Acid peroxide treated wood chips reduce black cloud TMP energy consumption

Swedish university scientists and technicians used acid peroxide to treat black cloud top preheated wood chip wood pulp (TMP) to reduce refining energy consumption.

The chemical treatment system includes ferrous sulfate and peroxide. It is preferable to add a reinforcing agent such as sodium ethylenediaminetetraacetate, 3,4-dimethylphenyl alcohol or oxalic acid, sodium oxalate. In the first stage refiner, chemicals and chips are mixed directly for internal processing. The results showed that when the amount of hydrogen peroxide used was 1% and 2%, the TMP freeness reached 100 mL CSF, the energy consumption was reduced by 20% and 35%, respectively, and the fiber length, pulp fraction composition, and sheet tensile strength were reduced. No change, but the whiteness of the pulp has decreased. The addition of ferrous sulfate in the chemical system will affect the whiteness of the pulp. Too high ferrous sulfate will cause the whiteness of the pulp to decrease. If the amount of ferrous sulfate is reduced, the discoloration of the pulp can be significantly reduced. This technology does not require additional equipment. In the TMP production process, chemicals and wood chips are mixed in the refiner.

Although wood pulp treated with acid peroxide can significantly reduce the refining energy consumption, the disadvantage is that the pulp becomes brown during the refining process. Swedish university scientists and scientists experimented to reduce whiteness loss by washing, chelating and treating the pulp with dithionite or peroxide. The results show that the washing and chelating operations can significantly reduce the iron ion content in the TMP slurry after the chemical treatment, but the whiteness is increased by up to two units. The use of a reducing agent helps to completely eliminate pulp discoloration in the chelating section (Q). . The whiteness of pulp after chemical treatment is reduced not only because of the higher iron ion content in the pulp but also by the type of iron compound and the coloured compounds produced with the acid peroxide treated wood chips.

The bleaching of TMP after acid peroxide treatment using QP (chelating-hydrogen peroxide bleaching) bleaching can achieve a whiteness of 75% ISO when the peroxide amount is 3.8%.