The interplay of mineralogical variation and mineral phase distribution within varying particle sizes on the dissolution behaviour of a low grade complex sulphide ore was investigated through bioleaching experiments and electrochemical technique. Investigations were carried out utilizing mineralogical data on the variations in mineral and phase distribution within particle sizes of＜53 μm, 53−75 μm, 75−106 μm and 106−150 μm in mixed mesophilic cultures of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans. Electrochemical behaviour was studied using particulate electrodes from the four varying particle sizes and from massive electrodes prepared from the two major sulphide mineral rich phases (sphalerite-rich and galena-rich) and a complex mineralogical phase of the bulk ore. Bioleaching studies reveal the highest recoveries at a particle size of 75 μm, while electrochemical investigations reveal the highest dissolution at particle size of 106 μm. Electrochemical results show that sphalerite rich phase has the highest dissolution rate while galena-rich complex phase has the least. SEM studies confirm the highest bacterial attack at the sphalerite-rich phase. The discrepancies between the dissolutions within particle sizes obtained from bioleaching experiments and electrochemical studies are consistent with and attributed both to the physical and mineralogical influences. Electrochemical behaviour is influenced and controlled by galvanic interaction resulting from mineralogical variation, while bioleaching behaviour is influenced by mineralogical variation as well as physical effect of particle size.

A surfactant containing a mixed aliphatic structure, with a hydrocarbon chain and a diamine group, has proven to be collector for the flotation of quartz, calamine and calcite. And research about its collecting capability was carried out in laboratory. The test results show that the flotation recovery ascends sharply with increasing the concentration of collector. When the concentration of collector reaches 1.83×10⁻⁴ mol/L, the flotation recoveries of quartz, calamine and calcite get their maximum of 97.64%, 91.04% and 95.99%, respectively. The flotation recoveries of quartz, calamine and calcite rise sharply with the rise of pH. And in a wide range of pH, their flotation recoveries all exceed 90%. And in the whole flotation experiment, the flotation recovery of hematite rises with the increase of collector concentration and pH, while the maximal recovery is not more than 55%. Compared with dodecylamine, the N-dodecylethylenediamine has strong capability to quartz and calamine, while the flotation recoveries of calcite are closely. Hydrogen binding adsorption and electrostatic adsorption occur between the collector and the surface of quartz.

The behaviours of complexation and dissolution of PbCl₂ on the surface of galena were investigated to explore the process of hydro-chemical conversion of galena (PbS) in chloride media. By means of solution chemistry calculation, the production and dissolution of the products PbCl₂ were studied. And the passivation of the galena was studied by Tafel curve. The results show that PbCl₄²⁻ is the main form of PbCl₂ presented in the saturated potassium chloride (KCl) solution. The PbCl₂ crystal is easy to precipitate when the total concentration of chloride ion ([Cl⁻]_T) is equal to 0.92 mol/L, and it is inclined to dissolve when [Cl⁻]_T is more than 0.92 mol/L. The chloride complexing reaction rate strongly depends on the Fe³⁺ ion concentration when it is less than 6×10⁻⁴ mol/L, while passivation occurs on the surface of the electrode when Fe³⁺ concentration is larger than 6×10⁻⁴ mol/L. The reaction rate increases obviously when KCl is added, since the activity of Cl⁻ increases; thus accelerates the dissolution of PbCl₂.

The experiments were conducted to evaluate the Cr(Ⅵ) resistance and reduction by Pseudomonas aeruginosa. After this bacterium tolerated 40 mg/L Cr(Ⅵ), the growth of cells was observed. The bacterial growth was obviously lower than the controls over 24 h and the binary cell fission was observed in cell morphology by scanning electron microscope. P. aeruginosa was found to be able to reduce Cr(Ⅵ) although Cr(Ⅵ) had toxic effects on the cells. The results demonstrate that Cr(Ⅵ) is reduced from 40 mg/L to about 18 mg /L in 72 h. The value of pH drops from 7.02 to around 5.65 after 72 h. A significant increase in the value of redox potential occurs during Cr(Ⅵ) reduction and Cr(Ⅵ) reduction can be observed over a range of redox potential from +3 mV to +91 mV. Both of SO₄²⁻ and NO₃⁻ have no effect on Cr(Ⅵ) reduction. The presence of Zn²⁺ has a notable inhibitory effect on Cr(Ⅵ) reduction while Cu²⁺ substantially stimulates Cr(Ⅵ) reduction. In the presence of Zn²⁺, Cr(Ⅵ) decreases from 40 mg/L to only 26−27 mg/L, whereas Cr(Ⅵ) drops to 1−2 mg/L after 48 h in the presence of Cu²⁺.

A great amount of red mud generated from alumina production by Bayer process not only threatens the environment but also causes waste of secondary resources. High-iron-content red mud from Bayer process was employed to recover alumina and ferric oxide by the process of reduction-sintering, leaching and then magnetic beneficiation. Results of thermodynamic analyses show that ferric oxide should be reduced to Fe if reduction of ferric oxide and formation of sodium aluminate and calcium silicate happen simultaneously. Experimental results indicate that alumina recovery of Bayer red mud can reach 89.71%, and Fe recovery rate and the grade of magnetite concentrate are 60.67% and 61.78%, respectively, under the optimized sintering conditions.

High purity titanium was prepared by thermal decomposition of titanium iodide. The feasible synthetic route and optimum decompositon temperaure were obtained by thermodynamic analysis in the process of thermal decomposition of titanium iodide and nucleation growth theory. The temperature for the formation of titanium iodide is in the range of 800−900 K, at which a large amount of titanium iodide vapour can be obtained. The decomposition temperature of titanium iodide is in the range of 1 300−1 500 K, at which a favourable decomposition rate can be achieved. The experiment results show that the purity of the produced titanium is more than 99.995%.

Leaching of heavy metals from Sedum alfredii Hance biomass was studied with ammonia-ammonium chloride solution as leaching agent. The research was carried out in two phases:1) a leaching study to determine the zinc extraction efficiency of this leaching agent, and 2) a thermodynamic analysis to identify the likely reactions and stable Zn(Ⅱ) species formed in the leaching systems. Taguchi orthogonal experiment, with four variable parameters, leaching temperature, molar ratio of NH₄Cl to NH_3, leaching time and solid-to-liquid(L/S) ratio, and each at three levels, was used to optimize the experiment parameters by the analysis of variances. The results indicate that leaching temperature has the most dominant effect on metal extraction performance, followed by molar ratio of NH₄Cl to NH₃, solid-to-liquid ratio and leaching time. The optimum condition was obtained as follows:temperature of 60℃, molecular ratio of NH₄Cl to NH₃ of 0.6, leaching time of 2 h and solid-to-liquid ratio of 5׃1. The total zinc leaching efficiency under optimum conditions reaches 97.95%. The thermodynamic study indicates that the dominant species produced by the leaching process should be the soluble Zn(NH₃)₄²⁺.

Air stripping was adopted to treat nickel ammonia complex ion-containing wastewater in order to remove nickel and ammonia simultaneously in one technological process. The relationship among pH, the concentration of nickel ammonia complex ion and total ammonia concentration was analyzed theoretically. Influence of pH value, water temperature, airflow rate and time on air stripping was studied in detail by static experiment in laboratory. The results show that at pH 11, temperature of 60 ℃ and airflow rate of 0.12 m³/h, NH₃ and Ni²⁺ concentrations remained in wastewater are less than 2 and 0.2 mg/L, respectively, after blowing for 75 min, which reaches the standard of the state discharge. When the tail gas is absorbed by 0.5 mol/L H₂SO₄ in order to avoid the secondary pollution, the absorption rate can achieve 70%.

Cu(Ⅱ) biosorption by orange peel that was chemically modified with sodium hydroxide and calcium chloride was investigated. The effects of temperature, contact time, initial concentration of metal ions and pH on the biosorption of Cu(Ⅱ) ions were assessed. Thermodynamic parameters including change of free energy  enthalpy  and entropy  during the biosorption were determined. The results show that the biosorption process of Cu(Ⅱ) ions by chemically treated orange peel is feasible, spontaneous and exothermic under studied conditions. Equilibrium is well described by Langmuir equation with the maximum biosorption capacity(q_m) for Cu(Ⅱ) as 72.73 mg/g and kinetics is found to fit pseudo-second order type biosorption kinetics. As the temperature increases from 16 ℃ to 60 ℃, copper biosorption decreases. The loaded biosorbent is regenerated using HCl solution for repeatedly use for five times with little loss of biosorption capacity.

Lead-loaded modified spent grain regenerated by desorption process was investigated. HCl, H₂SO₄, H₃PO₄, NaOH, NaCl and ultrapure water were chosen as desorption agents to treat lead-loaded modified spent grain for 30 min. The structures and components of regenerated modified spent grain before and after adsorbing Pb(Ⅱ) were investigated using scanning electron microscopy(SEM), energy-dispersive analysis of X-ray(EDAX) and Fourier transform infrared spectrometry(FTIR). The results indicate that lead-loaded modified spent grain treated in 0.1 mol/L HCl exhibits higher elution efficiency (86.44%) as compared with other agents. The enrichment of carboxyl and hydroxyl groups susceptible to combine with Pb(Ⅱ) are observed in the regenerated modified spent grain, which may result in high re-absorption efficiency of Pb(Ⅱ). Moreover, C—Cl, N—H, C—N and O—H (polysaccharides) also play an crucial role in Pb(Ⅱ) binding to regenerated modified spent grain.

The transformation behaviors of Pb fractions during composting of Pb-polluted waste without inoculants and with the inoculants of Phanerochaete chrysosporium were studied. Results show that the active Pb ions with high toxicity and transferability are transformed into the inactive Pb with low toxicity and transferability, confirming that Pb ions can be efficiently immobilized during composting without or with the inoculants. The soluble-exchangeable Pb in composting without inoculants reaches 49.0 mg/kg at day 60, while that with the inoculants is reduced to 0 mg/kg dry mass compost. The higher contents of organic-bound Pb (59.0 mg/kg) and residual Pb (69.2 mg/kg) with low toxicity are found after 60-day composting with inoculants, compared with those without inoculants. The above data indicate the better immobilization effect of Pb and the greater alleviation of Pb hazards in composting with the inoculants of Phanerochaete chrysosporium than without inoculants, which may be due to the more microbial biomass and the higher pH value in composting of Pb-polluted waste with inoculants.

A novel method to prepare soil nutrient amendment by calcining a mixture of white mud and potassium feldspar and its environmental assessment were investigated. Under the optimal conditions of a blending mass ratio of 70׃30 for white mud to potassium feldspar, a calcination temperature of 1 000 ℃, a calcination time of 1.5 h and spherulitic diameter of 2.0 cm, the calcined product, as a soil nutrient amendment, could be prepared with the following nutrient composition (mass fraction):K₂O 4.16%, CaO 23.43%, MgO 5.04%, SiO₂ 22.92%, SO₄²⁻ 3.71%, and Cl⁻ 3.87% in 0.1 mol/L citric acid solution. The concentrations of heavy metals in the calcined product and the emission concentrations of harmful gases from a mixture of white mud and potassium feldspar during calcination process could qualify the National Standards without causing secondary environmental pollution.

To relate froth structural information with mineral flotation performance, segmentation analysis was performed on froth images characterized by fully occupied convex bubbles with white spots effect. An improved valley edge detection method was proposed to extract structural features and overcome fake white spot edges seriously affecting the segmentation performance. After preprocessing, detection template was designed based on the local minimal intensity, and a binary image containing segmented boundaries was obtained by applying logical rules, thinning and filtering. Statistical features such as bubble size were estimated for control purpose. Experimental results demonstrate that the proposed method avoids over-segmentation or ill-segmentation caused by uneven illumination, and the industrial application reveals the reliability of bubble size estimation.

Biofilm systems are effective for biosorption of metal ions. Shewanella oneidensis MR-1, a Gram-negative facultative anaerobe, is a natural pellicle-like biofilm former. The mechanisms of pellicle formation by S. oneidensis MR-1 have not yet been understood. 17 S. oneidensis MR-1 deletion mutants, including 12 c-type cytochromes were generated and tested if they were involved in pellicle formation. The results show that ∆SO4666, ∆SO1777, ∆SO1782, ∆SO2361 and ∆SO2363 have varying deficiency in pellicle formation. The deletion mutant ∆SO4666 cannot form a pellicle under non-shake conditions, suggesting that it may play an important role in pellicle formation by S. oneidensis MR-1. Overall, these data suggest a very complex picture of aerobic respiration by S. oneidensis MR-1.

The amenability of a refractory ore to the extraction of gold and silver by cyanide leaching was investigated. Diagnostic leaching tests were also performed to shed light on the refractory characteristics of ore. The leaching tests show that the extraction of gold and silver is consistently low, i.e. ≤47% and ≤19.2%, respectively, over a leaching period of 24 h. Even fine grinding (e.g. ＜38 µm) does not improve the recovery of gold and silver. Diagnostic leaching approach provides information into the cause of the refractoriness of the ore. The findings suggest that the refractoriness is induced by the dissemination and encapsulation of the very fine gold and silver particles largely in the carbonates, oxides and sulfides and, to a small extent, with silicates present in the ore matrix. These findings highlight the practical importance of diagnostic leaching for the understanding of the refractory characteristic of such an ore and for the identification of possible pretreatment options to overcome its refractoriness prior to cyanide leaching.

Low gold and silver leaching kinetics has been commonly observed in traditional gold-silver cyanidation process, especially in heap leaching and in situ leaching operations. The different mineralogy of gold and silver in the ores is suspected to be the main reason, e.g., the occurrence of low solubility acanthite (Ag₂S) typically results in low overall silver extraction. Due to the low solubility of oxygen in cyanide solution, the reactivity and availability of oxidant is believed to be the critical limitation for gold and silver dissolution. The use of ferricyanide as the auxiliary oxidant for gold and silver cyanidation has been examined. The rotating disc test results prove the assistant effect of ferricyanide on increasing the dissolution rate of gold and silver. The potential use of ferricyanide in gold/silver cyanidation process is proposed based on the leaching results of actual ores.

Electrical conductivity of NaF-AlF₃ melts was measured by continuously varying cell constant(CVCC) technique. Relationships between equivalent conductivity at 990−1 030 ℃ and temperature and composition, and relationship between equivalent conductivity activation energy and composition of the melts were then studied on the basis of two-step decomposition mechanism of AlF₆³⁻. According to the changes of molar fractions of different anions in NaF-AlF₃ melts, courses of dependence of equivalent conductivity and its activation energy on composition were analyzed. The results show that the influence of temperature on equivalent conductivity of the melts is small in the researched temperature range, and equivalent conductivity increases with increasing the molar fraction of AlF₃; there is a minimum point in the activation energy—composition curve when molar fraction of AlF₃ is 0.29.

The influence of aluminum electrolyte component on its temperature is an important issue within the field of aluminum reduction with pre-baked cells. The characteristic correlation between excess AlF₃ concentration and aluminum electrolyte temperature was explored through the modeling of heat and mass transfer processes in industrial pre-baked aluminum reduction cells. A coupled heat/mass-balance model was derived theoretically from the mass and energy balance of an electrolysis cell, and then was simplified properly into a practical expression. The model demonstrates that if environmental temperature and Al₂O₃ concentration keep constant, the excess AlF₃ concentration decreases with the aluminum electrolyte temperature linearly and its decrease rate is dependent on the heat transfer property of aluminum electrolyte, side wall and cell shell. Secondly, experiments were conducted on site with two industrial cells in an aluminum electrolysis plant. Excess AlF₃ concentration and aluminum electrolyte temperature were obtained simultaneously together with other parameters such as Al₂O₃, CaF₂, MgF₂ and LiF concentrations. Results show that the maximum absolute error between the tested value and the calculated value of excess AlF₃ concentration using the proposed model is less than 2%. This reveals that the coupled heat/mass-balance model can appropriately characterize the correlation between excess AlF₃ concentration and aluminum electrolyte temperature with good accuracy and practicability.

In chloride system, thermodynamic analysis is a useful guide to separate lead and antimony as well as to understand the separation mechanism. An efficient and feasible way for separating lead and antimony was discussed. The relationships of [Pb²⁺][Cl⁻]²—lg[Cl]_T and E—lg[Cl]_T in Pb-Sb-Cl-H₂O system were studied, and the solubilities of lead chloride at different antimony concentrations were calculated based on principle of simultaneous equilibrium. The results show that insoluble salt PbCl₂ will only exist stably in a certain concentration range of chlorine ion. This concentration range of chlorine ion expands a little with increasing the concentration of antimony in the system while narrows as the system acidity increases. The solubility of Pb²⁺ in solution decreases with increasing the concentration of antimony in the system, whereas increases with increasing the concentration of total chlorine. The concentration range of total chlorine causing lead solubility less than 0.005 mol/L increases monotonically.

The separation techniques of vanadium and molybdenum were summarized, and a new method of removal V(Ⅴ) from Mo(Ⅵ) by adsorption with chelate resin was presented. Nine kinds of chelate resins were used to investigate the adsorbent capability of V(Ⅴ) in ammonium molybdate solution with static method. The test results show that DDAS, CUW and CW-2 resins can easily adsorb V(Ⅴ) in ammonium molybdate solution, but hardly adsorb Mo(Ⅵ). The dynamic experimental results show more than 99.5% of V(Ⅴ) can be adsorbed, and the adsorption rate of Mo(Ⅵ) is less than 0.27% at 294−296 K for 60 min at pH 7.42−8.02. The mass ratio of V to Mo decreases to l/5 0000 in the effluent from 1/255 in the initial solution. The loaded resin can be desorbed by 5% NH₃∙H₂O solution, and the vanadium desorption rate can reach 99.6%. The max concentration of vanadium in desorbed solution can reach 20 g/L, while the concentration of molybdenum is less than 0.8 g/L.

The adsorption behavior of Cd²⁺ on 001×7 strong-acid cation exchange resin was studied with the static adsorption method. The adsorption process was analyzed from thermodynamics and kinetics aspects. The influences of experimental parameters such as pH, temperature, initial concentration and adsorption rate were investigated. The experimental results show that in the studied concentration range, 001×7 resin has a good sorption ability for Cd²⁺, and the equilibrium adsorption data fit to Freundlich isotherms. The adsorption is an exothermic process which runs spontaneously. Kinetic analysis shows that the adsorption rate is mainly governed by liquid film diffusion. The best adsorption condition is pH 4−5. The saturated resin can be regenerated by 3 mol/L nitric acid, and the desorption efficiency is over 98%. The maximal static saturated adsorption capacity is 355 mg/g (wet resin) at 293 K. The adsorption mechanism of Cd²⁺ on 001×7 resin was discussed based on IR spectra.

α-alanine was adopted as a new additive to elucidate the seeded precipitation mechanism of sodium aluminate solution. α-alanine has the inhibitory effect at the initial period of reaction, but the favorable effect in subsequent reaction. The combined effect of amino and carboxyl group in α-alanine was confirmed by investigating the effect of propionic acid, ethamine and the mixture of propionic acid and ethamine (mole ratio 1׃1) on the precipitation of sodium aluminate solution, respectively. The inhibitory effect derives from the adsorption of amino or carboxyl group in α-alanine on the active surface sites of gibbsite, which was confirmed by the alleviating inhibitory effects of propionic acid, ethamine and α-alanine due to the double crystal seed mass. The semi-quantitative IR spectrum  analysis of the relative concentrations of Al₂O(OH)₆²⁻ with the band at about 550 cm⁻¹ and polynuclear aluminate ion with the bands at about 880 cm⁻¹ and 635 cm⁻¹, indicates that the dynamic balance among some aluminate species present in sodium aluminate solution is broken due to the addition of α-alanine, thus resulting in the change of the seeded precipitation ratio of sodium aluminate solution.

The recovery of Ni, Co and Mn from spent battery material is very important to environment protection, utilization of resources and cost reduction of the material. The dissolution rates of Ni, Co and Mn with hydrochloric acid as leachant are all over 95% under the optimal conditions of initial hydrochloric acid of 6 mol/L, particle size of 120 μm for the exhausted scraps, molar ratio of H₂O₂ to MeS of 2, leaching temperature about 60 ℃, ratio of liquid to solid of 8, and leaching time of 2 h. The Ni_xCo_yMn_z precursor for cathode material prepared from the purified leaching solution, can meet the demand of precursor by pure chemicals. The process is economic and feasible for base metals from spent battery material.

To evaluate the metal chromium (Cr) contamination of soil at a chromium-containing slag site by ferrochromium production, the contaminated sites, under slag heap, in the vicinity of slag heap and arable soils near the outlet of sewer channel, and unpolluted site 5 km away from one ferroalloy plant in Hunan Province, China, were selected. The concentrations of total Cr and water soluble Cr in bulk soil samples and profile depth samples were determined. The results show that the soils in the vicinity of slag heap have the highest total Cr content followed by the soils under the slag heap and near the outlet of sewer channel of the factory. The mean concentrations of total Cr in the top soils at above three contaminated locations exceed the critical level of Secondary Environmental Quality Standard for Soil in China by 3.5, 5.4 and 1.8 times. In most Cr polluted soils, total Cr has a relative accumulation in soil depth of 40−60 cm, but this trend is not found in unpolluted soils. The average concentrations of water soluble Cr (Ⅵ) in top soils under slag heap and in the vicinity of slag heap are 176.9 times and 52.7 times higher than that in the uncontaminated soils, respectively. However, water soluble Cr (Ⅵ) contents in soils near sewer channel are all low and the values are close to that in the uncontaminated soils. Although water soluble Cr (Ⅵ) content in soil profiles decreases with soil depths, it in soils under slag heap maintains a high level even at a depth of 100−150 cm. The results imply that the transportation of Cr (Ⅵ) can result in a potential risk of groundwater system in this area.

Environmental availability and profile characteristics of arsenic (As), cadmium (Cd), lead (Pb) and zinc (Zn) were studied in contaminated vegetable soils from the Pb/Zn mining and smelting areas in Hunan Province of China, and the potential environmental risks of these metals were also assessed. The results show that the concentrations of As, Cd, Pb and Zn in vegetable soils are higher than the levels of Soil Environmental Quality of China (GB15618—1995). The mobility of metals in soil profiles is mainly characterized by the low pH and organic matter content of soil. The major part of As, Cd, Pb and Zn is restricted to the upper soils and the contamination of these metals in soils is significantly influenced by the long-term Pb/Zn mining and smelting activities. Based on the results from the BCR sequential extraction, the fraction of Cd in the soil profiles is predominantly existed in the acid-extractable form and the large amount of Pb is closely associated with reducible fraction. The environmental availability of Cd and Pb is predominantly higher than that of As and Zn in the soil profiles, suggesting Cd and Pb have more huge potential risk for human health and surrounding environment.

The novel felt-metal supported PVA composite hydrophilic ultrafiltration membrane was used for the treatment of oil/water(O/W) emulsion. The effects of transmembrane pressure(TMP), cross flow velocity, feed concentration on membrane performance were investigated, and ultrasonic cleaning of the fouled membrane was also investigated. The results show the flux increases with the increase of cross-flow velocity and TMP within the given TMP range from 0.20 MPa to 0.40 MPa. With increase of initial oil concentration increases, the oil rejection increases while the permeate flux decreases. The composite membrane shows more than 90% oil rejection within the initial oil concentration range from 0.05% to 0.50% (mass fraction) at TMP of 0.30 MPa. The fouling of the composite membrane increases rapidly during the initial 20 min at given TMP range from 0.20 MPa to 0.40 MPa, and it increases slowly after 30 min. The results also show that ultrasound is very effective in removing oil fouling of the fouled membrane, and the properties of the composite ultrafiltration membrane can be completely recovered by 10 min of sonication.

Two types of Sb-doped SnO₂ films on titanium substrate were prepared by the combination of electro-deposi, tion and dip-coating (Ti/SnO₂-Sb₂O₄/SnO₂-Sb₂O₄) and single dip-coating (Ti/SnO₂-Sb₂O₄), respectively. The surface morphology and crystalline structure of both film electrodes were characterized using X-ray diffractometry(XRD) and scanning electron microscopy(SEM). XRD spectra indicate that the rutile SnO₂ forms in two films and a TiO₂ crystallite exists only in Ti/SnO₂-Sb₂O₄ electrode. SEM images show that the surface morphology of two films is typically cracked-mud structure. The photooxidation experiment was proceeded to further confirm the two electrode activity. The results show that the photoelectrocatalytic degradation efficiency of Ti/SnO₂-Sb₂O₄ electrode with sub-layer is higher than that of simple Ti/SnO₂-Sb₂O₄ electrode using phenol as a model organic pollutant. The Ti/SnO₂-Sb₂O₄/SnO₂-Sb₂O₄ photoanode has a better photoelectrochemical performance than Ti/SnO₂-Sb₂O₄ photoanode for the removal of organic pollutants from water.

During deep drawing process, the material parameters of blank have a significant effect on the quality of the drawn part and the determination of process parameters. Here, a 3D finite element model is developed for the deep drawing process of a thin-walled hemispheric surface part. Then the influences of material parameters including hardening exponent n, yield stress σ_s and elastic modulus E on the process are investigated by simulation. The results show that the effects of n and σ_s on punch force, thickness variation and equivalent strain are more notable. The maximum equivalent plastic strain occurs outside the die corner. However, when the value of n is 0.03 or σ_s is smaller than 120 MPa, higher equivalent plastic strain occurs at ball top.

The dynamic corrosion process of bio-oxidation of copper-nickel sulfide from Karatungk in northern Xinjiang Province of China was studied. The polished wafer of the copper-nickel sulphide was used to carry on a series of oxidation corrosion experiment by Acidithiobacillus ferrooxidans. The changes of superficial corrosion appearance and the mineral dynamic corrosion process were discovered by microscope observation. Then, the galvanic cell model was established, and the bio-oxidation activation order of typical copper-nickel sulphide minerals was ascertained as pyrrhotite＞pentlandite＞chalocopyrite.

To search a novel class of effective silicate mineral collectors, the Gemini quaternary ammonium salt surfactant (butane-α, ω-bis(dimethyl dodeculammonium bromide), 12-4-12) and its corresponding conventional monomeric surfactant (dedecyl trimethyl ammonium bromide, DTAB) were adopted to comparatively study the flotation behaviors of illite, pyrophyllite and kaolinite. Three silicate minerals with the Gemini surfactant as collector reveal floatability far better than with the corresponding traditional one. At pH 6, the best recoveries of illite, pyrophyllite and kaolinite with 3.5×10⁻⁴ mol/L 12-4-12 are 99.2%, 91.7% and 99.6%, respectively. The fluorescence and contact angle measurement were also conducted for the further investigation of surfactants aggregation behavior and silicate mineral surface hydrophobic properties. FTIR spectra analysis and electrokinetic analysis show that the mechanism of adsorption of collector molecules on mineral surfaces is almost identical for the electronic attraction and hydrogen bonds effect. The superior collecting power of dimeric collector may be attributed primarily to its special structure and its essential properties.

The effects of mineral processing wastewater on sulfide minerals were investigated by flotation, infrared spectrometry and electrochemistry test. The results show that lead-concentrate water can improve the flotation of galena, while the sulfur-concentrate water has negative effect on flotation of galena compared with distilled water. The flotation behavior of pyrite is contrary to that of galena in three kinds of water. Infrared spectra indicate that the residual collector in the lead-concentrate water is beneficial to the formation of lead xanthate on the surface of galena. Electrochemistry results indicate that electrochemistry reaction on galena surface has apparent change. The anode polarization is improved and cathode polarization is depressed.

The thermodynamics equilibrium principle was used to construct the diagrams for the concentration of complex ions (pc) vs pH, the distribution ratio of lead hydroxyl complex ions (α_n) vs pH, and the conditional solubility product of Pb(OH)₂ vs pH in the Pb²⁺-H₂O system. The relationship between the equilibrium concentration of each kind of lead hydroxyl complex ions in equilibrium with Pb(OH)₂(s) and pH value was shown in the system. The minimum solubility of lead is at the pH value of 10.096−10.997. The distribution ratio of each kind of the lead hydroxyl complex ions is determined as a function of the pH value and the total lead concentration ([Pb]_T). The diagram for the conditional solubility product, pK_SP vs pH, shows that each kind of lead hydroxyl complex ions existing in the system is dependent upon an optimized pH value at the established concentration of [Pb]_T, and that pK_SP reaches the minimum at the pH value of 10.3−11.2. The results can provide a theoretical basis for removing lead ions from wastewater by the neutralization and hydrolyzation technology.

A purification process was developed to remove impurity element boron from the metallurgical grade silicon by the electric arc furnace refining. The thermodynamic equilibria calculation and experiment to remove boron in the oxidizing atmosphere were performed and analyzed. Boron is removed as the gaseous species B_xO_y and B_xH_zO_y in O₂ and H₂O-O₂ atmosphere respectively. The equilibrium pressure of B_xH_zO_y is 10⁵−10¹⁰ times that of B_xO_y. Boron is removed and its content in silicon is reduced from 18×10⁻⁶ to 2×10⁻⁶ in the Ar-H₂O-O₂ atmosphere in the electric arc furnace.

Simultaneous recovery of rare earth, nickel and cobalt resources from the anode material of hydrogen-nickel battery was performed through a hydrometallurgical process. Most of rare earth elements are separated from nickel and cobalt in the form of sulfates when the anode material is firstly leached with sulfuric acid. Then, the precipitated rare earth sulfates are dissolved with sodium hydroxide to form rare earth hydroxides. The rare earth element, zinc and manganese ions in the lixivium are also separated from nickel and cobalt by using PC-88A extractant system, and the organic phase loaded rare earth is stripped with hydrochloric acid. By neutralizing the stripping solution with rare earth hydroxide, the rare earth chloride is obtained. Under the suitable leaching conditions of sulfuric acid 3 mol/L, leaching time 4 h and temperature 95 ℃, 94.5% of rare earth in the anode material is transformed into the sulfate precipitates, and the leaching ratios of nickel and cobalt can approach 99.5%. When the pH value of the extractive system is controlled in the range of 3.0−3.5, the rare earth elements in the lixivium can be extracted completely into the organic phase, and the stripping recovery of the rare earth can reach 98% in the extraction stage. The total recoveries of rare earth, nickel and cobalt are 98.9%, 98.4% and 98.5%, respectively.

The refractory niobium bearing minerals, Samarskite, Fergusonite, Betafite and Pyrochlore of the ore sample obtained from Kadabora, Egypt, was subjected to sulfuric acid leaching using acid concentrations varied from 17.6 to 4.5 mol/ L. The extraction of niobium from the sulfate leach liquors was done using the synthesized 8,9-dihydro[1,2,4]triazolo[1,5-a]quinazolin- 6(7H)-one dissolved in methylene chloride. It has been found that extraction efficiency of 84% was achieved by contacting equal volumes of 0.32% extractant with 4.5 mol/L sulfate solution for 15 min. The stripping was performed by 0.5 mol/L HF with efficiency of 86.7%.

A new approach to prepare PbSO₄ powder is studied. Using the methods of the leaching of galena concentrates in the ferric chloride media, selective purification and chemical sedimentation, PbS concentrate can be converted into PbSO₄. The conversion recovery is 97.39%, the purity of PbSO₄ powder is above 99% and its average crystallite size is about 42 nm. In this process, emission of lead vapour and SO₂ cannot occur. The experimental results demonstrate the feasibility of realizing a green route to prepare the lead sulfate powder.

The effects of Na⁺ and Ca²⁺ in the purified water on the conductivity of zinc electrolyte and the current efficiency of zinc electrolysis were studied by the alternating current bridge method and the simulated electrolysis experiments, and the water quality index of reused water was established. The results show that the conductivity of the solution and the current efficiency decrease as these two kinds of positive ions are added in the electrolyte. The effect of Ca²⁺ is much more remarkable than that of Na⁺. ρ(Na⁺)≤ 8 g/L and ρ(Ca²⁺)≤20 mg/L are the quality indexes in the zinc electrolysis process and the concentrations of Na⁺ and Ca²⁺ in the purified water reused to the process should be less than the limited values, i.e. the water quality index of the purified water should be controlled by its reused amount.

The flow and concentration fields in a new style tubular stirred reactor were simulated by simulating the fluids dynamics(CFD), in which FLUENT software was used and the standard k—ε model and multiple reference frame(MRF) were adopted. The various values of initial rotating speed and inlet flow rate were adopted. Simulations were validated with experimental residence time distribution(RTD) determination. It is shown that the fluid flow is very turbulent and the flow pattern approaches to the plug flow. The velocity increases from shaft to the end of impeller, and the gradient is enlarged by increasing the rotating speed. Comparison between RTD curves shows that agitation can improve the performance of reactor. As the flow rate increases, the mean residence time decreases proportionally, and the variance of RTD lessens as well. When rotating speed increases to a certain value, the variance of RTD is enlarged by increasing rotating speed, but the mean residence time has no obvious change.

The corrosion process of AZ91D magnesium alloy in neutral 1% (mass fraction) sodium chloride aqueous solution was investigated by electrochemical noise(EN), SEM and EDX. Fractal theory was primarily used to depict the corrosion process of the alloy. The fast wavelet transform(FWT), as well as the fast Fourier transform(FFT), was employed to analyze the EN data. The results show that the overall corrosion process can be described by three stages. The first stage corresponds to the pit nucleation and growth; the second stage involves the growth of a passive oxide layer; and the third stage involves reactivation. With increasing immersion time, fractal dimension increases fast initially, fluctuates in the medium and increases again at last. Pitting corrosion and fractal dimension increase due to the initiation and formation of pits in the initial and the end of immersion, while depresses due to the passivation in the medium period. The results of SEM and EDX support the above conclusions.

A one-step pickling-activation process was proposed as an environmental friendly pretreatment method in phosphate-permanganate solution before electroplating on magnesium alloys. The effects of pickling-activation on qualities of coating were assessed by adhesion and porosity testing of copper plating. The interfacial reactions between specimen and solution were analyzed with SEM, EDX and XRD. The results show that the developed process of pickling-activation can equalize the potentials on substrate surface. The compacted zinc film can be obtained by zinc immersion after treating magnesium alloy in the pH 4−6 phosphate-permanganate solution for 3−5 min. The adhesion and corrosion resistance of copper plating are enhanced. The one-step pickling-activation can replace the existing two-step process of acid pickling and activation which contains a great deal of chromium and fluorine. The procedure of surface pretreatment is simplified and the production environment is improved.