Decarbonization in the Steel Industry: The Impact of Raw Material Quality

Decarbonization in the steel industry is often framed as an agenda driven by large investments and major structural changes to production processes. In recent years, this view has gained momentum through projects based on Electric Arc Furnaces and Direct Reduction routes, motivated by the need to cut CO₂ emissions.

 

At the same time, many of these projects have been postponed or even canceled. Not because the urgency to reduce emissions has diminished, but due to rising economic, operational, and competitiveness constraints.

 

This context highlights a critical point: decarbonization in steelmaking does not necessarily begin with changing the production route. It begins with how decisions are made within the existing process.

 

Reducing Emissions Has Always Been a Matter of Operational Efficiency

 

The steel industry has lived with efficiency targets for decades. Long before the current carbon discussion, the sector was already continuously working to:

 

• reduce specific energy consumption,
• improve fuel efficiency,
• adapt to raw materials of variable quality,
• and control operating costs.

 

These improvements have always had a direct impact on reducing emission intensity per ton of steel produced. This means that operational efficiency and sustainability have never been separate topics. Operating more efficiently has always meant emitting less.

 

What has changed today is not the principle, but the level of scrutiny. Emissions are now explicitly measured, monitored, and benchmarked.

 

The Current Context of the Steel Industry

 

Today, the steel sector operates under multiple, simultaneous constraints:

 

• clear CO₂ reduction targets,
• the need to maintain or increase production volumes,
• intense global cost-based competition,
• increasingly heterogeneous raw material quality,
• and real limitations on large capital investments.

 

In this scenario, large-scale structural decarbonization projects face significant economic feasibility challenges in the short and medium term. This does not eliminate the need to reduce emissions, but it shifts the focus toward solutions that deliver immediate results, controlled risk, and measurable returns.

 

Within the current decarbonization debate in steelmaking, several technological initiatives have been discussed as potential pathways for reducing CO₂ emissions, especially in blast furnace–based and integrated steel routes. These initiatives reinforce the trend of seeking solutions at the process level, often associated with greater operational complexity and substantial investment requirements.

 

Examples include the use of hydrogen as a reducing agent, charging sponge iron into blast furnaces, or the use of preheated scrap in converter feeds.

 

Understanding Emission Scopes in Steelmaking

 

To identify where real reduction opportunities lie, it is essential to understand the different carbon emission scopes.

 

Scope 1 — Direct emissions

These refer to emissions generated directly by the operation itself. In steelmaking, this mainly includes fuel combustion in blast furnaces and process furnaces, the use of reductants such as coke and coal, and the chemical reactions inherent to iron and steel production.

These emissions are directly influenced by operational decisions, especially the selection and combination of raw materials.

 

Scope 2 — Energy consumption indirect emissions

This scope includes emissions associated with the generation of electricity consumed by the plant. The higher the consumption and the more carbon-intensive the power generation, the greater the impact.

Operational efficiency, productivity, and specific energy consumption are direct levers on this scope.

 

Scope 3 — Value chain emissions

This scope encompasses indirect emissions across the value chain, such as raw material production and transportation, logistics, and, in some cases, the use of the final product.

Although these emissions depend on external factors, decisions regarding suppliers, inputs, and logistics routes have a significant influence.

 

Where Operational Decisions Have the Greatest Impact

 

A significant share of steel industry emissions, especially within Scopes 1 and 2, is directly linked to routine operational decisions, such as:

 

• the choice of raw material suppliers,
• the proportions of ore, sinter, pellets, scrap, and direct-reduced iron,
• the average chemical quality of inputs,
• efforts to reduce fossil fuel consumption,
• and the balance between productivity, cost, and specific consumption.

 

These decisions are not independent. Changing one raw material affects energy consumption, process stability, cost, and emissions at the same time.

For this reason, isolated decisions rarely deliver good overall results.

 

The Mathematical Model Experiment

 

To objectively evaluate the impact of these decisions, Cassotis carried out rigorous scenario analyses using its integrated cost optimization solution, which also estimates emissions based on material usage and production levels. The mathematical model represents the entire production chain and includes the various mass, chemical, and thermal balances for each production unit. It also captures the impact of quality (from both raw materials and intermediate products) on process efficiency indicators and fuel requirements.

 

Two burden scenarios were simulated using the model applied to an integrated steel plant composed of coke ovens, sinter plant, blast furnaces, and converters. The first simulation prioritized materials with lower operational efficiency and poorer quality. The second focused on higher-quality materials with better efficiency.

 

Unsurprisingly, the first scenario resulted in higher CO₂ emissions in Scopes 1 and 2, totaling 2.45 tons of CO₂ per ton of steel produced.

In the second scenario, the use of higher-quality, more efficient raw materials led to lower emissions, reducing them to 2.11 tons of CO₂ per ton of steel.

The result was a 14% reduction in total emissions, achieved solely through the use of better-quality materials.

 

The Central Role of Raw Materials

 

The key takeaway from the experiment was clear. Raw materials play a decisive role in the emissions intensity of steelmaking.

Changes in the input mix and average quality directly affect:

 

• the amount of fuel required,
• the efficiency of chemical reactions,
• electricity consumption,
• and, consequently, Scope 1 and Scope 2 emissions.

These results highlight the potential for emissions reduction through raw material decisions when the system is analyzed in an integrated manner.

 

Why Optimization Is Necessary

 

The simulated burdens showed significantly different costs! This is a fact. Choosing higher-quality raw materials to reduce emissions can substantially increase the cost of material blends.

 

However, higher quality also delivers indirect cost reductions (such as flux and energy) and improves operating conditions, enabling better yields and higher production levels.

 

In addition, in some regions of the world, economic penalties for CO₂ emissions must be considered in decision-making. In such cases, purchasing higher-quality raw materials may become advantageous, as the increase in raw material cost can be offset by reduced emission penalties.

 

All of this demonstrates the complexity of raw material decisions, an issue that must be addressed through integrated optimization that considers all these factors simultaneously.

 

Conclusion

 

This study demonstrates how strongly CO₂ emissions are influenced by raw material selection, regardless of the production route.

 

It also shows that environmental considerations must be part of this decision, especially for plants with ambitious emission reduction targets or those subject to carbon-related penalties.

 

This opens a powerful optimization pathway, with significant levers on both cost and emissions. Cassotis operates precisely at this intersection, transforming operational complexity into superior economic decisions, with real impact on cost and carbon.