Conversion of pulp and paper mill sludge to papermaking pulp
US5137599A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 28, 1990 |
| Grant date | Aug 11, 1992 |
| Priority date | — |
| Expiry date | Sep 28, 2010 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S210/928
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A process for the production of papermaking fiber or pulp from waste solids emanating from pulp and paper mills, particularly waste solids in process water streams containing fibrous solids that cannot be directly recycled by paper mill "saveall" devices, from pulp and paper mill process water streams conveyed by the sewerage system to wastewater treatment plant facilities, and from "sludge" emanating from the underflow of a primary clarifier or sedimentation basin at pulp and paper mill wastewater treatment facilities either before or after the "sludge" is thickened and dewatered. The process comprises a defibering stage to release individual fibers from bundles, a screening stage to separate long fiber and debris from short fiber and clay, a centrifugal cleaning stage to separate debris from the long fiber, a bleaching stage to increase the brightness of the fiber, a dewatering stage to remove excess water from the pulp, a clarification stage to separate the short fiber-clay-debris from the defibering effluent which is substantially recycled, and a biological treatment process to remove dissolved organic materials from the excess water generated which can be either discharged fro…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.