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Chemical pulping
- Chemical pulping involves the dissolution of lignin from the cell wall of lignocelluloses and liberates cellulosic fibers.
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Pulping is a process of converting lignocellulosic materials into pulp. Pulp is an intermediate material applied in papermaking. There are huge numbers of technologies of pulping methods that can be generally divided into three categories: mechanical (MP), chemical (CP), and hybrid pulping (HP).
- Chemical Pulping
The defibration of wood and nonwood into individual fibers...
- Kraft Process
Kraft process is the foremost pulping process in the board...
- Mechanical Pulp
Generally, mechanical pulping process physically tears the...
- Pulping Process
Pulping is the process of breaking down paper (or wood) into...
- Chemical Pulping
Pulping is the process of breaking down paper (or wood) into individual fibers with the help of an elevated temperature (40–55 °C), alkaline pH (9.0–10.5), and mechanical force. During the pulping process of MSW paper, fibers flex, bend, and rub against one another to promote ink removal.
Jan 3, 2021 · The Kraft pulping process is a full chemical pulping method, which uses sodium hydroxide (NaOH) and sodium sulfide (Na 2 S) at a pH above 12, temperature of 155–180 °C, and steam pressure of 800 kPa as the main cooking conditions to breakdown wood chips into pulp .
- Drake Mboowa
- dmbooowa@mail.ubc.ca
- 2021
- 1 Chemical Pulping
- 2 Mechanical Pulping
- 3 Semi-Chemical Pulping
- 4 Secondary Fibre Pulping
- 5 Dissolving Kraft and Sulphite Pulping Processes
- 6 Non-Wood Pulping
Chemical pulping (i.e., kraft, soda, and sulphite) involves “cooking” of raw materials (example, wood chips) using aqueous chemical solutions and elevated temperature and pressure to extract pulp fibres. Chemical pulps are made by cooking the raw materials, using the kraft (sulphate) and sulphite processes (Casey 1983a). Kraft pulping is by far the...
There are three main categories of mechanical pulp: groundwood pulp, refining pulp, and chemi-mechanical pulp. In both the grinding and refining processes, the temperature is increased to soften the lignin. This breaks the bonds between the fibres (Gullichsen 2000; Casey 1983b). Groundwood pulp shows favorable properties with respect to brightness ...
Semi-chemical pulping uses a combination of chemical and mechanical (i.e., grinding) energy to extract pulp fibres. Wood chips first are partially softened in a digester with chemicals, steam, and heat. Once chips are softened, mechanical methods complete the pulping process. The pulp is washed after digestion to remove cooking liquor chemicals and...
Recovered paper has become an increasingly important source of fibre for papermaking (Bajpai 2013). Currently, nearly 50 % of the fibre raw material for papermaking is based on recycled fibre. In the recycling process, recycled paper or paperboard is rewetted and reduced to pulp, principally by mechanical means. Inks, adhesives, and other contamina...
Dissolving kraft and sulphite pulping processes are used to produce highly bleached and purified wood pulp suitable for conversion into products such as rayon, viscose, acetate, and cellophane (EPA 2002).
Worldwide, non-wood sources make up about 6 % of the total fibre supply for papermaking. Non-wood fibres are derived from agricultural fibres such as straw and other plant fibres such as bamboo, bagasse, and annual fibre crops such as kenaf (Ince 2004). In general, non-wood plant fibres are more costly to collect and process than wood fibre in regi...
- Pratima Bajpai
- 2015
Sep 23, 2024 · Pulping is the process of using chemical or mechanical methods, or a combination of both, to dissociate plant fiber raw materials into natural pulp (unbleached pulp) or bleached pulp. The main function of pulping is to provide high-quality pulp for papermaking and other fiber processing industries.
The pulping process is aimed at removing as much lignin as possible without sacrificing fiber strength, thereby freeing the fibers and removing. impurities that cause discoloration and possible future disintegration of the paper. Hemicellulose is similar to cellulose in composition and function.
The defibration of wood and nonwood into individual fibers by mechanical and or chemical treatment or in combination with both treatments is called pulping process. Chemical pulping involves the dissolution of lignin from the cell wall of lignocelluloses and liberates cellulosic fibers.
