Steelmaking Slag Free Lime Estimation Using LIBS Spectra

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Solution Overview

Problem

Existing methods for quantifying the free lime content in steelmaking slag are complex, time-consuming, and lack accuracy, leading to inconsistent aging treatment and potential expansion issues in steelmaking slag used for road construction.

Innovation Solution

A method using laser-induced breakdown spectroscopy (LIBS) to estimate free lime content by analyzing the emission spectrum of steelmaking slag, employing a partial least squares regression model to correlate emission line intensities with free lime content, enabling rapid and accurate estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional methods (ethylene glycol extraction, thermogravimetric analysis) are used to quantify free lime content, then measurement capability is achieved, but the process becomes complex and time-consuming

Engineering Contradiction:
Improvefree lime content measurementVSAvoidmeasurement process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex chemical extraction and thermal analysis methods with laser-induced breakdown spectroscopy (LIBS), which uses laser plasma emission to directly measure free lime content. This substitution of measurement methodology eliminates the need for multi-step chemical procedures while achieving accurate quantification through spectral analysis of Ca, Fe, and Si emission lines.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an estimation model that uses emission spectrum intensities as an intermediary to determine free lime content. Instead of directly measuring free lime through complex chemical means, the model correlates the intensities of specific emission lines (Ca, Fe, Si) with free lime concentration, providing a simplified measurement pathway while maintaining accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If conventional methods are used to evaluate expansibility and free lime content, then measurement capability is achieved, but the time required for aging treatment determination increases

Engineering Contradiction:
Improvefree lime content and expansibility evaluationVSAvoidaging treatment time determination
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces time-consuming wet chemical analysis and thermogravimetric measurements with rapid LIBS spectroscopy. The laser-based method provides immediate emission spectrum data that can be processed by the estimation model to determine free lime content and predict expansibility, reducing analysis time from hours to minutes while maintaining measurement precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If steelmaking slag is subjected to extended aging treatment to ensure expansion stability, then reliability of road construction material is improved, but productivity and manufacturing efficiency decrease

Engineering Contradiction:
Improveexpansion stability of steelmaking slagVSAvoidsteelmaking slag manufacturing efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent implements a feedback mechanism where the estimation model continuously monitors free lime content and predicts expansibility. This feedback information allows for real-time adjustment of aging treatment duration, ensuring that slag receives only the necessary treatment time required to achieve target expansion stability, thereby optimizing both reliability and productivity.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent uses the estimation model to dynamically adjust aging treatment parameters based on measured free lime content and predicted expansibility. By changing the aging time parameter according to actual material properties rather than using fixed extended periods, the process achieves required reliability while improving manufacturing efficiency.

Inventive Principle:
Principle #35Parameter changes

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 simple, rapid, and highly accurate estimation of free lime content, allowing for optimized aging treatment and efficient management of steelmaking slag for road construction, reducing manufacturing costs and improving expansion stability.

Implementation Method 1

a step of acquiring an emission spectrum by irradiating steelmaking slag with a laser to convert a portion of a surface of the steelmaking slag into plasma and acquiring an emission spectrum from the plasma

Methodology Applied
Scientific EffectLaser-induced breakdown spectroscopy (LIBS): Laser

Implementation Method 2

acquiring an emission spectrum from the plasma

Methodology Applied
Scientific EffectPlasma emission: Plasma

Implementation Method 3

inputting intensities of an emission spectrum including peaks caused by emission lines of Ca, Fe, and Si

Methodology Applied
Scientific EffectEmission spectroscopy: Luminescence

Data Source

PatentEP4660614A1Method for generating steelmaking slag free lime content estimation model, method for estimating free lime content of steelmaking slag, steelmaking slag shipment management method, and method for manufacturing steelmaking slag for roads
Publication Date: 2025.12.10 JFE STEEL CORP
  • EP4660614A1 patent drawingFigure 1~2
  • EP4660614A1 patent drawingFigure 3
  • EP4660614A1 patent drawing

AI summary

Provided are a method for generating a free lime content estimation model for steelmaking slag, by which the free lime content of steelmaking slag can be estimated in a simple, rapid, and highly accurate manner, a method for estimating the free lime content of steelmaking slag, a method for managing shipment of steelmaking slag, and a method for manufacturing iron and steel slag for road construction. The method for estimating the free lime content of steelmaking slag includes: a step of acquiring an emission spectrum by irradiating steelmaking slag with a laser to convert a portion of a surface of the steelmaking slag into plasma and acquiring an emission spectrum from the plasma; and a step of estimating a free lime content by inputting intensities of an emission spectrum including peaks caused by emission lines of Ca, Fe, and Si, within the emission spectrum acquired in the step of acquiring the emission spectrum, into a free lime content estimation model, to output the free lime content of a steelmaking slag irradiated with the laser.