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Chemical pulping involves dissolving lignin in order to extract the cellulose from the wood fiber. The different processes of chemical pulping include the Kraft process, which uses caustic soda and sodium sulfide and is the most common; alternatively, the use of sulfurous acid is known as the sulfite process, the neutral sulfite semichemical is treated as a third process separate from sulfite ...
Chemical pulp is used for materials that need to be stronger or combined with mechanical pulps to give a product different characteristics. The kraft process is the dominant chemical pulping method, with the sulfite process second. Historically soda pulping was the first successful chemical pulping method.
The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component of paper. The kraft process involves treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na 2 S), known as white ...
The competing chemical pulping process, the sulfate or kraft process was developed by Carl F. Dahl in 1879 and the first kraft mill started (in Sweden) in 1890. [3] The first sulphite mill in the United States was the Richmond Paper Company in Rumford, Rhode Island in the mid-1880s.
A roll of kraft paper. Kraft paper or kraft is paper or paperboard (cardboard) produced from chemical pulp produced in the kraft process. Sack kraft paper (or just sack paper) is a porous kraft paper with high elasticity and high tear resistance, designed for packaging products with high demands for strength and durability. [1]
Chemical pulping can be characterized by two main methods: sulfate (Kraft process) pulping and sulfite pulping, and these two methods have different benefits. Sulfate pulping can be performed on a wide range of tree varieties and results in the creation of a strong type of paper.
Chemical pulping processes are not used to make paper made from cotton, which is already 90% cellulose. The microscopic structure of paper: Micrograph of paper autofluorescing under ultraviolet illumination. The individual fibres in this sample are around 10 μm in diameter.
A pulp mill in Rauma, Finland Woodchips for paper production. A pulp mill is a manufacturing facility that converts wood chips or other plant fiber sources into a thick fiber board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical, or fully chemical methods (kraft and sulfite ...