The function of the screening equipment is to minimize the amount of the impurities in the pulp suspension that do not meet the process requirements, so that clean good pulp can be sent to the next process directly.
There are many types of impurities in the pulp, and there are typically non-fibrous and fibrous impurities suspension such as sand, metal particles, ink, and the like which are mixed into the pulp from the outside and fiber bundles generated during the pulping process. if they are not removed before papermaking, these impurities can cause serious paper problems and even affect production.
One of the methods of removing impurities from the pulp is screening. That is, the pulp goes through screening equipment to achieve the purpose of removing impurities based on the differences in morphology between the impurities and the fibers.
The screening equipment works on the removing principle of coarse impurities, and has a screen plate with a round drum shape, a conical shape or a flat plate shape. The opening of the screen plate can processed into a hole shape (cylindrical, conical, etc.), or can be processed into a long slit shape. The holes or slits are of a moderate size to allow a single fiber to pass while blocking impurities on the surface of the screen. The good pulp flows through the screen holes by means of static position difference on both sides of screen plate and dynamic pressure head generated by the movement of the equipment itself, and the tail pulp or coarse slag blocked by the plate is discharged by axial thrust or gravity. The screen equipment must be equipped with a pulse generating mechanism to prevent screen holes from being blocked by coarse slag. The screen equipment can be divided into centrifugal screen, pressure screen and vibration screen according to different mechanisms.
AGICO can provide high quality screening equipments for clients.
At present, the medium-concentration screening equipment has been widely used in the screening process of mechanical pulp or chemical pulp. It is operated at a concentration of 7-15%. Medium-concentration screening is another important medium-concentration pulping operation technology after medium-concentration storage and transportation, bleaching, washing and the like. Using the principle of “fluidization” of pulp, the fibers and impurities are freely moved each other in the medium-concentration screening equipment, and the effective separation of fibers and impurities is completed under low-concentration conditions.
The effect of the screening equipment is mainly reflected in the separation of coarse slag and good pulp. This effect is usually evaluated in terms of the relationship between the separation achievement and the discharge amount of the tailings.