There is a diverse use of pulp and paper products in a number of fields like news printing, toilet papers, etc. Pulp is a soft and wet mass of wood fibre and is further processed into paper. It is an intermediate product of paper-making industry. There are a number of processes involved in order to make the desired form of wood pulp.

The mechanical pulp is made by grinding of wood logs using grindstones. For a good result, the logs have to be steam treated at high pressure prior to grinding. The use of grindstones is no longer applicable in the modern paper mills. They instead use refiner plates made of metal disks. This separates wood fibres from each other for better paper refining.

There is the thermomechanical method which uses heat and mechanical application of force on wood. The bark is removed from wood logs first and the logs are cut into small chips. These are then pressed by an applied mechanical force to crush them. Heat and water vapor is evolved and this softens lignin which hold the fibres together and so they separate very easily. This is very hard and rigid since lignin is not removed in the process.

In the making of chemical pulp, it involves the combination of the wood chips and chemicals in vessels known as digesters. The natural glue is broken down by the chemical and the applied heat. The wood fibre is left intact or less affected by the chemicals. Since lignin is not present, it is not hard and it is mixed with other forms to change its characteristics.

All the above methods can be put into play in the making of pulp. The wood logs are pretreated with chemicals like sodium hydroxide, sodium carbonate and other suitable compounds and then taken to the mills for refining. The fibre is separated from wood with ease and saves time because of the chemical treatment done first before grinding process.

Recycled pulp is another product made from the recycling of used paper. Organosolv pulping is where organic solvents are used to break down lignin at high temperatures. The fibre product is attained through distillation. Another alternative method is the biological pulping which is just like the chemical process. The difference is only that it uses fungi to break down the natural glue which holds wood fibre together.

In the production of white paper, bleaching is done. Drying process is done in different ways. The commonly used method is air drying which leaves 10% of moisture. This moisture content prevent binding together of the product which will make dispersion for further processing hard. Flash drying is also applied where the masses are pressed against a nylon mesh to remove up to 50% of moisture content. They are then passed down silos of 15m high with gas ejected hot air. The bales dried using this method are not as compact as those that are air dried.

The whole industrial process is manageable in order to prevent environmental degradation. The cutting of trees for the industries is controlled and also good forest management methods are put into play to ensure that the sources are renewed now and then. Chemical effluents from the industries are treated first to make them nontoxic for the environment.

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