High-grade deinking paper are generally defined as office paper of high quality like printing and writing paper product, A4 paper, Copy paper, etc. Innovations in modern deinking plants enable these plants to produce excellent pulps even for high-grade printing and writing papers. Leizhan supplies advanced waste paper deinking process technology and equipment for high grade deinking paper making.
Various process stages are needed to remove undesirable and non-fiber components (such as stickies and printing ink particles) from the pulp, or to at least minimize their negative impacts without harming the fiber material.
Pulping
Improving the optical cleanliness of pulp begins in the pulping process when the printing ink is detached. The high percentage of stickies in many office waste collections clearly favors the use of a drum pulper instead of a high-density pulper. For example, the proven Leizhan Drum pulper uses gentle dropping and rolling forces to slush the pulp and defiberize it. This allows contaminants to be rejected virtually intact, taking stickies and trash from the pulp very early in the process.
Screening
The screening process removes most flat contaminants and stickies. Coarse screening is accomplished with pressure screens having screen baskets with very small hole diameters .
Flotation
The selective separation of the pulp suspension into two fractions – accept and reject – increases the brightness of the pulp. Dirt specks and ink particles are discharged from the flotation unit with the foam that is generated by injectors (aerating elements which mix the pulp with air). In the new generation Leizhan flotation system, the improved design of the multi-injectors achieves highly effective aeration with the lowest energy consumption, also allowing it to operate at significantly lower pressure than before.
Dispersing
The dispersion process is responsible for detaching very small ink particles so that they can be removed, and also for fragmentation of any remaining specks to render them invisible – improving the optical properties of the final pulp.
