<p>The leaching behavior of metallic elements in steel slag during acetic acid treatment is critical for its application in carbon sequestration. X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) characterized the content and morphology of major elements (Ca, Mg, Fe) in steel slag. The acid leaching kinetics of 3.2–5.0&#xa0;mm steel slag in acetic acid was investigated via the fractal shrinking core model, where the introduction of fractal dimension improved the accuracy of describing leaching kinetics for large particles. Results showed that Ca²⁺ and Mg²⁺ leaching was dominated by ash-layer diffusion, while Fe³⁺ leaching was controlled by surface reactions. Based on the surface zeta potential of steel slag, benzyltrimethylammonium chloride (TMBAC) was used to neutralize the anion shield layer, reducing ash-layer diffusion resistance and enhancing Ca²⁺ and Mg²⁺ leaching rates. Optimization of reaction parameters yielded a maximum Ca²⁺ leaching rate of 61.51%. This study provides a basis for enhanced approaches to utilizing steel slag in processes requiring metal extraction, such as carbon sequestration.</p> Graphical Abstract <p></p>