Patent ID: 6514379
Filing Date: 2003-02-04
Classification: D21C,D21F,Y10S

Abstract:
A procedure for arranging water circulations in an integrated paper mill the paper making process of which is divided into three partly separate process phases considering the water circulations (I,II,III) of which:in the first process phase, the fibre raw material is pretreated, defibered and cleaned for producing mechanical, chemi-mechanical or recycled pulp, in the second process phase, the pulp is treated further for improving the quality thereof and in the third process phase, the braked pulp is made into paper or board in a paper or board machine, in which process, between the first and the second process phases, pulp thickening (4) and pressing (7) are arranged, wherebetween the pulp is diluted with water (53) which is cleaner than the filtrates (46, 47, 52) of the thickening and press phases, the procedure comprising the steps of: concentrating the circulation waters of the first process phase by circulating filtrates (46, 47, 52) of the thickening and pressing phases within the water circulation (I) of the first process phase counter-current, and conducting the circulation water (110) thus concentrated into an effluent evaporation plant (31) to be concentrated to an effluent concentrate, the effluent concentrate (113) then being burn t in a combustion boiler (29, 122, 125) appropriate for the purpose; replacing the water quantity discharged from the water circulation (I) of the first process phase by conducting into a front dilution (53) of the press (7) at least one circulation waters (114, 115, 116) of the paper mill which do not contain at least one of the chemicals harmful to combustion of the effluent concentrate (113), recovery of chemicals and utilization of combustion residue; and selecting chemicals that are not harmful to the combustion of said at least one of effluent concentrate (113), recovery of chemicals and utilization of combustion waste when chemical addition (37) is used in the first process phase.