Chemical pulp
For the production of wood pulp, the pure fibre has to be set free, which means that the lignin has to be removed as well. To achieve this, the wood chips are cooked in a chemical solution.
In case of wood pulp obtained by means of chemical pulping, we differentiate between sulphate and sulphite pulp, depending on the chemicals used. The yield of chemical pulping amounts to approximately 50%. The fibres in the
pulp produced by this process is called woodfree. It is this type of pulp which is used for all Sappi fine papers.
The sulphate process is an alkaline process. It allows for the processing of strongly resinous wood types, but this requires expensive installations and intensive use of chemicals.
The sulphite process utilises a cooking acid consisting of a combination of free sulphur acid and sulphur acid bound as magnesium bi-sulphite (magnesium bi-sulphite process).
In the sulphite process, the cooking liquid penetrates the wood in the longitudinal direction of the fibres, which are aligned in this same longitudinal direction in the chips. When the cooking liquid penetrates the wood, it decomposes the lignin, which, during the actual cooking process, is converted into a water-soluble substance that can be washed out. The decomposition products of the carbohydrates are included in the cooking liquid as sugar.
When the waste fluids are concentrated in order to recycle the chemicals, these sugars are processed to alcohol and ethanoic acid. In this stage, the sulphite pulp is slightly brown and therefore has to be bleached to obtain a base colour suitable for white papers. This bleaching process, in which no chlorine or chlorine compounds are used, also takes place in the pulp mill as an integrated part of the over- all operation.
The strength of sulphite pulps is less than that of sulphate pulps. Sappi uses only the magnesium bi-sulphite process
resulting pulp are very clean and undamaged. The wood
in its own pulp mills.
* yield = usable part of the wood
Chemical pulpFor the production of wood pulp, the pure fibre has to be set free, which means that the lignin has to be removed as well. To achieve this, the wood chips are cooked in a chemical solution.In case of wood pulp obtained by means of chemical pulping, we differentiate between sulphate and sulphite pulp, depending on the chemicals used. The yield of chemical pulping amounts to approximately 50%. The fibres in the pulp produced by this process is called woodfree. It is this type of pulp which is used for all Sappi fine papers.The sulphate process is an alkaline process. It allows for the processing of strongly resinous wood types, but this requires expensive installations and intensive use of chemicals.The sulphite process utilises a cooking acid consisting of a combination of free sulphur acid and sulphur acid bound as magnesium bi-sulphite (magnesium bi-sulphite process).In the sulphite process, the cooking liquid penetrates the wood in the longitudinal direction of the fibres, which are aligned in this same longitudinal direction in the chips. When the cooking liquid penetrates the wood, it decomposes the lignin, which, during the actual cooking process, is converted into a water-soluble substance that can be washed out. The decomposition products of the carbohydrates are included in the cooking liquid as sugar.เมื่อของเหลวเสียเข้มข้นเพื่อการรีไซเคิลสารเคมี น้ำตาลเหล่านี้จะประมวลผลให้กรดแอลกอฮอล์และ ethanoic ในระยะนี้ sulphite เนื้อเยื่อเป็นสีน้ำตาลเล็กน้อย และมีการถูก bleached สีพื้นฐานที่เหมาะสำหรับการประชาสัมพันธ์การรับ ตอนนี้ฟอกสี ซึ่งไม่มีคลอรีนหรือสารประกอบคลอรีนใช้ ใช้สถานที่ในโรงงานผลิตเยื่อกระดาษเป็นส่วนหนึ่งที่รวมของการดำเนินงานทั้งหมดยังความแข็งแรงของ sulphite pulps จะน้อยกว่าของ pulps ซัลเฟต Sappi ใช้เฉพาะแมกนีเซียม bi sulphite กระบวน เยื่อกระดาษที่ได้จะสะอาด และไม่เสียหาย ไม้ ในโรงงานผลิตเยื่อของตัวเอง * ผลตอบแทน =ส่วนใช้ไม้
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