Paper pulping

Papermill wastes Paper, photographic Paper pouches Paper preservative Paper processing Paper pulp Paper pulps Paper pulp slurries Paper, recycled Paper recycling mills Paper release coatings Papers Paper sizes Paper sizing Paper wastes... 

Pulp and paper Pulp and paper industry Pulp and paper mills Pulp bleaching... 

Binding fine ceUulose fibers and soHd inorganic additives to long ceUulose fibers as the paper pulp is being formed into sheets on a paper machine... 

Two main operational variables that differentiate the flotation of finely dispersed coUoids and precipitates in water treatment from the flotation of minerals is the need for quiescent pulp conditions (low turbulence) and the need for very fine bubble sizes in the former. This is accompHshed by the use of electroflotation and dissolved air flotation instead of mechanically generated bubbles which is common in mineral flotation practice. Electroflotation is a technique where fine gas bubbles (hydrogen and oxygen) are generated in the pulp by the appHcation of electricity to electrodes. These very fine bubbles are more suited to the flotation of very fine particles encountered in water treatment. Its industrial usage is not widespread. Dissolved air flotation is similar to vacuum flotation. Air-saturated slurries are subjected to vacuum for the generation of bubbles. The process finds limited appHcation in water treatment and in paper pulp effluent purification. The need to mn it batchwise renders it less versatile. 

Because of these characteristics electromagnetic flow meters have been widely appHed to the measurement of difficult Hquids such as raw sewage and wastewater flows, paper pulp slurries, viscous polymer solutions, mining slurries, milk, and pharmaceuticals. They ate also used in less demanding apphcations such as the measurement of large domestic water volumes. 

Cross Correlation. Considerable research has been devoted to correlation techniques where a tracer is not used. In these methods, some characteristic pattern in the flow, either natural or induced, is computer-identified at some point or plane in the flow. It is detected again at a measurable time later at a position slightly downstream. The correlation signal can be electrical, optical, or acoustical. This technique is used commercially to measure paper pulp flow and pneumatically conveyed soHds. 

Pseudoplastic fluids are the most commonly encountered non-Newtonian fluids. Examples are polymeric solutions, some polymer melts, and suspensions of paper pulps. In simple shear flow, the constitutive relation for such fluids is... 

Bulk Enzymes. Enzymes such as proteases, amylases, glucose isomerases, and rennin are used in food processing. Similarly proteases and Hpases are used in detergents. CeUulases and xylanases are used in the paper pulp industry. The genes for most of the enzymes used in the various commercial processes have been cloned and overexpressed. Rennin (chymosin) produced from E. coli and A. nigerhas been approved by FDA for use in the dairy industry. 

Pina Abstracts Pina International Data-Star, Dialog, Orbit, STN paper, pulps... 

Rotary kilns and, to a lesser extent, Fluo-SoHds kilns are used to calcine a wet precipitated calcium carbonate filter cake in the kraft or sulfate paper-pulp process (15). Lime is regenerated for use as a causticization reagent in recovering caustic soda for pulp digestion. Losses in lime recovery are replaced by purchased lime (see Paper Pulp). 

Industrial Wastewater Treatment. Industrial wastewaters require different treatments depending on their sources. Plating waste contains toxic metals that are precipitated and insolubiHzed with lime (see Electroplating). Iron and other heavy metals are also precipitated from waste-pidde Hquor, which requires acid neutralization. Akin to pickle Hquor is the concentrated sulfuric acid waste, high in iron, that accumulates in smokeless powder ordinance and chemical plants. Lime is also useful in clarifying wastes from textile dyeworks and paper pulp mills and a wide variety of other wastes. Effluents from active and abandoned coal mines also have a high sulfuric acid and iron oxide content because of the presence of pyrite in coal. 

Low consistency pulping (3—6% soflds) is common in newsprint and many tissue mills. Medium (6—12%) and high consistency pulping (12—18% sohds) is common in mills deinking office papers. Pulping temperature is typically 40—55°C, the pH is usually 9.0—10.5, and process time ranges from 4 to 60 minutes. 

Natural resins were probably known to early people, who recognized them as exudates from trees. Collection and use of these resins have been recorded by early Roman and Greek historians. Many products have been collected by the same methods throughout history to the present time. However, increased labor costs and competition from synthetic resins have reduced the demand for some natural resins, so they have become less available. In other cases, such as that of rosin, the traditional collection of gum from trees has been supplemented or replaced by isolation from other sources, such as paper pulping and tree stumps. 

P perApplications. In beater additions, the latex is mixed with the beaten paper pulp either by addition at the beater or to the stock chest at the wet end of the paper machine. In either case, the pH of the pulp is reduced to 4.0—4.5, usually by the addition of a solution of alum to the pulp—latex mixture which has been thoroughly agitated. The latex, which for this appHcation must be based on an anionic emulsifier, coagulates as the pH drops. The latex soHds separate ia intimate associatioa with the pulp fibers. The pulp is thea screeaed and the paper web formed ia the coaveatioaal way. A latex for this purpose must possess the proper balance between mechanical and chemical stabiHty. 

The majority of the turpentine comes from the southeastern United States, which consists of 60—70% a-pinene, 20—25% P-pinene, and 6—12% other components. Because there is variation in components from different species of the pine tree as well as variation from the many paper pulp mills, there is obviously variation in the analysis of sulfate turpentines. Some of the other components consist of -menthadienes, alcohols, ethers such as anethole [104-46-1] and methylchavicol [104-67-0] and the sesquiterpene hydrocarbon, P-caryophyUene [87-44-5]. 

Titanium metal is especially utilised ia environments of wet chlorine gas and bleaching solutions, ie, in the chlor—alkaH industry and the pulp and paper industries, where titanium is used as anodes for chlorine production, chlorine—caustic scmbbers, pulp washers, and CI2, CIO2, and HCIO storage and piping equipment (see Alkali and cm ORiNE products Paper Pulp). 

Sodium Tetrahydroborate, Na[BH ]. This air-stable white powder, commonly referred to as sodium borohydride, is the most widely commercialized boron hydride material. It is used in a variety of industrial processes including bleaching of paper pulp and clays, preparation and purification of organic chemicals and pharmaceuticals, textile dye reduction, recovery of valuable metals, wastewater treatment, and production of dithionite compounds. Sodium borohydride is produced in the United States by Morton International, Inc., the Alfa Division of Johnson Matthey, Inc., and Covan Limited, with Morton International supplying about 75% of market. More than six million pounds of this material suppHed as powder, pellets, and aqueous solution, were produced in 1990. 

Calcium sulfite [10257-55-3] and acid sulfite may be prepared by reaction of SO2 and hydrated lime or limestone. Calcium acid sulfite [13780-03-5] Ca(HS02)2, has been used to remove lignin (qv) from wood pulp in paper manufacture (6) (see Paper Pulp). 

A variety of waxy hydrophobic hydrocarbon-based soHd phases are used including fatty acid amides and sulfonamides, hydrocarbon waxes such as montan wax [8002-53-7], and soHd fatty acids and esters. The amides are particularly important commercially. One example is the use of ethylenediamine distearamide [110-30-5] as a component of latex paint and paper pulp blackHquor defoamer (11). Hydrocarbon-based polymers are also used as the soHd components of antifoaming compositions (5) examples include polyethylene [9002-88-4], poly(vinyl chloride) [9002-86-2], and polymeric ion-exchange resins. 

Paper Pulping, Resins and Additives. Considerable interest has been generated in the sulfur-free deHgnification of wood chips with EDA—soda Hquors since the late 1970s (242—244), with more recent interest in EDA—sulfide pulping (245,246). Improved rates of EDA recovery have been developed for the latter process (247). 

Chlorine Dioxide. Like ozone, chlorine dioxide [10049-04-4] is a powerflil oxidant. It is usually generated as used. It has been used for disinfecting drinking water and bleaching paper pulp. Its effectiveness in killing microorganisms is well documented (305,306), and it has received recent study as a gas to sterilize medical devices. It requites 50% rh or higher to be effective. Bacterial cells had a D-value of 2.6 min and spores of 24 min (307). 

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