Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Waste paper or textile waste
Reexamination Certificate
2000-10-17
2001-11-27
Nguyen, Dean T. (Department: 1731)
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Waste paper or textile waste
C162S055000, C241S024290, C241S027000, C241S029000, C241S079300
Reexamination Certificate
active
06322664
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of processing recycled waste paper, and more particularly, to a method of processing a mixture of different types of waste paper.
2. Description of the Related Art
A stock preparation system is used to prepare a fiber suspension for use within a paper-making machine. Typically, the stock preparation system receives a source of fiber, such as wood or recycled waste paper. The fiber source is then broken down into individual fibers and further processed such as by screening, cleaning, deinking and bleaching to prepare the fiber suspension with physical properties suitable for the manufacture of the fiber web.
Recycled waste paper includes both white fibers and brown fibers, depending upon the source of the recycled waste paper. For example, recycled waste paper with brown fibers may be in the form of old corrugated carton (OCC) and/or sack paper. Recycled waste paper with white fibers may be in the form of news print, magazine, printing paper and/or writing paper. The white fibers typically were processed to a greater extent relative to the brown fibers when previously used in the paper-making process. Accordingly, the white fibers have physical properties such as fiber length, adhesion properties, etc. which are different from the brown fibers. Given the different physical properties between white fibers and brown fibers, it may be desirable to process the white fibers separately from the brown fibers to manufacture a fiber suspension. A known technique is to separate waste paper made from white fibers from waste paper made from brown fibers prior to the stock preparation processing. However, separating and sorting the white fibers from the brown fibers is time consuming and expensive.
It is also known to merely mix the white fibers and brown fibers together and use the resultant fiber suspension for the production of a suitable fiber web. However, mixing the white fibers and brown fibers together limits the types of fiber webs which may be produced with the resultant fiber suspension, and may not be the best use of the different types of fibers within the recycled waste paper.
What is needed in the art is a method of processing recycled waste paper which does not require pre-sorting of waste paper having both white fibers and brown fibers, and provides improved flexibility in terms of different types of fiber suspensions which may be produced using the mixed waste paper.
SUMMARY OF THE INVENTION
The present invention provides a method of processing recycled waste paper wherein white fibers and brown fibers are separated from each other during stock preparation and separately processed for subsequent manufacture of different types of fiber webs.
The invention comprises, in one form thereof, a method of processing recycled waste paper. The waste paper is pulped in a first drum pulper. White fibers are separated from the waste paper in a first screen drum. The white fibers are then processed by screening, cleaning, deinking and bleaching. The remaining waste paper is then pulped within a second drum pulper. The brown fibers are separated from the waste paper in a second screen drum. The brown fibers are processed by screening, cleaning and bleaching.
An advantage of the present invention is that waste paper including both white fibers as well as brown fibers may be processed in a continuous manner.
Another advantage is that white fibers and brown fibers are separated from each other during stock preparation and further processed in parallel.
Yet another advantage is that the white fibers and brown fibers may be separately used for the manufacture of different types of fiber webs, or may be mixed together for the manufacture of a fiber web.
A further advantage is that the screen separators used to separate the white fibers and the brown fibers from the waste paper may be configured as screen drums which provide effective screening while being simple and low cost.
REFERENCES:
patent: 5733412 (1998-03-01), Markham et al.
patent: 5766448 (1998-06-01), Markham
patent: 6000640 (1999-12-01), Krebs et al.
Nguyen Dean T.
Taylor & Aust P.C.
Voith Sulzer Paper Technology North America Inc.
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