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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 ...
Recycled pulp is also called deinked pulp (DIP). DIP is recycled paper which has been processed by chemicals, thus removing printing inks and other unwanted elements and freed the paper fibres. The process is called deinking. DIP is used as raw material in papermaking.
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 ...
Mechanical pulping is the process in which wood is separated or defibrated mechanically into pulp for the paper industry.. The mechanical pulping processes use wood in the form of logs or chips that are mechanically processes, by grinding stones (from logs) or in refiners (from chips), to separate the fibers.
The use of wood to make pulp for paper began with the development of mechanical pulping in the 1840s by Charles Fenerty in Nova Scotia [1] and by F. G. Keller [2] in Germany. Chemical processes quickly followed, first with Julius Roth 's use of sulfurous acid to treat wood in 1857, followed by Benjamin Chew Tilghman 's US patent on the use of ...
The dried pulp is cut, stacked, bailed and shipped to another facility for whatever further process is needed. Bleached kraft pulp and bleached sulfite pulp are used to make high quality, white printing paper. One of the most visible uses for unbleached kraft pulp is to make brown paper shopping bags and wrapping paper where strength is ...
Most kraft pulp mills use recovery boilers to recover and burn much of the black liquor they produce, generating steam and recovering the cooking chemicals (sodium hydroxide and sodium sulfide used to separate lignin from the cellulose fibres needed for papermaking). This has helped paper mills reduce problems with water emissions, reduce their ...
A Hollander beater. A Hollander beater is a machine developed by the Dutch [who?] in 1680 to produce paper pulp from cellulose containing plant fibers. It replaced stamp mills for preparing pulp because the Hollander could produce in one day the same quantity of pulp it would take a stamp mill eight days to prepare.