Waste paper pulper introduction

The first process of waste paper processing is to purify and disintegrate, that is, to remove inclusions in waste paper. The general method is to manually sort the waste paper in each package and then dissect the paper after sorting. For further processing, the author introduces the horizontal hydraulic pulper (this type of pulper is the most commonly used one in China's waste paper processing industry)

1, horizontal hydraulic pulper

The horizontal hydraulic pulper rotates at a speed of 1200-1800 rotations per minute to rotate the pulp in the groove, and the pulp and rotating impeller, the relative motion between the fixed blades and the internal velocity of the pulp flow are different. The frictional effect makes the fibers disperse, and the pore size of the sieve pores is 4 to 8 mm, and the disintegrated concentration is 2.5 to 3.5%. The dispersed fibers are continuously discharged through the sieve box and are included in the waste. The ropes, rags, wire, and plastic film in the paper are put into the pulp with a barbed wire at one end. The inclusions themselves have a rope effect, and the winch at the top of the groove continuously pulls them from the pulp. Out of the major impurities are regularly discharged at the bottom of the tank.

2, high concentration sand remover

The high-strength sand remover removes the heavy impurities in the pulp at a concentration of 2.5 to 3.5%. The pulp is fed into the high-strength sand remover from the top, and the top turntable rotates at 1400 rpm. The pulp is made to rotate at high speed in the device. The impurities (such as book nails, sand stones, etc.) that are significantly larger than the others are subjected to the centrifugal force and are thrown to the wall of the device. By gravity, the clear water is sprayed into the sludge collector. The debris is separated from the pulp and the pulp rises out of the center tube.
3, spalling machine

The slurry processed by the hydraulic pulper still contains small pieces of paper that are not fully dispersed. Further desorption is very important to improve the quality of the waste paper pulp. The pulp can be dissolved in the general beater, refiner, and In the disc mill, but since the waste paper has already been beaten, if the general pulping equipment is used for dissolving, not only the power consumption is high, the utilization rate of the equipment is low, and the fiber is cut off again, so that the strength of the pulp is reduced, therefore, the waste Paper desorption requires the fiber to be adequately dispersed without cutting the fiber. There are many models of the disintegrator. The author will mainly introduce the disperser used in our country. ¡ High-frequency spaller

1, high frequency spaller

Although the model and structure of the high-frequency spaller are different, the working principle is basically the same. The rotor rotates at a high speed of around 3,000 rpm, and the pulp is subjected to a large impact and strong between the rotor and the stator. The fluid shear force makes the fiber fully dispersed. After dehydration, the degree of hydration and deuteration of the pulp increase, the fiber is rarely cut off, and the ink is separated from the surface of the fiber by mechanical action.

The rotating tooth plate (rotor) and the fixed tooth plate (stator) each have three rows of ring gears. The ring gears of the rotor and the stator are meshed with each other. The size of the tooth grooves gradually decreases from the center outward, but the number gradually increases, and when running, The slurry enters into the center of the tooth plate and is forwarded by the centrifugation from the center through the tooth slot. The concentration of the treated slurry is excluded from the outer ring of the tooth ring by about 3%, and the gap between the teeth of the stator and the rotor is generally at 0.8. ~ 1.0 mm, which is equivalent to the average length of the fiber, and therefore, the relative motion of the tooth edge has no shear effect on the fiber (the average fiber length has not changed significantly after the pulp is processed by the deflaker)

Because the gap between the rotor and the stator is small, the tooth plate is easily damaged by the metal inclusions in the slurry. Therefore, the sand must be fully removed before the deflaker, and the tooth plate must be made of wear-resistant steel.

With the development and widespread use of processed paper, the increase in materials such as asphalt, resins, and plastics in waste paper has caused difficulties in the resolution of waste paper. In view of the above-mentioned situation, in order to expand the use of waste paper, the In recent years, there have been a number of dissolving equipments adapted to the processing of waste paper. The development trend of these equipments is to knead and squeeze the pulp at a relatively high concentration of about 30 to 35% to increase the friction between the fibers and to dissolve them. The temperature is also increased accordingly, which is conducive to the dispersion of ink, asphalt and other substances.

2. Single-axis spaller

The working principle is the same as that of a general hammer crusher. Both the moving hammer and the fixed blade are cast with wear-resistant chrome steel. The pulp is loosened at a concentration of about 30%. The degree of beating of the pulp after desorption is not changed. Big

3, double spiral spaller

It consists of a pair of intermeshing spirals. Feeding at one end of the feed has a larger pitch and gradually decreases toward the discharge end. The feed is operated at a concentration of about 35%. The paper stock is squeezed, rubbed, and dispersed into individual fibers between the spirals.