compressed air. The thermal load is lower than during hot-dip galvanizing. This can be important for sensitive materials. If the zinc is mechanically applied to the workpiece, it is called plating. One method used for galvanizing small parts, such as screws, is sherardizing. The zinc layer is formed by diffusion of zinc into the iron of the workpiece. Another possible application of zinc coatings is zinc sprays.

Zinc is used as a sacrificial anode to protect larger steel parts. The object to be protected is conductively connected to the zinc. The result is a galvanic cell with zinc as the anode and the object as a cathode. Since the base zinc is preferentially oxidized and slowly dissolves, the steel part remains unchanged. As long as zinc is present, thus the steel piece is protected against corrosion.

Tasks of corrosion protection also have the white and color pigments based on zinc compounds. Zinc compounds are also part of the phosphating (phosphating), the processes, such as the bender of sheets allow only.

Zinc in batteries

Metallic zinc is one of the most important materials for negative electrodes (anodes) in non-rechargeable batteries and is used on an industrial scale. Examples are alkaline-manganese batteries, zinc-carbon batteries, zinc-air batteries, silver oxide-zinc batteries and mercury-oxide-zinc batteries. Zinc has also been used as an anode in many historical galvanic elements. These include, among others, the Voltasche column, the Daniell element and the Bunsen element. To a lesser extent, zinc is also used for negative electrodes in accumulators (rechargeable batteries).

The reason for the varied use of zinc in batteries lies in the combination of physical and electrochemical properties with good environmental compatibility and relatively low cost. Zinc is a good reducing agent with high theoretical capacity (0,82 Ah / g). Due to the low standard potential of about -0,76 V or in alkaline medium -1,25 V relatively high cell voltages can be realized. Furthermore, zinc has good electrical conductivity and is sufficiently stable in aqueous electrolyte solutions.

In order to reduce the corrosion of zinc in the battery and to improve the electrochemical properties, previously amalgamated zinc with a mercury content of up to 9 percent was used. For environmental reasons, this practice has been almost completely discontinued, at least in industrialized countries. In the year 2006, amalgamated zinc powder is only used in zinc-air and silver-oxide-zinc button cells.

The anode in zinc-carbon batteries has the form of a zinc cup. The cups are made by multi-stage deep drawing of zinc sheet or by impact deformation of round or hexagonal discs made of thick zinc sheet (so-called dome). To improve moldability and to inhibit corrosion, the zinc used for this purpose contains small amounts of cadmium, lead and / or manganese. In alkaline manganese batteries, zinc powder is used as the active material in the anode. It is usually produced by atomizing molten zinc in the air jet. To inhibit corrosion, zinc is mixed with small amounts of other metals. These include, for example, lead, bismuth, indium, aluminum and calcium.

Zinc sheet in construction

Important zinc products are also semi-finished products, usually in the form of alloyed zinc / titanium zinc sheets. Titanium zinc sheet is used as a material in construction. Today, titanium zinc is used almost exclusively, which is more corrosion-resistant, less brittle and therefore significantly more load-bearing than unalloyed zinc or the zinc sheet used until about 50 years ago, which has been produced in so-called package rolling process. Rolled, massive Titanzinkblech is mainly for roofing, as cladding, for the roof drainage (gutters, downpipes), for covers z. B. of cornices or exterior window sills or used for connections and roofs. It lasts up to 100 years and does not need to be serviced or repaired during this time if properly handled. The processing is done by the plumbing trade.

Zinc sheet should not be confused with hot-dip galvanized sheet steel, which is falsely called zinc sheet or tinplate.

Alloy zinc sheet is supplied in coils or in sheets. For the roofing often metal sheets (coulters) are used, which are between 40 and 60 centimeters wide and can be up to 16 meters long. The material thickness varies, but is usually 0,7 millimeters. The connection of the individual sheet metal parts takes place in small-scale elements usually by soldering, in roofing mostly by double folding (Doppelstehfalzdeckung). Due to the thermal expansion of 22 · 10-6 / K alloyed zinc, the connections and connections of the zinc profiles must permit material movement.

Modern architects realize extravagant ideas with titan zinc. Daniel Libeskind has z. For example, the Jewish Museum Berlin or the Libeskind Villa in Datteln are equipped with a façade made of zinc. Zaha Haddid chose the material for the Transport Museum in Glasgow, which impressively demonstrates the deformation properties of the material.

Die-cast zinc

Zinc diecasting is the common name for die-cast parts made of fine zinc casting alloys. These alloys provide far better casting values ​​than are possible when casting pure zinc. The alloys are standardized. The alloy GD ZnAl4Cu1 (Z 410) is widely used. Zinc diecasting - like any die casting process - enables the production of large quantities. The castings are characterized by high dimensional stability, have very good mechanical properties and are well suited for a surface treatment such as nickel plating or chrome plating. The range of applications includes automotive accessories and those in mechanical and apparatus engineering, also fittings of all kinds, parts for the sanitary industry, for precision equipment and electrical engineering, for metal toys and many household utensils.

coinage

Since zinc costs comparatively little as coin metal, it was used in times of need, most recently in the two world wars, in the form of zinc alloys for coinage, this use was divided as so-called "war metal" but with coins from an aluminum alloy. Since 1982, the US cents (penny) in the core of zinc.

Analytics

Analytically pure zinc powder serves as the original substance according to the pharmacopoeia for the adjustment of EDTA standard solutions.

Organic chemistry

In organic synthesis it serves several purposes. Thus, it acts as a reducing agent and as such can be activated in different ways. An example is the Clemmensen reduction of carbonyl compounds with amalgamated zinc. Furthermore, allylic alcohols can be reduced to alkenes, acyloins to ketones. The reduction of the aromatic nitro group may, depending on the reaction conditions, lead to different products: arylamine, arylhydroxylamine, azoars, N, N'-diarylhydrazine.

In the organometallic region, zinc organyls offer selectivity advantages over Grignard compounds because they tend to be less reactive and tolerate more functional groups, a circumstance that the Reformatzky reaction uses. The organyls can be prepared directly or by transmetalation. In the presence of asymmetrically complexing auxiliaries, of which catalytic amounts may suffice, stereoselective addition is possible. The effect of chirality enhancement was observed.

Last but not least, halogen elimination and dehalogenation are possible. The Simmons-Smith reaction is one of the rarer preparation methods. The journal Organic Syntheses lists a series of syntheses using elemental zinc as a reagent.

Production of hydrogen

Zinc is used in the so-called Solzinc process for the production of hydrogen. For this purpose, in a first step zinc oxide is thermally decomposed by solar energy into zinc and oxygen, and in a second step, the zinc thus obtained is reacted with water to form zinc oxide and hydrogen.

Biological significance

Inaccuracies The following paragraphs are missing the following important information:
Importance of zinc for plants (deficiency, oversupply and possibly fertilization)
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Effect in the body

Zinc is one of the indispensable (essential) trace elements for the metabolism. It is part of a variety of enzymes, such as RNA polymerase and carbonic anhydrase. Zinc fulfills many different functions in the body. So it plays key roles in sugar, fat and protein metabolism and is involved in the structure of the genetic material and cell growth. Both the immune system and many hormones need zinc for their function. Zinc promotes the immune system, inter alia, by weakening the immune reaction in excessive reactions of the immune system. Zinc is also part of zinc finger proteins, which are important transcription factors. In the blood, zinc is predominantly bound to albumin.

Recommended daily dose

The recommended daily allowance for zinc was 1996 according to the World Health Organization for adult men, 15 mg for women, 12 mg for prepubescent children and 10 mg for infants. Because the body can absorb less zinc than expected - only 5 percent can be absorbed - the German Nutrition Society has lowered the recommended amount of zinc for adult men to 30 mg per day, for adult women to 10 mg per day. In the United States, dietary intake is currently 7 mg / day for women and 9 mg / day for men. Persistent increased zinc intake can lead to copper deficiency and blood clotting disorders.

The European Food Safety Authority's Tolerated Upper Intake Level is 25 mg zinc per day, and the Standing Committee on the Scientific Evaluation of the Dietary Reference, Intakes of the Food and Nutrition Board, Institute of Medicine, National Academy of Sciences, recommends 40 for adults mg / day as tolerable upper intake level. According to the magazine Ökotest, the Federal Institute for Risk Assessment recommends a daily intake of up to 2,25 mg of zinc per dietary supplement. In addition, it considers 25 mg / day as a tolerable upper intake.

It is not recommended to take more than 100 mg per day. 200 mg may cause symptoms such as nausea, vomiting or even diarrhea. In humans, the absorption of zinc from about 2 g leads to acute symptoms of intoxication. Zinc supplements should be taken only in case of zinc deficiency (see below) and increased zinc requirements (eg after surgery, trauma or burns).

If zinc is taken in high dose, eg. B. Zinc fumes are inhaled during the flame-cutting of galvanized steels, the so-called "zinc fever" arises. In this case, the poisoned develops flu-like symptoms with sometimes severe attacks of fever. The symptoms generally resolve after 1-2 days.

performance increase

An 2005 study presented at a conference by the US Society of Nutritionists in San Diego suggests that children who receive twice the daily recommended daily dose of zinc (20 mg) experience a significant improvement in mental performance. Zinc improved visual memory, performance in a word-finding test, and the ability to concentrate.

deficiency

The trace element can not be stored in the body, it must be regularly supplied from outside. Due to poor dietary habits, zinc deficiency is not uncommon in western countries, especially in infants, seniors, adolescents and women of childbearing age. It is estimated that two billion people around the world suffer from zinc deficiency and that this deficiency is partly responsible for the death of one million children a year.

Zinc deficiency leads to a hypofunction of the gonads, growth disorders and anemia. A low zinc level is also often expressed by a reduced immune function, hair loss, dry skin and brittle nails. In domestic dogs, zinc-reactive dermatoses occur. Zinc deficiency can lead to male infertility. Zinc deficiency is often caused by a high level of copper (for example, when there is plenty of drinking water from domestic copper piping networks), as zinc and copper are antagonists. The same applies to iron, z. For example, by a very iron-rich diet or the intake of iron-containing drugs. The uptake of zinc (as well as other metal ions) from the gut is also reduced by phytic acid-containing foods.

The following foods are good sources of zinc:

• red meats
• Käse,
• Oatmeal and oatmeal
• Sunflower seeds
• Pumpkin seeds
• Wheat germ (wheat)
• Walnuts and pecans
• Mushrooms and yeasts
• Lentils
• Seafood and shellfish
• Green tea

Although peanuts contain a relatively large amount of zinc (about 3 mg per 100 g), but like other legumes also contain a lot of phytic acid, which hinders absorption. The same applies to oilseeds and whole grains.

Zinc content in foods

a lot of zinc	per 100 g	a lot of zinc	per 100 g	on average a lot of zinc	per 100 g	little zinc	per 100 g
oysters	7,0-160,0 mg	Brazil nuts	4,0 mg	Millet	3,4 mg	Chicken	1,0 mg
Liver (veal, pork, beef)	up to 6,3 mg (pork)	Lamb	2,3-6,0 mg	crispbread	3,1 mg	Fish	0,4-1,1 mg
soy flour	5,7 mg	Lentils (dried)	3,7 mg	Pasta (uncooked)	3,1 mg	Vegetables	0,2-1,0 mg
Emmentaler 30% or 45% FiTr.	4,6 mg	Soybeans (dried)	0,7-4,2 mg	walnut	2,7 mg	yogurt	0,3-0,5 mg
oatmeal	4,0-4,5 mg	More	2,5-3,5 mg	Wholemeal biscuits	2,7 mg	Kartoffel	0,4-0,6 mg
Butter cheese, Tilsiter, Gouda, Edamer	3,5-4,0 mg	Peanuts (roasted)	3,0-3,5 mg	Camembert	2,7 mg	whole milk	0,4 mg
Beef	3,0-4,4 mg	Mixed wheat bread	3,5 mg	Beans (white)	2,6 mg	Fruits	0,1-0,5 mg

Zinc as a remedy

Zinc ointments are used in wound healing and rash (eczema). Examples of pharmaceutically used zinc salts: zinc acetate, zinc acacate, zinc chloride, zinc gluconate, zinc oxide, zinc stearate, zinc sulfate, zinc undecylenate.

Zinc affects the metabolism of the intestinal cells to the extent that less copper is absorbed. Zinc salts (eg, zinc sulfate, zinc acetate) are therefore useful as drugs in the treatment of Wilson's disease, a disease in which the copper metabolism in the liver is disturbed and thereby to an increased accumulation of copper in the liver, the eye, the central nervous system and other organs.

An often-cited meta-study by the Indian Institute of Medical Education and Research to prove that zinc has a mitigating and shortening duration in colds was so serious that it was withdrawn by the Cochrane Collaboration. Older examinations could not prove a positive effect either.

2004 issued a statement on the treatment of acute diarrhea by the World Health Organization (WHO) and the United Nations Children's Fund (UNICEF), recommending co-treatment with zinc and oral rehydration (ORS). A meta-analysis of the Cochrane Collaboration also found a positive effect of zinc in the treatment of diarrhea in children, limited to children over the age of six and from regions with potential zinc deprivation.

proof

A simple zinc detection is based on heating a sample with a few drops of a dilute solution of a cobalt salt on a magnesian egg in the Bunsen burner. If zinc is present, the so-called Rinmans green is visible after a short time.

The quantitative determination can be carried out by means of complexometry with a standard EDTA solution. For trace determination, the different methods of polarography come into question. In the ultra trace range one uses the graphite tube AAS. Zinc is a relatively volatile element, which is why matrix modifiers such as palladium and magnesium nitrate are important because they increase the potential pyrolysis temperature. Alternatively, inverse voltammetry or ICP-MS are extremely sensitive instrumental methods.

 

Zinc prices

Zinc price -> prices for base metals

Sources: wikipedia, roskill, ECHA