# US 7,967,947 B2 · Methods for beating pulp, methods for treating process waters, and methods for producing pulp and paper

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- Number: US 7,967,947 B2
- Document ID: US7967947B2
- Status: Granted
- Kind: B2
- Application number: 11/884,012
- Filed: 2006-02-09
- Published: 2008-04-03
- Granted: 2011-06-28
- Earliest claimed: 2005-02-09
- Assignees: Nippon Paper Industries Co., Ltd.
- Inventors: Shisei Goto; Hiromichi Tsuji; Keigo Watanabe; Takeshi Iimori
- Web page: https://patentgrep.com/patent/US7967947B2

## CPC

- D21D 1/00: Methods of beating or refining; Beaters of the Hollander type (knotter screens D21F)
- D21B 1/325: {de-inking devices}
- D21C 5/02: Working-up waste paper (mechanical part D21B1/08, D21B1/32)
- D21D 1/02: Methods of beating; Beaters of the Hollander type
- D21F 1/0009: {Regulating the freeness of the pulp}
- D21H 11/14: Secondary fibres (working-up waste paper D21C5/02)
- Y02W 30/64: Paper recycling
- D21D: TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
- D21B: FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
- D21C: PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21F: PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21H: PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

The first invention aims to provide a method for preparing stiffer bulky pulp at a freeness level comparable to that obtained by mechanical treatments to improve the bulkiness of product paper by searching for a method capable of adjusting freeness while suppressing damage to pulp fibers and internal fibrillation in a process for producing pulp. The second invention aims to strip contaminants deposited on pulp fibers and/or inorganic particles to reduce adhesion of the contaminants and decrease microorganisms in a treatment of process water containing long pulp fiber fractions used in a process for producing pulp and paper, thereby clarifying process water and thus preparing high-quality pulp and paper. According to the first invention, cavitation is generated in a pulp suspension preferably by a liquid jet and the resulting fine bubbles are introduced into the pulp suspension to adjust the pulp suspension to a desired freeness by means of the impact force induced by collapse of the fine bubbles in a process for producing pulp. According to the second invention, process water containing 50% by weight or less, based on total solids, of long pulp fiber fractions used in a process for producing pulp and/or paper is treated by cavitation generated by a liquid jet and then returned to the process for producing pulp and/or paper and reused.

## Claims

### Claim 1

A method for beating pulp in a process for producing pulp, which comprises: generating cavitation in a pulp suspension by emitting a fluid jet via a nozzle or an orifice tube, wherein an upstream pressure of the nozzle or the orifice tube is 2 MPa or more and 30 MPa or less, and a ratio between a downstream pressure and the upstream pressure of the nozzle or the orifice tube is in the range of 0.001-0.5, and wherein a jet flow rate of the fluid jet is in the range of 20 m/sec or more and 100 m/sec or less.

### Claim 2 (depends on 1)

The method for beating pulp of claim 1 wherein said process for producing pulp comprises a pulping step and a blending step.

### Claim 3 (depends on 1)

The method for beating pulp of claim 1 wherein the pulp suspension is emitted as the fluid jet.

### Claim 4 (depends on 1)

A method for beating pulp of claim 1 wherein the target pulp is a softwood or hardwood kraft pulp.

### Claim 5 (depends on 1)

A method for beating pulp of claim 1 wherein the target pulp is a softwood or hardwood mechanical pulp.

### Claim 6 (depends on 1)

The method for beating pulp of claim 1 wherein the target pulp is a recycled pulp derived from waste paper.