Contents - Previous - Next

Nickel

DESIGNATIONS

CAS No.: 7440-02-0
Registry name: Nickel
Chemical name: Nickel
Synonyms, Trade names: Nickel, Raney nickel, nickel catalyst
Chemical name (German): Nickel
Chemical name (French): Nickel
Appearance: Nickel is a silvery white, shiny, malleable and ductile heavy metal with cubic-compact metallic lattice (beta-nickel) or a less-stable hexagonal configuration (alpha-nickel). Ni is slightly ferromagnetic.

BASIC CHEMICAL AND PHYSICAL DATA

BASIC DATA OF SELECTED COMPOUNDS

ORIGIN AND USE

Usage:
Primarily for hard, malleable and corrosion-resistant alloys (81%), coatings ("nickelising", "plating", 11%), coins, catalysts, chemical apparatus, laboratory equipment, thermocouples, Ni-Cd batteries and magnetic materials.
The most important compounds are as follows:

- Nickel tetracarbonyl (Ni(CO)₄): highly poisonous, colourless liquid; forms explosive mixtures with air; parent substance for manufacture of superpure nickel;

- Nickel oxide (NiO); greyish green powder not soluble in water; used to make glasses grey and to manufacture Ni catalysts for hydration processes;

- Nickel dichloride (NiCl₂): for dyeing ceramics, for producing Ni catalysts and for nickel electroplating.

Origin/derivation:

Ni is the 28th most common element. It makes up approx. 0.008% by weight of the Earth's crust. The Earth's core probably contains large amounts of nickel. Ni is not found in elemental form except in meteorites.

Nickel minerals are widespread in small concentrations; extractable deposits would have to be enriched to at least 0.5% Ni content by geochemical processes. Deep-sea manganese nodules contain large quantities of Ni. The most important nickel minerals are magnetic pyrites, pyrrhotine, garnierite, niccolite, arsenical nickel and antimony nickel.

Extraction involves widely differing methods depending on the nature of the ore and the intended use. In some cases the Ni-Fe alloys obtained as intermediate products are passed on directly for steelmaking. In the case of sulphide ores, the first step is to obtain "raw stone" then "fine stone" before using the high-pressure carbonyl process to produce high-purity Ni powder by way of nickel tetracarbonyl. With oxide ores the metal is obtained electrolytically.

Production figures:
The largest deposits are to be found in Canada, the Soviet Union, New Caledonia, Australia and Cuba. Worldwide reserves are estimated at about 50 million tons. Annual worldwide production amounts to roughly 800,000 tons (ULLMANN, 1991).

Emission figures:

Natural emissions (in t/a, acc. BENNETT 1981):

Aeolian deposits: 4,800; volcanoes: 2,500; vegetation: 800; forest fires: 200; meteorite deposits: 200; sea spray: 9

Anthropogenic emissions (in t/a, acc. BENNETT 1981):

Oil burners: 27,000; nickel industry: 7,200; refuse incineration: 5,100; steel production: 1,200; industrial processing: 1,000; motor vehicles: 900; coal burners: 700

Coal-fired power plants in the Federal Republic of Germany approx. 84 t/a (RÖMPP, 1988).

Toxicity

Note:

¹⁾ Low carbonate hardness in water coincides with lower toxicity values.

Characteristic effects:

Humans/mammals: Ni is a trace element. The metal and its inorganic compounds are classed as being comparatively non-toxic. Sustained skin contact can however cause "nickel itch". On the other hand, certain organic Ni compounds are extremely toxic (e.g. nickel tetracarbonyl) and have a considerable allergenic/mutagenic potential). Ni vapour and dust are probably carcinogenic as are some other Ni compounds.

Plants: Ni is an important trace element for plant growth.

Synerg./antagon.: "Laboratory experiments have shown that the toxic effect of nickel changes in the presence of other elements. Copper, zinc and nickel are thought to have an additive effect on the acute toxicity level with rainbow trout. Synergetic effects are attributed to nickel/zinc and nickel/copper combinations. Other laboratory results likewise provide evidence of changes in effect with mixtures of different heavy metal salts... " (ATRI, 1987).

ENVIRONMENTAL BEHAVIOUR

Water:
Nickel is usually found in the form of Ni²⁺ in aquatic systems. The form in which it is found in water is dependent amongst other factors on the pH value. Nickel compounds in surface water or groundwater are generally recorded and listed as "total nickel" despite the fact that the spectrum of the compounds anthropogenically introduced into stretches of water ranges from soluble salts and insoluble oxides to metallic nickel dust. As yet, there is no evidence of nickel compounds occurring exclusively in water.

Air:
Nickel is encountered in the atmosphere as an aerosol. Its metallic form is stable. The determination of air-specific Ni compounds is extremely difficult since, on the one hand, there are comparatively few compounds and on the other hand, the different analytical methods result in the substances concerned being modified. According to the available emission figures, the atmosphere is primarily impacted by Ni sulphates, complex Ni oxides and Ni oxide itself with metallic nickel dusts playing a far less important role.

Soil:
Nickel is found in various forms in soil, namely as inorganic crystalline mineral (or as precipitation), in complex chelates or as a free ion. The behaviour of Ni compounds in soil depends not only on the properties of the individual compounds, but also on the type of soil. Thus, generalisations are not possible. Desorption and the nickel content in the soil solution increase with decreasing pH.

Degradation, decomposition products, half-life:
Data of this type can only be provided for individual Ni compounds and, for the element itself, only the half-lives of the eight non-stable Ni isotopes. The values range between 0.005 s (⁵³Ni) and 7.5 x 10⁴ a (⁵⁹Ni).

Food chain:
Numerous plants accumulate nickel from the soil, mainly via the roots (e.g. pines up to 700 times more). Under natural conditions, plants contain less than 1 mg/kg; concentrations of 100 mg/kg have however been found in soils over serpentinites and levels of up to 1150 mg/kg in sewage-sludge soils (acc. U.S. EPA, 1985).

Environmental standards

Notes:

¹⁾ Drinking water treatment involving the use of simple physical purification methods
²⁾ Drinking water treatment involving the use of physical/chemical purification methods
³⁾ Baden-Württemberg Regional Environment Office
⁴⁾ Direct and indirect introduction
⁵⁾ Overall content
⁶⁾ Available content
⁷⁾ Content in affected soil; values are to be reduced for pH values < 6; up to 10% excess is permitted
⁸⁾ The use of sludges is banned in pastures and fodder growing areas during use and in fruit and vegetable cultivation during vegetation
⁹⁾ The use of sewage sludge is not permitted for the following: saturated, snow-covered soil, moorland, hedges, perimeters of forests, banks of rivers/streams, etc., scattering areas and protected groundwater catchment areas; a maximum of 7.5 t of sewage sludge (dry matter) may be spread in 3 years.
¹⁰⁾ Application intervals are governed by heavy metal concentration and quantity concerned, making allowance for the last two compost analyses.
¹¹⁾ Quality stamp aimed at better marketing with state and partly state-run supervision
¹²⁾ On discharge from pumping and/or treatment systems and their secondary systems
¹³⁾ Respirable dust/aerosols of Ni and its compounds, stated as Ni
¹⁴⁾ Listed in group of substances which have been shown to cause cancer in humans, have proven to be carcinogenic in animal experiments or for which a considerable carcinogenic potential can be construed.

Comparison/reference values

Notes:

¹⁾ Baden-Württemberg Regional Environment Office
²⁾ The average human absorption rate is approx. 0.1 - 0.3 mg of nickel per day; the contamination of foodstuffs may also result from preparation in nickel-plated domestic utensils.

Assessment/comments

Nickel is a trace element encountered in large quantities in nature. Naturally-occurring nickel ores are not hazardous. However, the products of synthetic processing are a considerable hazard. Environmental accumulation is caused by sewage sludges and composts. Hazards arise in the nickel processing industry when extremely toxic intermediary and waste products are formed. An outline of the range of possible effects of nickel in various environmental sectors is given by the spectrum of standards quoted. Any assessment of measures used for the extraction, processing or industrial utilisation of nickel presupposes in-depth determination of the individual chemical compounds concerned. Their specific properties must be known before the effect on the environment can be established in detail.

Contents - Previous - Next