Study on the fabrication of active CaO from steel slag of the converter and its application in CO2 adsorption process
J. Min. Metall. Sect. B-Metall., 61 (1) (2025) 71-84. DOI:10.2298/JMMB241025006C
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Available online 09 May 2025
(Received 17 October 2024; Accepted 09 April 2025)
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An acetic acid leaching process was used to extract calcium components from converter steel slag, followed by evaporation and crystallization to obtain high-purity CaO material. The effects of the different leaching parameters on the CaO content were systematically investigated. The shrinking core model was used to analyze the leaching rate of weakly acidic solutions. Subsequently, the CO2 adsorption performance of the CaO material was evaluated under different conditions, and the adsorption process and reaction mechanism were investigated by XRD and SEM analyses. The results showed that the leaching temperature and acetic acid concentration significantly affected the CaO content. 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 were found to be the optimum leaching parameters, resulting in a maximum CaO content of 86.3%. Kinetic studies showed that stirring shifted 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 was the rate-controlling step. XRD and SEM analyses confirmed the high purity of the CaO material. CaO initially converted to Ca(OH)2, which adsorbed CO2 and formed CaCO3. The deposition of CaCO3 on the surface of the material prevented further contact between Ca(OH)2 and CO2, reducing the efficiency of carbon adsorption and increasing the CaO content, which significantly improved the adsorption performance. In the adsorption temperature range of 0-100 °C, ensuring effective contact between Ca(OH)2 and CO2 was crucial. 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. This study provides valuable insights into the high-quality utilization of steel slag and the reduction of CO2 emissions in iron and steel companies.
Keywords: Steel slag; CO2 emission reduction; Calcium-based adsorbent; Metal element recovery; Acid leaching kinetics
Correspondence Address:
R. Mao,
Jiangsu (Shagang) Iron and Steel Research Institute, Zhangjiagang, China; Jiangsu Shagang Group Co. LTD, Zhangjiagang, China;
email: maorui0138@163.com
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