Institute of Comprehensive Exploitation of Mineral Resources, Russian Academy of Sciences, Moscow, Russia.

T. N. Matveeva, Head of the Laboratory of Mineral Components Separation Theory, e-mail: tmatveyeva@mail.ru
T. A. Ivanova, Senior Researcher
N. K. Gromova, Researcher

The results of the study of adsorption and flotation properties of the reagents of plant origin — tannin and OBE (oak bark extract) to be used as modifiers of iron sulfides flotation in processing of multicomponent ores are defined. The main tasks of the experiments are to examine the conditions for complex-formation, flotation and adsorption characteristics of tannin and OBE at sulfide minerals flotation with the aim to increase the selectivity of their separation. A method of obtaining the reagent OBE is designed that helps to get a product with a fixed content of extractable tannins. Tannin complexation with ions of iron (II) and (III) in aqueous solutions and the change in residual concentration of the reagents after contact with pyrite, arsenopyrite and pyrrhotite are studied by UV spectrophotometry, and the adsorption of reagents on the studied minerals is evaluated. It is found that the OBE and tannin, that possess hydrophilic and complexing properties are capable of forming complexes with iron in aqua solutions at flotation and at low concentrations are selective depressors for pyrite and pyrrhotite in a weakly acidic, neutral or slightly alkaline medium. The mechanism of action of depressing tannin-bearing reagents is based on their adsorption on the surface of pyrrhotite and arsenopyrite to form strong complexes with iron ions (III) at concentrations below the concentration of micelle formation, and the pre-adsorption of xanthate does not prevent the consolidation of OBE on the surface of the mineral. The application of tannin and the OBE as depressors of pyrrhotite, pyrite and arsenopyrite will help to increase the extraction of valuable components and quality of concentrates by improving the selection of gold and platinum-bearing sulfide minerals of copper, nickel and iron.

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