Recycling metals from secondary materials and more complex ores has recently been attracting more attention, creating a need for more precise separation methods of different elements. This study proposed a sulfation-roasting method and designed thermodynamic conditions to selectively facilitate the formation of copper sulfate while separating iron as oxide.The roasting behaviors for chalcopyrite, copper slag, and pure copper compounds were investigated in a 0.5% SO2–0.5% O2–99% Ar atmosphere at 600°C. X-ray fluorescence spectroscopy, x-ray diffractometry, scanning electron microscopy, and energy dispersive x-ray spectrometry were used to characterize the raw materials and roasting products.The proposed methodology was confirmed for a complete separation of Cu from Fe, and, further, the sulfation-roasting mechanism of chalcopyrite was confirmed by thermodynamic calculations and experimental observations. These will provide a theoretical basis for copper recycling from both complex primary and secondary copper-bearing materials.