STUDY ON OIL AGGLOMERATION FLOTATION FOR DEINKING

摘要

Mixed Office Wastepaper (MOW) is increased considerably in recent years, generated mainly by laser printing and photocopying. It has become a worldwide hot subject for how to better recycle the MOW. Traditional deinking methods are not suitable for such kind of wasterpaper, because the printing methods and the ink used are much different from those of traditional ones. In the process of pulp breaking, ink particles will be generated with various grain sizes, Those extremely fine particles are very active to be reabsorbed on the paper fibres. Traditional deinking methods can not separate them, so the quality of recycling pulp will be affected badly. The author of the paper applies microscopic analysis methods to study the constitutes and characteristics, of MOW and the ink concerned. The process of oil agglomeration and flotation is introduced for optimising the MOW deinking process. The theoretical discussion is held on the basis of the principle of surface chemistry, colloid chemistry, interface separation, kinetics of oil agglomeration, physicochemistry, etc. A new deinking method is proposed by adding certain amount of oleic acid into paper pulp during pulp breaking. Through the force and total energy calculations show that the ink grains will move closer to each other , finally, direct contact and form the structure of aggregates closely, in the action of liquid bridge. In the system of ink particles and paper fiber, the oleic acid will selectively to absorb on the surface of ink particles, and form oil bridge between ink particles, so that oil agglomeration is formed to facilitate to the ink-fibe separation. The process has a potential to decrease production cost, simplifies recycling production process, with advantage of low investment, low pollution, higher recovery, and broad application of the recycled paper pulp.