Hydrometallurgy presents, as compared to pyrometallurgy, advantages associated to lower energy consumption and much lower emissions of polluting gases, including the ones generating the greenhouse effect. The physicochemical properties of ionic solutions are employed in order to develop processes which facilitate the recycling of industrial inorganic residues (electric arc furnace steel dust after being treated in the Waelz process, salt cakes from the secondary smelting of aluminum, etc.). Among the developed projects, the production of metallic zinc or commercial zinc salts from Waelz oxide, and the reduction in fluoride content in several residues stand out. In these processes lixiviation, oxidation, cementation and selective precipitation steps are involved. An integrated part of these processes are also the steps which allow regeneration of lixiviation liquids and adequate treatments of the residual currents generated in order to minimize the process environmental impact.