Processing of Paper Material Before Papermaking

1. Dilution of paper material

Generally, the concentration of paper material in the pulp tank is 2.5-3.5%. Such a high concentration cannot evenly disperse the fibers and it is difficult to remove impurities. Therefore, it is necessary to dilute with water to form a good dispersion of paper material in a low concentration state, which is beneficial for purification and screening.

There are two methods of dilution, namely dilution inside the mixing box and dilution outside the mixing box.

2. Screening and purification of paper materials

Purification: It is to remove significant impurities such as metals, coal slag, sand particles, etc. from paper materials.

The principle of purifying operating equipment is to use the difference in density to screen impurities.

Screening: It is to remove impurities with small specific gravity and large volume from paper materials, such as pulp, fiber bundles, grass clippings, etc.

The principle of screening operation equipment is to use the differences in geometric dimensions and shapes to select impurities.

3. Degassing of paper materials

Paper material is not simply a suspension system formed by solid substances such as fibers and fillers suspended in water, and it also contains air. Due to the harm of air in paper material to the operation of paper machines and the quality of paper production, it is necessary to remove air from paper material from the perspective of production and quality management.

The methods of degassing include: firstly, eliminating the air that has been mixed into the paper material, usually using physical or chemical methods; secondly, preventing and avoiding the mixing of air into the paper material. Use degassing equipment to remove gas.