Coal transforming into energy with steel structures in the background.

From Coal to Kilowatts: Unlocking the Secrets of Energy Efficiency in Steelmaking

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Jordan Keane in Tech & Innovation August 2025 • 4 min read.

"Discover how understanding lump coal degradation can revolutionize melting gasifiers and pave the way for greener steel production."


The steel industry is undergoing a significant transformation, driven by the need for enhanced environmental performance and sustainable practices. Traditional methods like blast furnaces are gradually being replaced by innovative technologies such as the COREX/FINEX process, which utilizes lump coal instead of coke. This shift not only eliminates the coking process but also drastically reduces pollutant emissions, marking a crucial step towards greener steelmaking.

However, the degradation of lump coal within the melting gasifier presents a major challenge. Unlike coke, lump coal has a lower strength, and its behavior at high temperatures significantly impacts the overall efficiency of the process. Understanding how lump coal breaks down and how it reacts under intense heat is vital for optimizing energy consumption and minimizing waste.

Recent research has focused on unraveling the complexities of lump coal degradation, exploring the energy dynamics and reaction processes that occur within the melting gasifier. By adopting theories such as the volume hypothesis, scientists are gaining valuable insights into the factors influencing coal breakdown and are developing strategies to improve the stability and performance of lump coal during steel production.

The Science of Lump Coal Degradation

Coal transforming into energy with steel structures in the background.

The degradation of lump coal in melting gasifiers is a multifaceted process influenced by several key factors. When lump coal is introduced into the high-temperature environment (above 1073 K) of a melting gasifier, it undergoes rapid pyrolysis, leading to the release of tar and other volatile compounds. This fast heating and devolatilization can cause significant structural changes within the coal particles, affecting their strength and stability.

Researchers have identified that the initial stages of heating are particularly critical. During this phase, the coal absorbs a substantial amount of heat as it undergoes coke formation. This heat absorption, coupled with the rapid temperature increase, can create significant thermal stresses within the coal structure, leading to the formation of pores and cracks. The increased porosity weakens the coal particles, making them more susceptible to breakage.

Key factors influencing lump coal degradation include:
  • Heating Rate: The speed at which the coal is heated significantly impacts the rate of pyrolysis and the development of thermal stresses.
  • Temperature: High temperatures promote rapid devolatilization and coke formation, altering the coal's structural integrity.
  • Residence Time: The amount of time the coal spends in the high-temperature zone affects the extent of pyrolysis and the degree of degradation.
  • Gas Composition: The composition of the gases within the gasifier can influence the reaction rates and the overall degradation process.
To better understand these degradation mechanisms, scientists often employ theories such as the volume hypothesis, which relates the energy required for crushing materials to their volume. By analyzing the breakage energy of coal chars (the solid residue after pyrolysis) under different heating conditions, researchers can gain insights into the factors affecting coal strength and stability. Compression tests and drum experiments are commonly used to assess the mechanical properties of coal chars and to predict their degradation behavior under various operating conditions.

Towards a Sustainable Steel Industry

By meticulously analyzing the energy dynamics and degradation processes of lump coal, researchers are paving the way for a more sustainable and energy-efficient steel industry. Optimizing the performance of lump coal in melting gasifiers not only reduces waste and minimizes environmental impact but also enhances the overall economic viability of steel production. As the steel industry continues to evolve, these advancements promise a cleaner, greener future for both manufacturers and consumers alike.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/s1006-706x(17)30116-4, Alternate LINK

Title: Analysis Of Energy Consumption For Lump Coal Degradation In Melting Gasifier

Subject: Materials Chemistry

Journal: Journal of Iron and Steel Research International

Publisher: Springer Science and Business Media LLC

Authors: Qi-Hang Liu, Xiao-Ming Li, Jun-Xue Zhao

Published: 2017-08-01

Everything You Need To Know

1

What are the key factors that influence lump coal degradation within melting gasifiers?

Lump coal degradation in melting gasifiers is influenced by several key factors: the heating rate, which impacts pyrolysis and thermal stresses; temperature, as high temperatures accelerate devolatilization and alter structural integrity; residence time, affecting the extent of pyrolysis; and gas composition, which influences reaction rates and the overall degradation process. These factors collectively determine the stability and performance of lump coal during steel production.

2

How does the COREX/FINEX process contribute to greener steelmaking, and what specific material does it utilize?

The COREX/FINEX process represents a significant advancement in steelmaking by using lump coal instead of coke. This eliminates the coking process, which is environmentally harmful, and substantially reduces pollutant emissions. This transition marks a move towards greener steel production, though managing lump coal degradation remains crucial for optimizing the process's efficiency and sustainability.

3

How is the volume hypothesis applied to better understand lump coal degradation in melting gasifiers?

The volume hypothesis is employed to understand lump coal degradation by relating the energy required for crushing materials to their volume. By analyzing the breakage energy of coal chars under different heating conditions, scientists gain insights into factors affecting coal strength and stability. This helps in predicting the degradation behavior of lump coal under various operating conditions within melting gasifiers. Compression tests and drum experiments are also used.

4

What happens to lump coal during rapid pyrolysis within a melting gasifier, and why is this significant?

Rapid pyrolysis occurs when lump coal is introduced into the high-temperature environment of a melting gasifier, typically above 1073 K. This rapid heating leads to the release of tar and other volatile compounds, causing significant structural changes within the coal particles. These changes affect the coal's strength and stability, often resulting in increased porosity and susceptibility to breakage.

5

What are the broader implications of optimizing lump coal performance within melting gasifiers for the steel industry's sustainability?

Optimizing the performance of lump coal in melting gasifiers leads to a more sustainable and energy-efficient steel industry by reducing waste, minimizing environmental impact, and enhancing the overall economic viability of steel production. Further research and improvements in managing lump coal degradation could lead to even greater advancements, promoting a cleaner, greener future for steel manufacturing.

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