Coal Blend Surface Tension Evaluation for Consistent Coke Strength

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Solution Overview

Problem

Existing methods for blending coals to produce metallurgical coke of desired strength are inadequate when using coals from multiple locations with varying properties, often resulting in coke with undesired strength.

Innovation Solution

A method for evaluating coal based on inert content and surface tensions of semi-coke, utilizing a regression line to determine surface tensions for inert and reactive components, allowing accurate specification of coal blend fractions to achieve desired coke strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If coal blends are prepared using conventional blending methods based on mean surface tension values, then the blending process is simple, but the coke strength cannot be consistently ensured when using coals from multiple locations with varying properties

Engineering Contradiction:
Improvecoke strength consistencyVSAvoidsurface tension measurement precision
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent segments the coal sample into multiple subsets with different inert component contents (e.g., 10%, 30%, 50%, 70%, 90% inert content). Each subset undergoes heat treatment to produce semi-coke, and the surface tension of each semi-coke is measured individually. This segmentation allows the patent to capture the relationship between inert content and surface tension, enabling more accurate prediction of coke strength when blending coals from different locations.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If coal blends are prepared using detailed evaluation methods that account for inert content variations, then the coke strength can be accurately predicted, but the evaluation process becomes more complex

Engineering Contradiction:
Improvecoal evaluation precisionVSAvoidevaluation process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent performs preliminary heat treatment on coal samples with varying inert content to produce semi-coke, and measures the surface tension of each semi-coke before blending. By conducting these measurements in advance, the patent establishes a relationship between inert content, surface tension, and coke strength. This preliminary action enables accurate prediction of coke strength for any coal blend composition without requiring complex real-time measurements during the blending process.

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

Enables the production of coke with consistent strength by accurately specifying coal blend fractions, ensuring the coke meets metallurgical requirements.

Implementation Method 1

surface tensions of semi-coke, which is obtained by heat treating each of the brands of coal

Methodology Applied
Scientific EffectSurface tension: Surface Tension

Implementation Method 2

heat treating each of the brands of coal that constitute a coal blend

Methodology Applied
Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentEP3936586B1Evaluation method for coal, preparation method for blended coal, and production method for coke
Publication Date: 2025.09.03 JFE STEEL CORP
  • EP3936586B1 patent drawingFigure 1~2
  • EP3936586B1 patent drawingFigure 3~4
  • EP3936586B1 patent drawing

AI summary

Types of coal that are to constitute a coal blend from which coke having a desired strength can be produced and mass fractions of the types of coal can be accurately specified compared with related-art techniques. A method for preparing a coal blend includes determining an interfacial tension of a coal blend from a surface tension γ100, a surface tension γ0, a blending ratio, a mass fraction of inert, and a mass fraction of reactive of each of brands of coal of the coal blend, the surface tension γ100 corresponding to an inert amount of 100%, the surface tension γ0 corresponding to an inert amount of 0%; determining a correlation between the interfacial tension and a strength of coke produced from the coal blend; determining, from the correlation, an interfacial tension corresponding to a desired strength of the coke; determining mass fractions of at least two brands of coal such that the interfacial tension corresponding to a desired strength of the coke or a lower interfacial tension is achieved; and preparing a coal blend by mixing together the at least two brands of coal in the mass fractions.