Black Liquor
European Commission - Eurostat

Food and Agriculture Organisation (FAO)
Black liquor: is the alkaline-spent liquor obtained from the digesters used in the production of sulphate or soda pulp during the process of paper production, in which the energy content is mainly derived from the content of lignin removed from the wood in the pulping process.

International Energy Agency (IEA)
This is a recycled by-product formed during the pulping of wood in the paper making industry. In this process, lignin in the wood is separated from cellulose, with the latter forming the paper fibres. Black liquor is the combination of the lignin residue with water and the chemicals used for the extraction of the lignin and is burned in a recovery boiler. The boiler products steam and electricity and recovers the inorganic chemicals for recycling throughout the process.

United Nations Economic Commission for Europe (UNECE)
This is a recycled by-product formed during the pulping of wood in the paper making industry. In this process, lignin in the wood is separated from cellulose, with the latter forming the paper fibres. Black liquor is the combination of the lignin residue with water and the chemicals used for the extraction of the lignin and is burned in a recovery boiler. The boiler products steam and electricity and recovers the inorganic chemicals for recycling throughout the process.