Various Pulping Processes

Written by Abdul Halim-pulping Process is a process for obtaining the extract cellulose from biomass raw material, usually wood. Extract the cellulose is used as a raw material for paper.

Pulping process generally consists of three kinds, namely chemical process, mechanical process and semimechanical process. Chemical process can be divided into three kinds, namely soda pulping, kraft pulping and sulfite pulping. Soda pulping using Na2CO3as active substances to degrade lignin. This method is very wasteful with chemicals especially soda therefore, recoveryis performed with Na2CO3 evaporating to get back apemasak solution of Na2CO3 have been used. The addition of Na2CO3 is done because of the loss of Na2CO3 during the process. Then, because the preparationof Na2CO3 are more expensive compared to the preparation of Na2SO4, Carl Dahltried using Na2SO4 in lieu of Na2CO3 and gives better results. The next process is patented by Dahl in 1884. This process is called the kraft process with a strong meaning in Swedish. Pulp results this process is difficult to dibleaching and dark colored, however strong that good to use as a paper packaging that is more concerned with power. The problems in this process is the active substance recovery and bleaching. On some of the early years of this process not too grown up to the discovery of Combustion Furnace and Tomlinson technique of bleaching.

The second process is the sulfite process, the process is easier dibleaching and cheaper but lacks the strength of the pulp. The process is growing rapidly before the invention of the Combustion Furnace and Tomlinson technique of bleaching. In 1925, the pulp that is produced through chemical processes gained through soda pulping as much as 20%, kraft and sulfite pulping 20% 60%. This percentage continues to fall up to 20% in the year 1967, 9.2% in 1979 and 3.7% in the year 2000.

Several methods of modification on the kraft process such as LAYOFFS (Prehydrolysis-Kraft), namely, the existence of treatment with steam at a temperature of between 160 & 180 ° C, between 30 minutes to 2 hours or with acid solution (0.3-0.5% H2SO4) with temperatures between 140 ° C 120 &. pretreatment of releasing organic acids such as acetic acid, formic acid, from wood.

Semichemical process produces a yield between 65-85%. An example of this process is the neutral sulfite semichemical process (NSSC). Chip suffered partial chemical pulping uses a solution of Na2SO3 and ditreatment in disc refiner to separate the fiber.

Mechanical pulping can be divided into two kinds, namely grinding stone (stone groundwood and pressure groundwood) and refiner Refiner Mechanical pulping process (Pulp (RMP), Pressurized Refiner Mechanical Pulp (PRMP), Thermomechanical Pulp (TMP), and other). The process of using groundwood have brightness > = 85% and meets ISO after bleaching. The pulp of the TMP process more powerful compared to groundwood pulp. Softwood is used as raw material in the process of TMP because hardwood has the characteristic strength are ugly. This is because the hardwood do not form fibrils during the process of refining. Treatment using H2SO3before refining lead sulfonasi in the middle lamella of the transition temperatures has lignin so glass is lower and swelling better to facilitate the separation of the fiber. Mechanical pulp is cheaper and produces a yield up to 85-95% but weaker.

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The following example process of pulping

Reference:

Sixta, H., 2006, "Introduction", Handbook of Pulp, eds. Sixta, H., WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

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Abdul Halim
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