Surface Relaxation and Structural Reconstruction of Copper Sulfide Minerals
Brass is a typical ore mineral crystals, minerals crushing process, and a fresh surface produced about the internal structure of the crystal, but the internal structure of crystals having a significant difference, the difference is formed on the surface of the surface caused by instantaneous relaxation . This surface relaxation and reconstitution of chalcopyrite has an important influence on the surface properties of the flotation.
The papers and Deng Jiushuai obtained a three-dimensional microstructure topography and a two-dimensional topography of surface electron cloud distribution on the surface of the chalcopyrite by atomic force microscopy. AFM analysis revealed that the longitudinal and lateral alignment of the surface of the chalcopyrite surface changed compared to the interior of the crystal. In the longitudinal direction, the copper, iron and sulfur atoms are displaced relative to the original position, ie surface relaxation occurs, and as a result of the relaxation, the sulfur atoms are located in the outermost region of the surface. The X-ray photoelectron spectroscopy results also show that the sulfur atom content on the surface of the chalcopyrite is larger than the sulfur atom content in the crystal, forming a sulfur-rich surface. In the horizontal direction, the AFM spectrum shows that the atomic spacing is irregular and the surface is reconstructed. The result of the recombination brings two or more atoms close together to form an atomic aggregate. Using the plane wave supersoft pseudopotential method based on density functional theory, the unit cell is geometrically optimized. The results show that the atomic arrangement on the surface of the surface becomes irregular, and the surface sulfur atom moves outward along the z-axis. The bond and iron-sulfur bond length increase, the z-axis direction value of the model increases, the unit cell volume expands, the surface relaxes, and the crystal structure remodels.
De Lima et al. studied the remodeling properties of the chalcopyrite (0 01) surface and the adsorption of water molecules on the surface. Studies have shown that a sulfide dimer with a bond length of 2.23 × 10-10 is formed after reconstitution. And forming a surface of a metal atom and a sulfur atom staggered plane. The interaction between water molecules and relaxation surfaces at different adsorption sites and the cleavage mechanism of water molecules were studied. For the sulfur-rich surface of the (0 01) plane, water molecules are most likely to adsorb on the iron atoms. In the metal layer of the (0 01) plane, no lowest point of the potential energy surface is found, and water molecules are more likely to form hydrogen bonds with sulfur atoms. The adsorption characteristics of water molecules and surfaces indicate surface hydrophobic properties.
The surface chemistry of copper sulfide minerals is critical to the floatability of the ore particles and the process is complex. Grinding and secondary grinding are important causes of changes in surface properties. The change in surface properties caused by grinding has a greater impact on the recovery of minerals than simply changing the ore particle size. In addition, the chemical conditions during the grinding process also affect the flotation characteristics and surface properties of the copper sulfide ore. In addition to the effect of particle hydrophobicity and particle size on flotation, the surface roughness of minerals also plays an important role. The surface roughness of mineral crystals affects the basic process of particle-foam action.
Liu Shujie et al. studied the effects of different grinding methods on the surface properties of chalcopyrite and subsequent flotation. The results show that the dry-grinding chalcopyrite floatation is better than that of wet-grinding chalcopyrite. The chalcopyrite suspension of porcelain media grinding is better than the chalcopyrite of iron media grinding. The metal-deficient and sulfur-rich surface formed by the oxidation of chalcopyrite will greatly improve its flotation recovery rate and floating speed.
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