<p>The waste heat boiler (WHB) of the copper flash smelting furnace is an essential component of the copper smelting process. However, corrosion within the WHB can markedly reduce its operational efficiency and hinder effective energy utilization. In this study, the corrosion mechanisms of the WHB have been systematically investigated through a combination of industrial-scale material characterization and laboratory-based corrosion experiments. The results revealed that the ferrous sulfate-alkali metal complex salts (M₃Fe(SO₄)₃ (M=K/Na)) are the primary corrosive agents, which can form low-melting eutectic phases that induce corrosion under high temperature. Kinetic analysis of the overall reaction between the radiant dust and the steel flue boundary yielded an apparent activation energy (ΔE) of 62.37 kJ/mol and a pre-exponential factor (A) of 0.054 kg/m² s. Temperature was found to exert a significant influence on the corrosion behavior by accelerating the reaction kinetics; the average corrosion rate at 515°C (1.4850 g/cm² h × 10⁻⁴ g/cm² h) was approximately seven times higher than that observed at 380°C.</p> Graphical Abstract <p></p>