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In this work, the bioleaching process of pyrite, chalcocite and covellite which were the main phase compositions for Zijin copper mineral was comprehensively studied. The influence parameters, such as leaching temperature, Fe3+ concentration, pH of solution and bacteria concentration were investigated. The leaching kinetics of the pyrite, chalcocite and covellite under the studied conditions was successfully modeled by an empirical diffusion-like equation, respectively. The apparent activity energy of pyrite leaching, chalcocite leaching (stage II) and covellite leaching was calculated to be 69.29, 65.02 and 84.97 kJ/mol, respectively.

Arsenic (As)-contaminated paddy soil could result in elevated levels of As in rice plants and sequentially harm human health. The Fe3O4-modified biochar (NBC-Fe) prepared by the coprecipitation method was applied in a pot experiment to investigate its effect on mobility and bioavailability of As in soil and to reduce As accumulation in rice tissues (brown rice, husks, spikelets, leaves, stems, and roots). Compared with non-application (CK), application of NBC-Fe significantly increased the cation exchange capacity (CEC), decreased As availability, and raised the As concentration of crystalline hydrous oxide–bound fraction in the soil. The addition of 0.05–1.6% (w/w) NBC-Fe significantly reduced the As concentrations in brown rice by 9.4–47.3%, which was lower than the level set by the National Food Safety Standards of China (0.2 mg/kg). The NBC-Fe treatment decreased As concentrations in iron plaque (DCB-As), and the DCB-As had the very significant correlations (P

Coating superparamagnetic iron oxide particles, i.e., Fe3O4, as adsorbents have major advantages over bare adsorbents for water treatment. As a versatile material, zirconium has been extensively studied for phosphate removal. In this study, the Fe3O4 core was pre-coated with branched polyethyleneimine (PEI) first, and then loaded with zirconium to result in a highly selective adsorbent (i.e., Zr-PEI@Fe3O4) for phosphate with a greatly broadened pH range. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), BET surface area, and magnetization were used to characterize the resulting adsorbent and to explore the underlying adsorption mechanism. The adsorption performance of Zr-PEI@Fe3O4 toward phosphate was performed by batch experiment. The results showed that Freundlich model better fit the adsorption isotherms, while the Elovich equation better described the kinetic process. The maximum adsorption capacity of dephosphorization 32.2 mg·g−1 (according to P element) emerged in the condition of 1.0 g·L−1 and pH at 2 with 303 K. The process was spontaneous and endothermic. Zr-PEI@Fe3O4 has the potential to remove phosphate from solution due to its easy separation and some good adsorption property.

A palladium catalyzed desulfurative coupling of allylthioethers with organoboronic acids under mild reaction conditions is described. The reaction exhibits high chemoselectivity and good functional group tolerance, allowing the synthesis of a wide range of α-branched enones. In addition, this approach enables a new retrosynthetic disconnection to multi-functionalised allylic molecules via selective cleavage of the C–S bond, thus providing a complementary allylation protocol to Tsuji–Trost reactions.

For the high sulfur refractory gold concentrate with 41.82% sulfur and 15.12 g/t gold, of which 82.11% was wrapped in sulfide, a well-controlled stirring tank leaching was carried out to improve the bio-oxidation efficiency. Results show that bio-oxidation pretreatment can greatly improve the gold recovery rate of high-sulfur refractory gold concentrate, and at the optimum pH 1.3 in this study, compared with the process without pH control, the oxidation rate of sulfur increased from 79.31% to 83.29%, while the recovery rate of gold increased from 76.54% to 83.23%; under this condition the activity of mixed culture could be sustained and the formation of jarosite could diminish. The results also displayed that for the high sulfur refractory gold concentrate, the recovery of gold is positively correlated with the oxidation rate of sulfur, and the recovery rate of gold increases with the increase of sulfur oxidation rate within a certain range.

A highly effective adsorbent of lanthanum-modified D751 resin (D751 resin for macroporous styrene chelated resin, sodium form) was prepared to enhance the effect of removing phosphate from solution. FTIR, SEM were used to explore the functional groups and structural features on the surface of D751-La; XPS analyzed the action mechanism between phosphate and D751-La. The adsorption performance about D751-La toward phosphate was investigated by batch experiment. The results showed that Langmuir, Freundlich, Temkin, Koble-Corrigan as well as Redlich-Peterson models fitted well for the adsorption isotherms. The adsorption kinetics could be better fitted by Double Constant, Elovich, and Pseudo-second-order model. The effect of salinity was not significant, such as Cl− and SO42−. When the solid-liquid ratio was 15 g·L−1 with setting the reaction time as 8 h, the unit adsorption quantity of D751-La to phosphate (calculated in P) reached up to 26.3mg·g−1 under the solution pH=3 at 293 K. The process was spontaneous and exothermic from thermodynamic analysis. It shows that D751-La has potential to remove phosphate from solution.

Herein, we report a straightforward, environmentally friendly, and controllable palladium/ligand catalytic system to enable reductive/oxidative Heck reactions of cyclic enones with thiophene or furan derivatives via C-H activation. The key to this tunable reaction is the appropriate intercepting thienyl-Pd(II)-enolate during the enolization process. Such a controllable and economic protocol would not only provide efficient methods to construct various value-added β-heteroarylated cyclic ketones/enones but also shed light on developing other conjugate addition reactions via C-H activation.

Hydrogen evolution reaction (HER) is an essential step in converting renewable energy to clean hydrogen fuel. Exploring highly efficient, stable and cost-effective electrocatalysts is of crucial significance for sustainable HER. Here, we report the design of a coupled ruthenium/cobalt oxide (Ru/CoO) hybrid electrocatalyst for alkaline HER. In this hybrid metal/oxide system, the complicated alkaline HER pathways are overall facilitated; oxygen (O)-vacancy-abundant oxide enhances water splitting and Ru promotes successive hydrogen intermediates to generate hydrogen. The resulting Ru/CoO hybrid electrocatalyst exhibits significantly promoted catalytic activity compared with benchmark Ru catalyst, displaying an overpotential of 55 mV to generate a HER current density of 10 mA cm−2, comparable with the state-of-the-art Pt/C catalyst and the most efficient alkaline HER electrocatalysts. Furthermore, the strong interaction of Ru nanoparticles with oxide support and the in-situ growth of oxide support on conductive substrate guarantee the long-term stability of as-fabricated Ru/CoO hybrid electrocatalyst. This newly designed hybrid catalyst with abundant metal/oxide interfaces may pave a new pathway for exploring efficient and stable HER electrocatalysts.

Driven by the intensified demand for energy storage systems with high-energy density and safety, all-solid-state zinc (Zn) air batteries have drawn extensive attentions. However, the development of non-precious metals with high catalytic activity as the air electrode is still a big challenge. In this work, we realize the large-scale fabrication of single-crystal CoO nanorods with high active facets and abundant oxygen vacancies in-situ on conductive substrate, which exhibits superior electrocatalytic activity in both oxygen reduction reaction and oxygen evolution reaction. The all-solid-state Zn-air batteries assembled with such free-standing CoO NRs show low charge/discharge overpotentials, a high energy density and a high cyclic stability. Our work indicates that the rational structure design of catalysts can pave a new route to next generation efficient and durable electrochemical devices.

FeCo2O4 nanoparticles with abundant oxygen vacancies were produced by laser fragmentation. The oxygen vacancies can lower the thermodynamic energy barriers as well as accelerate the electron transfer, eventually promoting oxygen evolution and reduction reactions simultaneously.

Selenised glucose (SeGlu) is a newly invented organic selenium compound being synthesised through the selenisation reaction of glucose with NaHSe. We hypothesised that glucose could be used as a carrier for the stable low-valent organoselenium to enhance the selenium concentrations of eggs. To probe the effects of SeGlu on production performances of laying hens, egg selenium concentration, egg quality, and antioxidant indexes, 360 Hy-Line Brown laying hens were randomly assigned to three treatment groups fed with a basal diet alone or the diet supplemented with 5 or 10 mg/kg of Se from SeGlu. The results showed that SeGlu treatment not only enhanced (P < 0.001) the Se concentration in albumen and yolks, glutathione peroxidase activity, and total antioxidant capacity of eggs but also increased (P = 0.032) the Haugh unit of eggs being stored for 2 weeks, while the production performances and egg qualities of fresh eggs were not affected. Moreover, SeGlu supplementation linearly (P < 0.001) increased the scavenging ability of superoxide radicals in eggs. Briefly, SeGlu can enhance the selenium deposition and antioxidant activity of eggs, thereby meeting the nutritional requirement for Se-deficient humans.

Platinum-rare earth metal (Pt-RE) nanoalloys are the most promising candidates for fuel cells because of their superior activity and stability for oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). However, the preparation of Pt-RE nanoalloys with chemical method is still challenge due to their huge standard reduction potential differences and the oxophilicity of the latter. Herein, this work provides a novel and facile strategy for the chemical synthesis of Pt5La nanoalloys to apply in both ORR and MOR. Pt5La nanoalloys are synthesized by co-reduction of Pt2+ and La3+ in LaCl3 and H2PtCl6 solution containing carbon powder and C2H4N4 by first heating at 550 °C for 2 h under N2, and then heating to 700 °C under H2/Ar for 2 h. The as-synthesized Pt5La nanoalloys present a high alloying degree at 700 °C, with the average particle size of 7.8 nm. The results indicate Pt5La nanoalloys lead to a significant enhancement in ORR and MOR performances related to the commercial JM-Pt/C catalyst.

Herein, we report a palladium-catalyzed dehydrogenative cross-coupling of indoles with cyclic enones to give β-indolyl cyclic enones under mild and neutral reaction conditions. The key to the success is to explore a mild condition, which ensures the indole C-H activation and subsequent syn β-hydride elimination through rapid enolization isomerization of Pd(II)-enolate while suppressing other undesired side reactions. Synthetic utility has also been demonstrated in the flexible transformation of the coupling products to meta-phenols and benzo[a]carbazoles.

In order to extract gallium from a high-silica-content flue dust generated in corundum production, a mixed acid solution of H2SO4 and HF was used for leaching, and test parameters of the leaching process were optimized. Experimental results show that the leaching rate of gallium was only 38% when H2SO4 was used as leaching agent. Composition analysis results of micro areas in this corundum flue dust indicate that the content of gallium in silica-enriched phases was high; this portion of gallium was insoluble in H2SO4 solution. The leaching rate of gallium increased significantly with addition of HF due to corrosion of silica. Effects of reaction time, temperature, and concentrations of HF and H2SO4 on leaching rates of gallium were investigated. The leaching rate of gallium reached 91% when this corundum flue dust was leached in a mixed acid solution of H2SO4 and HF for 4 h, at a temperature of 80 °C, with a liquid-to-solid ratio of 5:1 (mL/g). The optimal concentrations of H2SO4 and HF in the mixed acid solution were 1.5 and 6.4 mol/L, respectively.

Cost-effective carbon-based catalysts are promising for catalyzing the electrochemical N2 reduction reaction (NRR). However, the activity origin of carbon-based catalysts towards NRR remains unclear, and regularities and rules for the rational design of carbon-based NRR electrocatalysts are still lacking. Based on a combination of theoretical calculations and experimental observations, chalcogen/oxygen group element (O, S, Se, Te) doped carbon materials were systematically evaluated as potential NRR catalysts. Heteroatom-doping-induced charge accumulation facilitates N2 adsorption on carbon atoms and spin polarization boosts the potential-determining step of the first protonation to form *NNH. Te-doped and Se-doped C catalysts exhibited high intrinsic NRR activity that is superior to most metal-based catalysts. Establishing the correlation between the electronic structure and NRR performance for carbon-based materials paves the pathway for their NRR application.

To extract gold from a low-grade (13.43 g/t) and high-sulfur (39.94wt% sulfide sulfur) Carlin-type gold concentrate from the Nibao deposit, Guizhou, a bio-pretreatment followed by carbon-in-pulp (CIP) cyanide leaching process was used. Various methods were used to detect the low-grade gold in the concentrate; however, only time-of-flight secondary-ion mass spectrometry (TOF-SIMS) was successful. With bio-pretreatment, the gold recovery rate increased by approximately 70.16% compared with that obtained by direct cyanide leaching of the concentrate. Various attempts were made to increase the final gold recovery rate. However, approximately 20wt% of the gold was non-extractable. To determine the nature of this non-extractable gold, mineralogy liberation analysis (MLA), formation of secondary product during the bio-pretreatment, and the preg-robbing capacity of the carbonaceous matter in the ore were investigated. The results indicated that at least four factors affected the gold recovery rate: gold occurrence, tight junctions of gold-bearing pyrite with gangue minerals, jarosite coating of the ore, and the carbonaceous matter content.

Biohydrometallurgy has broad application prospect in the treatment of low-grade nickel sulfide ore. However, quite a number of nickel sulfide deposits are associated with basic gangue minerals such as contain olivine, serpentine. The high basic gangue minerals will lead to a higher acid consumption and make it difficult to bioleach at pH below 2.5. It is crucial to improve processes and adapt bacteria with this kind of ore. This paper reviews the experimental researches and industrial applications for bioleaching of the high acid consumption nickel sulfide ores. It is suggested that bioleaching at elevated pH will have similar leaching rate compared with pH below 2.5, meanwhile the cost will be decreased remarkably due to a lower acid consumption and less dissolved impurity ions.

The experiment focused on the Deerni pyrite roasting residues mainly made of magnetic materials such as hematite and magnetite in Qinghai Deerni Copper Deposit. The method of bioleaching sulfuric acid residue by bacteria was proposed for roasting residues desulfurization and valuable metal extraction. First of all, the study systematically performed multi-elements analysis, which provided scientific and technique basis for extraction of valuable metals. Subsequently, the effect of the pH value on the bacterial growth was investigated. The data revealed that pH at 1.2 was the optimum culture condition for the bacteria. The concentration of the bacteria at the best culture condition reached 8.5×107 cells/mL. Finally, the bioleaching experiments were performed to explore the ability of the NB bacteria to oxidize the Deerni pyrite roasting residues. The study demonstrated that the microorganism was able to effectively extract valuable metals such as copper and zinc. The total Fe and sulfur contents of the bioleaching residues account for 68.38% and 0.39%, respectively. The desulfurization effects are evident and bioleaching residues meet the requirements as magnetic materials in steel making industry.

The comprehensive recovery of small amounts of valuable minerals such as gold and base-metal sulfide minerals from a low-grade refractory ore was investigated. The following treatment strategy was applied to a sample of this ore: gold flotation–gold concentrate leaching–lead and zinc flotation from the gold concentrate leaching residue. Closed-circuit trials of gold flotation yielded a gold concentrate that assayed at 40.23 g·t−1 Au with a recovery of 86.25%. The gold concentrate leaching rate was 98.76%. Two variants of lead-zinc flotation from the residue—preferential flotation of lead and zinc and bulk flotation of lead and zinc—were tested using the middling processing method. Foam from the reflotation was returned to the lead rougher flotation or lead–zinc bulk flotation, whereas middlings from reflotation were discarded. Sulfur concentrate was a byproduct. The combined strategy of flotation, leaching, and flotation is recommended for the treatment of this kind of ore.

In the past decade, progress in the field of biohydrometallurgy had been significant. A total of 17 novel biomining microorganisms were discovered, and eight copper heap bioleaching plants and 11 gold biooxidation plants were established or expanded. In this review, it was summarized the physiological properties of the newly isolated biomining microorganisms and three novel microbial ecological methods for studying microbial community dynamics and structure. In addition, biohydrometallurgy research on rare metals such as uranium, molybdenum, tellurium, germanium, indium, and secondary rare metal resources, as well as heavy nonferrous metals such as copper, nickel, cobalt, and gold has been reviewed, with an emphasis on China. In future, further studies on bioleaching of chalcopyrite, rare metals, secondary resources from waste, and environmental pollution caused by resource utilization are necessary. Zijinshan heap bioleaching plant restarted operation in 2012 with capacity of 30,000 ton·year−1. The average copper grade is 0.308 %. The ore particle size is 40 mm accounting for 80 %. The heap height is 8 m. The solution pH is controlled at 1.5–1.7, and redox potential is maintained at 730–760 mV. After 185 days leaching, copper leaching rate of more than 76 % and iron leaching rate of

MnO@C composites with three-dimensional cross-linked structure were designed and fabricated through hydrothermal treatment. Cation exchange resin was used as the precursor to create a three-dimensional cross-linked porous carbon structure, which was evenly decorated by nanosized MnO particles. When compared with pristine MnO, those MnO@C composites showed much better stability during charge-discharge cycling, retaining a specific capacity of 615 mAh g−1 (62.5 wt% MnO) after 100 cycles at a current density of 0.2 A g−1. This could be ascribed to the special three-dimensional cross-linked porous carbon that not only accelerated the transport of Li+ ions but also buffered the volume change and prevented agglomeration of MnO particles during the repeated lithiation and delithiation process.

Iron ore is the raw material for steel production, in addition to iron and slag major component, still contains sulfur and phosphorus compounds and other harmful elements, is the potential adverse effects of factors constitute the steel product quality and environment. Sulfur in iron ores into the steel products will not only produce "heat brittle" phenomenon, but also in the sintering process by roasting produce sulfur dioxide into the air, causing damage to the atmosphere and ecological environment. A typical of the high sulfur iron ore from Inner Mongolia, China, iron grade of 53.06% and sulfur content is 2.76%, the main metal mineral in the ore is magnetite, followed by magnetic pyrite, pyrite and siderite, otherwise a small amount of copper mineral chalcopyrite, bornite. In this work, a mixed culture composed by Sulfobacillus thermotolerans, Leptospirillum ferriphilum and Ferroplasma acidiphilum was used to leach the sulfur in iron ore samples, we investigated the leaching rate of sulfur under different initial pH, temperature and pulp density conditions. The results showed that under the condition of the initial pH of 1.8, the temperature was 33 °C, and pulp density 15%, after 7 days of oxidation, we got a yield of 80.16% product in which iron grade of 62.31% and sulfur content is 0.17%. Compared with original sample, sulfur content decreased 95.06%, iron grade increased by 9.25%, and iron recovery was 94.13%. From the results it can be concluded that this microbial process for high sulfur iron ore lead to a significant effect of sulfur reduction and substantial increase in iron grade.

The effect of solvent extractants, such as M5774, Cyanex 272, P204, P507 and N235, on the activity and community structure of acidophilic microorganisms were tested. Cobalt extractant Cyanex 272 did not show much inhibition effect on the growth of acidophiles, while iron extractant N235 had great inhibition effect. When the culture solution contacted with iron extractant P204, nickel extractant P507 and copper extractant M5774, the inhibition effect increased gradually. 16S rRNA gene clone library were used to analyze the initial and extractant contacted final microbial community structure. The initial inoculation microbial populations were mainly composed by Leptospirillum ferriphilum and Acidithiobacillus ferrooxidans. After cultivated in solution containing extractant M5774, Cyanex 272, P204 and P507, the number of the two species decreased, while heterophilic Acidiphilium cryptum became the dominant population. When cultured by M5774 and Cyanex 272, the proportion of Acidithiobacillus ferrooxidans was higher than Leptospirillum ferriphilum, while when cultivated by P204 and P507, the number of Leptospirillum ferriphilum was higher.

The microorganism trench-leaching process of a low-grade uranium ore with a high content of fluorine was experimentally studied through the technique of Real-time PCR by using the fluorine-tolerance bacteria of Retech-3 as the leaching-ore bacteria. It was found that the Retech-3 strains of fluorine-tolerance domestication grown well in a fluoride solution with concentration of 0.0~3.0 g·L-1, and the oxidation of Fe2+ ions to Fe3+ ions occurred rapidly to promote the extraction of uranium. The experimental results showed that the bioleaching rate (89.82%) of uranium can be improved of 13.80% than acid leaching in 30 days with 65 kg ore and its particle size of-6 mm (fraction of 100%) in trench. The Real-time PCR analysis of microbial population compositions revealed that Retech-3 strains were mainly composed of Leptospirillum sp. and Acidithiobacillus sp. in the leaching process. The obvious improvements of fluorine-tolerance domestication of bacteria and the uranium leaching process will provide fundamentals for the smooth utilization of a high fluorine-containing uranium ore with the aid of microorganism trench-leaching.

Flue dust generated during the process of manufacturing corundum is a carrier of critical metal gallium. In this study, a process of alkali leaching-carbonation-acid leaching-solvent extraction was developed to recover and enrich gallium from corundum flue dust. Over 93% of the gallium in corundum flue dust could be recovered through a two-stage alkali leaching process, which consists of 120 min of concentrated alkali leaching in NaOH solution and a subsequent 30-min dilute alkali leaching (after dilution), with an alkali-to-ore mass ratio of 1.2:1. Liquid to solid ratios in two alkali leaching stages were 1.5:1 and 8:1, respectively. The carbonation process was employed to remove high-level Si in alkali leachate. After carbonation and HCl leaching, over 96% of gallium in the NaOH leachate could be dissolved into acid solution. After extracting gallium from the HCl leachate using N235 as extracting agent, 1% NaOH solution was used to strip gallium from the organic phase. The extraction and stripping efficiency of gallium was over 99% and 97%, respectively.

In this paper, we jointly use the Pitzer model and the Meissner model to study thermodynamic laws of bioleaching solution in a lean nickel-cobalt ore in the Jilin Baishan, by using the Pitzer model to calculate activity coefficients of single electrolyte aqueous solutions and the Meissner model to calculate activity coefficients of components in the bioleaching solution. Also we studied the rules of activity coefficient of NiSO4 and CoSO4 in the solution. Results show that when separating and purifying foreign ions from bioleaching solution of the lean nickel-cobalt ore, the descending sequence of their ion concentration’s effect over the solution is Mg2+, Fe3+, Fe2+, Ni2+, Co2+ and Ca2+.

This study is to assess the effect of magnesium-rich gangue dissolution on the ore containing chalcopyrite and carrollite from Democratic Republic of the Congo (DRC). The ore contains 11.0 wt% magnesium and 2.4 wt% copper. When Mg2+ concentration is over 20 g·L−1 after 2 months in column bioleaching, the redox potential of leachate keeps stable, much less than that when Mg2+ concentration is below 20 g·L−1. Meanwhile, the extractions of Cu2+ and Co2+ from chalcopyrite with carrollite obviously inhibited by Mg2+ concentration of over 20 g·L−1 were investigated. The extraction of cobalt depends on chalcopyrite dissolved in column reactor. The growth and oxidation activity of bacteria are affected by high Mg2+ concentration (>20 g·L−1) in leachate of column reactor. As the rate of gangue dissolution depends on the amount of sulfuric acid, the decrease of the particle size relates to the increase of the total particle surface area and acid consumption. Therefore, the operation of pre-leaching for magnesium removal is not the most effective and economical way to solve the problem of magnesium-rich gangue minerals dissolution.

Process mineralogy research of a mixed copper ore is studied to identify the occurrence mode of copper and to analyze the mineralogical factors influencing the floatation results. The results show that the ore has features of "high-sulfur, high copper", "various copper mineral types", "fine copper mineral granularity" "disorderly copper mineral distribution", which belongs to the more difficult processing high sulfur mixed copper ore. Therefore, in order to effectively utilize the copper mine resource, floatation process or combination of floatation-hydrometallurgy process should be adopt.

The copper extraction yield from chemical leaching of chalcopyrite depends on temperature, pH, and the oxidation-reduction potential (ORP), as well as on the different genetic type of the chalcopyrite used. The chemical leaching characteristics of chalcopyrite from marine volcanic type and porphyry type were studied. It was found that the intermediates of marine volcanic chalcopyrite and porphyry chalcopyrite elucidated from the MLA were elemental sulphur and non-stoichiometric minerals, such as Cu3.5Fe4S2.5, Cu5Fe4S and Cu3.5Fe1.5S5. The results suggested that the main difference between marine volcanic chalcopyrite and porphyry chalcopyrite is the rates of copper and iron ions dissolution from chalcopyrite crystal lattice.

Gold ores can be categorized into two types-free milling and refractory. Free milling ores are easy to treat. Gold in such ores is recovered by gravity separating techniques or direct cyanidation. Refractory gold ores, on the contrary, are difficult to treat and require pre-treatment prior to cyanidation, such as roasting, pressure oxidation, fine grinding and biooxidation. A number of bacteria are used in biomining but the prominent ones that are known to be involved in the oxidation of sulfide ores include Thiobacillusferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans. In this study, the gold concentrate was biooxidized in a reactor at 45°C over a period of 10 days at a pulp density of 15% solids using a culture of already grown Ferroplasma acidiphilum. The initial pH was adjusted to 1.5 with sulfuric acid, resulted in 85.39 % oxidation of sulfur from initial grade of 33.83 %, and the slag rate was 68.52 %. The products of sulfide biooxidation were leached at a pulp density of 20 %(v/w) for 24 h at pH 11. The pH was adjusted using CaO and cyanide strength was 10 kg/t, we got a gold extraction of 90.71 %, which ncreaseed 80.09 % compared with the direct cyanide leaching.

A new improved method is proposed for the leaching and extraction of niobium from a low-grade refractory niobium–tantalum ore.The ore was roasted and decomposed with concenrated H2SO4 then leached with dilute sulfuric acid. The effects of various factors, such as roasting temperature and time, acid to ore mass ratios,as well as particle size, on the dissolution kinetics of niobium were comprehensively investigated. The optimal conditions were particle size-38μm, roasting temperature 300°C,reacting time 2h and acid to ore mass ratio 1:1. The roasting residue reacted for 2 h with sulfuric acid in the ore/acid weight ratio of 3:1 at 90°C, the niobium was recoveried as high as 90.3%.

Contrastive research was carried out to study the thermal properties of open-celled aluminum foams prepared by counter-gravity infiltration casting system and the traditional process respectively. The experimental results show that the thermal conductivity coefficients of aluminum foams prepared by two different infiltration methods have similar increasing trend with the increase of particle size; along with the reducing porosity, the thermal conductivity coefficients will be enhanced oppositely. However, with the same particle size, the open-celled aluminum foam prepared by the former method has a higher thermal conductivity coefficient obviously. It is largely because that the sample prepared by counter-gravity infiltration casting has a lower void content and better dense crystallization of metal-matrix after the constant pressure process.

This paper studied the influence of pH, temperature and particle size on the chemical leaching of chalcopyrite. The results show that H+is not only responsible for the hydrolysis and precipitation of ferric ion as jarosite, but also related directly to chalcopyrite dissolution. The mechanism of chalcopyrite leaching is as follows: the first stage is H+attacking valence band and electron transition during oxidation, which needs a great deal of the energy to the system. The second stage is the transport of electrons from the chalcopyrite surface to the dissolved oxygen. However, the limiting step changes into diffusion control from chemical control when the elemental sulphur film formed, which obstructs transport of electrons.

As an effective method for increase extraction efficiency and selectivity,synergistic extraction has been studied for many years because the theoretical and applicative importance. Using synergistic effect of two extractants, distribution ratios of their mixture can be obviously enhanced than those of their individual contributions. Separation of nickel and cobalt for bioleaching solution were studied using a synergistic extraction system with P507 andCyanex272. The test results indicate that the system has better extraction effect. Contrasts the separation effect on nickel and cobalt using three extraction systems of P507, Cyanex272, P507-Cyanex272. Identified during the initial pH value of 1.5-2.2, balance pH value under the condition of 4.0-5.0,synergistic extraction system of P507-Cyanex272 have a good separation effect of nickel and cobalt. The extraction kinetics was investigated using a constant interfacial cell with laminar flow. The effects of temperature, extractant and cobalt concentration were studied. Co extraction rate was compared in the different extraction systems of individual P507 and synergistic P507-Cyanex272 .The results indicated that the extraction apparent action energy in synergistic system was lower than that of signal P507.The separation factor of nickel and cobalt was increased in synergistic system.

In the zinc hydrometallurgy process, iron is usually present in leach solutions and its elimination is a major operational problem. The first step of iron removal is iron oxidation by MnO2, but this process have some disadvantages such as the cost is relatively high and decreased the current efficiency in the electro-winning stage. In this paper, a new iron oxidation process in zinc leaching solution by ozone oxidation was conducted and evaluated. The results showed that Fe2+ concentration decreased from 7.45 g/L to 0.51 g/L in 80min at pH 3. Oxidation of Fe2+ by O3 is controlled by chemical reaction. O3 dissolve rate, pH and initial iron concentration are key parameters for this process. Our finding indicated the potential application of O3 oxidation in iron removal process of zinc hydrometallurgy.

Shake flask bioleaching of a low-grade nickel-cobalt-copper sulfide ore from Lao was investigated to test the technical feasibility to recovery metals from this ore. The mineralogical results indicated that the valuable minerals were disseminated finely and the ore had a low content of sulfur and high content of iron and magnesium, which was very harmful for bioleaching. The effects of different parameters such as the amount of acid addition, inoculation volume, initial pH, temperature and leaching time on the bioleaching performance of the ore were evaluated after pre-leaching with dilute acid. The results showed that nickel, cobalt, copper leaching rates reached 81.61%, 80.75%, 70.97% at 33 °C and 83.40%, 82.13%, 70.34% at 45 °C. The mineralogical analysis of the leaching residues revealed that the leaching rate of nickel sulfide was more than 92% and the unleached nickel was mainly present as nickel silicate.

The distribution and diversity of bacterial community in Zijinshan commercial non-aeration copper bioheapleaching system operated at pH 0.8 for three years were investigated. The 24 meters high heap was cut off by mechanical digger. On the trapezoidal cross-section of the heap, 9 ore samples were taken from different vertical and horizontal locations and investigated by 16S rRNA gene clone library. Another 3 liquid samples from raffinate solution pond, spray solution pond and pregnant solution pond were also applied to 16S rRNA gene clone library analysis. The retrieved 1166 clone sequences from 12 samples were mainly related to genus Acidithiobacillus (42.36%), genus Leptospirillum (37.73%) and genus Sulfobacillus (6.52%). Relative high amount of heterotrophic bacteria were distributed at the ore surface in the internal part of the heap and in the liquid samples respectively. The retrieved heterotrophic bacterial sequences were mainly related to genus Acidiphilium (accounting 11.11% to 32.00% percent in the liquid samples), genus Acidovorax (accounting 12.37% in A1 sample), genus Pelomonas (accounting 4.17% to 10.31% in several ore samples) and genus Aquabacterium (accounting 10.31% in C2 sample). Bacterial diversity in the heap was increased from the surfcae layer to the interior of the heap. The proportion of genus Leptospirillum horizontally increased from the inner to the outer part while vertically decreased from lower depth (2-3 years leaching time) to higher depth(3-6 month leaching time), and reverse correlation of genus Acidithiobacillus was found in the heap. Our finding indicated that heterotrophic bacteria may play very important roles in the commercial bioheapleaching system, and revealed high distribution of genus Leptospirillum in the outer part of this non-aerated heap.

This paper presents the effect of mineralization on chalcopyrite chemical leaching in very simple H2SO4 solution systems at pH 1.0, with 5 % chalcopyrite concentrate at 65 °C. The copper extractions after 12 days leaching of marine volcanic and porphyry chalcopyrite were 85.7 and 66.6 %, respectively. It was found that sulphur element formed on the surface of two samples as a result of XRD and SEM-EDAX, which was very porous that did not inhibit chemical leaching reaction. Meanwhile, (Cu, Fe)12As4S13 formed on the surface of porphyry type chalcopyrite, which may cause low leaching ratio of porphyry type chalcopyrite as passivation. (Cu, Fe)12As4S13 may be one kind of the polysulphide compounds. The residues of marine volcanic chalcopyrite and porphyry chalcopyrite were investigated by XRD and SEM-EDAX. The results indicate that elemental sulphur is formed on the surface of marine volcanic and porphyry chalcopyrite, which is porous and does not inhibit chemical leaching reaction. The passivation layer of porphyry chalcopyrite is mainly composed by (Cu, Fe)12As4S13.

Lead-zinc sulphide ore contains lead sulphide (galena), and zinc sulphide (sphalerite). In the first flotation stage, galena is rendered hydrophobic with an organic collector such as xanthate, while sphalerite is kept from floating by depressants, and in the second flotation stage, activator was used to activated zinc flotation. Since the organic regent used are different in the two flotation stage, wastewater from the second zinc flotation stage can’t be directly recycled to the first lead flotation stage. Wastewater from flotation process for concentrating lead-zinc sulphide ore often containing organic compounds such as diethyldithiocarbamate(DDTC), xanthate, terpenic oil(2# oil) and thionocarbamate esters (Z-200), are environmentally hazardous. Their removal from contaminated water and the reuse of the water is one of the main challenges facing lead-zinc sulphide ore processing plants. In this study, synthetic wastewater containing DDTC, xanthate, 2# oil and Z-200 at concentrations ranging from 21 to 42 mg/L was fed into an Ozone/Biological activated carbon (BAC) reactor. Analyses of the effluent indicated a chemical oxygen demand (COD) removal over 86.21% and Total organic carbon (TOC) removal over 90.00% were achieved under Hydraulic retention time (HRT) of 4h and O3 feeding concentration of 33.3mg/L. The effluent was further recycled to the lab scale lead concentrating process and no significant difference was found in compare with fresh water. Furthermore, lead-zinc sulphide mineral concentrating process was carried out at lab scale. The produced wastewater was treated by Ozone/BAC reactor at O3 feeding concentration of 16.7mg/L and HRT of 4h. The effluent analysis showed that TOC removal was 74.58%. This effluent was recycled to the lab scale lead-zinc sulphide mineral concentrating process and the recovery of lead was not affected. The results showed that by using Ozone/BAC technology, the lead-zinc sulphide mineral processing wastewater could be recycled.

Conditions for the ortho-selective trimethylsilylation of oxalyl amide protected benzylamine and phenylethylamine derivatives are developed which tolerate a diverse range of functional groups.

An efficient methodology for oxidative cross-coupling of indene and derivatives with electron-deficient olefins catalyzed by palladium was developed. The corresponding diene products were obtained in moderate to good yields.

In order to investigate the existing form and action mechanism of minor scandium (Sc) and zirconium (Zr) in Al-Cu-Mg alloy, microstructures of Al-4Cu-1Mg-Sc-Zr alloy under different conditions, including states of as-cast, homogenized, hot-rolled, as-solution and natural aged, were observed by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and transmission electron microscopy (TEM). It is revealed that Sc and Zr are completely dissolved into the supersaturated solid solution in as-cast ingot, but grain refinement is not observed. Coffee-bean-like Al3(Sc, Zr) particles deposit during homogenization of ingot induce an increase in hardness. Al3(Sc, Zr) particles are slightly coarsened in as-solution samples, but they still maintain coherent to matrix, which indicates a high thermal stability of these particles. Good coherency of Al3(Sc, Zr) particles makes some benefits for inhibiting recrystallization and reserving work-hardening.

The distribution and diversity of acidophilic microbe at the ore surface of Zijinshan commercial low-grade copper bioleaching heap operated at pH 0.8 were investigated. Samples taken from -1m, -2 m, -3m from the top of heap surface were investigated by 16S rRNA gene clone library. Phylogenetic analyses of 16S rRNA fragments revealed that the retrieved bacterial sequences mainly related to genus Acidithiobacillus (64.6%), genus Leptospirillum (27.3%), genus Sulfobacillus (3.1%) and genus Ferrimicrobium(1.6%). For archaea, only Ferroplasma acidiphilum was detected. Bacterial diversity in the heap was increased from surface layer to underground. The proportion of genus Leptospirillum was sharply reduced (from 48.5% to 5%) from higher depth to lower depth and reverse correlation of increased A.ferrooxidans (from 0.9% to 15%) and S. thermotolerans (from undetectable to 7%) were found in the heap. Sulfur oxidizers including A.albertensis, A.caldus and A.thiooxidans also vertically increased from higher depth to lower depth (from 50.5% to 80%). These results indicated that genus Acidithiobacillus especially sulfur oxidizers A.albertensis, A.caldus and A.thiooxidans may play very important roles in the commercial low-grade copper bioleaching heap.

Diphenyl(vinyl)stannylbis(3,5-dimethylpyrazol-1-yl)methane and diphenyl(vinyl)stannylbis(3,4,5-trimethyl- pyrazol-1-yl)methane have been synthesized by the reaction of bis(3,5-dimethylpyrazol-1-yl)methyl or bis(3,4,5- trimethylpyrazol-1-yl)methyllithium with diphenyl(vinyl)tin iodide. Treatment of these bis(pyrazol-1-yl)methanes modified by the vinyltin groups with M(CO)5THF (M=Mo and W) in refluxing THF resulted in new heterobimetallic complexes R3SnCHPz2M(CO)3 (R3Sn represents trivinyltin or diphenyl(vinyl)tin, and Pz represents substituted pyrazol-1-yl), in which a vinyl group bonds to the molybdenum or tungsten atom in η2-fashion to lead to bis(pyrazol-1-yl)methanes acting as a tridentate κ3-(π,N,N) ligand. Reaction of (CH2=CH)3SnCH(3,5-Me2Pz)2W(CO)3 and Ph2(CH2=CH)SnCH(3,5-Me2Pz)2W(CO)3 with I2 has been investigated. The former gave a complex CH2(3,5-Me2Pz)2W(CO)4, while the latter yielded a four-membered heterometallocyclic complex CH(3,5-Me2Pz)2W(CO)3I with the loss of the organotin group. Treatment of this four-membered heterometallocyclic complex with PhSNa led to the iodide anion replaced by the thiophenolate anion to give a complex CH(3,5-Me2Pz)2W(CO)3SPh.

An integrated sulfate reducing process was used to treat Acid Mine Drainage with high concentrations of Cu2+, Fe and SO42-. The water treatment system integrated a sulfidogenic UASB bioreactor with a precipitation reactor which was used to recover copper. Sodium lactate was used as energy source. The effective volume of the UASB reactor was 2 L and the hydraulic retention time was 12.57h. In the sulphate removal reactor, sulphate was removed from 21160 to 195 mg/L with a rate of 4427.8 mg/L/d. Cu2+ and Fe was removed by biologically generated S2- and OH- from 360 and 6520 to 0.049 mg/L and less than 10 mg/L respectively. The average COD, copper and iron removal rate was 2523.2, 15.21 and 274.98 mg/L/d separately. The effluent pH reached 6.0-7.0. The results showed potential usage of this bioreactor in treating Acid Mine Drainage.

Based on the bioleaching mechanism and electrochemical studies of metal sulfides, the dissolution rate of secondary copper sulfides and pyrite are controlled by redox potentials. Experiment on the bioleaching of the secondary copper sulfides under constant potential by sparging with nitrogen gas demonstrated, by analyzing Cu and Fe content of the bioleaching solution and residues, the pyrite and secondary cooper sulfides dissolution rates have large difference in various redox potential. The pyrite and secondary cooper sulfides have good selection when the redox potential controlled between 700mV and 760mV, we can realize the secondary copper sulfides bioleaching process be controlled, then supply theoretical guide for the iron-acid balance during copper bioleaching process.

Reaction of (isopropyl)diphenylstannylbis(3,5-dimethylpyrazol-1-yl)methane [(i-Pr)Ph2SnCH(3,5-Me2Pz)2] and tricyclohexylstannylbis(3,5-dimethylpyrazol-1-yl)methane [Cy3SnCH(3,5-Me2Pz)2] with W(CO)5THF in refluxing THF yields heterobimetallic complexes (i-Pr)Ph2SnCH(3,5-Me2Pz)2W(CO)4 and Cy3SnCH(3,5-Me2Pz)2W(CO)4, respectively. Treatment of these heterobimetallic complexes, R3SnCH(3,5-Me2Pz)2W(CO)4 (R3 = (i-Pr)Ph2, Cy3, Et3), with I2 results in the formation of a novel η1-bis(pyrazol-1-yl)acyl complex CHC(O)(3,5-Me2Pz)2W(CO)3I, with the loss of the organotin group from the methine carbon. In addition, the reaction of R3SnCH(3,5-Me2Pz)2W(CO)4 with SnCl4 in a 1:1 molar ratio gives heterotrimetallic complexes R3SnCH(3,5-Me2Pz)2W(Cl)(CO)3SnCl3 (R = Cy, Et). It is unexpected that these heterotrimetallic complexes are also reactive in solution. They change to a novel four-membered heterometallacyclic complex CH(3,5-Me2Pz)2W(CO)3Cl in dichloromethane solution at room temperature. Furthermore, this complex can als...

Based on the bioleaching mechanism and electrochemical studies of covellite, the dissolution rate of covellite mineral is accelerated through increasing the redox potential (Eh) of the leach. In the present work, some methods were adopted to enhance the bioleaching of covellite concentrate (collected from Zijinshan copper mine, Fujian province, China) by adding different oxidants such as pure pyrite, ferric ions and H2O2. The goal of this study was to provide appropriate operating parameters for the industry application and increase the efficiency of the bioleaching of copper mine. The results showed that the optimal way to increase the redox potential (Eh) level was the addition of pure pyrite. This method could effectively raise the Eh of bioleaching process while the effect of environmental change was negligible. It could quicken the leaching process and enhance the final copper recovery through the addition of pyrite by 1:1 or 1:2 ratio of covellite concentrate to pyrite.