Carbonization

Carbonization is a thermochemical process in which organic material is converted into a carbon-rich residue by heating in a restricted or oxygen-free environment. The process differs from combustion in that most of the volatile components are driven off as gases and vapors, while the solid char remains.

In industrial contexts, carbonization has several forms. Wood or agricultural residues can undergo slow pyrolysis to produce charcoal or biochar, used for fuel or soil amendment. Coal under heat in the absence of air produces coke, a porous carbon material used as a reducing agent in metallurgical processes such as ironmaking. Biomass char is often called biochar when intended for soil improvement.

Conditions vary: temperatures typically range from roughly 400 to 1000 degrees Celsius, with slower heating favoring char formation and faster heating yielding more condensable liquids and gases. The presence or absence of oxygen, moisture content, and residence time influence yields and properties. Activated carbon is produced from carbonized material by post-treatment to increase surface area for adsorption.

Applications of carbonization include fuel (charcoal, coke), metal production, gasification, filtration and environmental remediation, and soil enhancement (biochar). In geology, carbonization can refer to the process that forms carbonaceous residue in fossils, leaving carbon films.

Environmental and safety considerations include emissions of volatile organic compounds and tar, energy demands, and the need to manage byproducts.