What is the waste paper pulp? The waste paper pulp means the used waste paper or slitting deckle edge of printing house is treated by bleaching or deinking with the paper pulper machines. The fiber strength and property of waste paper are decided by the types of paper pulp. Due to the fiber is corroded again by the chemical liquor or damaged by the mechanical force, so the fiber of waste paper pulp is worse than before. According to the quality of waste paper pulp’s raw materials, the waste paper pulp can be applied to manufacturing printing paper, writing paper, paperboard or cheap paper.
The waste paper pulp is a typical pattern of secondary fiber. It is friendly, ecological and sustainable. Compared to other kinds of paper pulp, waste paper pulp saves amount of wood. In addition to, waste paper pulp also has features of low cost, low energy consumption and low loadings of pollutant.
Global waste paper pulp market
In fact, global paper pulp industry has been entered into a new time of secondary fiber recycling. With the mature technology of waste paper pulp processing, it is possible for using 100% waste paper pulp to make corrugated paper, industrial paper, facial tissue, toilet paper, newsprint and copying paper, etc. corrugated paper, cardboard paper, and newspaper are the widest application of waste paper pulp. Relatively, equipment for waste paper pulp making developed rapidly.
Process of waste paper pulp
The process of waste paper pulping can be simply summed up into 7 steps, including sorting, repulping, filtration, deslagging, fiber separation and knead, deinking, bleaching and stickies.
Sorting of waste paper
As we all know, the quality reduction and the complex structure of waste paper become a confusion of waste paper recycling. To ensure the quality of raw materials, waste paper recycling requires more cost-effective way to collect, sort and classify the waste paper.
Repulping
The repulping is used to defiber the fiber of recycled waste paper and paper of separated waste paper pulp. Besides that, repulping also improve the separation of printing ink, other polluting substance, and fibers. Repulping makes printing ink separated into ideal size that is perfect to be removed in the next process. At the moment, polluting substance should maintain the status quo, which is good to be removed in the process of filtration and deslagging.
Filtration
The filtration is the second process of whole waste paper pulp processing. The impurities of waste paper is everywhere if the size of impurity is bigger than the width of nozzle or screen cut, it is easy to be filtrated. In the process of waste paper pulp making, there are two kind of filtration like impurity filtration and classifying screen.
Deslagging
High concentration slag separator means the end diameter of large-scale slag separator is longer than 200mm. it is usually installed on the back of pulper, and remove the heavy impurities like metals, gravel, glass and etc. low concentration slag separator refers to the end diameter of small slag separator is less than 100mm. It can both remove the heavy impurities and light impurities. In general, some impurities of waste paper are easier to be removed, their density is bigger or less than water, such as metal, glass, gravel, foam, plastic. Meanwhile, some sticks have same density like water, which makes them harder to be removed by slag separator.
Fiber separation and knead
The fiber separation and knead of waste paper pulping has a lot of functions as below.
- Diminish the impurity particles of waste paper.
- Improve the separation of printing ink and fibers.
- Makes waste paper pulp homogeneous.
- Apply for pulp bleaching. The dispersing equipment is used in the hydrothermal pretreatment of pulp bleaching process or mix of chemicals and reactor bleaching.
- Eliminate the pollution of microbe.
- Improve the properties of fabrics.
Deinking
Deinking is made up of a series of units. The purpose of deinking is separate ink from fibers and separate the ink from the waste paper pulp. Deinking agent is the necessary part of deinking process. Deinking agent consists of soda ash, caustic soda, sulfonated oil, surfactant, detergent, dispersant and etc. Adding flotation into deinking process is an important technological development of waste paper pulping.
Bleaching
Pulp bleaching is generally known as the necessary process like pulp cooking and pulp washing. Simply, add bleaching agent into paper pulp, in the process of chemical action, the fibers of pulp remove the lignin with colorful substances or change chromophoric group of lignin. Finally, the bleached pulp must have certain whiteness and physical and chemical specification. Common equipment of paper pulp bleaching process includes disc filter, single screw press, twin roll press and etc.
Stickies
Stickies is a big challenge of waste paper recycling. Especially for the OCC paper pulp mill. OCC contains appreciable quantity of wax, PSA, and hot-melting impurities, etc. Most of the stickies can be removed by the screen and slag separator, but tiny stickies is also a problem for waste paper pulp making. The formula of stickies can reduce the influence of stickies.
In conclusion
Except for waste paper pulp, wood pulp, and straw pulp are also applicable in the paper and pulp industry. CNBM is a leading paper pulp mill machinery manufacturer from China. We help clients design paper pulp project according to their requirement, and provide related paper pulp machines for pulp mill, such as pulp digester, blow tank, disc filter, twin roll press, vacuum drum washer, and other chemical pulping machines.
