Neutral Sulfite Semi-Chemical pulping

Neutral Sulfite Pulping Neutral sulfite pulping is mainly used for the production of high-yield pulps from hardwoods. The process is often named the "NSSC" (Neutral Sulfite Semi-Chemical) process. The wood is delignified only partially and mechanical fiberization is thus required. The prod-... 

In this case, the paper machine manufactures flat sack kraft paper from a blend of virgin pine (long-fibre) kraft pulp with typical Kappa range of 55-65 and eucalyptus (short-fibre) neutral sulfite semi-chemical (NSSC) pulp. The most important properties for sack papers are stretch and tensile energy absorption (TEA) in both cross direction (CD) and machine direction (MD). The major problems with the quality of sack papers currently made on this machine were poor stretch and TEA profile in fhe cross direction as shown in... 

Semi chemical pulps are usually prepared by the neutral sulfite semichemical (NSSC) process, although modifications of the full chemical processes can be used. Active pulping chemicals are (in the sodium-base NSSC process) sodium sulfite buffered with sodium bicarbonate (pH 7,0-9.0) and (in the ammonium-base NSSC process) ammonium sulfite with ammonium hydroxide used as a buffer. Defiberization is usually accomplished by attrition mills of the disk type. 

The dominant process of semiwith sodium or ammonium sulfite as the digestion chemicals. The pulp yield is in the range 70-80% depending on the wood species, most commonly hardwood species like birch, beech, maple, oak and eucalyptus. This pulp is used for fluting production - often as the sole component in furnish. 

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