Abstract: CaCl₂ was used to chlorinate ZnFe₂O₄,an important component in metallurgical dust.The changes of the reaction surface between ZnFe₂O₄ and CaCl₂ and the microstructure of reaction products were investigated by scanning electron microscopy(SEM) and energy dispersive spectrometry(EDS),and the reaction mechanism was discussed.It is considered that the whole process includes a solid-liquid reaction and a gas volatilization.ZnFe₂O₄ particles are coated by melted CaCl₂ and the chlorination reaction occurs at the liquid-solid interface,the product ZnCl₂ dissolves in the liquid membrane of CaCl₂ and escapes from the gas-liquid interface.During the chlorination reaction,the product layer of ZnFe₂O₄ increases companying with the adhering and growing up of the particles.