METHOD FOR CONTROLLING PITCH OF PULP OF WASTE PAPER OF NEWSPAPER

PURPOSE:To control pitch contained in pulp of waste paper in a method for producing recycled paper from waste paper of newspaper as a raw material. CONSTITUTION:In a method for deinking to obtain recycled pulp from a raw material of waste paper of newspaper, when the waste paper of newspaper, is macerated, selected and passed through deinking.bleaching process to give pulp and the pulp is cleaned and diluted with white paper, a pitch controlling agent is added and in the following cleaning process, both the white water and the pitch are discharged out of the system to give a method for controlling pitch of pulp of old paper of newspaper. The pitch controlling agent is constituted of a secondary aggregate on reaction of a treated material of acidic clay with an acid and an aluminum salt and talc. The pitch is also discharged out of the system when ink is collected by FLT from the white water delivered from a cleaner and the white water is recycled and reused for macerating the raw material and as cleaning and diluting water for pulp.