The characteristics of Huimin siderite ore with high content of phosphorus and the reduction of this ore bearing pulverized coal and sodium carbonate were investigated. The study focuses on the influence of Na2CO3 dosage on the carbothermic reduction process. Iron particle size in reduced ore is tiny and the fayalite is abundant without Na2CO3 additive. With ratio of Na2CO3 to ore at 1:20 or 1:10, iron particle size in reduced ore is coarse and the diffraction intensity of metallic iron increases obviously in the XRD pattern. The reduction of siderite can be catalyzed by adding an appropriate amount of Na2CO3. The catalyzing activity may be caused by the increase of the reducing reaction activity of FeO and the acceleration of the carbon gasification reaction rate. The phosphorus compounds were not reduced in the low temperature reduction process and remained as fluorapatite in the gangue phases. Ultrafine grinding-magnetic separating of magnetic minerals is an efficient way to obtain qualified iron concentrate.
This study aims to determine the presence and release of fluid inclusions in natural pure bornite while investigating the types, structures, and compositions of such inclusions. This work also measures the total concentrations of Cu (C CuT ), Fe (C FeT ), and Cl − , SO 4 2− , which are released to the bornite aqueous solution from fluid inclusions. The results indicate that numerous fluid inclusions are distributed in isolation or along the crevices in the bornite. The fluid inclusions take on such shapes as long strips and irregular strips, with the body sizes ranging from 3 to 40 μm. Through the crushing and grinding process, the inclusions that are captured from the diagenetic and metallogenic process of bornite would be released to the flotation pulp along with Cu, Fe, Cl − , SO 4 2− , etc. Results indicate that the C CuT and C FeT values in the solution are significantly higher than those from the experimental dissolution. Therefore, results confirm that the release of inclusions is a new source of Cu and Fe ions in the aqueous solution. Moreover, the findings exhibit a new discovery of an unavoidable ion source in the flotation pulp, and the residual position domain after the release of the inclusions causes the difference in bornite surface composition and roughness. The new discovery expands the research objectives and scope in flotation solution chemistry and is significant in the study of flotation theory.
The surface states of pyrite (FeS 2 ) were theoretically investigated using first principle calculation based on the density functional theory (DFT). The results indicate that both the (200) and (311) surfaces of pyrite undergo significant surface atom relaxation after geometry optimization, which results in a considerable distortion of the surface region. In the normal direction, i.e., perpendicular to the surface, S atoms in the first surface layer move outward from the bulk, while Fe atoms move toward the bulk, forming an S-rich surface. The surface relaxation processes are driven by electrostatic interaction, which is evidenced by a relative decrease in the surface energy after surface relaxation. Such a relaxation process is visually interpreted through the qualitative analysis of molecular mechanics. Atomic force microscopy (AFM) analysis reveals that only sulfur atom is visible on the pyrite surface. This result is consistent with the DFT data. Such S-rich surface has important influence on the flotation properties of pyrite.
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