Two-Stage Slurry Separation for Paper Dust and Foreign Matter

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Solution Overview

Problem

Existing methods face challenges in efficiently separating paper dust and solid foreign matter from aqueous slurries, particularly with screw presses, due to mesh damage from hard foreign matter and difficulty in maintaining low water content in retrieved paper dust.

Innovation Solution

A screw press with mesh openings between 1.5 mm and 3 mm is used to separate solid foreign matter and paper dust, followed by a sieve with openings not greater than 1 mm to further separate these components from the liquid component, reducing mesh damage and maintaining acceptable water content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If screw presses with small mesh openings are used to separate paper dust and solid foreign matter from slurry, then separation efficiency is improved, but mesh damage from hard foreign matter increases

Engineering Contradiction:

Improveseparation efficiencyVSAvoidmesh durability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The separation process is divided into two stages: first, a screw press with larger mesh openings (1.5-3 mm) removes most solid foreign matter and paper dust, reducing the load on the second stage; second, a sieve with smaller openings (≤1 mm) performs final separation of paper dust from the liquid component. This segmentation allows each stage to be optimized for its specific function, preventing mesh damage while maintaining separation efficiency.

Inventive Principle:

Principle #1Segmentation

2Ease of operation

If belt presses are used to press aqueous slurry, then operation is simpler, but paper dust retrieval with low water content is difficult

Engineering Contradiction:

Improvepressing operation simplicityVSAvoidpaper dust water content control

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The invention replaces the belt press mechanical pressing system with a screw press system that uses rotational motion and mesh filtration. The screw press applies mechanical pressure through rotating screws while simultaneously filtering through the mesh, achieving both pressing and separation functions that belt presses cannot accomplish, particularly in retrieving paper dust with low water content.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If screw presses with small mesh openings are used to separate paper dust, then paper dust water content is reduced, but mesh damage from hard foreign matter increases

Engineering Contradiction:

Improvepaper dust water contentVSAvoidmesh damage

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The screw press with larger mesh openings (1.5-3 mm) performs preliminary removal of hard foreign matter and bulk paper dust before the final separation stage. This preliminary action protects the subsequent sieve with smaller openings (≤1 mm) from damage by hard foreign matter, while still achieving the required low water content in the final paper dust product.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method effectively reduces mesh damage and maintains the water content of separated paper dust and foreign matter within an acceptable range, ensuring continuous operation and efficient recovery.

Implementation Method 1

a pressing step for pressing said aqueous slurry by means of a screw press, provided with a mesh having openings not less than 1.5 mm and not greater than 3 mm, such that said aqueous slurry is separated into the solid foreign matter and the paper dust not passing through said mesh, and liquid component passing through said mesh

Methodology Applied

Scientific EffectMechanical pressure: Pressure Increase

Implementation Method 2

a sieving step for sieving said liquid component by means of a sieve having openings not greater than 1 mm such that the solid foreign matter and the paper dust are separated from the liquid component

Methodology Applied

Scientific EffectFiltration: Filter (physical)

Implementation Method 3

a deposition step for mixing gypsum hemihydrate and/or anhydrous type III gypsum, derived from waste gypsum boards with an aqueous medium to form a gypsum slurry including paper dust and solid foreign matter and then for depositing gypsum dihydrate particles in the gypsum slurry

Methodology Applied

Scientific EffectSedimentation: Sedimentation

Data Source

PatentUS12559380B2Method for compression of aqueous slurry containing solid foreign matter and paper dust, and treatment method of waste gypsum board

Publication Date: 2026.02.24 TOKUYAMA CORP

AI summary

Aqueous slurry which includes solid foreign matter and paper dust is pressed by means of a screw press, provided with a mesh having openings not less than 1.5 mm and not greater than 3 mm, to separate the aqueous slurry into the solid foreign matter and the paper dust, and liquid component passing through the mesh. Then, the liquid component is sieved by means of a sieve having openings not greater than 1 mm to separate from the liquid component the solid foreign matter and the paper dust.