Xianzhong Bu

The inhibiting mechanism of high pH on the molybdenite flotation was studied using an experimental and DFT method. The experimental results found that adverse effects of pH on molybdenite flotation should be attributed to the adsorption of OH⁻ on molybdenite [100] surface (MS100). The DFT results show the adsorption energy of H₂O/OH⁻ to molybdenite [001] surface (MS001) and MS100 is −8.61/288.30 kJ·mol⁻¹ and −226.81/−302.44 kJ·mol⁻¹. These indicate that H₂O is weakly adsorbed on MS001, while OH⁻ is not. Both H₂O and OH⁻ can be adsorbed onto MS100. The adsorption energy of OH⁻ to MS100 is much stronger than that of H₂O. The results of state density and charge transfer of the adsorption of OH⁻ on MS100 further show that OH⁻ can be chemically adsorbed on MS100 through the bonding of the O atom of OH⁻ and the Mo atom of MS100. This causes a significant reduction in the MS100 hydrophobicity and deteriorates the fine molybdenite flotation.

In the salt lake industry, large amounts of steamed ammonia liquid waste are discharged as byproducts. The conversion of the residues into high value-added vaterite-phase calcium carbonate products for industrial applications is highly desirable. In this research, the feasibility of preparing vaterite-phase CaCO₃ in different CaCl₂-CO₂-MOH-H₂O systems using steamed ammonia liquid waste was studied in the absence of additives. The effects of initial CaCl₂ concentration, stirring speed and CO₂ flow rate on the composition of the CaCO₃ crystal phase were investigated. The contents of vaterite were researched by the use of steamed ammonia liquid waste as a calcium source and pure calcium chloride as a contrast. The influence of the concentration of CNH₃·H₂O/C_Ca²⁺ on the carbonation ratio and crystal phase composition was studied. The reaction conditions on the content, particle size and morphology of vaterite influence were discussed. It was observed that single vaterite-phase CaCO₃ was favored in the CaCl₂-CO₂-NH₄OH-H₂O system. Additionally, the impurity ions in steamed ammonia liquid waste play a key role in the nucleation and crystallization of vaterite, which could affect the formation of single-phase vaterite. The obtained results provided a novel method for the preparation of single vaterite particles with the utilization of CO₂ and offered a selective method for the extensive utilization of steamed ammonia liquid waste.

Flotation kinetic models can be applied to describe the flotation process and to predict mineral recoveries. However, the size composition of the target minerals in the feed ore fluctuates considerably, resulting in insufficient accuracy with flotation kinetic models. There have been many studies...

In this study, the electronic structure of the galena surface was investigated using the first-principle calculation. The results of band structure, density of states, Mulliken population distribution, and frontier orbital analysis showed that galena was the p-type semiconductor of the direct band gap. During the formation of galena crystals, the 3p orbital of the S and the 6p orbital of the Pb played a primary role. Additionally, S atoms in galena quickly lose electrons and are oxidized, while Pb readily reacts with anions. The results of surface structure and electronic properties, such as surface relaxation, surface state energy levels, electronic density of states, and atomic charge distribution showed that the electronics in the 6p orbital of the Pb are transferred to the 3p orbital of the S in galena crystal. They caused the change of atomic valence states in lattice surfaces. The total electron number of the outermost surface layer was also higher than the bulk, giving the galena surface the properties of electron enrichment. This research is of great significance for developing new galena flotation reagents and for further in-depth exploration of the adsorption of reagents on the galena surface.

The properties of flash-roasted products from low-grade refractory iron tailings (IGRIT) and the improved method for their magnetic separation index were investigated by the MLA, XRD, iron phase analysis, and magnetic separation test. The results show the siderite and hematite in the IGRIT have...

Refractory iron ore is often discarded as tailings. This causes a great waste of iron resources. In this paper, the flash roasting-magnetic separation process was designed by combining the magnetic separation process of magnetite and the process mineralogy of iron tailings. The flash suspension roasting effects with 3–4 s roasting time were evaluated by magnetic separation. The MLA results show that the tailings are ground to a fineness of P90 −75 μm, where the distribution of siderite and M/H in the −75 μm particle size is 85.37% and 92.75%, respectively. Moreover, M/H and siderite are mainly associated with muscovite and quartz. This indicates that regrinding for contiguous bodies of M/H and siderite is beneficial for improving the grade and recovery of iron concentrates. The results of the flash roasting-magnetic separation process show that a mixed iron concentrate containing 60.10% Fe with an iron recovery of 81.13% would be achieved after selective grinding and staged magnetic separation of the roasted ore. The result indicates that the flash suspension roasting effects with 3–4 s roasting time are achievable. The study provides an efficient approach for recovering refractory iron from tailings.