Coagulation and Magnetic Deinking of Waste Office Paper Using Kerosene

Abstract

Recently, a new method for deinking waste officer paper by magnetic separation after hetero-coagulation of magnetic and non-magnetic toner has been reported. The selection of flocculants which can produce large and strong coagulates is very important to reject toner coagulates effectively in this method. 1-octadecanol whose melting point is 60 °C is used in their report. Coagulation was carried out at 70 °C and then the 1-octadecanol liquid was cooled to make strong solid coagulates. Although high toner liberation must also be achieved before magnetic separation to obtain high deinking and paper recovery, no investigations on liberation methods were done in that report. A paper disintegration method using kerosene was reported in our previous paper, and it was shown that almost 100 % of toner liberation could be attained. As kerosene has ability to soften toner, strong coagulates may be produced by that adhesion when used as a flocculant. In this study, the size of liberated toner by the kerosene disintegration method has been investigated, and the bonding strength between toner particles by adding kerosene as a flocculant has been compared with that by 1-octadecanol. After these investigations, coagulating and deinking properties of kerosene and that of 1-octadecanol have been compared by rejecting toner coagulates with a NdB magnet. From the results, close to 100 % of deinking can be expected with little paper loss even in room temperature because large and strong coagulates can be produced by the use of kerosene as a flocculant. When kerosene was used in the disintegration and coagulation stages, the average coagulate size was 1114um and 98.4 % of deinking was attained by separation with the NdB magnet.