Optimal treatment of waste pulp by the hottest med

2022-10-15
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Optimal treatment of waste pulp by medium consistency beating

key words: medium consistency beating; Waste pulp; Optimized treatment

China's demand for waste paper is increasing. This trend makes the variety range of recycled waste paper expand day by day, and the quality of recycled waste paper is getting lower and lower. This is manifested in two aspects: first, there are many kinds of impurities in waste paper, which increases the difficulty of treatment; Second, the physical strength index of recycled fibers is greatly reduced due to the repeated reuse of paper. The phenomenon of "keratinization" of fibers in the process of repeated recycling also reduces the papermaking performance of recycled fibers, thus affecting the quality index of the paper

therefore, in order to achieve better results in the treatment of waste paper, two measures should be taken: first, try to remove impurities in waste paper to obtain clean pulp; The second is to adopt new technology and equipment to optimize the use quality of waste pulp to expand its scope of use. This paper mainly discusses the second aspect as follows

1 medium and medium consistency beating optimizes the use effect of secondary fibers. These three groups often replace the crime.

the National Engineering Research Center for papermaking and pollution control of South China University of technology has successfully developed ZDPM medium consistency platen mill, which is applied to the treatment of waste pulp. The application effect shows that the physical strength index of paper-making is increased by 15% - 35% compared with the traditional low consistency beating, The energy consumption of beating is reduced by less than 3. We analyzed several faults that will occur in the equipment. 0% - 50% of the fiber length can be retained well, and it can reduce the loss of partial fiber and improve the speed of papermaking. Compared with the traditional double disc mill low consistency beating geom, it has the requirements of fast operation speed, friendly interface, simple operation, and can meet the experimental methods of different data. The supply of agic freeform 2017 is expected to start in June. See Table 1 for the comparison

Table 1 waste pulp Comparison of low consistency beating effect

beating

type

beating degree

° SR

wet weight

G

beating energy consumption

kwh/T

fracture length

m

ring pressure index

n · M/g

tear index

mm n · m2/g

low concentration

medium concentration

28 ~ 30

28 ~ 30

3.5 ~ 3.7

4.3 ~ 4.5

90 ~ 110

40 ~ 60

3500 ~ 3600

4000 ~ 4300

4.5 ~ 5.0

6.5 - 7.5

6.5 ~ 7.5

9 ~ 9.5

note: the figures in the table are production statistics for a period of time

the beating concentration of traditional low consistency beating equipment in China, whether it is trough beating machine, double disc refiner and large taper refining machine, is low, ranging from 3% to 5%. Then at a low beating concentration, the slurry can actually be regarded as a special suspension, with water as the main body, in which a small amount of fibers are suspended. When beating with traditional beating equipment in a low concentration state, most fibers are centrifuged along the alveolar without being subjected to internal and external fine fibrillation. In this process, only a few fibers are severely cut by shearing, which leads to uneven fiber length and fine fibrosis after beating (as shown in Figure 1). In order to improve the beating condition, enterprises have to reduce the throughput of absolutely dry pulp, so as to prolong the residence time of fiber grinding disc and reduce the grinding disc gap in order to improve the beating effect of fiber. On the one hand, this practice causes a large increase in beating energy consumption. At the same time, in order to pursue high beating degree, the fibers are excessively cut off, resulting in difficulties in partial dehydration, large loss of fine fibers and difficulties in improving the speed. This is particularly unfavorable for waste pulp fiber

Figure 1 treatment of low consistency beating fiber

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