The Kappa number of pulp is an indication of the lignin content or bleachability of pulp. We use it to estimate the required amount of bleach chemicals to achieve targeted brightness. If the kappa number value is higher then, the required bleaching chemicals are also higher. On the other hand low kappa pulps are easier … Read more
Hydrogen peroxide is a total chlorine free (TCF) bleaching agent. It is appropriate for chemical, mechanical and recycled pulp to achieve a wide range of brightness. It has both oxidizing and reducing properties which is pH depended. The chemical formula of this bleach is H2O2. Pure hydrogen peroxide is very light blue color but colorless … Read more
Chlorine dioxide is an oxidizing agent for pulp bleaching. The chemical formula of this chlorine dioxide bleach is ClO2. It is a yellowish-green gas, bad odor and liquefied in 11⁰C which is red in color. It is an ECF (elemental chlorine-free) bleaching process which is currently most important bleaching technology in worldwide, especially for sulfate … Read more
Hypochlorite bleach is an oxidizing agent. There are two types of hypochlorite bleaching agent that are used in pulp and paper industries such as calcium hypochlorite and sodium hypochlorite. Generally, this stage is placed after chlorination and alkali extraction stages. It can be single stage or multiple stage process. Single stage hypochlorite bleaching process is … Read more
Chlorination bleaching is the second stage of the pulp bleaching process. It is the cheapest bleaching agent for eliminating lignin. Elemental chlorine (EC) reacts selectively with the non carbohydrate compounds. It is another significant delignification process. It ruptures the lignin bonds and make important amount of chlorinated organic compounds. All most all the products of … Read more
Oxygen Delignification is one of the most significant and well proven pulp bleaching process for ECF (elemental chlorine free) and TCF (total chlorine free) bleached pulp production. It is the first stage of the bleaching process; in this case oxygen and alkali are used to eliminate a portion of the residual lignin in the pulp … Read more
Kraft pulping process is the most used pulping process in the world. In this process lignin goes into the reactions with the cooking liquor chemicals and split into fragment. These fragments dissolved with the solution and wood disintegrates into fiber. During the kraft pulping process about 80 percent of lignin, 50 percent of hemicelluloses and … Read more
Lignin is an aromatic complex polymer of monolignols (aromatic alcohols) which is found in plant cell walls. Later than cellulose, lignin is the most abundant natural polymer in the planet. It is not composed of carbohydrate monomers whereas the rest of polymers found in plant cell walls are composed of carbohydrate monomers for example cellulose. … Read more
Globally, there are several bleaching sequences are shown in different pulp mills to achieve the bleaching action. Different chemicals are used in each stage usually with washing between two stages to removes products. The preference of bleaching sequences depends on many things such as pulp categories, environment issue, operating cost, product quality of final bleached … Read more
The objective of pulp bleaching is to produce white pulp. Unbleached pulps are not suitable for manufacturing of high grade of white paper. Since all the processing pulp brightness is very low, especially Kraft pulp. The sulfite pulping process produces comparatively bright chemical pulps, while the others pulping process such as kraft, soda and semichemical … Read more