BLACK LIQUOR Meaning and
Definition
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Black liquor is a term used to describe a byproduct of the pulping process in the papermaking industry. It refers to a dark, viscous liquid mixture that is left over after extracting the cellulose fibers from wood in a pulp mill. This substance is typically obtained from the digesting or cooking process, where chemicals are applied to the wood chips to dissolve the lignin and release the fibers.
Black liquor is composed of water, organic materials, and inorganic chemicals. It has a characteristic deep brown or black color, high viscosity, and alkaline pH. The organic components of black liquor consist of lignin, hemicellulose, and organic compounds derived from wood. The inorganic chemicals present vary depending on the pulping process and may include sodium hydroxide, sodium sulfide, and sodium carbonate. These chemicals play a crucial role in dissolving lignin and breaking down the wood's structure.
Because black liquor contains valuable chemicals, it is not considered waste and is instead treated as a valuable resource. It is typically separated from the remaining pulp fibers through a series of evaporators and centrifuges. The recovered chemicals are then reused in the pulping process, helping to reduce the environmental impact of paper production.
Black liquor is a significant source of renewable energy and is often burned in modern recovery boilers to generate steam and electricity for the paper mill. This process, known as black liquor recovery, allows pulp mills to be self-sufficient energy-wise, minimizing their reliance on external power sources.
Etymology of BLACK LIQUOR
The word "black liquor" is derived from the Old English word "blæc" meaning "black" and the Latin word "liquor" meaning "liquid". "Black liquor" specifically refers to a dark liquid waste product generated during the paper-making process, resulting from the pulping of wood or other materials.
