The images of granular ore media were captured by X-ray CT scanner. Combined with digital image processing and finite element techniques, the three-dimensional geometrical model, which represents the realistic pore structure of the media, was constructed. With this model, three dimensional pore scale fluid flow among particles was simulated. Then the distributions of fluid flow velocity and pressure were analyzed and the hydraulic conductivity was calculated. The simulation results indicate the fluid flow behaviors are mainly dominated by the volume and topological structure of pore space. There exist obvious preferential flow and leaching blind zones simultaneously in the medium. The highest velocities generally occur in those narrow pores with high pressure drops. The hydraulic conductivity obtained by simulation is the same order of magnitude as the laboratory test result, which denotes the validity of the model. The pore-scale and macro-scale are combined and the established geometrical model can be used for the simulations of other phenomena during heap leaching process.

To find the analytical solution of the acoustic emission/microseismic(AE/MS) source location coordinates, the sensor location coordinates were optimized and simplified. A cube monitoring network of sensor location was selected, and the AE/MS source localization equations were established. A location method with P-wave velocity by analytical solutions (P-VAS) was obtained with these equations. The virtual location tests show that the relocation results of analytical method are fully consistent with the actual coordinates for events both inside and outside the monitoring network; whereas the location error of traditional time difference method is between 0.01 and 0.03 m for events inside the sensor array, and the location errors are larger, which is up to 1080986 m for events outside the sensor array. The broken pencil location tests were carried out in the cross section of 100 mm×98 mm, 350 mm-length granite rock specimen using five AE sensors. Five AE sources were relocated with the conventional method and the P-VAS method. For the four events outside monitoring network, the positioning accuracy by P-VAS method is higher than that by the traditional method, and the location accuracy of the larger one can be increased by 17.61 mm. The results of both virtual and broken pencil location tests show that the proposed analytical solution is effective to improve the positioning accuracy. It can locate the coordinates of AE/MS source only using simple four arithmetic operations, without determining the fitting initial value and iterative calculation, which can be solved by a conventional calculator or Microsoft Excel.

The method of infrared thermography to predict the temperature of the sulfide ores has a large error. To solve this problem, the temperature of the sulfide ores is measured by thermal infrared imager and recording thermometric instrument contrastively. The main factors, including emissivity, distance, angle and dust concentration that affect the temperature measurement precision, are analyzed. The regression equations about the individual factors and comprehensive factors are obtained by analyzing test data. The application of the regression equations improves the precision of the thermal infrared imager. The geometric information lost in traditional infrared thermometry is determined by visualization grid method and interpolation method, the relationship between the infrared imager and geometry information is established. The geometry location can be measured exactly.

Electrochemical studies on silicon deposition were performed in molten salt electrolytes. Purification of metallurgical grade silicon by electrorefining was carried out in molten Si-chloride salts at temperatures from 973 K to 1223 K. It was found that the use of a liquid alloy anode of silicon and copper was beneficial in molten CaCl₂ with NaCl, CaO and dissolved Si. ICP-AES analysis results showed efficient removal of metal impurities, such as titanium, aluminum and iron, which are present in significant quantities in the feedstock. The contents of boron and phosphorus in the silicon after electrorefining were reduced from 36×10^-6 and 25×10^-6 to 4.6×10^-6 and 2.8 ×10^-6, respectively. The energy consumption of electrorefining was estimated to be about 9.3 kW·h/kg.

The formation characteristics of calcium aluminates in the CaO-Al₂O₃-SiO₂ system with sodium oxide was investigated by XRD, SEM-EDS and DSC-TG technologies. The main phases in the clinker after sintering at 1350 °C are 12CaO·7Al₂O₃, 2CaO·Al₂O₃·SiO₂ and 2CaO·SiO₂ when the mass ratio of Al₂O₃ to SiO₂ is 3.0 and the molar ratio of CaO to Al₂O₃ is 1.0. The proportion of 12CaO·7Al₂O₃ increases with the increase of Na₂O addition when the molar ratio of Na₂O to Al₂O₃ is from 0 to 0.4, while the proportion of 2CaO·Al₂O₃·SiO₂ decreases with the increase of Na₂O addition. Na₂O forms solid solution in 12CaO·7Al₂O₃, which increases the volume of elementary cell of 12CaO·7Al₂O₃. The formation temperature of 12CaO·7Al₂O₃ is decreased by 30 °C when the molar ratio of Na₂O to Al₂O₃ increases from 0 to 0.4 determined by DSC. The alumina leaching property of clinker increases obviously with the increase of Na₂O addition.

Electrical resistivity and viscosity of Pb-Sb alloys are measured to investigate Peierls distortion behavior in the melts. In Pb₃₀Sb₇₀, Pb₂₀Sb₈₀, and Pb₁₀Sb₉₀ melts, temperature dependence of resistivity deviates from linear dependence during cooling. At  663 °C, different trends in isothermal behavior between experimental and theoretical resistivities, are interpreted as the existence of Peierls distortion in Sb-rich melts. In Pb₃₀Sb₇₀ and Pb₂₀Sb₈₀ melts, abnormal viscosity results verify the existence of abnormal structure transition, which is attributed to the formation of large Sb clusters with Peierls distortion. In undercooled liquid Pb₂₀Sb₈₀, minute resistivity coefficient and quadratic resistivity behavior are interpreted as the rapid increase of cluster size of Sb clusters with Peierls distortion, which provides preferential nucleation sites for higher structure similarity to the crystalline and lower liquid-solid interfacial energy.

The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied. The results show that the extraction rates of Fe, Cu and Zn from the slag reach 86.7%, 90.3% and 66.7% after adsorbed bacteria sterilize, while those with adsorbed bacteria are 91.9%, 96.0% and 84.5% in conditions of pulp density 2%, pH 1.0, temperature 65 °C and stirring rate 120 r/min, respectively. Some stretching peaks of functional groups from bacterial secretes on the bioleached residue surface, such as 1007 cm^-1 and 1193 cm^-1, turn up through FI-IR analysis and indirectly reveal the presence of the adsorbed bacteria on the slag particles surface. Besides, the corrosion of zinc smelting slag is enhanced by bacteria according to the characteristics of cyclic voltametry and Tafel curves in bioleaching system.

Ionic liquid (IL) trihexyl (tetradecyl) phosphonium bis 2,4,4-trimethylpentylphosphinate (Cyphos IL 104) was impregnated on XAD-7 resin. The solvent impreganated resin (SIR) was prepared and applied in Cr(VI) removal. The morphology and the thermal stability of the resins were explored. The effects of equilibrium time and initial pH value on Cr(VI) adsorption were investigated. Adsorption isotherm, separation and desorption of the SIR, and selectivity of SIR were also explored. The results show that Cyphos IL 104 exists in the inner XAD-7 resin, and the optimum pH value range of the SIR for Cr(VI) extraction is 0 to 2. When NaOH used as desorption solution, the Cr(VI) can be effectively desorbed from the SIR.

Removal of lead and cadmium ions from aqueous solutions by adsorption process was investigated. Low cost and locally available natural mineral of manganoxide mineral was used as an adsorbent. The kinetics of adsorption process data was examined using the pseudo-first-order, pseudo-second-order kinetics and the intra-particle diffusion models. The rate constants of adsorption for all these kinetics models were calculated and compared. The adsorption kinetics was best described by the pseudo second-order model. The Langmuir and Freundlich adsorption isotherm models were applied to the experimental equilibrium data at different temperatures. The experimental data well fitted to Langmuir isotherm model. The maximum adsorption capacities of manganoxide mineral for lead and cadmium ions were calculated from the Langmuir isotherm and were 98 and 6.8 mg/g, respectively. Thermodynamic parameters such as the change of Gibbs free energy, enthalpy and entropy of adsorption were also calculated and it was found that the lead and cadmium uptake reactions by manganoxide mineral were endothermic and spontaneous in nature. Therefore, manganoxide mineral can be used as adsorbents for lead and cadmium ions removal processes as an alternative natural mineral among the others.

A novel adsorbent was prepared from granular red mud mixed with cement and its potential to be a suitable adsorbent for the removal of cadmium ions from aqueous solutions was evaluated. The wet red mud was directly mixed up with cement at different mass fractions of 2%-8% a, nd their properties were investigated. Based on the textural characteristics and strength, the granular red mud with 2% addition of cement maintaining for 6 d is identified to have better properties. The batch adsorption experiments for adsorption of Cd²⁺ ions from solution were performed at 30, 40 and 50 °C at different initial concentrations under the condition of constant pH of 6.5. The equilibrium adsorption was found to increase with the increase of temperature during the adsorption process. Langmuir adsorption isotherm model was found to match the experimental adsorption isotherm better. The kinetics of adsorption was modeled using a pseudo second order kinetic model and the model parameters were estimated.

The effects of surfactant Tween-80 on the growth, sulfur oxidation, and expression of selected typical sulfur metabolism relevant genes of Acidithiobacillus ferrooxidans ATCC 23270 were investigated. The results showed that in the presence of 10^{-2 g/L Tween-80, the growth of A. ferrooxidans and its metabolism on the insoluble substrate S0} and CuFeS₂ were promoted. After 24 d of bioleaching, the copper extraction yield of chalcopyrite at 10^-2 g/L Tween-80 increased by 16% compared with the bioleaching experiment without Tween-80. FT-IR spectra analysis revealed that the result was probably caused by the extracellular polymeric substances whose composition could be changed by the surfactant addition. RT-qPCR was used to analyze the differential expressions of 17 selected sulfur metabolism relevant genes in response to the addition of Tween-80. Down-regulation of the extracellular protein genes indicated the influence of Tween-80 on bacteria-sulfur adsorption. Variation of the expression level of the enzymes provided a supplement to sulfur metabolism investigation.

The mechanism of antithrombotic of Dahuangzhechong Fang separated and purified by Ti-Al intermetallic compound porous material (TAICPM) was researched. Dahuangzhechong Fang, which was isolated and screened by TAICPM, was used to oral rats. At the end of study, their blood and thrombus were collected. The results show that TAICPM with the pore size of 1-5 μm can screen Dahuangzhechong Fang well. Dahuangzhechong Fang can increase 6-keto-PGF1α, lower content of TXD2 and platelet. Dahuangzhechong Fang has good effect to resist arterial thrombosis.

Acoustic emission (AE) technique is a useful tool for investigating rock damage mechanism, and is used to study the temporal-spatial evolution process of microcracks during the similar pillar material experiment. A combined AE location algorithm was developed based on the Least square algorithm and Geiger location algorithm. The pencil break test results show that the location precision can meet the demand of microcrack monitoring. The 3D location of AE events can directly reflect the process of initiation, propagation and evolutionary of microcracks. During the loading process, stress is much likely concentrated on the area between pillar and roof of the specimen, where belongs to danger zone of macroscopic failure. When rock reaches its plastic deformation stage, AE events begin to decrease, which indicates that AE quiet period can be seen as precursor characteristic of rock failure.

The experiments were conducted to investigate the behavior of airborne particles adhering to the glass slides which were coated by several reagent films. The results showed that the adhesion level could be significantly changed by the reagent films. There were no evident rules between the average size of particles and sampling time interval, the placing angle and reagent concentration. The average particle size on the surface coated by composite reagent (2-3 μm) was smaller than that on the single reagent coated surface, while the largest particle size (4-5 μm) was observed on the surface coated with the Tween 60. The experiment also demonstrated that the best adhesive performance was obtained on the surface which was coated with 0.5% SDBS and 0.5% fluorocarbon composite reagents. The experiment results indicated that each reagent had a certain optimum adhesive range to the particle. The composite reagents with different proportion of single reagents exhibited some particular physical and chemical properties, which could effectively change the adhesive performance between the solid surface and the particles.

High phosphorous oolitic hematite ore is one of typical intractable iron ores in China, and the conventional beneficiation methods are found to be impracticable to , remove phosphorus from the ore effectively. Better beneficiation index were gotten by direct reduction roasting with dephosphorization agent followed by two stages of grinding and magnetic separation. P content decreases from 0.82% in the raw ore to 0.06% in the magnetic concentrate, and the total iron grade increases from 43.65% to 90.23%, the recovery of iron can reach 87%. Mechanisms of phosphorus removal in the beneficiation of high phosphorous oolitic hematite ore by direct reduction roasting with dephosphorization agent were studied using XRD, SEM and EPMA. The results showed that about 20% of the apatite in the raw ore transferred into phosphorus and volatilized with the gas in the process of reduction roasting, while the rest 80% apatite was not involved in the reaction of generation of phosphorus, and remained as apatite in the roasted products, which was removed to tailings by grinding and magnetic separation. A small amount of phosphorus existed in the magnetic concentrate as apatite. The oolitic texture of raw ore was partly changed during roasting, resulting in the formation of nepheline in the reaction between the dephosphorization agent, SiO₂ and Al₂O₃ in the raw ore, which greatly improved the liberation degree of minerals in the roasted products, and it was beneficial to the subsequent grinding and magnetic separation.

Non-metallic particles and metallic impurities present in the feedstock affect the electrical and mechanical properties of high quality silicon which is used in critical applications such as photovoltaic solar cells and electronic devices. SiC particles strongly deteriorate the mechanical properties of photovoltaic cells and cause shunting problem. Therefore, these particles should be removed from silicon before solar cells are fabricated from this material. Separation of non-metallic particles from liquid metals by imposing an electromagnetic field was identified as an enhanced technology to produce ultra pure metals. Application of this method for removal of SiC particles from metallurgical grade silicon (MG-Si) was presented. Numerical methods based on a combination of classical models for inclusion removal and computational fluid dynamics (CFD) were developed to calculate the particle concentration and separation efficiency from the melt. In order to check efficiency of the method, several experiments were done using an induction furnace. The experimental results show that this method can be effectively applied to purifying silicon melts from the non-metallic inclusions. The results are in a good agreement with the predictions made by the model.

The leaching kinetics of copper from low-grade copper ore was investigated in ammonia-ammonium sulfate solution with sodium persulfate. The effect parameters of stirring speed, temperature, particle size, concentrations of ammonia, ammonium sulfate and sodium persulfate were determined. The results show that the leaching rate is nearly independent of agitation above 300 r/min and increases with the increase of temperature, concentrations of ammonia, ammonium sulfate and sodium persulfate. The EDS analysis and phase quantitative analysis of the residues indicate that bornite can be dissolved by persulfate oxidization. The leaching kinetics with activation energy of 22.91 kJ/mol was analyzed by using a new shrinking core model (SCM) in which both the interfacial transfer and diffusion across the product layer affect the leaching rate. A semi-empirical rate equation was obtained to describe the leaching process and the empirical reaction orders with respect to the concentrations of ammonia, ammonium sulfate and sodium persulfate are 0.5, 1.2 and 0.5, respectively.

Removal of Cr(VI) from aqueous solution by strong alkaline anion exchange fiber (SAAEF) was achieved using batch adsorption experiments. The effect of contact time, initial Cr(VI) concentration and pH was investigated. The results showed that the maximum adsorption capacity of SAAEF was 187.7 mg/g at pH=1.0. The adsorption capacity increased with Cr(VI) concentration but decreased with pH value when pH>1.0. Adsorption isotherms at various temperatures were obtained. Langmuir, Freundlich, Dubinin-Radushkevich and Temkin models were adopted and the equilibrium data fitted best with the Langmuir isotherm. The constants of these models indicated that the adsorption process involved both chemisorption and physisorption. The values of thermodynamic parameters, including DH, DG and DS, suggested that the adsorption of Cr(VI) on SAAEF was a spontaneous, entropy-driven and endothermic process. Q_(iso) was not a constant value, which indicated an inhomogenous energy distribution on SAAEF.

The effect of surfactant polyoxyethylenesorbitan monolaurate (Tween-20) on the nickel bioleaching from pre-treated chromite overburden (COB), Sukinda with fungal strain Aspergillus niger, was examined in shake flasks. Along with the nickel recovery from COB by the fungal bioleaching, the effect of surfactant on the growth of the A. niger was also investigated. Results show that the addition of surfactant in low concentration was favorable for the recovery of nickel from pre-treated COB. Normally, the carbon source (sucrose) in the culture medium was utilized by the A. niger for its cellular metabolism and organic metabolites (bio acids) were produced, which were responsible for the bioleaching of minerals. However, the addition of surfactant (Tween-20) accelerated the rate of sucrose consumption by the fungi, and thus enhancing the extraction of nickel from pre-treated COB. During the study, around 39% nickel extraction was achieved in A. niger mediated bioleaching performed at 2% pulp density of pre-treated COB at 30 °C, in the presence of surfactant whereas only 24% nickel was extracted without surfactant.

Valonia tannin (VT) was gelated through polymerization with formaldehyde to prepare an adsorbent, which was found effective to remove Ag⁺ from aqueous solution. The adsorption-desorption behaviors of valonia tannin resin (VTR) were investigated under various initial Ag⁺ concentrations, solution temperatures, pH values etc. The applicability of empirical kinetic models was also studied. The pseudo-second-order model studies revealed the Ag⁺ sorption was very rapid. VT and VTR were characterized using FTIR and SEM before and after adsorption. The Ag⁺ biosorption on VTR increased with a rise in initial concentration of Ag⁺ and with a decrease in temperature. Desorption experiments were conducted at low pH values and the solutions of H₂SO₄, HNO₃ and HCl were used for desorption. The VTR shows high adsorption capacity to Ag⁺ in a wide pH range of 2.0-7.0, and a maximum adsorption capacity of 97.08 mg/g was obtained at pH 5.0 and 296 K when the initial concentration of Ag⁺ was 100.0 mg/L. Ag⁺ ion desorption could reach 99.6% using 1 mol/L HCl+1% thiourea (NH₂CSNH₂) solution. By utilizing such characteristics of VTR, it is expected that it can be applied to recovering Ag⁺ efficiently and simply with low cost.

The reduction mechanism of Ir in the NaCl-KCl-IrCl₃ molten salt was investigated by cyclic voltammetry and chronopotentiometry, and Ir film was deposited effectively on platinum in potentiostatic mode. The morphology and constitution of Ir film were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). It is found that the reduction mechanism of Ir(III) is a three-electron step and electro reaction is a reversible diffusion controlled process; the diffusion coefficients of Ir(III) at 1083, 1113, 1143 and 1183 K are 1.56×10^-4, 2.23×10^-4, 2.77×10^-4 and 4.40×10^{-4 cm2}/s, respectively, while the activation energy of the electrode reaction is 102.95 kJ/mol. The compacted Ir film reveals that the applied potential greatly affects the deposition of Ir, the thickness of Ir film deposited at the potential of reduction peak is the highest, the temperature of the molten salt also exerts an influence on deposition, the film formed at a lower temperature is thinner, but more micropores would occur on film when the temperature went too high.

To acquire understanding of Ni enrichment from laterite ore, the mineralogy and crystal chemistry of a low grade limonite type nickel laterite ore sample assaying 0.97% Ni from Indonesia were studied using optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). According to EPMA results, the mineral includes 80% goethite ((Fe, Ni, Al)O(OH)) with 0.87% Ni, 15% silicate minerals with lizardite ((Mg, Fe, Ni)₃Si₂O₅(OH)) and olivine ((Mg, Fe, Ni)₂SiO₄), and 1.19% Ni, and other minor phases, such as hematite, maghemite, chromite and quartz, and no Ni was detected. The mineralogy of the laterite ore indicates that due to the complicated association of the various phases and the variable distribution of Ni, this refractory laterite ore can not be upgraded by traditional physical beneficiation processes.

In order to discuss the particle-bubble interaction during the electro-flotation of cassiterite, the recovery of cassiterite with different particle sizes was investigated, and the collision mechanism between the cassiterite particles and H₂ bubbles was explored. The flotation tests were carried out in a single bubble flotation cell. The results show that cassiterite particles <10 μm, 10−20 μm, 20−38 μm and 38−74 μm match with bubbles with size of 50−150 μm, about 250 μm, 74 μm and 74 μm, respectively, and a better recovery can be obtained. It is demonstrated that the recovery of cassiterite is influenced by the size of cassiterite particles and bubbles. Furthermore, the probabilities of collision, adhesion, detachment and collection were calculated using the collision, attachment and collection models. Theoretical calculation results show that the collision probability decreases sharply with decreasing particle size and increasing bubble size (below 150 μm). The attachment probability would increase from the effective collision, leading to the increase of recovery.

Lanthanum oxalate hydrate La₂(C₂O₄)₃·10H₂O, the precursor of La₂O₃ ultrafine powders, was prepared by impinging stream reactor method with PEG 20000 as surfactant. Thermal decomposition of La₂(C₂O₄)₃·10H₂O from room temperature to 900 °C was investigated and intermediates and final solid products were characterized by FTIR and DSC−TG. Results show that the thermal decomposition process consists of five consecutive stage reactions. Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira- Sunose (KAS) methods were implemented for the calculation of energy of activation (E), and the results show that E depends on α, demonstrating that the decomposition reaction process of the lanthanum oxalate is of a complex kinetic mechanism. The most probable mechanistic function, G(α)=[1−(1+α)^1/3]², and the kinetic parameters were obtained by multivariate non-linear regression analysis method. The average E-value that is compatible with the kinetic model is close to value which was obtained by FWO and KAS methods. The fitting curve matches the original TG curve very well.

The kinetics of isothermal reduction of Ag₂O with graphite under argon atmosphere for a non-activated sample and mechanically activated sample was investigated. It is found that Johnson-Mehl-Avrami model appropriately explained the thermal and mechanochemical synthesis of Ag from Ag₂O+ghraphite mixture. The process kinetics was investigated using the same approach for milled and unmilled samples. The results show that the Avrami exponent of mechanochemical reduction is higher than that of high temperature thermal reduction. Also, the mechanisms of nuclei growth in thermal and mechanochemical reduction are diffusion controlled and interface controlled, respectively.

A novel and facile wet-chemical method for synthesis of silver microwires was developed. The well-defined particles were prepared by adding an iron (II) sulfate heptahydrate solution into a silver nitrate solution containing citric acid drop by drop at 50 °C. The resulting products were characterized by scanning electron microscopy and X-ray diffraction. It was found that the particles consisted of numerous silver microwires. The reaction temperature greatly affected the morphologies of the as-prepared particles. Both of the mean length and width of the silver microwires increased with the decrease of the concentration of silver nitrate. And the lower concentration was unfavorable for the formation of more silver microwires. Similar findings were also observed when the concentration of iron (II) sulfate was decreased. The amount of citric acid also greatly affected the shape of the as-prepared particles. It was concluded that citric acid was the key role in the formation of silver microwires via the Oswald ripening mechanism.

The electrodeposition of antimony in alkaline solutions containing xylitol was investigated using cyclic voltammetry, linear sweep voltammetry and chronoamperometry. The antimony electrodeposition and the chemical stability of xylitol in alkaline solutions were studied by cyclic voltammetric technique. Apparent activation energy, apparent transfer coefficient and exchange current density were obtained by linear sweep voltammetric technique. Initial stages of antimony electrocrystallization were determined by chronoamperometry. Xylitol in alkaline solutions exhibits high chemical stability and there is no redox in solutions when the potential ranges from −1.20 V to +0.60 V (vs Hg/HgO). There is no other redox reaction but hydrolysis occurring on stainless steel in the potential range of −1.75 V to 1.25 V (vs Hg/HgO) while the xylitol decomposition maybe take place on antimony electrode when potential is more negative than −1.70 V (vs Hg/HgO). Cyclic voltammograms with different scan rates indicate that the antimony electrodeposition process is an electrocrystallization which is a completely irreversible electrode process. The apparent activation energy, apparent transfer coefficient and exchange current density were calculated to be 46.33 kJ/mol, 0.64 and 4.40×10^{−6 A}/m², respectively. The analyses of the chronoamperometric responses support the view of a three-dimensional growth under progressive nucleation. The average diffusion coefficient of antimony was calculated to be 1.53×10^{−6 cm2}/s.

The investigation on purification of metallurgical grade silicon by solidification of hypereutectic Al−Si melt with super gravity as an intensified separation way was carried out. The results indicate that the refined silicon grains are successfully enriched at the bottom of the Al−Si alloy along the direction of super gravity. Then the refined silicon was collected by aqua regia leaching. The purity of the collected silicon is analyzed as 99.92%, which is obviously improved compared with the purity of the metallurgical grade silicon of 99.59%, proving the feasibility of this purification method. Furthermore, the mass fraction of B is reduced from 8.33×10⁻⁶ to 5.25×10⁻⁶ and that of P from 33.65×10⁻⁶ to13.50×10⁻⁶.

The effect of electroslag refining on iron reduction from commercial aluminum was investigated. Cast electrodes of commercial aluminum were electroslag refined using KCl−NaCl−Na₃AlF₆ slag containing Na₂B₄O₇. Experimental results indicate that the iron content decreases with increasing Na₂B₄O₇ addition and remelting time, and the iron content decreases from 0.400% to 0.184% under 9% Na₂B₄O₇ addition for 30 min remelting. The elastic modulus, yield strength and ultimate tensile strength commercial aluminum are improved, and the tensile elongation is increased by 43% after electroslag refining. The chemical reaction between melt and slag to form Fe₂B is the main reason for iron reduction and the thermodynamic calculation of the chemical reaction theoretically accounts for the formation of Fe₂B.

The corrosion behaviors and corresponding electrochemical impedance spectroscopy (EIS) and polarization curves of pure Mg in neutral 1.0% NaCl solution were investigated. The fractal dimension of EIS at different time was studied. The corrosion process and EIS evolution are divided into three stages. In the initial stage, EIS is composed of two overlapped capacitive arcs, the polarization resistance and charge transfer resistance increase rapidly with immersion time, and the corrosion rate decreases. Then, two well-defined capacitive arcs appear, and the charge transfer resistance and corrosion rate remain stable. After a long immersion time, inductive component appears in a low frequency range, the charge transfer resistance decreases and the corrosion rate increases with the immersion time. The fractal dimension obtained from the time records of EIS seems to be a promising tool for the analysis of corrosion morphology because of its direct relationship with the metal surface.

The corrosion behaviors of Sn−0.75Cu solder and Sn−0.75Cu/Cu joint in 3.5% NaCl (mass fraction) solution were studied by potentiodynamic polarization test and leaching measurement. The polarization curves indicated that the corrosion rate of Sn−0.75Cu solder was lower than that of Sn−0.75Cu/Cu joint. The morphology observation and phase composition analysis on the corroded product at each interesting potential suggested that Sn₃O(OH)₂Cl₂ formed on the surface of Sn−0.75Cu solder at active dissolution stage. As the potential increased from active/passive transition stage, all the surface of Sn−0.75Cu solder was covered by the Sn₃O(OH)₂Cl₂ and some pits appeared after the polarization test. Compared to the Sn−0.75Cu solder alloy, much more Sn₃O(OH)₂Cl₂ formed at active dissolution stage and the pits with bigger size were observed after polarization test for the Sn−0.75Cu/Cu solder joints. The leaching test confirmed that the faster electrochemical corrosion rate resulted in the larger amount of Sn released from the Sn−0.75Cu/Cu solder joints.

In order to break the complex bonds and treat the organic wastewater containing heavy metal, such as Cu−EDTA solution, a novel process of Fe−C micro-electrolysis was proposed. Based on the principle of iron−carbon micro-electrolysis reaction, •OH radicals which were generated under the acidic aerobic condition during the micro-electrolysis process attacked to the organic groups of coordination compounds, which resulted in complex bonds breaking. Therefore copper (II) ions were removed via nascent gelatinous ferric hydroxide and ferrous hydroxide, and EDTA was degraded by •OH radicals. Effects of pH value, temperature, electrolysis time and mass ratio of Fe to C on residual concentrations of total organic carbon (TOC) and Cu(II) were studied. The mechanism of Fe−C micro-electrolysis was investigated and verified by analyzing micrographs of scanning electron microscopy (SEM), energy dispersive analysis (EDS) and Fourier transform infrared spectrometry (FTIR).The removal efficiency is optimal at pH value of 2.0, temperature of 25 °C, the mass ratio Fe to C of 0.02, and reaction time of 60 min. Under above conditions, the concentration of TOC decreases from 200 mg/L to 40.66 mg/L and the residual concentration of Cu(II) decreases from initial 60 mg/L to 1.718 mg/L.

Experimental studies on phase equilibria and liquidus temperature in the PbO−ZnO−CaO−SiO₂−“Fe₂O₃” system, with the mass ratios of CaO/SiO₂=1−1.6 and Fe/SiO₂= 1.3−1.7, and 40% PbO and 8% ZnO, were carried out between 1273 and 1573 K. Slags were equilibrated at 1273 to 1573 K and cooled rapidly by quenching. The XRD and SEM−EDS results showed that the slag compositions are in the franklinite primary phase field. Calcium and lead silicates are formed between 1373 and 1473 K. The Ca/Pb silicate and magnetoplumbite phases are partially formed by an incongruent reaction. The experimental and thermodynamical results showed that the liquidus increased by increasing CaO/SiO₂ mass ratio and decreasing Fe/SiO₂ mass ratio.

The modelling and optimization for the alkaline sulphide leaching of a complex copper concentrate containing 1.69% Sb and 0.14% Sn were studied. Response surface methodology, in combination with central composite face-centred design (RSM-CCF), was used to optimise the operating parameters. The leaching temperature, sulphide ion concentration and solid concentration were chosen as the variables, and the response parameters were antimony and tin recovery, and the time required to achieve 90% Sb dissolution. It was confirmed that the leaching process was strongly dependent on the reaction temperature as well as the sulphide ion concentration without any significant dependence on the solid concentration. Furthermore, a mathematical model was constructed to characterise the leaching behaviour. The results from the model allow identification of the most favourable leaching conditions. The model was validated experimentally, and the results show that the model is reliable and accurate in predicting the leaching process.

The adsorption behavior of D301 for molybdenum blue was investigated. The thermodynamics parameters in adsorption process were calculated and the adsorption kinetics was studied. The experimental results show that the adsorption characteristic of D301 for molybdenum blue fits well with the Freundlich adsorption isotherm equation. In the adsorption process of D301 for molybdenum blue, both the enthalpy change ΔH and entropy change ΔS are positive, while the free energy change ΔG is negative when temperatures are in the range of 303−333 K. It is indicated that the adsorption is a spontaneous and endothermic process, and the elevated temperatures benefit to the adsorption. Kinetic studies show that the kinetic data are well described by double driving-force model, and the adsorption rate of molybdenum blue on D301 is controlled by the intraparticle diffusion during the adsorption process. The total kinetic equation is determined.

Zn reduction was investigated by the vacuum carbothermic reduction of hemimorphite with or without CaF₂ as catalyst. Results indicate that CaF₂ can catalyze the carbothermic reduction of zinc silicate, decrease the reaction temperature and time. The lower the reaction temperature and the more the amount of CaF₂, the better the catalytic effect. The optimal process condition is obtained as follows: the addition of about 10% CaF₂, the reaction temperature of 1373 K, the molar ratio of C to Zn_Total of 2.5, the pressure of system lower than 20 kPa, the reaction time of about 40 min. Under the optimal process condition, the zinc reduction rate is about 93% from hemimorphite.

Alumina coating was formed on AA7075 aluminum alloy by micro arc oxidation (MAO) method and its corrosion and stress corrosion cracking (SCC) behaviors were examined in 3.5% (mass fraction) NaCl solution. Electrochemical impedance spectroscopy (EIS) was used to evaluate the degradation of the coating as a function of immersion time and was modeled with appropriate equivalent circuits. Constant load stress corrosion cracking (SCC) results followed by post-test metallographic observations demonstrated the usefulness of MAO coating to avoid the premature failure of the alloy due to severe localized corrosion initiated by Cu- and Fe-rich intermetallic phases.

Cyclic voltammetry and chronopotentiometry were used to study the reaction mechanism of Pb(II) and the co-deposition of Pb, Mg and Li on molybdenum electrodes in LiCl−KCl−PbCl₂−MgCl₂ melts. The diffusion coefficient of lead ions in the melts was determined by different electrochemical techniques. The results obtained by cyclic voltammetry and chronopotentiometry indicated that the underpotential deposition of lithium on pre-deposited Pb leads to the formation of a liquid Li−Pb alloy, and the Mg−Li−Pb alloys are formed after the addition of MgCl₂. X-ray diffraction confirmed that in the Mg−Li−Pb alloy, PbLi₃, Mg₂Pb and Li₇Pb₂ phases exist by galvanostatic electrolysis at 6.21 A/cm² for 2 h at 873 K and the phases can be controlled by changing the concentration of PbCl₂ and MgCl₂.

The corrosion process of tinplate in 0.5 mol/L NaCl solution was investigated using the electrochemical impedance spectroscopy (EIS), and the morphology and structure of the corrosion products were characterized by scanning electron microscope (SEM), scanning probe microscopy (SPM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that the resistance of tin coating, R_c, was essentially constant but the charge transfer resistance, R_ct, decreased by 2 orders of magnitude, which indicated that the tin coating was not seriously corroded while the carbon steel substrate was corroded continuously. The corrosion of tinplate in 0.5 mol/L NaCl solution was mainly the dissolution of carbon steel substrate because of the defects in the tin layer and the corrosion product was mainly γ-FeOOH.

A detailed mineralogical characterization of a tin-polymetallic ore from Mengzi, Yunnan Province, China, was undertaken by automated electron microprobe-based mineral mapping and quantitative analysis methods. The results show that the most valuable metal is Sn (0.98%, mass fraction). The main tin minerals are cassiterite and stannite, which account for 94.90% of total tin. Other metals, such as Cu (0.261%), Zn (0.612%) and Pb (0.296%) can also be seen as valuable metal to be recovered. Minerals such as pyrrhotite, pyrite, arsenopyrite, sphalerite, galena and chalcopyrite are disseminated in the ore. Quartz, sericite and dolomite are the main gangue. The optimal grinding fineness should be chosen as 0.037 mm to make sure that most of the tin minerals can be liberated from other minerals.