The 3D numerical simulation model of deep hard-rock deposit in Kaiyang Phosphate Mine of Guiyang was established based on the practical engineering using 3DEC numerical simulation software. The distribution characteristics of displacement fields and plastic zones of the orebody were simulated in three different excavation cases, including the case of excavation artificial inducted roadway in the orebody, the case of horizontal or vertical excavation direction and the case of the upward or downward excavation order. The simulation results indicate that the plastic zone and displacement field of surrounding rock around the inducted roadway are continuously increasing with the increase of the exposure time after digging an artificial inducted roadway in the orebody. Thus the raw rock ore becomes easier to be fragmented, which provides advantageous conditions for roadheader to cut high stress hard-rock. It is worthy noting that there is a large difference in effective utilization of deep ground pressure between horizontal and vertical excavation directions. The later can produce larger deformation and fracture zone than the former on the rock mass around the deduced roadway, which means that the later may utilize the high ground pressure more effectively to break hard-rock. And the obtained results also show that upward excavation order is more helpful for ground pressure to break rock than downward excavation order.

The effect of electrolyte on settling behavior of kaolinite was studied. Effects of hard water on selective flocculation of diasporic bauxite was tested and the measures were taken to eliminate the effects of Ca²⁺ and Mg²⁺ in hard water. The results indicated that, not only the concentration of electrolyte ions but also the ionic valence of the electrolyte ions affects the settling behavior of kaolinite; hard water significantly affects its selective flocculation owing to Ca²⁺ and Mg²⁺; general dispersants could not eliminate the effects of Ca²⁺ and Mg²⁺. Self-made softening agent in our lab could weaken or eliminate the effects of hard water on flocculation processes. The results of molecular dynamics simulation show that softening agent molecules could restrict Ca²⁺ and prevent them from playing their roles, so as to eliminate the effects. The continuous pilot experiment results of bauxite flocculation were even better than those obtained in laboratory.

Passivation is a common phenomenon on the surface of chalcopyrite in the process of bioleaching. The ordinary leaching and strengthening leaching by adding glass beads were carried out. The results show that the passivation of chalcopyrite was greatly weakened in strengthening leaching due to the change of leaching conditions. The copper leaching efficiency was increased from 50% to 89.8% through adding beads. The SEM and X-ray diffraction (XRD) analyses illustrate that there are few jarosite precipitates and weak passivation on the surface of chalcopyrite in strengthening leaching. In contrast, there are thick and compact jarosite precipitate and obvious passivation in ordinary leaching, which hinders further dissolution of chalcopyrite.

High gradient magnetic separation was conducted in order to separate insoluble zinc ferrite from zinc calcine before acid leaching of hydrometallurgical process. Chemical composition and structural characterization of zinc calcine were studied via inductively coupled plasma (ICP), X-ray diffraction (XRD), Mössbauer spectra, scanning electron microscopy (SEM) and laser particle analysis (LPA). The parameters of magnetic separation which affect the distribution of zinc ferrite and undesired elements, such as calcium, sulfur and lead in magnetic concentrate were investigated. The results of high gradient magnetic separation indicate that more than 85% of zinc ferrite is distributed into magnetic concentrate from the zinc calcine under the magnetic induction of 0.70 T. In addition, about 60% of calcium and 40% of sulfur distribute in non magnetic phases of tailings during magnetic separation process. Most of lead distributes uniformly along the zinc calcine in superfine particle size.

Cu, As, Sb and Bi in copper electrolyte could be efficiently removed by reducing with SO₂ followed by evaporative crystallization. As₂O₃ and CuSO₄·5H₂O were obtained after crystallized product was treated by dissolution, oxidation, neutralization, sedimentation, filtration and evaporative crystallization. The removal rates of Cu, As, Sb and Bi are 87.1%, 83.9%, 21.0% and 84.7%, respectively, when As (V) in copper electrolyte is fully reduced to As (III) by SO₂, and the H₂SO₄ in concentrated copper electrolyte is 645 g/L. The removal rate of As is 92.81% when 65 g crystallized product is dissolved in 200 mL water at 30 °C. The CuSO₄·5H₂O content is 98.8% when the filtrate is purified under the conditions that n(Fe):n(As) is 1.2, the dosage of H₂O₂ is 19 times the stoichiometric needed, temperature is 45 °C, time is 40 min, pH is 3.7, and then is evaporation crystallized.

Cathode material of spent lithium-ion batteries was refined to obtain high value-added cobalt and lithium products based on the chemical behaviors of metal in different oxidation states. The active substances separated from the cathode of spent lithium-ion batteries were dissolved in H₂SO₄ and H₂O₂ solution, and precipitated as CoC₂O₄∙2H₂O microparticles by addition of (NH₄)₂C₂O₄. After collection of the CoC₂O₄∙2H₂O product by filtration, the Li₂CO₃ precipitates were obtained by addition of Na₂CO₃ in the left filtrate. The experimental study shows that 96.3% of Co (mass fraction) and 87.5% of Li can be dissolved in the solution of 2 mol/L H₂SO₄ and 2.0% H₂O₂ (volume fraction), and 94.7% of Co and 71.0% of Li can be recovered respectively in the form of CoC₂O₄·2H₂O and Li₂CO₃.

Aluminum was leached out from coal fly ash by pressure acid-leaching method. The effects of coal fly ash size, sulfuric acid concentration, reaction time and reaction temperature on extraction efficiency of aluminum were investigated comprehensively. The phase and morphology of coal fly ash and solid residues after reaction were analyzed by XRD, SEM and IR. The optimal technological conditions for extracting aluminum from coal fly ash were eventually confirmed that coal fly ash with size of 74 μm and sulfuric acid with concentration of 50% are mixed in pressure reaction kettle to react for 4 h at 180 °C. Under the optimal conditions, the extraction efficiency of aluminum can reach 82.4%.

α-Bi₂O₃ powders were prepared from nanometer Bi powders through low-temperature oxidation at less than 873.15 K. XRD, SEM, TEM and HRTEM were used to characterize the structure and morphology of Bi powders and Bi₂O₃ particles. Kinetic studies on the bismuth oxidation at low-temperatures were carried out by TGA method. The results show that bismuth beads should be reunited and oxidized to become irregular Bi₂O₃ powders. The bismuth oxidation follows shrinking core model, and its controlling mechanism varies at different reaction time. Within 0-10 min, the kinetics is controlled by chemical reaction, after that it is controlled by O₂ diffusion in the solid α-Bi₂O₃ layer. The apparent activation energy is determined as 55.19 kJ/mol in liquid-phase oxidation.

The application of leaching process to extracting Mn from a low-grade manganese ore was investigated using a software based design of experiments. Four main parameters, i.e. sulfuric acid concentration, oxalic acid concentration, time and temperature were considered in a central composite response surface design. The recoveries of Mn and Fe were selected as response of design. The optimum conditions under which the Mn and Fe recoveries were the highest and the time and temperature were the lowest were determined using statistical analysis and analysis of variance (ANOVA). The results showed that Mn and Fe recoveries were 93.44% and 15.72% under the optimum condition, respectively. Also, sulfuric acid concentration was the most effective parameter affecting the process. The amounts of sulfuric and oxalic acid were obtained to be 7% and 42.50 g/L in optimum condition and the best time and temperature were 65 min and 63 °C.

Anodic electrochemical behavior was studied on graphite anode at 1000 °C in cryolite-alumina molten salt by means of cyclic voltammetry. The high current peak in a typical cyclic voltammogram was discussed. It is considered that a type of oxyfluoroaliminate complex anions reacts with carbon to form a high-resistance CF film on the anode surface at a high potential. The passivation potential is 3.28 V in 0.5% alumina-containing electrolyte, and the passivation potential increases with alumina content increasing which indicates that the alumina content determines the anodic process in the cryolite-alumina molten salt system.

Crystallization of intermetallic compound layer between Cu and SnZn alloy under uniform magnetic field was studied. The effect of magnetic field density on the growth behavior of the intermetallic layer such as microstructure, crystal orientation and composition was analyzed by scanning electron microscopy, X-ray diffraction and electron-probe microanalysis, respectively. Compared with the intermetallic layer without magnetic field, 0.1 T of magnetic flux density decreases the layer thickness. However, further increasing magnetic flux density promotes the layer growth. Application of magnetic field also changes the crystal orientation of intermetallic layer, but has no obvious influence on the layer composition. This phenomenon can be attributed to the role of thermo-electromagnetic convection and Lorentz force on the Cu dissolution as well as the accumulation of Cu solute at the interface front.

The corrosion behaviors of 91W-6Ni-3Fe (91W) refractory alloy, TiAl intermetallic compound and two types of iron based alloys (QT700 and H13 tool steel) in a liquid aluminum were investigated. Corrosion experiments or static immersion-tests were carried out in pure molten aluminum at 750 °C. The surface micro-topographies, corrosion interfaces and phase compositions of the immersed samples were investigated by 3D optical microscopy, SEM, EDS and XRD. The results show that 91W exhibits the best corrosion resistance, followed by QT700, H13 and TiAl alloy, consequently. The corrosion mass loss of the four metallic materials adheres to parabolic criterion, and the corrosion rate trends to be stable after initial acceleration. The diffusion-reaction mechanism is proposed for the dissolution of materials in molten aluminum, and the diffusion process is the rate-determining step during the dissolution of 91W in molten aluminum, while the low activation energy for the reaction between TiAl-(TiAl₃)-Al couple results in poor corrosion resistance of TiAl alloy in molten aluminum.

Social stock for metal determines secondary or recoverable resources to a certain extent. Top-down analysis method for the studying of metal in social stock was given. Influences of metal consumption under three circumstances, that is keeping constant, varying in a linear trend and in an exponential trend, on one kind of metal’s social stock, recyclable ratio and average age were analyzed. Al-contents and Cu-contents in social stock for China during the period 2006-2009 were calculated. The results reveal that Al-contents and Cu-contents in social stock kept increasing and reached 88.9 million tons and 51.4 millions tons in 2009, respectively, their average recyclable ratios are 1.45% and 0.30%, and the average ages are 4.65 years and 6.89 years, respectively. The recyclable ratios and average ages of Al-contents and Cu-contents in social stock will rise in future along with the decline of the increasing rate of aluminum consumption and copper consumption.

A novel process for the separation of hafnium from thiocyanic acid medium using the mixture of diisobutyl ketone (DIBK) and tributyl phosphate (TBP) as the extractant was developed. This extraction process was investigated experimentally as a function of the amount of TBP added, acidity, zirconium and hafnium concentrations, salting-out agent, temperature, duration, respectively. The results show that hafnium is enriched in the organic layer and zirconium is in aqueous layer in DIBK-TBP system. Under the optimal technological conditions: TBP addition 20% (v/v), aqueous phase acidity 3.0 mol/L, ammonium sulfate addition 0.8-1.25 mol/L, room temperature and extraction time 10 min, the separation factor of hafnium from zirconium is 9.3.

Thermodynamics of the precipitation from Li-Fe(II)-P-H₂O system at 298 K was investigated. The results demonstrate that LiFePO₄ can be formed at room temperature under pH value of 0-11.3, and the impurities Li₃PO₄ and Fe(OH)₂ will be yielded at pH value above 11.3 and 12.9, respectively. The optimum pH value for LiFePO₄ precipitation is 8-10.5. Considering the low rate of phase transformation kinetics, metastable Li-Fe(II)-P-H₂O system was also studied. The results indicate that equimolar ratio of co-precipitation precursor Fe₃(PO₄)₂·8H₂O and Li₃PO₄ cannot be obtained at the initial molar ratio 1:1:1 and 1:1:3 of Li:Fe:P. In contrast, equimolar ratio of the co-precipitation precursor can be yielded by adjusting the pH value to 7-9.2, matching the molar ratio 3:1:1 of Li:Fe:P, meaning that Li⁺-excess is one of the essential conditions for LiFePO₄ preparation by co-precipitation method.

Sulfate-modified titanium dioxide-bearing blast furnace slag (STBBFS) photocatalysts were prepared by the high energy ball milling method with (NH₄)₂SO₄ and titanium dioxide-bearing blast furnace slag (TBBFS) as raw materials. X-ray photoelectron spectroscopy(XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), UV-visible diffuse reflectance absorption spectra (UV-Vis), adsorption experiment and photocatalytic degradation measurement were conducted to characterize the structure, surface status, light absorption capacity, adsorption capacity and photocatalytic activity of the obtained photocatalysts. The adsorption equilibrium was described by the Langmuir isotherm model with a maximum adsorption capacity of 8.25 mg/g of Cr(VI) ions onto the STBBFS photocatalysts. As a result, sulfation of TBBFS improved the photocatalytic activities of STBBFS_x photocatalysts. At a low calcination temperature, the photocatalytic activity of STBBFS₃₀₀ photocatalyst was markedly higher compared with TBBFS_x prepared at high calcination temperature, indicating that the photocatalytic activity of STBBFS_x photocatalyst was determined by the balanced result between adsorption capacity and perovskite content.

A kind of environmental friendly anodizing routine for AZ91D magnesium alloy, based on an alkaline borate-potassium acid phthalate (KAP) electrolyte, was studied. The effect of KAP on the properties of the anodized film was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), respectively. The results showed that the anodizing process, surface morphology, thickness, phase structure and corrosion resistance of the anodized film were strongly dependent on the concentration of KAP. In the presence of adequate KAP, a compact and smooth anodized film with excellent corrosion resistance was obtained.

Ceramic oxide coatings were prepared on AZ91D magnesium alloys in alkaline silicate solution using micro-arc oxidation (MAO) technique. The corrosion behavior of MAO coating on AZ91D magnesium alloys in NaCl solutions with different concentrations (0.1%, 0.5%, 1.0%, 3.5% and 5.0% in mass fraction) was evaluated by electrochemical measurements and immersion tests. The results showed that the corrosion rate of the MAO coated AZ91D increased with increasing chloride ion concentration. The main form of corrosion failure was localized corrosion for the MAO coated AZ91D immersed in higher concentration NaCl solutions (1.0%, 3.5% and 5.0%), while it was general corrosion in dilute NaCl solutions (0.1% and 0.5%). Two different stages of the failure process of the MAO coated AZ91D could be identified: 1) occurrence of the metastable pits and 2) growth of the pits. Different equivalent circuits were also proposed based on the results of electrochemical impedance spectroscopy (EIS) for the MAO coated AZ91D immersed in different concentrations of NaCl solutions for 120 h.

The background pulp potential of zinc anode slime, and its influence on the occurrence of lead, silver and xanthate, were investigated with thermodynamic method. The thermodynamic conclusion and XRD analysis pointed out that in zinc anode slime, the thermodynamically stable compound of xanthate is dixanthogen, anglesite is the only mineral of lead, and kerargyrite is one of silver minerals occurring. Microflotation tests on single minerals of anglesite and kerargyrite in sulfuric acid solution by amyl dixanthogen indicated that dixanthogen has a much stronger collecting ability to kerargyrite than to anglesite. Molecular dynamic simulation indicated that amyl dixanthogen can only be adsorbed on the surface of kerargyrite in the presence of SO₄^2-. The FTIR tests also verified the selective adsorption of amyl dixanthogen on the surface of kerargyrite in the presence of SO₄^2-.

The effects of five amendments such as acetic acid(AA), citric acid (CA), ethylenediamine tetraacetic acid (EDTA), sepiolite and phosphogypsum on growth and metal uptake of giant reed (Arundo donax L.) grown on soil contaminated by arsenic (As), cadmium (Cd) and lead (Pb) were studied. The results showed that the shoot biomass of giant reed was enhanced by 24.8% and 15.0%, while superoxide mutase and catalase activities slightly varied when adding 5.0 mmol/kg CA and 2.5 mol/kg EDTA to soil as compared to the control, respectively. The concentrations of As, Cd and Pb in shoots were remarkably increased by the addition of 2.5 mmol/kg AA and CA, 5.0 mmol/kg EDTA, and 4.0 g/kg sepiolite as compared to the control. The accumulations of As and Cd were also significantly enhanced in the above condition, while the shoot Pb accumulation was noticeably enhanced by amending with 4.0 g/kg sepiolite and 8.0 g/kg phosphogysum, respectively. The results suggested that AA, CA and sepiolite could be used as optimum soil amendments for giant reed remediation system.

Modified potential ecological risk index (MRI) was proposed based on the potential ecological risk index (RI) and risk assessment code (RAC) by modifying an index. The modified index was relevant to the chemical speciation of heavy metals. Xiawan Port, a typical region contaminated by industrial production, was selected as a case study area. The total concentrations and chemical speciation of heavy metals in sediments of Xiawan Port were analyzed. The experimental data indicate that Xiawan Port is seriously polluted by heavy metals, especially by Cd. The risks of heavy metals are evaluated by RI, RAC and MRI, respectively. The resluts of MRI show that the risks of heavy metals are in the decreasing order of Cd>Pb>Cu>Zn. Comparison of results by different methods reveals that MRI integrates the characters of RI and RAC. MRI is recognized to be useful for risk managemnt of heavy metals in sediments.

In order to provide the theoretical guidance for applying the neutralization method to treatment of heavy metals wastewater with high concentration of sulfate, and to better understand the mechanism of calcium sulfate scale formation, the equilibrium solubility data of CaSO₄-Ca(OH)₂-H₂O system at 298.15 K were theoretically calculated via the Pitzer semi-empirical ion-interaction theory, and determined experimentally by the optical method combining with X-ray diffractometry, and the calculated and determined phase diagrams of CaSO₄-Ca(OH)₂-H₂O system were plotted and compared. Physical definition of each area was studied, and the physical law of characteristic point and line was explained in detail. Adjusting the pH value of neutralization-hydrolysis solution depended on the SO₄^2- concentration in the system. And interaction characteristics between the solubilities of CaSO₄(s) and Ca(OH)₂(s) were found out.

Ce_1-xSm_xO₂ (x=0, 0.1, 0.2 and 0.3) and Sm-doped ceria+(2%-8%)Al₂O₃ were synthesized through sol-gel process followed by low temperature combustion. The synthesis, structure, densification, conductivity and thermal expansion were studied, and the structure and phase were confirmed by XRD. Dense ceramics were obtained through sintering the pellets at 1300 °C. 2% and 4% Al₂O₃ were added into Ce_0.8Sm_0.2O₂ to promote the densification at 1250 °C. The surface morphology of the sintered pellets was analyzed using SEM. A two-probe, AC impedance spectroscopy was used to study the total ionic conductivity.

The electrochemical behavior of lithium incorporated in aluminum electrode in LiTFSI/KTf (lithium bis (trifluoromethylsulfonyl) amide/CF₃SO₃K) molten salt electrolyte was studied by a variety of electrochemical techniques including cyclic voltammetry, chronopotentiometry and chronoamperometry. The reduction reaction is found involving a nucleation process on the aluminum electrode. The results of chronopotentiometry indicate that the process of lithium incorporation in aluminum is smooth and uniform. The galvanostatic cycle experiments show that the coulombic efficiency is very low in the first cycle, which is mainly due to the “retention capacity” of Li-Al alloys. This characteristic is testified by the results of XRD and SEM. The results of chronoamperometry indicate that the incorporation of lithium into aluminum for the formation of a-phase Li-Al alloy is limited by its diffusion rate, with a measured diffusion coefficient of 1.8×10^{-10 cm2}/s.

In order to obtain bioelectrical impedance electrodes with high stability, the chemical etching process was used to fabricate the copper electrode with a series of surface microstructures. By changing the etching processing parameters, some comparison experiments were performed to reveal the influence of etching time, etching temperature, etching liquid concentration, and sample sizes on the etching rate and surface microstructures of copper electrode. The result shows that the etching rate is decreased with increasing etching time, and is increased with increasing etching temperature. Moreover, it is found that the sample size has little influence on the etching rate. After choosing the reasonable etching liquid composition (formulation 3), the copper electrode with many surface microstructures can be obtained by chemical etching process at room temperature for 20 min. In addition, using the alternating current impedance test of electrode-electrode for 24 h, the copper electrode with a series of surface microstructures fabricated by the etching process presents a more stable impedance value compared with the electrocardiograph (ECG) electrode, resulting from the reliable surface contact of copper electrode-electrode.

V-Ti-Fe master alloys were prepared by metallothermic reduction method, and the influences of the mass ratio of V₂O₅ to TiO₂, Al and Al-Mg alloy addition amounts on the metal recovery rates and alloy compositions were investigated. The results show that appropriate technological parameters are: the mass ratio of V₂O₅ to TiO₂ is 0.5:1, Al addition represents 95% of the theoretical value, and the Al-Mg alloy addition amount is one third that of the Al addition. The results from energy spectrum analysis show that V and Fe distribute uniformly in the prepared alloy, while the segregation for Ti, i.e. Ti-rich phase is detected. A spray refining process was carried out to reduce the impurity contents of Al and O in the prepared alloys. The Al content drops from 4.27% to 1.86%, and the O content drops from 2.10% to 0.91% after the refining process.

The solubility of zinc oxide in sodium hydroxide solution was measured in a closed polytetrafluoroethylene vessel from 25 to 100 °C. The ZnO solubility was determined by employing the method of isothermal solution saturation. The results show that only ZnO solid exists in the equilibrium state in the low concentration alkali regions, and the solubility of zinc oxide is almost invariable with temperature. With the increase of alkali concentration, equilibrium solid turns from ZnO to NaZn(OH)₃ suddenly, this mutation is called invariant point, 3: 55ents on the X-ray intensities from Ti3-2aL ce dynamics of the compounds AlCo and AlNi []tweight. The alkali concentration of the invariant points increases with increasing temperature, but the solubility of NaZn(OH)₃ decreases with increasing alkali concentration at the same temperature. At the same Na₂O concentration, the higher the temperature is, the higher the solubility of NaZn(OH)₃ is.

A computational fluid dynamics (CFD) simulation was carried out with CFX4.3 to investigate the melt flow and temperature distributions in the settler of a flash furnace. Sixteen cases of one slag tap hole adopted with one matte tap hole (1-to-1) and one slag tap hole adopted with two matte tap holes (1-to-2) operation modes were modelled. The simulation results show that the melt flows are similar in both two operation modes, but evident circulations can be found in the case of the 1-to-2 operation mode. The combination modes of the slag and matte tap holes are found to have a significant effect on the temperature distributions of the melt. The melt temperature is more uniform in the case of the 1-to-2 mode. Selection of a matte tap hole farther away from the inlet is more conducive to achieve a uniform distribution of the melt temperature in the settler in practical tapping operation.

A general analytical method to calculate the passive rigid retaining wall pressure was deduced considering all displacement modes. First, the general displacement mode function was setup, then the hypotheses were made that the lateral passive pressure is linear to the corresponding horizontal displacement and the soil behind retaining wall is composed of a set of springs and ideal rigid plasticity body, the general analytical method was proposed to calculate the passive rigid retaining wall pressure based on Coulomb theory. The analytical results show that the resultant forces of the passive earth pressure are equal to those of Coulomb’s theory, but the distribution of the passive pressure and the position of the resultant force depend on the passive displacement mode parameter, and the former is a parabolic function of the soil depth. The analytical results are also in good agreement with the experimental ones.

Anisotropic surface broken bond densities of six different surfaces of calcite and three surfaces of fluorite were calculated. In terms of the calculated results, the commonly exposed surfaces of the two minerals were predicted and the relations between surface broken bonds densities and surface energies were analyzed. Then the anisotropic wettability of the commonly exposed surfaces was studied by means of contact angle measurement. The calculation results show that the , and surfaces for calcite and (111) for fluorite are the most commonly exposed surfaces and there is a good rectilinear relation between surface broken bond density and surface energy with correlation of determination (R²) of 0.9613 and 0.9969, respectively. The anisotropic wettability of different surfaces after immersing in distilled water and sodium oleate solutions at different concentrations can be explained by anisotropic surface broken bond densities and active Ca sites densities, respectively.

The species of arsenic in secondary zinc oxide generated from fuming furnace were investigated. The results revealed that there are mainly three types of secondary zinc oxide based on three arsenic species. The main phase of As is As₂O₃ in type I, zinc arsenite (Zn(AsO₂)₂) in type II and lead arsenate (Pb(As₂O₆), Pb₄As₂O₉) in type III, respectively. Selective leaching of zinc oxide of type II was carried out. The leaching rate of As kept at 65%−70% with 30 g/L NaOH and L/S ratio of 3 at 20 °C for 1 h, while the losses of Pb and Zn were both below 1%.

The extraction behaviors of zinc from ammoniacal solutions were investigated using β-diketone (HA) and their mixtures with CYANEX923 or LIX84I. The effects of pH, total ammonia concentration, extractant concentration, anion species and temperature on zinc extraction were examined. The synergistic mechanism was discussed with regard to the structure of extractant and the extracted zinc complexes. It is found that the increase of total ammonia concentration and pH inhibits zinc extraction for all extraction systems due to the formation of zinc ammine complexes in aqueous phase. This effect of HA with CYANEX923 is evidently smaller than that of HA with LIX84I or HA alone system. Effect of anion species on the zinc extraction by HA with CYANEX923 can be neglected, but this effect of HA alone and the mixture of HA with LIX84I decreases in the order of (NH₄)₂SO₄ > NH₄NO₃ > NH₄Cl.

A novel adsorbent was prepared by modifying orange peel with sodium hydroxide and calcium chloride. The morphological and characteristics of the adsorbent were evaluated by infrared spectroscopy (IR), scanning electron microscopy (SEM) and N₂-adsorption techniques. The adsorption behavior of Cu²⁺, Pb²⁺ and Zn²⁺ on modified orange peel (SCOP) was studied by varying parameters like pH, initial concentration of metal ions. Equilibrium was well described by Langmuir equation with the maximum adsorption capacities for Cu²⁺, Pb²⁺ and Zn²⁺ of 70.73, 209.8 and 56.18 mg/g, respectively. Based on the results obtained in batch experiments, breakthrough profiles were examined using a column packed with SCOP for the separation of small concentration of Pb²⁺ from an excess of Zn²⁺ followed by elution tests. Ion exchange with Ca²⁺ neutralizing the carboxyl groups of the pectin was found to be the predominant mechanism.

A new combination method consisting of ball milling, carbothermic reduction and hydrochloric acid leaching was proposed for the preparation of nanosized synthetic rutile from natural ilmenite. The ball milling was employed to grind ilmenite into small particles. The carbothermic reduction was carried out to yield a high titanium slag, which would be easily purified by subsequent leaching procedure. Factors affecting the hydrochloric acid process, namely the leaching time, temperature, and acid concentration, were studied. After leaching and calcining the milled and annealed mixture of FeTiO₃/C under the optimal conditions, the TiO₂ nanoparticles with size of 10−200 nm and purity>98.0% were obtained.

The atmospheric corrosion behavior of bronze under thin electrolyte layer (TEL) with different thicknesses was monitored using cathodic polarization curves, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS). Cathodic polarization result indicates that the cathodic limiting current density increases with decreasing the TEL thickness. EIS result shows that the corrosion rate increases with decreasing the TEL thickness at the initial stage because the corrosion is dominated by the cathodic process, whereas after long immersion time, the corrosion degree with the TEL thickness is in the sequence of 150 μm > 310 μm >100 μm ≈ bulk solution > 57 μm. The measurements of OCP and EIS present in-situ electrochemical corrosion information and their results are in good agreement with that of physical characterizations.

The electrochemical oxidation behavior of pyrite in bioleaching system of Acidthiobacillus ferrooxidans was investigated by cyclic voltammetry (CV), polarization curve and electrochemical impedance spectroscopy (EIS). The results show that in the presence or absence of A. ferrooxidans, the oxidation reaction of pyrite is divided into two steps: the first reaction step involves the oxidation of pyrite to S, and the second reaction step is the oxidation of S to SO₄²⁻. The oxidation mechanism of pyrite is not changed in the presence of A. ferrooxidans, but the oxidation rate of pyrite is accelerated. With the extension of reaction time of A. ferrooxidan with pyrite, the polarization current density of pyrite increases and the breakdown potential at which the passive film dissolves decreases. The impedance in the presence of A. ferrooxidans is obviously lower than that in the absence of A. ferrooxidans, further indicating that microorganism accelerates the corrosion process of pyrite.