Every industry adapts new methods of working as technology and knowledge become advanced with time. Pulp manufacturing is one such industry that has changed quite prominently over the last decades and keeps doing so. Pulp manufacturing is the term used for the method of converting wood chips or other plant fiber sources into a thick fiberboard which can be shipped to a paper mill for further processing.
There are a number of processes of pulping known to us by now which are unique in their own way.
1) MECHANICAL PULP
Small wood logs called "bolts'' can be ground to generate stone pulp using manufactured grindstones with incorporated silicon carbide or aluminum oxide (SGW). Pressure groundwood pulp is made by steaming the wood before grinding it and instead of logs, most modern mills employ chips and refiner plates, which are rigid metal discs with ridges.
2) THERMOMECHANICAL PULP
This process of pulping is a two-stage process in which the pulp is processed by heat and mechanical refined movement of wooden chips. The chips used are comparatively small with moisture being around 25 to 30 percent. The extraction from this method is much higher than any other process.
3) CHEMI-THERMOMECHANICAL PULP
This process is a completely different one as it uses chemical components and not mechanical ones to process pulp. The chips are pre-treated with sodium carbonate, sodium hydroxide, sodium sulfate. This process is not fully chemical and thus is referred to as a hybrid process.
4) CHEMICAL PULP
This process is a fully chemical method in which wood chips and chemicals are combined in large vessels called digesters. This process is used with materials that are stronger and can easily work towards giving the product new characteristics. There are many other ways of chemical pulping as well like kraft, soda, and sulfite.