Softwood pulp production

Alkyl-polychlorofluorenes (RPCFL) were detected at sub-ng 1 1 levels in effluents, at a few ng g 1 dw levels in biosludge and < ng g 1 dw concentrations in softwood pulp product of a kraft mill. The structures were deduced from high resolution mass spectra and verified by comparison to GC/HRMS/SIM of model substance mixtures from chlorination of methyl- and dimethylfluorenes... 

Table 1.3 World-wide hardwood, softwood and non-wood pulp production (1988).

NH Shin. A Modihed Soda-AQ/Oxygen Pulping Process as an Alternative to Kraft Process for the Production of Bleached Softwood Pulp. PhD Thesis, North Carolina State University, Raleigh, NC, 1988. 

The lignin residues from wood pulp production are another class of extractives currently receiving attention as phenolic resin additives. Substituted phenols, such as cresols and xylenols, have been used as glue mix additives for phenolic adhesive resins to improve assembly time tolerance. They are also used as solvents to remove oleo-resinous deposits on the surface of pitchy softwood veneers. They can be used as flow promoters in phenolic hardwood adhesives. To avoid interference with the rate of resin curing, the amount added should not exceed 3 to 4% of the phenolic resin solids content. 

The efficiency of defibrillation in the ultrasonic process is dependent on power, concentration, temperature, size of fibers, time and distance from probe tip to collector [77]. In some cases, researchers have been used a combination of ultrasonication with other methods to increase fibrillation of nanoscale cellulose. For example, Li et al. [78] prepared nanocrystalline cellulose by ultrasonication and acid hydrolysis with H SO from bleached softwood pulp. They found that ultrasonication led to folding and erosion of the cellulose surface, and thus provided more reactive site to penetrate acid and prepare high-crystalline and small-size nanocellulose. Furthermore, Wang and Chen [77] reported that a combination of ultrasonication and homogenization boosts uniformity and fibrillation of cellulose nanofiber in comparison to ultrasonication solely. In addition, when compared to mechanical blender, ultrasonic bath and ultrasonic probe, Mishra et al. [79] concluded that TEMPO-oxidized fiber treatment with ultrasonic probe was more efficient for nanocellulose production than the other three methods. 

Triglycerides are important constituents of resin. In softwood, the triglycerides account for 20—40% of total resin content, and in hardwood, 40—50%. The paper industry uses the term pitch for resins that create problems in paper machines. Traditionally, pitch is controlled or reduced by aging the wood, by use of chemicals to avoid deposits on the roUs, or by intensive washing of the pulp. AH these methods add to the cost of paper production. An alternative is to add a Upase to the pulp in a reaction lasting about one hour with the help of agitation. Results from Japanese paper mills show substantial... 

Lignosite Lignosulfonate products are derived from the lignin in softwood trees by the calcium bisulfite pulping process at GeorgiarPacific s mill in Bellingham, Washington. 

Provincial Papers Inc. is located on Lake Superior at Thunder Bay, Ontario. Sulphite/mechanical processes are used in the production of coated and uncoated fine papers from purchased kraft pulp and groundwood from softwood sources. Secondary treatment is carried out in an aerated lagoon system (a serpentine basin) and was installed at the mill in late 1995 (see Fig. 2). Effluent flow rates ranged from 25,000 to 35,000 m3/day in the two years following installation of secondary treatment. Treated effluent is discharged into the inner basin of Lakehead Harbour, a sheltered embayment created by a series of breakwaters. The Current River is the other major discharge to the immediate area of the mill outfall. A description of the EEM study is found in ESG (2000). 

Large quantities of hydroxy acids as well as acetic and formic acids are formed during kraft pulping (Tables 10-3 and 7-8). Among hydroxy acids from softwood, glucoisosaccharinic acid predominates. Especially when considering that the heat value of these hydroxy acids is only 25-50% of that of kraft lignin, their recovery seems motivated, but adequate markets have not yet been established for these products. Liberation of the aliphatic acids... 

When certain softwoods are pulped by the sulfite process, the resulting pulp usually contains a considerable proportion of uronic acid anhydride which cannot be removed entirely in subsequent alkaline refining. When the sulfate process is used on softwoods, a pulp which is free from uronic acid anhydride may be obtained. This important difference between the sulfite and sulfate pulps from softwoods does not apply to hardwoods, which, when pulped by either process, still retain a considerable proportion of uronic acid anhydride in the final product. 

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