What is carbonisation?

Carbonisation is the process of heating organic materials (like coal or wood) in little or no air to drive off volatile substances and leave behind a carbon-rich solid such as coke or charcoal.

Carbonisation means turning something that contains a lot of carbon—such as wood, coal, or plant matter—into a more carbon-rich solid by heating it without oxygen. When oxygen is absent (or very limited), the material does not burn into ash. Instead, it breaks down (decomposes) and gives off gases, vapors, and liquids, while the solid that remains becomes richer in carbon. This solid can be charcoal (from wood), coke (from coal), or biochar (from plant waste). The whole process is also called destructive distillation, because the heat “destroys” the original structure and “distils” many useful by-products.

Why oxygen must be limited

If there is enough oxygen, the material burns and turns to carbon dioxide and ash. That is not carbonisation. By limiting air, we stop full burning and let the material decompose into a carbon-rich residue and separate products like tar and gas.

Common examples and outputs

• Wood → Charcoal: Used for cooking, metallurgy, filters, and art.
• Coal → Coke: Used in iron and steel making (blast furnaces) because coke is strong, porous, and rich in carbon.
• Biomass → Biochar: Added to soil to improve fertility and lock carbon in the ground.

By-products you can collect

• Gases: “Coal gas” or syngas (hydrogen, methane, carbon monoxide) that can be used as fuel.
• Liquids: Tar and oils containing many organic chemicals (phenols, aromatics, etc.).
• Aqueous products: Ammoniacal liquor (water with dissolved ammonia and other compounds).

Temperature ranges and types (for coal)

1. Feed the organic material (wood, coal, shells, crop waste) into a closed reactor, kiln, or coke oven.
2. Heat it gradually with very limited air.
3. Volatile substances come out as gases and vapors; these are collected and cooled to separate tar, oils, and liquor.
4. A porous, carbon-rich solid (charcoal/coke/biochar) remains in the chamber.

Why carbonisation matters

• Metallurgy: Coke provides both heat and a reducing agent to turn iron ore into iron.
• Energy & cooking: Charcoal burns hotter and cleaner than raw wood.
• Environment & agriculture: Biochar can improve soil and store carbon for a long time.