Washing Link of Pulp

Unwashed pulp wastewater is mostly free in the flow space between fibers, about 80-85%, and about 15-20% in the cell lumen and cell wall of fibers. In the process of washing, most of the free waste liquid is relatively easy to separate. Pulping equipment can be extruded by extrusion force, which can be either static pressure of washing or external mechanical pressure. It is not feasible for the waste liquid in the cell cavity and cell wall to be extruded simply. Only by diffusion method, the dissolved substances in the waste liquid can be diffused by using the concentration difference between the washing water and the waste liquid.

Therefore, the washing of pulp must adopt a variety of principles. It mainly includes diffusion, filtration, extrusion and so on. One kind of washing equipment usually takes one kind of action process as the main one, and other functions as the supplementary one. Although there are various insoluble impurities with different properties in pulp, there are two principles to distribute these impurities: one is to separate them by sieving according to their size and shape, which is different from the fibers, and the other is to use gravity because the proportion of impurities is larger than that of fibers. The process of descending or centrifugal separation is called purification.