Destructive Distillation means driving off (and collecting) gas from some matter by heating it in the absence of air. This is the process called 'coking' when referring to the transformation of bituminous coal into coke (at 1,000 C). This process, also known as "dry distillation", is a pyrolysis process.

The earliest historical example of destructive distillation is tar making. Pinewood slices rich in terpenes are heated in an airless container until they decompose and produce tar. The by-products are turpentine and charcoal. This process is still used in Scandinavia for tar-making.

Examples of substances that are commonly destructive distilled to extract chemicals and other materials include:

• Wood
• Soft coal

Examples of substances extracted include:

• Acetic acid
• Methyl or wood alcohol (methanol)
• Coal gas
• Tar
• Turpentine

Other types of distillation include:

• Fractional distillation
• Continuous distillation
• Azeotropic distillation
• Extractive distillation
• Vacuum distillation

Related Information

Coal tar pitch volatiles (CTPV) are the result of destructive distillation of bituminous coal. They contain polynuclear aromatic hydrocarbons (PNA's). PNAs sublime readily and cause carcinogenic compounds in working areas. Evidence suggests that workers exposed to products of combustion or distillation of bituminous coal are at increased risk of cancer.

See also

• Pyrolysis

Distillation | Chemical processes | Industrial processes | Chemical engineering

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