In a significant stride towards sustainable industrial practices, researchers have uncovered a novel method to transform steel slag, a byproduct of steel production, into a high-purity calcium oxide (CaO) material capable of efficiently adsorbing carbon dioxide (CO2). This innovative approach, detailed in a study published in the Journal of Mining and Metallurgy. Section B: Metallurgy, not only addresses the environmental challenge of steel slag disposal but also presents a promising solution for CO2 emission reduction in the energy sector.
The research, led by Cheng J. from the Jiangsu (Shagang) Iron and Steel Research Institute in Zhangjiagang, China, focuses on the fabrication of active CaO from converter steel slag using an acetic acid leaching process. The study systematically investigates the effects of various leaching parameters on the CaO content, with the aim of optimizing the extraction process.
“Our findings demonstrate that the leaching temperature and acetic acid concentration significantly influence the CaO content,” Cheng explains. The optimal conditions identified include an acid concentration of 1 M, a solid/liquid ratio of 1:10, a leaching temperature of 70°C, and a duration of 2 hours, resulting in a maximum CaO content of 86.3%.
The study also delves into the kinetics of the leaching process, revealing that stirring shifts the rate-controlling step of calcium leaching from external diffusion and surface chemical reactions to internal diffusion. Within the temperature range of 40-70°C, internal diffusion emerges as the rate-controlling step.
The fabricated CaO material’s CO2 adsorption performance was evaluated under different conditions, with the adsorption process and reaction mechanism investigated through XRD and SEM analyses. The results indicate that CaO initially converts to Ca(OH)2, which then adsorbs CO2 to form CaCO3. However, the deposition of CaCO3 on the material’s surface can hinder further contact between Ca(OH)2 and CO2, reducing the efficiency of carbon adsorption.
To mitigate this issue, the researchers suggest increasing the CaO content to enhance adsorption performance. The calculated CO2 capture capacities at 30°C, 50°C, and 70°C were 0.32 g/g, 0.24 g/g, and 0.17 g/g, respectively, underscoring the material’s potential for CO2 emission reduction.
This research holds substantial implications for the energy sector, particularly for iron and steel companies seeking to minimize their environmental footprint. By converting steel slag into a valuable adsorbent material, this study paves the way for more sustainable industrial practices and contributes to the global effort to reduce CO2 emissions.
As Cheng notes, “This study provides valuable insights into the high-quality utilization of steel slag and the reduction of CO2 emissions in iron and steel companies.” The findings not only advance our understanding of metal element recovery and acid leaching kinetics but also offer a practical solution for enhancing the commercial viability of calcium-based adsorbents in the energy sector.
In the broader context, this research underscores the importance of innovative approaches to industrial waste management and the potential for such methods to drive progress towards a more sustainable future. As the energy sector continues to evolve, the insights gained from this study are likely to shape future developments in the field, fostering a more environmentally conscious and economically viable industrial landscape.