What are the specific steps of papermaking?

Generally speaking, after chemical cooking of plant fiber raw materials, 50-85% of the pulp is obtained, and about 15-50% of the material is dissolved in the cooking liquid, and the cooking liquid discharged by cooking is collectively referred to as waste liquid. 

1. The purpose of washing is to separate the waste liquid of the pulp to ensure the cleanliness of the pulp and to create good operating conditions for screening and bleaching in the next stage. It is necessary to protect the washing waste liquid with high pulp degree as far as possible, so as to facilitate the recovery or comprehensive utilization of drugs.Therefore, it is necessary to use less water on the premise of ensuring the washing quality of pulp. 

2. Screening is also an indispensable important link in the pulping process.The cooked pulp contains 1: 5% undigested matter. For wood pulp, it is mainly bark, wood knots, long strips, wood chips, etc.; for straw pulp, it is mainly grass knots, vines, etc.; in addition, there are non-fiber impurities such as sediment, gravel, iron shavings and so on. According to the requirements of pulp quality, these fibrous and non-fibrous sundries must be separated from qualified pulp fibers through the process of screening and purification.

3. In the process of washing, most of the free waste liquid is relatively easy to separate. The extrusion force can be used to press out, which can be either the static pressure of washing or the additional mechanical pressure. For the waste liquid in the cell cavity and cell wall, it is not possible to rely on a simple extrusion method. Only by using the method of diffusion, the dissolved matter contained in the waste liquid can be diffused by making use of the concentration difference between the washing water and the waste liquid. 
Therefore, the washing of pulp must adopt a variety of action principles.Mainly diffusion, filtration, extrusion and so on. A certain kind of washing equipment is often dominated by one action process, supplemented by other functions. 

4. Although there are all kinds of insoluble impurities with different properties in the pulp, the distribution of these impurities generally adopts two principles: one is to separate them by sieving according to their size, shape and fiber, which is called pulp screening; the other is a process in which the proportion of impurities is larger than that of fibers and is carried out by gravity drop or centrifugal separation, which is called purification. In the actual production process, the two methods are often combined to form the technological process of pulp screening and purification.

For different paper, different papermaking processes are needed. In the process of making paper, a large number of machines are used. But a piece of paper is good or bad, ultimately depends on how it is dried, the dried paper can be put into use normally, we Fengxin technology is focused on paper drying equipment.