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Fe impurity is abundant in rare earth leaching solutions. The optimal hydrate structure of Fe(OH)2+ was calculated based on the quantum chemical in the water environment to investigate the microscopic occurrence of Fe impurity on kaolinite surfaces. The adsorption structure and bonding mechanism (including outer and inner layer) of hydrate Fe(OH)2+ on the kaolinite (001) surface were investigated. According to the results, the stable hydrate form of Fe(OH)2+ is [Fe(OH)(H2O)5]2+. Hydrated Fe(OH)2+ has a tendency to adhere to the Si-O surface in the form of outer layer adsorption. Adsorbate tends to adsorb to the Ou (deprotonated upright hydroxyl) site, where it generates a monodentate adsorption compound, and to the Ol and Ou (deprotonated lying and upright hydroxyl) sites, where it generates a bidentate adsorption compound if inner layer adsorption occurs. The Mulliken population and density of state analysis demonstrate that the ionic properties of Fe-Os in the inner layer adsorption compound are reduced and Fe-Os bonds are filled with strong bonding and weak antibonding orbitals. More chemical bonds are formed in the bidentate adsorption compound, and the bidentate adsorption has lower adsorption energy. Therefore, in the process of inner layer adsorption, bidentate adsorption is more likely to occur. [ABSTRACT FROM AUTHOR]

This article summarizes the research progress of pyrrhotite beneficiation, and believes that pyrrhotite will remain a research hotspot in flotation and separation from polymetallic sulfide ore. The systematic study of the genetic characteristics of pyrrhotite minerals, and the development of a separation process and pharmaceutical system that are in harmony with the genetic characteristics of minerals are the key research directions in the future. [ABSTRACT FROM AUTHOR]

The galvanic interaction between chalcopyrite and monoclinic pyrrhotite and its effect on flotation separation were studied using monomineral flotation tests, adsorption capacity tests, X-ray photoelectron spectroscopy (XPS) characterization, and scanning electron microscopy (SEM) test. These results showed that the interaction promoted the reduction of O2 on the cathodic chalcopyrite surface and accelerated the generation of Fe(OH)3, which was not conducive to collector adsorption; hence, the flotation recovery decreased by 10–16%. On the other hand, galvanic interaction accelerated the oxidation of S on the anodic monoclinic pyrrhotite surface to S0 or SO42− and produced a large amount of H+, thus preventing the formation of Fe(OH)3. Meanwhile, the Cu2+ eluted from chalcopyrite surface activated monoclinic pyrrhotite; hence, the flotation recovery increased by 3–10%. Galvanic interaction reduced the floatability difference between the two minerals, and the separation difficulty was significantly increased. Even with an increase in the amount of lime, the separation could not be improved. [ABSTRACT FROM AUTHOR]