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Sulfidation roasting followed by flotation is widely known as a possible generic technology for enriching valuable metals in low-grade Zn-Pb oxide ores. Zn 2 SiO 4 is the primary Zn phase in willemite. Zn 4 Si 2 O 7 (OH) 2 (H 2 O), the main Zn phase in hemimorphite, transforms into Zn 2 SiO 4 at temperatures above 600 °C. To enrich the Zn in willemite and hemimorphite, the Zn species should first be converted to ZnS. Therefore, a thorough understanding of the sulfidation reaction of Zn 2 SiO 4 during roasting with pyrite is of vital important. In this study, the sulfidation behavior and reaction mechanisms of a Zn 2 SiO 4 -pyrite roasting system were determined using HSC 5.0 software, TG-FTIR spectroscopy, XRD, XPS and SEM-EDS. The results indicate that the sulfidation process can be divided into three steps: the decomposition of pyrite and formation of a sulfur-rich environment, the sulfur-induced migration of O 2− and transformation of sulfur vapor, and the sulfidation reaction via oxygen-sulfur exchange. During the sulfidation roasting process, pyrite was converted to loose and porous Fe 3 O 4 , whereas Zn 2 SiO 4 was transformed into ZnS and SiO 2 in situ. These findings provide theoretical support for controlling the sulfidation roasting process of willemite and hemimorphite. [ABSTRACT FROM AUTHOR]