Paper manufacturing

Paper manufacturing plays an important role in our daily lives and paper has been used for many years. Paper is made with the wood pulp, which is an environmentally friendly product. Paper is manufactured by means of the following processes:

1) Pulping procedure is done to separate and clean the fibers.
2) The refining procedure will be followed after the pulping processes.
3) Dilution process to form a thin fibre mixture
4) Formation of the fibres on a thin sieve.
5) Pressure increase to improve the material density
6) Drying to eliminate the density of materials
7) Finishing procedure to obtain a suitable surface for usage

Pulp and paper are manufactured from cellulose fibres and other materials. Some synthetic materials can be used to give special qualities to the final product. Paper is made from wood fibres. Used paper is also recycled, and after purification and sometimes de-inking it is often mixed with virgin fibres and reprocessed into paper. Products such as cellulose acetate, rayon, cellulose esters made from cellulose are used for packaging films, explosives.
The pulping process is aimed at removing lignin without loss of fibre strength, releasing the fibres and removing impurities that cause discoloration and possible future disintegration of the paper.
Hemicellulose plays an important role in the binding of fibres in paper production. It is similar to cellulose in composition and function. Various extraction residues such as waxes and oleoresins are contained in wood, but do not contribute to its strength properties; these are also removed during the pulping process.
The fibres extracted from each plant can be used for paper. However, the strength and quality of the fibres and other factors complicate the pulping process. In general, coniferous species (e.g. pine, spruce and spruce) produce long and strong fibres which contribute to the strength of the paper and are used for boxes and packaging.
Hardwood produces a weaker paper because it contains shorter fibres. Softwood is smoother, more transparent and better suited for printing. Softwood and hardwood are used to make paper and are sometimes mixed to improve both the strength and the printing capacity of the final product.
Steps in the pulp and paper making process:
Preparation of the raw material
Wood received in a pulp mill can be in various forms. It depends on the pulping process and the origin of the raw material. It can be received as bolts (short logs) of round timber with the bark still attached, as half a dollar's worth of chips that may have been produced from a sawmill of debarked round timber elsewhere.
When round timber is used, it is first debarked, usually by tumbling it into large steel drums in which washing water can be applied. These debarked wood bolts are then chipped in a shredder if the pulverization process requires chemical digestion. The chips are then screened by size, cleaned and temporarily stored for further processing.

Separation of the fibres

Different pulp production methods will be used in the fibre separation phase. The chips are stored in a large pressure cooker (digester), to which the appropriate chemicals are added in kraft chemical pulping.
The chips are then steam digested at specific temperatures to separate the fibres and partially dissolve the lignin and other extraction residues. Some digesters operate continuously with a constant supply of chips (upholstery) and liquor is loaded intermittently and treat one batch at a time.
After the fermentation process, the boiled pulp is discharged into a pressure vessel. This is where the steam and volatile substances are discharged. This boiled pulp is then brought back into the chemical recovery cycle. Fiber separation in mechanical pulp is less dramatic.
The debarked trunks are pushed against rotating stone grinding wheels in the rock chopping process. Refinery pulp and thermo-mechanical pulp are produced by means of chips. These chips are crushed by turning them quickly in both processes.
In the second phase after refining, the pulp is sieved, cleaned and most of the process water is removed in preparation for paper production.
Bleaching process
Raw pulp contains a considerable amount of lignin and other discolorations, it must be bleached to produce light colored or white paper, preferably for many products. The fibres are further delignified by dissolving additional lignin from the cellulose through chlorination and oxidation.

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Paper manufacturing

Separation of the fibres