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New Technique Developed in China Uses Steel Industry Waste and Can Cut Up to 80% of CO₂ Emissions in Cement Production by Integrating Catalysts Directly into the Process.
Chinese researchers have taken an important step towards decarbonizing the cement industry. A new technique, based on the use of solid waste from the steel industry, can reduce carbon dioxide (CO₂) emissions generated in cement production by up to 80% — a sector responsible for about 8% of global emissions.
The Weight of Cement in Global Emissions
Cement manufacturing is one of the most polluting industrial activities in the world. This occurs largely due to the decomposition of calcium carbonate (CaCO₃), which accounts for approximately 60% of the CO₂ released during the process.
Even with technological advances over the years, such as the evolution of kilns and the adoption of dry systems, the need for high temperatures, around 1,450 °C, limits more radical innovations.
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The search for alternatives has led to attempts such as the use of alternative fuels, including biomass and hydrogen.
However, these solutions mainly focus on the energy used in the process and do not address the central problem: the chemical reaction itself that releases carbon dioxide.
The New Proposal: Methane and Steel Waste
The novelty comes from a catalytic process that utilizes solid waste from the steel industry as catalysts.
This waste contains metals such as iron, aluminum, and zinc, which allow a reaction between calcium carbonate and methane (CH₄) in an environment rich in this gas.
The result of the reaction is the formation of two main products: calcium oxide (CaO), essential for clinker production, and synthesis gas (a mixture of CO and H₂), which can be used as an energy or chemical input.
Unlike other proposals, the catalysts do not need to be separated from the process after use.
They are incorporated directly into the clinker mass, simplifying operations and eliminating new waste.
Two Routes, A Cleaner Path
Scientists have identified two possible pathways for the reaction. In the direct route, methane interacts with CaCO₃, producing CO and H₂ without generating CO₂.
In the second pathway, CaCO₃ is initially decomposed into calcium oxide and CO₂, which then reacts with methane to form the same products.
Tests have shown that the direct route is the main one, thanks to the presence of iron oxides. The inclusion of aluminum and zinc increases efficiency by enlarging the active surface of the catalysts, creating a more favorable environment for the reaction.
Less Waste, More Efficiency
In addition to drastically reducing emissions, the new technique offers additional advantages. By using waste that would be discarded, the process reduces waste and raw material costs.
And by turning an environmental problem — the disposal of steelmaking solids — into part of the solution, the system creates value within the logic of a circular economy.
Life cycle assessment (LCA) studies indicate that the new technology has the potential to reduce carbon emissions by up to 80% in the most critical phase of cement production: the decomposition of calcium carbonate. The utilization of steel waste further contributes to the positive impact of the process.
Promising Path for the Industry
For experts, this innovation represents more than a simple improvement. It is a structural transformation in the way cement is produced.
The combination of residual raw materials, generation of useful by-products, and energy savings paves the way for a more sustainable industrial model.
Another positive point is the potential integration between sectors. With steel and cement working together in an interconnected production chain, new possibilities for industrial cooperation focused on sustainability arise.
Despite the great potential, the challenge now is to scale the solution. It will be necessary to ensure that the process is compatible with the existing infrastructure in cement plants. It will also be essential to prove its efficiency at an industrial scale.
If this step is successful, the technology could become one of the greatest advances towards carbon neutrality in the construction sector. The innovation points to a future where waste ceases to be a problem and becomes an essential part of the solution.
Study published in NSR.
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