The perfection of waste paper flotation deinking technology and equipment

In the waste paper flotation and deinking pretreatment, some Japanese paper mills have concentrated waste paper pulp to more than 30% during the processing of office waste paper such as electrostatic copying paper and laser printing paper, and they have been honed using a honing machine to ensure their use. The ink particle size is in the range of 20 to 60 μm to facilitate flotation separation, thereby significantly increasing the ink removal rate.
Flotation deinking of offset printing waste paper generally requires the use of alkaline media, but the new water-based aniline letterpress printing newsprint ink is easily dispersed in the alkaline medium, resulting in the ink particles are too thin, deposited on the fiber and difficult to remove. For the co-existence of various ink waste papers, such as water base and oil base, in waste paper recycling pulp mills, Canada has developed a two-stage flotation deinking process, ie pulping in a neutral medium and flotation to remove the water bases therein. Aniline ink; then the oil-based ink is floated under alkaline conditions to significantly improve the deinking effect. The two-stage flotation process can remove 70% of the sticky impurities and 40%-50% of the inorganic fillers, and allow the content of inorganic fillers in the waste to reach 70% for recycling.
In order to solve the problem of difficulty in deinking of new inks such as flexographic printing inks and laser printing inks, a series of new types of agents have been developed based on commonly used deinking agents such as sodium hydroxide, sodium silicate, and saponified compounds. A novel flotation deinking agent composed of a copolymer of epoxide hexane and propylene oxide and other surfactants, the deinking agent can significantly improve the quality of the regenerated pulp, the ink residue is small, the brightness is high, and the operation is stable; PPG has developed a defoamer with controllable amount of foam to reduce the adhesiveness of the ink, and has a good effect on the removal of ink such as electrostatic copy paper; Stephenson Chemical Recycling Plant developed a modified fatty acid sodium soap. The opportunity for fatty acids to enter the papermaking process is significantly reduced, thereby reducing a series of problems caused by fatty acid deposition, thereby improving the runnability of the paper machine.