Tar

Tar (from Middle Low German: ter " tar, resin ," akin to Germanic * trewwa "Tree " ) is a brownish to black, viscous mixture of organic compounds, the heat induced decomposition of (pyrolysis ) of organic natural products is obtained. Another, older name for tar tar ( the French word for tar), for example in " Goudronanstrich ".

As tar lake is called obsolete landfills for industrial liquid waste. Colloquially also asphalt lakes are mistakenly referred to as " tar pit " sometimes.

Products that result from nichtzersetzender distillation, hot bitumen.

Extraction

Tar can come from various organic compounds, so there are eg Schieferteer, tar or arising out of coal from charring Tieftemperaturteer ( tar ). Particular importance has high temperature tar ( Kokereiteer ), which arises as a viscous black liquid in the coking of coal. Brown coal tar produced by thermal decomposition of brown coal. Depending on the decomposition temperature and are distinguished Braunkohlenschwelteer Braunkohlenhochtemperaturteer. Torfteer can be obtained analogously from peat. From fat can be produced Fettteer, of crushed defatted bones to Win Knoch tar ( Hirschhorn oil, animal oil).

Use

Tar oils can be used for the extraction of aromatics such as naphthalene, anthracene, and phenanthrene as well as for the production of impregnating oils for wood protection and for the production of soot.

Creosote is still of great importance for industrial wood preservatives, such as railway sleepers or power conductor masts. It has been further developed in recent years to improve its environmental compatibility.

Tar Contrary to the name used in common parlance for the incorporation of asphalt on roads is tar in West Germany since the 1970s and in East Germany since 1990 been banned for use on public streets and roads and completely replaced by bitumen.

In some cases, even so -called carbonate bitumen was ( bad luck bitumen ) used. It is a mixture of bitumen and tar. This hybrid form is the same as the pure tar classified as a health hazard and must be disposed of separately.

Hazards

Long Timely action of the tar on the skin can cause skin lesions that are krebsverursachend at worst. Tar preparations are, however, used in medicine as well as externally applicable medicines for skin diseases, as they seem antipruritic, antiseptic and stimulates blood circulation.

The reason for the ban on the use of tar in the public sector is the risk to the environment and human health, particularly in its processing. On contact with water polycyclic aromatic hydrocarbons ( PAHs) may seep into the groundwater. Tar was replaced by bitumen in road construction. As the construction material asphalt mixture of aggregates and the binder bitumen is called.

If bituminous layers should be broken today at road works, where there is a suspicion of Teerhaltigkeit, give rapid tests with UV light or sprays, for example, silver iodide preliminary information about it. For further analysis, to be taken in case of positive test result samples in the laboratory where the PAK - value ( EPA) according to DIN ISO 18287 and determined based on the result a given disposal is made. Only slightly contaminated material may be used depending on the degree of stress in different ways again, for example in cold recycling [see: Technical delivery conditions for asphalt granulate (TL AG -StB ) ].

Pictures of Tar

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