Method of papermaking having zero liquid discharge
US5762758A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 28, 1996 |
| Grant date | Jun 9, 1998 |
| Priority date | — |
| Expiry date | May 28, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02W30/64
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A method of papermaking having zero liquid discharge. A cellulosic pulp composed of recycled materials is initially cleaned to remove contaminants and foreign material, and the clean pulp is then washed to remove dissolved solids and pulping chemicals, and the washed pulp is then utilized in the papermaking process. The contaminants are separated from the liquid residue resulting from the pulp cleaning operation, preferably by floatation clarification, and the effluent from the clarification is evaporated to produce steam or water vapor along with an evaporated residue. The evaporated residue is combined with the suspended solids that were removed from the liquid residue and the combined residue is then subjected to a mechanical dewatering operation to reduce the water content so that the dewatered material can then be either landfilled or incinerated. The condensate from the evaporation can be combined with fresh makeup water and used in the papermaking process. Water recovered from the papermaking process is recycled to the pulp washing operation and water recovered from the pulp washing is recycled to the pulp cleaning and pulping operations, thus resulting in zero liquid discha…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.