会社のニュース Steel Industry Shifts to Green Blast Electric Arc Furnaces

The evolution of steel production methods not only impacts industrial efficiency but also plays a crucial role in global environmental sustainability. As environmental challenges intensify and market demands grow, how will the steel industry navigate these pressures to achieve sustainable development?

Steel manufacturing primarily relies on two core processes: blast furnace ironmaking and electric arc furnace steelmaking. These distinct methods each play vital roles in efficient steel production.

Blast furnace technology dates back to the 14th century, when early versions produced just one ton of iron per day. Despite centuries of technological advancements, the fundamental principles of blast furnace operation remain unchanged. The process involves reducing iron ore using coke, iron ore, and limestone at high temperatures to produce molten pig iron.

Coke serves as an essential component in blast furnace operations. Traditional coke production involves crushing and grinding coal before heating it to approximately 1800°F (982°C) in oxygen-deprived coke ovens. During this 18-24 hour process, volatile compounds are released, leaving behind porous, high-carbon coke.

This durable, energy-dense material (containing 90-93% carbon) provides both the permeability and thermal energy required for ore reduction. Notably, many operations now supplement coke with natural gas to reduce carbon emissions—a significant step toward environmental sustainability.

Developed in the late 19th century, electric arc furnace (EAF) technology now dominates U.S. steel production, accounting for over 70% of output. Unlike blast furnaces, EAFs melt scrap steel, direct reduced iron, and/or pig iron using electrical arcs rather than combustion.

EAF technology offers superior environmental benefits by primarily using recycled materials, reducing reliance on virgin iron ore. The process achieves higher energy efficiency and enables easier emission control compared to traditional methods.

The steel industry's future lies in sustainable innovation. Key developments include:

• Advanced energy-saving technologies like optimized EAF systems and oxygen-enriched combustion
• Breakthrough production methods such as hydrogen-based and biomass metallurgy
• Smart manufacturing incorporating AI, IoT, and big data analytics

Blast furnace ironmaking involves six precise stages:

1. Charging: Precise loading of iron ore, coke, and limestone
2. Combustion: Hot air injection ignites coke, generating heat and reducing gases
3. Reduction: Complex chemical transformations convert iron oxides to metallic iron
4. Melting: Liquid iron collects at the furnace base
5. Slag Formation: Impurities combine with flux to form removable slag
6. Tapping: Periodic removal of molten iron and slag

Electric arc furnace operations involve four key phases:

1. Charging: Loading scrap metal and other raw materials
2. Melting: High-voltage arcs liquefy the charge
3. Refining: Chemical adjustments and impurity removal
4. Tapping: Transferring molten steel for casting

As a vital industrial sector facing significant environmental challenges, the steel industry must accelerate its transition to sustainable production. Through technological innovation and process optimization, steelmakers can reduce environmental impact while maintaining productivity—ensuring the material remains a cornerstone of modern infrastructure while meeting climate commitments.