Investigation of the acicular aragonite growth behavior in AOD stainless steel slag during slurry-phase carbonation

This study presents a novel method for producing acicular aragonite using argon oxygen decarburization (AOD) slag while controlling the reaction temperature, reaction time, stirring speed, and the magnesium-to-calcium stoichiometric ratio. This approach provides steel plants with an opportunity to decrease their CO2 emissions and promote efficient resource utilization and CO2 storage through the production of high-quality value-added products. The experimental results showed that reaction temperature was the most significant factor affecting the carbonation efficiency of AOD slag, followed by reaction time, stirring speed, CO2 partial pressure, and the liquid-to-solid ratio (L/S). The study also found that elevated temperature and prolonged reaction duration favored the preferential precipitation of aragonite. Additionally, raising the temperature and the magnesium-to-calcium stoichiometric ratio was shown to enhance the formation of aragonite, affecting its crystal growth orientation and dimensions. The optimal combination of reaction parameters for the preparation of acicular aragonite was found to be the reaction time of 8 h, the magnesium-to-calcium stoichiometric ratio of 0.8, the reaction temperature of 120 degrees C, and the stirring speed of 200 r center dot min(-1). Under these conditions, the resulting acicular aragonite exhibited excellent overall uniformity, a large aspect ratio, and a smooth crystal surface, with a content of 91.49 %, a single crystal length ranging from 9.86 to 32.6 mu m, and a diameter ranging from 0.63 to 2.15 mu m. This study provides valuable insights into the efficient production of acicular aragonite from steel slag while reducing CO2 emissions and promoting the sustainable use of resources.

Automated summary

This study presents a novel method for producing acicular aragonite using AOD slag while controlling various reaction parameters. The results showed that reaction temperature had the most significant impact on carbonation efficiency, followed by reaction time, stirring speed, CO2 pressure, and liquid-to-solid ratio. Higher temperature and longer reaction duration favored the precipitation of aragonite. Increasing both temperature and the magnesium-to-calcium stoichiometric ratio enhanced aragonite formation and affected its crystal growth orientation and dimensions. The optimal combination of reaction parameters resulted in acicular aragonite with excellent overall uniformity, high aspect ratio, and smooth crystal surface. This study provides valuable insights into the efficient production of acicular aragonite from steel slag while reducing CO2 emissions and promoting resource sustainability.