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Coal tar is produced through thermal destruction of coal.Its composition varies with the process and type of coal used – lignite, bituminous or anthracite. [13]Coal tar is a mixture of approximately 10,000 chemicals, of which only about 50% have been identified.
One can produce a tar-like substance from corn stalks by heating them in a microwave oven. This process is known as pyrolysis. Tar is a dark brown or black viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. [1]
Coal-tar creosote is the most widely used wood treatment today; both industrially, processed into wood using pressure methods such as "full-cell process" or "empty-cell process", and more commonly applied to wood through brushing. In addition to toxicity to fungi, insects, and marine borers, it serves as a natural water repellent.
Pitch is a viscoelastic polymer which can be natural or manufactured, derived from petroleum, coal tar, [1] or plants. Pitch produced from petroleum may be called bitumen or asphalt , while plant-derived pitch, a resin , is known as rosin in its solid form.
Goeckerman regimens use crude coal tar, which contains polycyclic aromatic hydrocarbon, a carcinogen. [8] [9] However, Goeckerman therapy is considered safe although use of tar may have the side-effects of contact dermatitis and mild local burning due to tar hypersensitivity.
Coal tar and coal tar sludges are frequently denser than water and are present in the environment as a dense non-aqueous phase liquid. In the UK, a number of former gasworks sites have been redeveloped for residential and other uses (including the Millennium Dome ), being seen as prime developable land within the confines of city boundaries.
Bituminous coal. Bituminous coal, or black coal, is a type of coal containing a tar-like substance called bitumen or asphalt. Its coloration can be black or sometimes dark brown; often there are well-defined bands of bright and dull material within the seams. It is typically hard but friable.
The decline of coke making in the US leads to a coal tar crisis since coal tar pitch is vital for the production of carbon electrodes for EAF/aluminium. US now has to import coal tar from China; Development of process to make methanol via hydrogenation of CO/H 2 mixtures. Mobil M-gas process for making petrol from methanol