Qicheng Feng

Adsorption and activation of copper ions on chalcopyrite surfaces: A new viewpoint of self-activation

The adsorption behaviors of copper ions on chalcopyrite surfaces were investigated based on zeta potential measurements, X-ray photoelectron spectroscopy, copper ion adsorption experiments, first-principles calculations, and Hallimond tube cell flotation experiments. The results show that copper ions activate the chalcopyrite as a result of the interactions between copper ions and sulfur on the chalcopyrite surface. This adsorption increases the flotation rate under certain conditions, and this is beneficial for the flotation of chalcopyrite. The copper ions in the flotation pulp are mainly derived from surface oxidation dissolution and the release of fluid inclusions, and these effects enable chalcopyrite to be activated.

A novel method for improving cerussite sulfidization

Evaluation of flotation behavior, solution measurements, and surface analyses were performed to investigate the effects of chloride ion addition on the sulfidization of cerussite in this study. Micro-flotation tests indicate that the addition of chloride ions prior to sulfidization can significantly increase the flotation recovery of cerussite, which is attributed to the formation of more lead sulfide species on the mineral surface. Solution measurement results suggest that the addition of chloride ions prior to sulfidization induces the transformation of more sulfide ions from pulp solution onto the mineral surface by the formation of more lead sulfide species. X-ray diffraction and energy-dispersive spectroscopy indicate that more lead sulfide species form on the mineral surface when chloride ions are added prior to sulfidization. These results demonstrate that the addition of chloride ions prior to sulfidization can significantly improve the sulfidization of cerussite, thereby enhancing the flotation performance.

New influence factor inducing difficulty in selective flotation separation of Cu-Zn mixed sulfide minerals

Selective flotation separation of Cu-Zn mixed sulfides has been proven to be difficult. Thus far, researchers have found no satisfactory way to separate Cu-Zn mixed sulfides by selective flotation, mainly because of the complex surface and interface interaction mechanisms in the flotation solution. Undesired activation occurs between copper ions and the sphalerite surfaces. In addition to recycled water and mineral dissolution, ancient fluids in the minerals are observed to be a new source of metal ions. In this study, significant amounts of ancient fluids were found to exist in Cu-Zn sulfide and gangue minerals, mostly as gas-liquid fluid inclusions. The concentration of copper ions released from the ancient fluids reached 1.02 × 10−6 mol/L, whereas, in the cases of sphalerite and quartz, this concentration was 0.62 × 10−6 mol/L and 0.44 × 10−6 mol/L, respectively. As a result, the ancient fluid is a significant source of copper ions compared to mineral dissolution under the same experimental conditions, which promotes the unwanted activation of sphalerite. Therefore, the ancient fluid is considered to be a new factor that affects the selective flotation separation of Cu-Zn mixed sulfide ores.

Dissolution regularities of smithsonite in methane sulfonic acid

Methane sulfonic acid (MSA) was proposed as a clean and efficient leaching agent to extract zinc from smithsonite. Experimental variables such as acid concentration, reaction temperature, particle size, and stirring speed were considered. Results indicated that zinc leaching fraction increased with increased MSA concentration, reaction temperature, stirring speed, and decreasing particle size. The dissolution kinetics of smithsonite in MSA solutions was investigated with respect to the corresponding experimental data and kinetics was analyzed using a new variant of the shrinking core model, in which both interfacial transfer and diffusion across the product layer affected the dissolution rate. The apparent activation energy of this process was determined to be 32.66 kJ/mol, and a semi-empirical rate equation was obtained to describe the process.

Effects of magnesium and cooling rate on titanium phase transformation for production of TiO2

X-ray diffraction (XRD) and crystal structure analysis were used to study the effects of Mg content and cooling rate on the titanium phase transformation of three types of titanium slag. The results indicate that in the rapid cooling process, the titanium phase is anosovite, whose chemical formula is MgnTi3–nO5 (0<n<1). In the slow cooling process, when the Mg content is high, anosovite transforms into karrooite MgTi2O5 structure; when the Mg content is low, karrooite MgTi2O5 and rutile TiO2 both exist. The stability of karrooite MgTi2O5 is better than that of anosovite MgnTi3–nO5. Slow cooling contributes to the doping of Mg into the anosovite crystal and stabilises the anosovite crystal structure.

Leaching characteristics and mechanism of copper flotation tailings in sulfuric acid solution

The copper deposit in Yangla zone of China is large, and its recovery is low only using flotation process. Therefore, the copper in the flotation tailings is leached by sulfuric acid can improve copper recovery. The factors affecting leaching process and the leaching mechanism were investigated in this study. Copper is leached at a rate of 53.8% when initial H2SO4 concentration is 0.428 mol/L, leaching temperature is 348 K, liquid-to-solid ratio is 3: 1, stirring speed is 300 r/min and leaching time is 60 min. Through combine the acid leaching process of tailings with the flotation process of raw ore, copper comprehensive recovery has been improved. Kinetics results show that the leaching process is controlled by internal diffusion with an activation energy of 9.796 kJ/mol. To characterize the mechanism of acid leaching, chemical analysis, X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy were used. The results indicate that the fine size of copper minerals and CaSO4 precipitation which generated during acid leaching process affected the leaching of copper minerals.

Dissolution kinetics of cerussite in an alternative leaching reagent for lead

The dissolution kinetics of cerussite was investigated using methanesulphonic acid (MSA) as an alternative leaching reagent. The effects of particle size, stirring speed, acid concentration, and reaction temperature on the lead dissolution rate were determined. The dissolution process followed the kinetic law of the shrinking-core model, and a corresponding mixed control model was found suitable for representing the rate-controlling step. The mixed kinetic model comprised two stages: surface chemical reaction (283 K to 303 K) and diffusion through the product layer (303 K to 323 K). The activation energies of these sequential stages were 43.20 kJ mol−1 and 17.20 kJ mol−1, respectively. The corresponding dissolution kinetic equations are also presented to describe the dissolution reaction. The results indicated that methanesulphonic acid could be used as an effective leaching reagent for extracting lead from cerussite minerals.