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for various applications in batteries, solder, dielectric materials, and piezoelectric materials. High-grade, easily concentrated ores are becoming scarcer: to meet world demands for zinc, it is necessary to develop economical and environmentally safe metallurgical technologies that use secondary materials such as leach residues of roasted zinc concentrates and electric arc furnace dusts. The zinc in the majority of these wastes occurs in the form of zinc ferrite (franklinite, ZnFe2O4), which is very stable and insoluble in most acidic and alkaline solutions (Langová and Matýsek, 2009; Youcai and Stanforth, 2000). Several pyrometallurgical and hydrometallurgical processes (Jankovi et al., 2014; Langová and Matýsek, 2010; Morcali et al., 2012; Shawabkeh, 2010) have been proposed for the treatment of zinc ferrites. Pyrometallurgical methods are costly owing to high energy consumption and their emissions of toxic gases are considered an environmental problem; hydrometallurgical methods are preferred for process economy and environmental reasons (Copur et al., 2004). Because of the need to eliminate elements such as Fe, Cd, Ni, and Co from the leachate and the high acid consumption incurred for the digestion of iron oxides, industrial-scale utilization of acidic leaching processes has been impeded. Only Zn and Pb dissolve effectively in caustic alkaline solution, so alkaline processes are often chosen to leach Zn and Pb selectively from Zn-bearing dusts and secondary resources (Youcai and Stanforth, 2001). However, it is difficult to extract zinc from zinc ferrite by NaOH solution under atmospheric pressure: the maximum reported extraction of zinc from decomposed zinc ferrite was only about 9%, after leaching in 10 M NaOH solution for 3 hours at 93°C (Xia and Pickles, 1999). Youcai and Stanforth (2000) showed that the zinc ferrite structure could be broken by fusing it with sodium hydroxide: the dust was hydrolyzed in water and then fused with caustic soda at 350°C, following which 95% of the zinc was leached. However, in addition to leachable Zn, elements such as Fe and Ca may also react with sodium hydroxide during fusion of the zinc ferrite, resulting in high consumptions of this reagent. Mechanical activation of minerals nowadays represents an important contribution to different fields of solids processing technology. Mechanical activation comprises high-energy ball milling, during which the particles undergo repeated fracturing and cold welding during collisions either between balls or between a ball and the inner wall of the mill (Gilman and Benjamin, 2009). In extractive metallurgy, activation by high-energy milling is reported to decrease the reaction temperature in pyrometallurgical processes and Extraction of zinc from zinc ferrites by alkaline leaching: enhancing recovery by mechanochemical reduction with metallic iron