METHOD FOR WASTE PAPER TREATMENT

摘要

The invention concerns a method for waste paper treatment with primary purification and a early, or primary, dewatering stage as a wash stage which largely separates printing inks from the branch circuit into a main circuit with adapted purification stage for the recycled water of the primary dewatering stage. The method is applied to a mixture containing waste paper imprinted with both hydrodispersible (hydrophilic) and other inks. Acid is selectively added to create an acid environment with a pH value between 6 and 7 in the circuit, up to the first primary dewatering stage. Base is selectively added to create an alkaline environment with a pH value between 9 and 11 in the treatment circuit downstream the primary dewatering stage. A dispersion stage is provided in the second circuit for the printing inks which are not hydrodispersible (hydrophobic). Additionally a stage of selective flotation is provided in the main circuit.