How to make pulp from waste paper? The main step of the waste paper pulping process is purification, remove the printing ink, padding, coating, chemicals, fine fibers and other impurities from waste paper. Generally, the waste paper pulp production process includes pulping, screening, deslagging, flotation, washing, dispersion, bleaching and etc. According to different pulp processing, different paper pulping machinery are required in the paper pulp plants.
By the features and waste paper pulp uses, the waste paper pulping process can be divided into two types, deinking pulp making process and non-deinking pulp making process.
CNBM is a paper pulp machine manufacturer from China, we can both provide paper pulp solution and single equipment for paper pulping production line, such as pulp digester, paper pulper, blow tank, vacuum drum washer, twin roll press, single screw press, disc filter, and pressure screen, etc.
Waste paper repulping is the core process of pulping process, including deflaking and defibering. Deflaking dissociates interlaced fibers into single fiber and keeps the virgin state and strength of fibers. Defibering is the continuous process of deflaking, it is used to dissociate the fiber without any damage of fibers, and decrease the fiber strength.
Deflacking of waste paper is affected by a variety of factors, including temperature, time, concentration, waste paper classification, and etc.
The common paper pulper for waste paper pulping mainly includes hydrapulper and cylindrical paper pulper. The hydrapulper is widely applied in the waste paper pulping process home and aboard. There is vertical and horizontal type according to the structure of paper pulper, continuous type, and batching type according to operation method, LC type and HC type according to pulp concentration.
Compared to LC waste paper repulping, HC type repulping has a lot of advantages as follows:
comparison of various types of paper pulper
|Waste paper type||Pulp consistency
|unit energy consumption
|relief hole diameter
Waste paper pulp screening and cleaning are used to treat coarse material of front end of line. To separate the large-size impurities from coarse pulp, the waste paper pulp should be diluted into low concentration. Common equipment includes pressure screen, pressure knotter, and etc.
Floatation deinking is mainly applied to deinked pulp production. Due to most of the printing ink is oil-based materials, Ink particles has hydrophobic property. Use surfactants collect ink particles and uplift them above pulp. Flotation tank is the core equipment of waste paper pulp deinking.
Pulp washing process uses water or diluent to dissolve nonfibrous and soluble substance in the pulp cooking process, meanwhile, separate them from fibers, and finally obtain the clean pulp. Generally, pulp washing process is also the process of waste liquor extraction. Common washing equipment includes vacuum drum washer, twin roll press, single screw press, disc filter, etc.
Concentration processes increase the pulp concentration and makes the pulp easy to stock, stabilize the pulp concentration to meet the requirement of next processing. It also saves the energy consumption in the pulp transportation. According to the concentration and washing principal, the washing and concentration equipment can be divided into LC type, HC type, medium consistency type, and displacement washing type. Gravity disc thickener is very common in the pulp concentration procedure.
The chemical environment can affect the dryness and swelling of recycled pulp fiber. The rosin size and aluminum sulfate of waste paper can damage the strength of waste paper pulp.
Pulp beating can obviously reduce swelling of pulp, decrease the length of fiber, and increase the content of fine fiber.
Wet pressing can cause the loss of fiber swelling.
The undried chemical pulp is easy to be keratinized, and the fiber bonding strength will be reduced in the paper recycling. The dried chemical pulp has low loss of fiber bonding strength in the paper recycling.
Press polish can cause the loss of water retention value, length and strength.
Printing has certain influence on the optical property; the adhesive for making paper box will prevent the combination of fibers.
The waste paper collection usually mixes various kinds of waste paper, some impurities affect the waste paper pulp quality.