Jiushuai Deng

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.

Extracting copper from copper oxide ore by a zwitterionic reagent and dissolution kinetics

Sulfamic acid (SA), which possesses a zwitterionic structure, was applied as a leaching reagent for the first time for extracting copper from copper oxide ore. The effects of reaction time, temperature, particle size, reagent concentration, and stirring speed on this leaching were studied. The dissolution kinetics of malachite was illustrated with a three-dimensional diffusion model. A novel leaching effect of SA on malachite was eventually demonstrated. The leaching rate increased with decreasing particle size and increasing concentration, reaction temperature and stirring speed. The activation energy for SA leaching malachite was 33.23 kJ/mol. Furthermore, the effectiveness of SA as a new reagent for extracting copper from copper oxide ore was confirmed by experiment. This approach may provide a solution suitable for subsequent electrowinning. In addition, results reported herein may provide basic data that enable the leaching of other carbonate minerals of copper, zinc, cobalt and so on in an SA system.

Dynamic Simulation of the Thermal Decomposition of Pyrite Under Vacuum

The ultrasoft pseudopotential plane wave method is applied to dynamic simulation of the thermal decomposition mechanism of FeS2 under vacuum. The FeS2 (100), (111), and (210) surface relaxation and the geometric and electronic structure of the reactants and products are calculated. The results indicate that FeS2 (100) is the most preferred surface to dissociate and also the most common cleavage surface. The thermal decomposition mechanism of FeS2 is explained by dynamic simulation on a micro stratum: in general, the S-Fe bond gradually elongated until it fractured, the S-S bond strengthened gradually, the S-Fe bond was cleaved to form S, the force is relatively weaker between different layers, and thermal decomposition occurred easily between the layers. Simultaneously, the intermediate products, such as FexSy, were formed. Evidence of Fe pyrolysis into Fe metal was not found, and the intermediate products decomposed further. The contributions of the p and d orbitals of Fe increased, whereas that of the s orbital decreased. The contributions of the s and p orbitals of S decreased. The results obtained from FeS2 thermal decomposition experiments under vacuum and differential thermal analysis—thermogravimetry are consistent with the results of calculation and simulation.

Leaching kinetics of cerussite using a new complexation reaction reagent

In this paper, an attractive organic complexation reaction reagent with lead ions was developed for lead extraction from cerussite. The leaching kinetics of cerussite was investigated using 5-sulfosalicylic acid solution as a lixiviant. The effects of several experimental parameters on the leaching of cerussite were investigated, and a kinetic model was developed to represent the relationship. The leaching process was controlled by a mixed kinetic model. The results showed that the leaching rate of cerussite increased with an increase in the stirring speed, temperature, and concentration, as well as a decrease in the particle size. The activation energy was found to be 37.07 kJ mol−1. The rate of reaction based on the mixed kinetic model-controlled process could be expressed as [1 − (1 − x)1/3]2 = [k0(SS)6.852(r0)−1.943(C)2.042 exp(−37.07/RT)]t. X-ray diffraction and scanning electron microscopy/energy-dispersive X-ray spectroscopy analyses indicated that a new solid reaction product may be formed.

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.

Theory analysis and vestigial information of surface relaxation of natural chalcopyrite mineral crystal

Abstract X-ray diffraction was used to measure the unit cell parameters of chalcopyrite crystal. The results showed that the chalcopyrite crystal is perfect, and the arrangement of its atoms is regular. A qualitative analysis of molecular mechanics showed that surface relaxation causes the chalcopyrite surface to be sulfur enriched. Atomic force microscope (AFM) was used to obtain both a microscopic three-dimensional topological map of chalcopyrite surface and a two-dimensional topological map of its electron cloud. The AFM results revealed that the horizontal and longitudinal arrangements of atoms on the chalcopyrite surface change dramatically compared with those in the interior of the crystal. Longitudinal shifts occur among the copper, iron and sulfur atoms relative to their original positions, namely, surface relaxation occurs, causing sulfur atoms to appear on the outermost surface. Horizontally, AFM spectrum showed that the interatomic distance is irregular and that a reconstruction occurs on the surface. One result of this reconstruction is that two or more atoms can be positioned sufficiently close so as to form atomic aggregates. The lattice properties of these models were calculated based on DFT theory and compared with the experimental results and those of previous theoretical works. On analyzing the results, the atomic arrangement on the (001) surface of chalcopyrite is observed to become irregular, S atoms move outward along the Z-axis, and the lengths of Cu—S and Fe—S bonds are enlarged after geometry optimization because of the surface relaxation and reconstruction. The sulfur-rich surface and irregular atomic aggregates caused by the surface relaxation and reconstruction greatly influence the bulk flotation properties of chalcopyrite.

Investigation of dissolution kinetics of zinc from smithsonite in 5-sulphosalicylic acid solution

Abstract The dissolution kinetics of smithsonite was investigated using 5-sulphosalicylic acid solution as leaching agent. The effects of several experimental parameters on the dissolution of smithsonite were investigated and a kinetic model was developed to represent these relationships. The dissolution rate increased with increasing solution temperature, concentration and stirring speed as well as with decreasing particle size. The dissolution was controlled by the shrinking core model for the surface chemical reaction. The activation energy of the dissolution process was determined to be 44·42 kJ mol−1. The rate of the reaction based on shrinking core model can be expressed by a semi-empirical equation as: 1–(1–x)1/3 = [k0(C)0·692(r0)−0·946(SS)1·250exp(–44·42/RT)]t. 5-Sulphosalicylic acid solution can therefore be used as an effective leaching agent for zinc extraction from smithsonite.

Reaction kinetics of malachite in ammonium carbamate solution

The dissolution of malachite particles in ammonium carbamate (AC) solutions was investigated in a batch reactor, using the parameters of temperature, AC concentration, particle size, and stirring speed. The shrinking core model was evaluated for the dissolution rate increased by decreasing particle size and increasing the temperature and AC concentration. No important effect was observed for variations in stirring speed. Dissolution curves were evaluated in order to test shrinking core models for fluid-solid systems. The dissolution rate was determined as being controlled by surface chemical reaction. The activation energy of the leaching process was determined as 46.04 kJ mol−1.

Recovering copper from volcanic ASH by NH3 · H2O–NH2COONH4

Volcanic ash from Xinjiang in the PRC contains malachite and cuprite. The volcanic ash has a copper content of 1.29%. However, because of severe argillization it is difficult to recover the copper through enrichment by flotation. Because the ash contains significant amounts of calcium and magnesium carbonates leaching the ash with acid requires a large amount of acid. We thus studied the use of ammonia-water and ammonium carbamate as effective leaching agents for copper. Leaching with ammonia-water and ammonium carbamate does not affect gangue minerals such as quartz and calcite and it can also promote the dissolution of minerals that contain copper. This leaching agent is highly specific. Using this system we recovered more than 90% of the copper from the volcanic ash. Higher reaction temperatures, smaller ore particle sizes, a higher stirring speed, a higher liquid to solid ratio and an increase in the agent’s concentration increased the copper leaching rate. SEM analysis, the activation energy (7.827 kJ/mol) and kinetics data comprehensively indicate that the reaction of copper minerals in the ammonia-water and ammonium carbamate system is controlled by internal diffusion.

Existence and release of fluid inclusions in bornite and its associated quartz and calcite

The existence and release of fluid inclusions in bornite and its associated minerals, namely, quartz and calcite were investigated and confirmed. The structures, forms, and phases of these large quantities of fluid inclusions were also studied. A mass of fluid inclusions with various sizes, distributions, shapes, and phases exist in bornite and its associated minerals. Their sizes vary from a few micrometers to tens of micrometers, and the forms appear as negative crystals, or elongated, elliptical, and irregular. At room temperature, fluid inclusions were mainly characterized as gas-liquid twophase. However, small amounts of fluid inclusions with pure gas phase and pure liquid single-phase were also observed in quartz and calcite. These fluid inclusions initially broke during the ore crushing and grinding process and then released into the flotation pulp in the flotation process. The quantitative analysis of fluid inclusions in the solution and the comparisons of mineral dissolution show that the amount of copper and iron released by fluid inclusions in the bornite sample is higher than the amount dissolved by the mineral; fluid inclusions in the associated gangue minerals, quartz, and calcite also make contribution.