DESIGNATIONS
CAS No.: 7440-66-6
Registry name: Zinc
Chemical name: Zinc
Synonyms, Trade names: Zinc powder; zinc dust, zinc clippings, zinc folings and others
Chemical name (German): Zink
Chemical name (French): Zinc
Appearance: Shiny, bluish white metal with elongated hexagonal lattice. The metal is brittle at ambient temperature. It becomes ductile at temperatures between 100 and 150°C and, above 250°C it is so fragile that it can easily be reduced to powder. Generally marketed as bluish grey powder.
BASIC CHEMICAL AND PHYSICAL DATA
Chemical symbol: Zn
Molar mass: 65.38 g
Density: 7.14 g/cm3 (at 20°C), 6.56 g/cm3 (at melting point)
Boiling point: 907°C
Melting point: 419.6°C
Vapour pressure: 1.3 x 10-7 Pa at 103.3°C
Ignition temperature: approx. 500°C
Solvolysis/solubility: dissolves in mineral acids with hydrogen being produced
BASIC DATA OF SELECTED COMPOUNDS
CAS No: | 1314-13-2 | 7733-02-0 |
Chemical name: | Zinc oxide | Zinc sulphate |
Chemical name (German): | Zinkoxid | Zinksulfat |
Chemical name (French): | Oxyde de zinc | Sulfate de zinc |
Appearance: | colourless crystals or white powder | colourless rhombic crystals |
Empirical formula: | ZnO | ZnSO4 |
Rel. molecular mass: | 81.37 g | 161.43 g |
Density: | 5.6 g/cm3 | 3.54 g/cm3 |
Melting point: | 1975°C | above 600°C decomposition |
Solvolysis/solubility: | in water: 1.6 x 10-3 g/l |
ORIGIN AND USE
Usage:
Mainly in alloyed form for castings, for the surface protection
(galvanisation) of sheet iron, iron wires and consumer goods such
as gutters, buckets, troughs and roofing materials. Zinc alloys
contain above all Al and Cu. Both metals considerably enhance the
strength of zinc. The addition of magnesium (up to 0.05%)
improves corrosion resistance. Zinc is used in mechanical
engineering, haulage and the motor vehicle industry. The chemical
industry requires large amounts of zinc dust as a reduction
agent. In comparison with the metal, zinc compounds play a minor
role. The most important compounds are as follows:
- zinc oxide (white pigment, filler for rubber goods, zinc ointments, parent substance for other zinc compounds),
- zinc sulphide (luminous coating on X-ray screens, in white paint),
- zinc sulphate (used in dyes, for the production of lithopones and as an impregnating agent for wood; parent substance for the production of hydrolysed zinc)
Origin/derivation:
Trace element in humans, animals and plants (2-4 g in human
body). Zn is the 26th most frequent element. It makes up 0.0058%
of the Earth's crust. Zinc ores are very common. They usually
contain other metals (e.g. Pb, Cu, Fe, Cd) which considerably
influence the economic viability of extraction. Sedimentary
deposits result from the weathering of primary layers. The most
important zinc minerals are: sphalerite, wurtzite, smithsonite,
hemimorphite, wilemite and zincite.
Zinc is chiefly obtained from zinc sulphides; slags containing zinc and blast-furnace dust likewise play a part. The crushed raw material is first enriched by floatation and then converted to oxides with the help of roasting methods. The roasted blends produced are further processed by zinc distillation or electrolytic methods to form metal. Zinc dust is either extracted as a by-product from the zinc distillation process or is obtained through mechanical atomisation by spraying liquid metal.
Production figures:
Extractable reserves are estimated at more than 100 million
tons. The principal deposits are to be found in Australia, the
USA, Canada, Russia, Peru, Mexico, Japan, Zaire, Zimbabwe,
Morocco, Yugoslavia, Spain and Sweden.
Worldwide production totals some 6.4 million t/a.
Emission figures (estimated):
Roughly 314,000 t of zinc were emitted into the atmosphere in
1975, but this figure has been reduced since then. Approximately
100,000 t find their way into the sea every year.
Toxicity
Plants:
Various species | 150-200 mg/kg | Reduced yield | acc. BAFEF, 1987 |
Young barley | 120-220 mg/kg | Reduced yield | acc. BAFEF, 1987 |
Characteristic effects:
Humans/mammals: The inhalation of zinc-oxide vapours causes metal-fume fever with the following symptoms: fever, pain, fatigue, shivering, sweating. Large quantities of zinc salts are corrosive. Acute zinc poisoning can result, for example, from pickled foods stored for lengthy periods in zinc vessels.
Plants: Necrosis, chlorosis, inhibited growth. The phytotoxicity is predominant to the adverse effects in other organisms.
ENVIRONMENTAL BEHAVIOUR
Water:
As zinc forms a protective layer, it is stable both in freshwater
and seawater. Zinc powder is highly reactive due to its large
specific surface: danger of dust explosion or formation of highly
flammable hydrogen.
Air:
A thin colourless layer made up of alkaline zinc carbonates and
zinc oxide forms on the surface of the metal and thus prevents
further reaction.
Soil:
Accumulation can be established in soil up to a distance of
several kilometers from zinc works. Agriculture is impossible in
the immediate vicinity of such works.
Degradation, decomposition products, half-life.
When exposed to heat, zinc oxidises to form zinc oxide.
Food chain:
Zinc is taken up by several plants.
ENVIRONMENTAL STANDARDS
Medium/ acceptor |
Sector | Country/organ. | Status | Value |
Cat. | Remarks | Source |
Water: | Drinkw | WHO | G |
5 mg/l |
WHO, 1984 | ||
Surface | D | G |
0.5 mg/l |
6) | DVGW, 1975 | ||
Surface | D | G |
1 mg/l |
7) | DVGW, 1975 | ||
Surface | EC | G |
0.5 mg/l |
Guide value3) | acc. LAU-BW1), 1989 | ||
Surface | EC | G |
3 mg/l |
Limit value3) | acc. LAU-BW, 1989 | ||
Surface | EC | G |
1 mg/l |
Guide value4) | acc. LAU-BW, 1989 | ||
Surface | EC | G |
5 mg/l |
Limit value5) | acc. LAU-BW, 1989 | ||
Surface | 9) | G |
5 mg/l |
Limit value5) | acc. LAU-BW, 1989 | ||
Waste water | CH | G |
2 mg/l |
Direct/indirect introduction | acc. LAU-BW, 1989 | ||
Waste water | D(BW) | G |
5 mg/l |
acc. LAU-BW1), 1989 | |||
Surface | EC | G |
0.3 mg/l |
Salmonoid weight2) | EC, 1978 | ||
Surface | EC | G |
1 mg/l |
Cyprinid weight2) | EC, 1978 | ||
Groundw | D(HH) | G |
0.2 mg/l |
Further investigation | acc. LAU-BW1), 1989 | ||
Groundw | D(HH) | G |
0.3 mg/l |
Rehabilitation | acc. LAU-BW, 1989 | ||
Groundw | NL | G |
65 m g/l |
Reference | acc. TERRA TECH, 6/94 | ||
Groundw | NL | L |
800 m g/l |
Intervention | acc. TERRA TECH, 6/94 | ||
Irrigation | USA | 2 mg/l (max.) |
Contin. irrigation | EPA, 1973 | |||
Irrigation | USA | 10 mg/l (max.) |
Fine-grain soils, 20a | EPA, 1973 | |||
Marine | USA | 0.1 mg/l (max.) |
Hazard threshold | EPA, 1973 | |||
Marine | USA | 0.02 mg/l (max.) |
Minimal risk | EPA, 1973 | |||
Soil: | G |
0.5-5 mg/kg DS |
acc. CES, 1985 | ||||
G |
130 mg/kg |
Available | acc. ICRCL, 1983 | ||||
CH | G |
200 mg/kg |
Total | acc. LAU-BW, 1989 | |||
CH | G |
0.5 mg/kg |
Available | acc. LAU-BW, 1989 | |||
D | G |
300 mg/kg |
Tolerance value | acc. LAU-BW, 1989 | |||
D(HH) | G |
1,000 mg/kg DS |
Further investigation | acc. LAU-BW, 1989 | |||
NL | G |
140 mg/kg |
Reference | acc. TERRA TECH, 6/94 | |||
NL | L |
720 mg/kg |
Intervention | acc. TERRA TECH, 6/94 | |||
USA | G |
250 mg/kg FS |
Available | acc. LAU-BW, 1989 | |||
USA | G |
5,000 mg/kg FS |
Total | acc. LAU-BW, 1989 | |||
Sew.sludge | CH | L |
3,000 mg/kg DS |
14) | acc. LAU-BW, 1989 | ||
Sew.sludge | D | L |
300 mg/kg |
9)12) | acc. LAU-BW, 1989 | ||
Sew.sludge | D | L |
3,000 mg/kg |
10)11) | acc. LAU-BW, 1989 | ||
Sew.sludge | EC | G |
150-300 mg/kg DS |
9)11)13) | acc. LAU-BW, 1989 | ||
Sew.sludge | EC | G |
2.5-4 g/kg DS |
10)13) | acc. LAU-BW, 1989 | ||
Fertilisers | D | L |
100 mg/kg |
Residual lime | acc. LAU-BW, 1989 | ||
Fertilisers | D | L |
<= 5% |
Copper fertiliser | acc. LAU-BW, 1989 | ||
Fertiliser | D | L |
<= 5% |
Co-cu-fertiliser | acc. LAU-BW, 1989 | ||
Compost | A | G |
300-1500 ppm DS |
acc. LAU-BW, 1989 | |||
Compost | CH | L |
500 mg/kg DS |
15) | |||
Compost | D | G |
300 mg/kg. |
9) | acc. LAU-BW, 1989 | ||
Air: | CH | (L) |
400 µg/m3/d |
a-average in dust | acc. LAU-BW, 1989 | ||
D | L |
50 µg/m3 |
MIK | a-average | acc. LAU-BW, 1989 | ||
D | L |
100 µg/m3 |
MIK | 24-h average | acc. LAU-BW, 1989 | ||
Zinc chloride: | Workpl | AUS | (L) |
1 mg/m3 |
8-h average | acc. MERIAN, 1984 | |
Workpl | B | (L) |
1 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | CH | (L) |
1 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | I | (L) |
1 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | NL | (L) |
1 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | PL | (L) |
1 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | S | (L) |
1 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | SF | (L) |
1 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | USA | (L) |
1 mg/m3 |
Long/short-time average | acc. MERIAN, 1984 | ||
Zinc chromate: | Workpl | B | (L) |
0.1 mg/m3 |
8-h average | acc. MERIAN, 1984 | |
Workpl | NL | (L) |
0.1 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Zinc oxide (fumes): | Workpl | AUS | (L) |
5 mg/m3 |
8-h average | acc. MERIAN, 1984 | |
Workpl | B | (L) |
5 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | BG | (L) |
5 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | CH | (L) |
5 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | CS | (L) |
5 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | CS | (L) |
15 mg/m3 |
Long-time value | acc. MERIAN, 1984 | ||
Workpl | D | L |
5 mg/m3 |
MAK | acc. DFG, 1994 | ||
Workpl | DDR | (L) |
5 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | DDR | (L) |
15 mg/m3 |
Long-time value | acc. MERIAN, 1984 | ||
Workpl | I | (L) |
5 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | H | (L) |
5 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | J | (L) |
5 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | NL | (L) |
5 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | PL | (L) |
5 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | SF | (L) |
5 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | S | (L) |
1 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | SU | (L) |
6 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Workpl | USA | (L) |
5 mg/m3 |
8-h average | acc. MERIAN, 1984 | ||
Plants: | Fodder plants | D | G |
500 mg/kg (max.) |
Poor quality | acc. BAFEF, 1987 |
Notes:
1) Baden-Württemberg Regional Environment Office
2) For protection of aquatic organisms
3) For simple physical drinking water treatment and sterilisation
4) For normal physical/chemical drinking water treatment and sterilisation
5) For physical and refined chemical drinking water treatment, oxidation
6) Impact limit up to which drinking water can be produced by natural methods
7) Impact limit up to which drinking water can be produced using known chemical/physical methods
8) Countries bordering on Rhine
9) Content in soil following application
10) Sludge dry residue for spreading on agricultural areas
11) Spreading possible with exceeding of limit values, approval required
12) Values should be reduced for pH values less than 6
13) Overstepping of values by 10% permitted
14) Pollutant content in dry residue of sewage sludge. Sewage sludge is not to be applied to saturated, snow-covered soil, moors, hedges, perimeters of forests, banks of surface water, areas where seed is sown and in the catchment areas of groundwater protection zones etc. A maximum of 7.5 t of sewage-sludge dry matter may be spread per hectare in 3 years.
15) Up to 31st August 1991 possible to exceed limit value 3 times
Comparison/reference values
Medium/origin | Country | Value | Source |
Soil: | |||
Normal overall content | D | 3-50 mg/kg | acc. LAU-BW,1), 1989 |
Tolerably contaminated | D | <10-300 mg/kg | acc. LAU-BW, 1989 |
Especially contaminated | D | up to 2000 mg/kg | acc. LAU-BW, 1989 |
Air: | |||
Deposition rates: | |||
"Clean-air" zones | D | 80 µg/(m2 d) | acc. SRU, 1988 |
Rural areas | D | 80-500 µg/(m2 d) | acc. SRU, 1988 |
Conurbations | D | 300-several 1000 µg/ (m2 d) | |
Near to source of emission | D | several 10 mg/(m2 d) | acc. SRU, 1988 |
Immission in suspended dust: | |||
Rhine Ruhr (1984) | D | 160-470 ng/m3 (mean range) | acc. SRU, 1988 |
Rhine Ruhr (1984) | D | 310 ng/m3 (mean) | acc. SRU, 1988 |
Stolberg (lead production) | D | 800 ng/m3 (a-average) | acc. SRU, 1988 |
Rural areas | D | £ 0.1 µg/m3 | |
Plants: | |||
Normal content | 10-100 mg/kg | acc. CES, 1985 |
Assessment/comments
As in the case of all other heavy metals, every effort should be made to stop anthropogenic zinc emissions impacting the environment. The hazard to the environment and the health risks involved with zinc are made abundantly clear by the numerous limit values for water. Other zinc compounds such as zinc chloride and zinc oxide are air pollutants and are likewise the subject of numerous regulations. Attention is to be paid to the zinc content as regards agriculture and the spreading of sewage sludge. Cultivation should be discontinued if necessary since zinc can be accumulated by plants and thus result in a human health hazard by way of the food chain.
From an ecological point of view, the assessment is the same as for aluminium, lead, cadmium, thallium etc.