<p>Electric arc furnace steelmaking using metallized pellets is crucial for the green, low-carbon, and high-quality development of the iron and steel industry. However, their melting mechanisms across the iron bath, slag bath, and slag−iron bath remain unclear, hindering application. This paper proposed a mathematical model considering slag−iron distribution, fluid flow, and heat transfer. Following validation of melting process of the iron ball in the slag bath, this model was used to investigate the melting behavior of metallized pellet in varied melt pool. The results indicate that the melting process can be categorized into three distinct stages: the frozen shell formation, the frozen shell remelting, and the metallized pellet parent melting. Due to the low thermal conductivity of the slag phase, the slag phase frozen shell acts as a thermal resistance barrier, hindering heat transfer. Consequently, the frozen shell is thin and the melting time is long in pure slag bath. Conversely, the iron phase frozen shell can promote the heat transfer, making metallized pellet consume more heat and the frozen shell thicker in pure iron bath. Simultaneously, metallized pellet heats up rapidly and melt faster. Underneath these dual influences, the maximum thickness of frozen shell and melting rate observed within slag−iron bath fall between iron bath and slag bath, and the metallized pellet in the slag−iron bath presents mushroom shape. In industrial practice, metallized pellets are supposed to be rapidly driven through the slag layer into the iron bath to achieve rapid melting.</p> Graphical Abstract <p></p>