Kinetic Analysis Considering Particle Size Distribution on Ca Elution from Slags in CaO–SiO2–MgO–Al2O3–Fe2O3 System

• Published in: ISIJ International 2020/12/15, Vol.60(12), pp.2859-2869
• Main Authors: Kashiwaya, Yoshiaki, Tauchi, Seitarou, Nomura, Takanori, Akiyama, Tomohiro
• Format: Article
• Language: English
• Subjects: alkali dissolution; kinetic analysis; new kinetic model; particle size distribution; slag utilization
• ISSN: 0915-1559; 1347-5460
• DOI: 10.2355/isijinternational.ISIJINT-2020-265

The understanding of the behavior of alkali elution from slags is important for their effective recycling and utilization. In a previous study, it was reported that the addition of iron oxide to steel slags significantly inhibited alkali elution. A lower modified basicity, i.e., CaO/(SiO2 + Fe2O3) ratio, indicates a lower alkali elution from the slags. In addition to the effect of Fe2O3 content, particle size distribution is an important parameter to determine the elution of Ca quantitatively.In this study, a kinetic model considering particle size distribution is developed and applied to the results of a dissolution experiment using samples of a slag, which is designated as SlagF4, with different particle size distributions. In the new kinetic model, an effective surface area and the effectiveness of total surface area α are introduced, and a kinetic analysis is performed. The rate constant k obtained is a fixed value for one sample type; k decreased with the increase in Fe2O3 content.The values of α increased significantly with the increase in the total surface area ST (i.e., a decrease in particle diameter) in different particle size distributions. It is discovered that α typically represents the Ca elution tendency. Additionally, the change in α is small with the change in the Fe2O3 content. It is demonstrated that the developed kinetic model is valid for the analysis of Ca elution for samples with different particle size distributions.