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Preparation of MnO2@Au nanorods, which can efficiently activate nickel foam for the electrocatalytic oxidation of ETOH, showing 31% increase in the oxidation current, 28% decrease in Tafel slope, and 40% more reactive sites, is realized.

With over 260 tons of gold reserves, the Shuiyindong gold mine is one of the largest Carlin-type gold deposits in China. A particular challenge in the processing of the ore is the presence of carbonaceous compounds, which can cause substantial losses in recoveries via the preg-robbing and adsorption of gold. To investigate the structural properties of the native carbon and to compare between different characterization techniques for such compounds, pre- and post-flotation mineral samples containing 0.9–4.8% non-carbonate carbon from the Shuiyindong mine have been examined via mineralogical and thermogravimetric approaches, as well as spectroscopic techniques, including X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine edge structure spectroscopy (NEXAFS), solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, Raman spectroscopy and preg-robbing measurements. NEXAFS and DRIFT yielded the most reliable results, indicating that 60–75% of the organic carbon in all samples consist of aliphatic alkenes with substantial unsaturated content, highly similar to activated carbon, with the remainder being graphitic and humic. Speciation by XPS was sub-optimal due to spectral overlaps between graphitic and aliphatic carbon, and between carboxylic and carbonate functionalities, while NMR spectroscopy could not provide reliable speciation of the carbon groups. The preg-robbing strength was strongly correlated to the aliphatic content and structural disorder in the carbon, while no such relationship was found with the graphitic and humic content.

ZJ 201 (modified starch) is a non-toxic, odorless, and biodegradable polymeric depressant, which selectively depressed galena in batch flotation tests while chalcopyrite was not significantly affected. In a plant trial, copper-lead separation was successful for the first time without using dichromate. Moreover, the plant process could be changed to sequential Cu-Pb flotation using ZJ 201 for higher grade lead concentrate. A copper concentrate was obtained with a Cu grade of 24.91% and a Pb grade of 5.11%, which recovered 76.6% of the copper from the original ore; a lead concentrate was also obtained with a Pb grade of 21.90% and a Cu grade of 5.31%, which recovered 52.6% of the lead. In addition to the effective copper-lead separation observed in the plant trial, another improvement observed is that gold was recovered mostly in copper concentrate, which could be sold for higher prices. Au grade reached 230.64 g/t, and its recovery reached 65.8% in the copper concentrate. Au grade in lead concentrate was only 18.90 g/t.

Publisher Copyright: © 2022 Elsevier B.V. During the reduction roasting of waste ternary Li-ion batteries (LIBs), a large amount of carbon reductant is introduced in the recycling process, which is not conductive to achieve the goal of carbon peaking and carbon neutrality. This research proposes to make full use of aluminum and carbon – main constituents of waste LIBs – as reductants in the roasting process. Results show that the aluminum-carbon reduction roasting method has a higher efficiency compared with the traditional carbon reduction. Lithium present in ternary materials can be almost completely transformed into soluble Li2CO3, while the associated Ni, Co and Mn are all converted into insoluble metal elements or their corresponding oxides at 650 °C (t = 90 min). The presence of Al decreases the carbothermal roasting temperature, while the presence of waste carbon allows Li to be converted into easily soluble lithium carbonate in preference to lithium aluminate. The optimal amount of carbon and Al in the spent LIBs were 14.7% and 7.0%, respectively. After roasting, > 97% of Li could be selectively leached by carbonated water leaching, while only < 0.5% of Al, Ni, Co, and Mn dissolved. The leach residues obtained were purified by alkali treatment with 3 mol/L NaOH at 90 °C to achieve > 99% Al separation. These results suggest that the in-situ aluminum-carbon reduction roasting, followed by selective leaching of Li and Al, mitigates several of the challenges related to battery recycling: (i) Li extraction is increased substantially above the state-of-the-art recovery efficiencies, (ii) Al - known to decrease battery metals extraction in hydrometallurgical processing - is selectively removed after making full use of its reducibility and (iii) battery metal-rich residues with low impurity levels is produced for further refining, therefore paving the way towards more economical, efficient and environmentally friendly spent LIBs recycling.

Pilot scale flotation tests (maximum capacity 1 mt h−1) on refloating smithsonite from sulphide flotation tail using cyclonic static microbubble flotation column (FCSMC) were carried out at the Wul...

The Zijinshan gold-copper mine, in spite of the low-grade nature of the ore, has become one of the largest production-scale and most profitable non-ferrous metal mines in China. The successful application of hydrometallurgy as well as proper engineering design are the key factors for large-scale development of the Zijinshan gold-copper mine. In this contribution, the practical experience acquired in the development of the Zijinshan gold and copper mines is summarized. This covers most aspects of the production process including mining, beneficiation, ore stacking, heap (bio)leaching, carbon-in-leach, solvent extraction, electrowinning, wastewater and tailing treatments. The authors believe that this practical experience will not only help to promote the development of hydrometallurgy, but can also serve as a model for other gold and/or copper plants around the world.

To design heap biooxidation process, it is necessary to understand its internal rules. The heap biooxidation of gold ore from Anhui province was researched in this study. The results showed that the main microorganisms in the heap were A. ferrooxidans, F. acidiphilum and L. ferrodiazotrophum. Under their combined action, gold leaching extent rose from 35.62% to 78.08% in 80 d. Boltzmann model matches the actual oxidation effect better and the model equations were obtained. The model predicted that the oxidation extents of arsenic and sulfur are 58.577% and 42.122% after one year, and the gold leaching extent was 80.40%. The arsenic and sulfur oxidation extents, and gold leaching extent were all linearly correlated. It is more reliable to predict gold leaching extent by sulfur oxidation extent. These results provided good guidance for practical application in the actual production.

DPANN is known as highly diverse, globally widespread, and mostly ectosymbiotic archaeal superphylum. However, this group of archaea was overlooked for a long time, and there were limited in-depth studies reported. In this investigation, 41 metagenome-assembled genomes (MAGs) belonging to the DPANN superphylum were recovered (18 MAGs had average nucleotide identity [ANI] values of 50%, while 14 MAGs showed a POCP of

Based on the homology principle in advanced pharmaceutical chemistry, a new high efficiency and low toxicity collector, O-butyl S-(1-chloroethyl)carbonodithioate, was designed. By using molecular simulation technology, MS (Materials Studio) was used to build the molecular model of the collector. The molecular structure was relaxed and optimized. The process of interaction between reagent and mineral surface was simulated and the interaction energy of reagent and mineral surface was calculated by density functional theory (DFT). The interaction process of the new collector and butyl xanthate on the mineral surface and the interaction energy of these two reagents and mineral surface were compared. The molecular structure of the new collector was designed from the perspective of the difference of the interaction energy between the reagents and the mineral surface. According to the results of molecular design and modelling, the new collector was synthesized. The flotation tests of pure minerals and real ores were carried out to verify the new collector. The experimental results showed that the collector has the characteristics of low toxicity, high selectivity, moderate collecting ability and low cost, and it is more suitable for flotation of the complex and refractory copper sulfide with low grade and fine dissemination.

Incorporating metal compound nanoparticles in carbonaceous matrix is a valid strategy to fabricate highly efficient oxygen reduction electrocatalysts. Herein, N, P-codoped carbon nanotubes embedded with Fe2P nanoparticles (Fe2P/NPCt) were synthesized in this work. Results show carbon nanotubes have a large specific surface area (987 m2 g−1) with an inner diameter of ∼60 nm. About 5.90 wt% nitrogen (35.18% pyridinic N) and 2.56 wt% phosphorus (mainly in the form of P–C and P–Fe) was doped in Fe2P/NPCt. HRTEM and XRD results confirmed the well dispersed Fe2P nanoparticles in 5 ∼10 nm on carbon nanotubes. The electrochemical performance of Fe2P/NPCt was evaluated in 0.10 M KOH using cyclic voltammetry, linear scanning voltammetry, and chronoamperometry. Fe2P/NPCt exhibits high electrocatalytic activity towards oxygen reduction with an onset potential of 1.029 V (vs RHE) and a limited current density of 6.79 mA cm−2, surpassing those of 20% Pt/C (0.950 V and 5.20 mA cm−2). Furthermore, Fe2P/NPCt presents outstanding durability and good methanol tolerance during long-term ORR. When assembled in a primary zinc-air battery (ZAB), the maximum power density and specific capacity of ZAB reach 175.48 mW cm−2 and 744.1 mAh g−1, respectively, outperforming ZAB equipped with 20% Pt/C.

Here, we report three new Acidiphilium genomes, reclassified existing Acidiphilium species, and performed the first comparative genomic analysis on Acidiphilium in an attempt to address the metabolic potential, ecological functions, and evolutionary history of the genus Acidiphilium. In the genomes of Acidiphilium, we found an abundant repertoire of horizontally transferred genes (HTGs) contributing to environmental adaption and metabolic expansion, including genes conferring photosynthesis (puf, puh), CO2 assimilation (rbc), capacity for methane metabolism (mmo, mdh, frm), nitrogen source utilization (nar, cyn, hmp), sulfur compound utilization (sox, psr, sqr), and multiple metal and osmotic stress resistance capacities (czc, cop, ect). Additionally, the predicted donors of horizontal gene transfer were present in a cooccurrence network of Acidiphilium. Genome-scale positive selection analysis revealed that 15 genes contained adaptive mutations, most of which were multifunctional and played critical roles in the survival of extreme conditions. We proposed that Acidiphilium originated in mild conditions and adapted to extreme environments such as acidic mineral sites after the acquisition of many essential functions. IMPORTANCE Extremophiles, organisms that thrive in extreme environments, are key models for research on biological adaption. They can provide hints for the origin and evolution of life, as well as improve the understanding of biogeochemical cycling of elements. Extremely acidophilic bacteria such as Acidiphilium are widespread in acid mine drainage (AMD) systems, but the metabolic potential, ecological functions, and evolutionary history of this genus are still ambiguous. Here, we sequenced the genomes of three new Acidiphilium strains and performed comparative genomic analysis on this extremely acidophilic bacterial genus. We found in the genomes of Acidiphilium an abundant repertoire of horizontally transferred genes (HTGs) contributing to environmental adaption and metabolic ability expansion, as indicated by phylogenetic reconstruction and gene context comparison. This study has advanced our understanding of microbial evolution and biogeochemical cycling in extreme niches.

The phenolic hydroxyoxime-based extractant has been discovered to degrade gradually in commercial copper solvent extraction plant. The main degradation products occurred through hydrolysis rather than oxidation or Beckmann rearrangement, which were identified as 1-(2-hydroxy-5-nonylphenyl)propan-1-one and 5-nonyl salicylaldehyde through instrumental analysis. The degradation products could reduce the extraction isotherm, the stripping isotherm and the transfer of copper. Moreover, the extractant regeneration of 5-nonyl salicylaldoxime from 5-nonyl salicylaldehyde was achieved with hydroxylamine sulfate. It was observed that the copper loading capacity of regenerated extractant increased by 64%, compared to the copper loading of untreated hydroxyoxime extractant.

In the present study, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray absorption near edge structure (XANES) spectroscopy, and Raman spectroscopy were used to investigate the effect of chloride ions on chalcopyrite bioleaching and chemical leaching at 25 °C. The leaching results show that the addition of chloride ions suppressed the dissolution of chalcopyrite in both chemical and bacterial leaching. In chemical leaching, the solution redox potential in the experiment without Cl− stayed in a range more suitable for chalcopyrite dissolution compared with experiments with Cl−. In bioleaching, the bacteria activity was suppressed by Cl− leading to low dissolution rates of Cu. Surface morphology and chemical speciation studies confirmed the formation of potassium jarosite on the surface of the chalcopyrite leach residues. In addition, S K-edge XANES indicated the formation of trace amount of elemental sulfur and covellite on the mineral surfaces.

A deep understanding of the role of Ca in geopolymers exposed to various environments is essential for geopolymerization. This work evaluates the role of Ca by observing the behavior of hierarchically calciferous geopolymers under different environments including air, carbonization and freezing-thawing cycles. The structural and morphological differences between the geopolymers and the related mechanisms in various environmental conditions are assessed based on compressive strength, brunauer emmett teller, X-ray diffraction, fourier transform infrared spectoscopy, nuclear magnetic resonance spectroscopy and scanning electron microscopy measurements. It is found that two kinds of geopolymer gels, calcium silicate hydrate and sodium aluminosilicate hydrate, are formed in the geopolymerization of blast furnace slag and fly ash. Regardless of the specific air, carbonization or freezing-thawing cycle environment, the former gel dominates the properties in low Ca geopolymers, while the latter gel determines the properties in medium and high Ca geopolymers. Moreover, the carbonization environment enables calciferous geopolymers with higher surface areas and smaller pore sizes. Such adequate pore structures can significantly improve the performance of the geopolymers. This study presents novel insights into the influence of Ca on geopolymerization and in strengthening geopolymer properties.

Developing a cost-effective and environmentally friendly strategy for elemental mercury (Hg0) entrapment from industrial flue gas becomes an urgent need to smoothly fulfil the Minamata Convention on Mercury. The conversion of gaseous Hg0 into stable mercury species using low-cost and recyclable materials has been a consensus. Herein, a novel 3D structure adsorbent, consisting of hierarchical cobalt-iron sulfide anchored on carbon fiber (FexCo(1-x)Sy@CF), was purposefully synthesized to provide a practicable support for efficient capture of Hg0. Benefiting from the hierarchical structure and synergistic effects between Fe and Co bimetal, the prepared Fe0.5Co0.5Sy@CF sorbent exhibits the best performance for Hg0 immobilization. Approximately 100% of Hg0 can be removed even under extreme conditions with SO2 concentration and gas hourly space velocity as high as 1.5% and 398000 h−1, respectively. The average Hg0 capture rate and adsorption capacity reached over 2.5 μg/g/min and 45.6 mg/g, respectively, which are much higher than previously reported metal sulfides and carbon material. The recycle experiment for Hg0 entrapment indicated that Fe0.5Co0.5Sy@CF could be efficiently regenerated and reused, adequately reflecting its potential application value. Bimetallic Fe/Co sulfide with a reasonable proportion benefits the formation of active short chain sulfur S22- which plays a crucial role in the immobilization of Hg0. Meanwhile, the final product is stable HgS that has negligible environmental toxicity. This work provides a practical and yet easy-to-adopt strategy for mercury pollution control, while opening a new avenue to realize the resource utilization toward toxic elements.

Comparisons on the bioleaching and sterile oxidation of pyrite were performed at controlled redox potential of 900 mV (vs. SHE) and different temperatures of 30 and 60 °C. For sterile experiments, the redox potential of irrigation solution was controlled by adding hydrogen peroxide solution (15 wt%), while the redox potential of irrigation solution for bioleaching was elevated by flowing through the packed bed in which bacteria were activated and colonized. The rate of pyrite bioleaching is faster than that of sterile oxidation at temperature of 30 °C. The reason is that the potential gradient of leaching solution in bioleaching column is much smaller than that in sterile column. The redox potentials of irrigation solution and leaching solution are similar for bioleaching; however, the redox potential difference of irrigation solution and leaching solution for sterile oxidation is about 150 mV. When temperature increases to 60 °C for sterile oxidation, the rate of pyrite leaching is faster than that of bioleaching at temperature of 30 °C, even though the redox potential gradient of leaching solution is great. The mineralogy analyses of pyrite residue were performed by scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. The results confirm that pyrite oxidation might only occur at specific sites with high surface energy on surface and obeys the “indirect mechanism” whether there are bacteria or not. The pyrite oxidation rate is not inhibited by inert sulfur on residue surface at elevated redox potential. According to the conclusions, the way to accelerate pyrite oxidation is proposed.

Based on the homology principle in advanced pharmaceutical chemistry, a new high efficiency and low toxicity collector

Heap biooxidation method was used to evaluate the availability of Paodaoling gold ore in Anhui province, China. 15,000 tons of gold ores (≤ 10 mm in diameter) were bioxidized under mesophilic conditions. Under the synergistic effect of microbial community, arsenic and sulfur were oxidized by 42% and 38% after 80 days. Relatively, leaching of gold was improved from 36 to 78% after heap biooxidation. The sequencing results showed there were 28 operational taxonomic units identified the microbial community in the heap. The main genera were Acidithiobacillus, Ferroplasma, Acidiferrobacter and Nitrospira. According to stoichiometry, the content of microorganisms with various functions tended to be balanced. The biomass production rate was 10 g/s, the CO2 fixation rate was 18 g/s, and the oxygen consumption rate was 60 g/s. This study provides a good basis for the further design and application of heap biooxidation technology.

Transition metal phosphide/carbon composites are promising electrocatalysts for oxygen reduction reaction (ORR). Herein, we propose a facile process to fabricate a bayberry-like N, P-enriched carbon nanospheres embedded with Fe2P nanocrystals (Fe2P/NPCs). Bayberry-like polyaniline nanospheres (PANI-NS) are firstly synthesized through microemulsion template method. Then, Fe is incorporated in PANI-NS during the hydrothermal treatment. Lastly FexP nanocrystals and N, P-enriched carbonaceous carriers are obtained by pyrolyzing the hydrothermal-treated PANI-NS. The resultant FexP/NPCs exhibit a uniform particle size (~250 nm), a large specific surface area (523 m2 g−1) and a homogeneous mesoporous structure (~3.46 nm). The phase structure of FexP depends on the Fe/P (molar ratio) during hydrothermal treatment. When Fe/P is around 0.2, a preferable Fe2P phase is obtained. The Fe2P/NPCs exhibit outstanding ORR electrocatalytic activity with a half-wave potential of 0.820 V (vs. RHE) and a diffusion-limited current density of 5.58 mA cm−2, comparable with commercial Pt/C. Moreover, Fe2P/NPCs possess a good duration stability and higher methanol tolerance than commercial Pt/C. When assembled in zinc-air batteries, Fe2P/NPCs contribute to an open circuit voltage of 1.449 V, a maximum power density of 128.38 mW cm−2, and a specific capacity of 691.0 mAh g−1, superior to the commercial Pt/C-based zinc-air battery.

The combination of narrow band gaps and notable stabilities against photoelectrochemical corrosion brings copper vanadates into the forefront of emerging photoanodes. Herein, we report a feasible approach to fabricate β-Cu3V2O8 thin film with a porous structure directly on indium-doped tin oxide (ITO) substrate for photoelectrochemical water oxidation. The porous β-Cu3V2O8 photoanode exhibits a photocurrent density of 220 μA cm−2 at 1.55 V vs RHE (reversible hydrogen electrode) in pH 9.2 borate buffer electrolyte under simulated solar irradiation. The present work could provide a base for further development of porous β-Cu3V2O8 as a solar fuels photoanode.

The nonferrous metal electrowinning process is energy intensive due to the sluggish dynamics of the oxygen evolution reaction (OER) on the anode. Developing novel anode materials with high OER activity and stability is imperative. Herein, we propose a novel Pb-ceramic composite anode by introducing ZnFe2O4. In this work, Pb-ZnFe2O4 and PS-Pb anodes were prepared through powder pressing and sintering processes. The effects of ZnFe2O4 particles on the phase composition, surface morphology and inner structure of the oxide layer formed on Pb-ZnFe2O4 anodes were investigated. Furthermore, the role of ZnFe2O4 in the anodic potential and stability of Pb-ZnFe2O4 anodes was discussed. The results show that as the ZnFe2O4 content increases, the oxide layer formed on Pb-ZnFe2O4 anodes exhibits higher surficial compactness, higher integrity, and much smaller thickness. ZnFe2O4 exhibits a trivial impact on the oxygen evolution dynamics. However, the anodic potential of the Pb-ZnFe2O4 anode declines as the ZnFe2O4 content increases, which could be attributed to the higher compactness and smaller thickness of the oxide layer. As the ZnFe2O4 content increases, the weight loss of the Pb-ZnFe2O4 composite anode increases, suggesting the unsatisfactory stability of Pb-ZnFe2O4, which could be attributed to the inevitable dissolution of ZnFe2O4 particles, smaller thickness of the oxide layer and larger porosity of the substrate. Although Pb-ZnFe2O4 composite anodes have the potential to reduce energy consumption, their unsatisfactory stability limits the feasibility of Pb-ZnFe2O4 anodes in the electrowinning industry.

Members of the genus Acidithiobacillus, which can adapt to extremely high concentrations of heavy metals, are universally found at acid mine drainage (AMD) sites. Here, we performed a comparative genomic analysis of 37 strains within the genus Acidithiobacillus to answer the untouched questions as to the mechanisms and the evolutionary history of metal resistance genes in Acidithiobacillus spp. The results showed that the evolutionary history of metal resistance genes in Acidithiobacillus spp. involved a combination of gene gains and losses, horizontal gene transfer (HGT), and gene duplication. Phylogenetic analyses revealed that metal resistance genes in Acidithiobacillus spp. were acquired by early HGT events from species that shared habitats with Acidithiobacillus spp., such as Acidihalobacter, Thiobacillus, Acidiferrobacter, and Thiomonas species. Multicopper oxidase genes involved in copper detoxification were lost in iron-oxidizing Acidithiobacillus ferridurans, Acidithiobacillus ferrivorans, and Acidithiobacillus ferrooxidans and were replaced by rusticyanin genes during evolution. In addition, widespread purifying selection and the predicted high expression levels emphasized the indispensable roles of metal resistance genes in the ability of Acidithiobacillus spp. to adapt to harsh environments. Altogether, the results suggested that Acidithiobacillus spp. recruited and consolidated additional novel functionalities during the adaption to challenging environments via HGT, gene duplication, and purifying selection. This study sheds light on the distribution, organization, functionality, and complex evolutionary history of metal resistance genes in Acidithiobacillus spp.IMPORTANCE Horizontal gene transfer (HGT), natural selection, and gene duplication are three main engines that drive the adaptive evolution of microbial genomes. Previous studies indicated that HGT was a main adaptive mechanism in acidophiles to cope with heavy-metal-rich environments. However, evidences of HGT in Acidithiobacillus species in response to challenging metal-rich environments and the mechanisms addressing how metal resistance genes originated and evolved in Acidithiobacillus are still lacking. The findings of this study revealed a fascinating phenomenon of putative cross-phylum HGT, suggesting that Acidithiobacillus spp. recruited and consolidated additional novel functionalities during the adaption to challenging environments via HGT, gene duplication, and purifying selection. Altogether, the insights gained in this study have improved our understanding of the metal resistance strategies of Acidithiobacillus spp.

In the original publication the section heading “Classification of microorganisms” appearing above the sub-section “Air and liquid circulation in the heap” in page four is incorrect. The correct section heading should be read as “Results and discussion". Korrektur zu 10.1007/s00792-020-01160-6

Members of the genus Acidithiobacillus, which can adapt to extremely high concentrations of heavy metals, are universally found at acid mine drainage (AMD) sites. Here, we performed a comparative genomic analysis of 37 strains within the genus Acidithiobacillus to answer the untouched questions as to the mechanisms and the evolutionary history of metal resistance genes in Acidithiobacillus spp. The results showed that the evolutionary history of metal resistance genes in Acidithiobacillus spp. involved a combination of gene gains and losses, horizontal gene transfer (HGT), and gene duplication. Phylogenetic analyses revealed that metal resistance genes in Acidithiobacillus spp. were acquired by early HGT events from species that shared habitats with Acidithiobacillus spp., such as Acidihalobacter, Thiobacillus, Acidiferrobacter, and Thiomonas species. Multicopper oxidase genes involved in copper detoxification were lost in iron-oxidizing Acidithiobacillus ferridurans, Acidithiobacillus ferrivorans, and Acidithiobacillus ferrooxidans and were replaced by rusticyanin genes during evolution. In addition, widespread purifying selection and the predicted high expression levels emphasized the indispensable roles of metal resistance genes in the ability of Acidithiobacillus spp. to adapt to harsh environments. Altogether, the results suggested that Acidithiobacillus spp. recruited and consolidated additional novel functionalities during the adaption to challenging environments via HGT, gene duplication, and purifying selection. This study sheds light on the distribution, organization, functionality, and complex evolutionary history of metal resistance genes in Acidithiobacillus spp. IMPORTANCE Horizontal gene transfer (HGT), natural selection, and gene duplication are three main engines that drive the adaptive evolution of microbial genomes. Previous studies indicated that HGT was a main adaptive mechanism in acidophiles to cope with heavy-metal-rich environments. However, evidences of HGT in Acidithiobacillus species in response to challenging metal-rich environments and the mechanisms addressing how metal resistance genes originated and evolved in Acidithiobacillus are still lacking. The findings of this study revealed a fascinating phenomenon of putative cross-phylum HGT, suggesting that Acidithiobacillus spp. recruited and consolidated additional novel functionalities during the adaption to challenging environments via HGT, gene duplication, and purifying selection. Altogether, the insights gained in this study have improved our understanding of the metal resistance strategies of Acidithiobacillus spp.

Micro-cracks produced in the crushing stage could improve the permeability and diffusion of leaching solution within the ore particles, which would favor for the leaching process. However, its influence on the extraction of copper by bioleaching has rarely been studied. In this work, we reported the enhancement effect of micro-cracks on the bioleaching of low-grade copper sulphide ore. Jaw crusher and high-pressure grinding rolls were adopted to prepare ore samples of the same size fraction but with different number of micro-cracks in the ore particles. Statistical data, scanning electron microscope (SEM) and stereomicroscopy (SM) images clearly showed that high-pressure grinding rolls could generate more and larger micro-cracks than the same produced by jaw crusher. Subsamples from the −0.9 mm and 3–6 mm size fractions were utilized for shake flask and column bioleaching experiments, respectively. The earlier change in pH and higher oxidation-reduction potential (Eh) indicated that more micro-cracks were beneficial for the growth of bacteria, which then enhanced the bioleaching efficiency of copper. In the shake flask experiments, the copper extraction efficiency was increased from 87.4% to 94.3% on the 30th day at 40 °C and 150 rpm. Similarly, in the column experiment with the ore sample prepared by high-pressure grinding rolls, an approximately 12.2% improvement of bioleaching efficiency was observed as compared to the system with the ore sample prepared by jaw crusher. These results demonstrated that creating micro-cracks could be crucial for heap bioleaching of low-grade copper sulphide ores.

Carbonaceous matters in Carlin-type gold deposit, especially the humic substance, which have a serious preg-robbing effect on the process of cyanidation. In this paper, the humic acid and fulvic acid were extracted from oxidizing slag via pre-activation alkaline-heat method, and using FTIR and UV-Vis spectra to study the molecular structure of humic acid extract and fulvic acid extract. The FITR spectrum demonstrated that hydroxyl, carboxyl and benzene rings characteristic stretching vibration peaks occurred in spectra of humic acid and fulvic acid, but humic acid extract had a finer molecular structure. The result of UV-Vis spectra analysis showed that the extract contained alkyl-substituted benzene ring structure, and the amount of carboxyl groups and hydroxyl groups in fulvic acid molecule was larger than that of humic acid. The fulvic acid extract contained more chromophores, while humic acid molecules have a higher degree of humification and a higher average molecular weight. Although there were some differences in the molecular structure of the both, they were both complex macromolecular organic compounds with a benzene ring as a basic unit.

Carbonaceous gold ores, containing carbonaceous matters which rob gold, is a kind of refractory gold ore. Humic acids are one of the gold-robbing carbons. In this paper, humic acids were extracted by mixed alkali heating leaching method from the gold concentrate of a carbonaceous gold mine in Guizhou, and the extraction rate was determined by the potassium dichromate oxidation-titration method. The influencing factors which were researched, were sodium hydroxide concentration, sodium pyrophosphate concentration, solid-liquid ratio, leaching temperature and stirring leaching time. The results showed that the optimum extraction conditions were sodium hydroxide concentration 0.3 mol/L, sodium pyrophosphate concentration 0.06 mol/L, solid-liquid ratio 1:4, leaching temperature 70°C, stirring leaching time 24 h, and the productivity of humic acids was 1.1049%.

Zijinshan commercial bioheapleaching–SX–EW plant has been in operation since December 2005. 13.9 million tonnes of low grade copper sulfide ore (Cu 0.38%) has been leached efficiently with an annual recovery of 80% in this distinct leaching system with high iron concentration, high temperature, high acidity and low microbial activity. This paper is to study the key factors which influence the heap operation in Zijinshan. Dissolution kinetics of diginite and covellite was carried out in acid ferric sulfate solution under controlled redox potential. Moreover, column bioleaching tests were conducted in the laboratory with raffinate from the plant. Both results showed that the main factors accelerating dissolution rate of Cu 1.8 S/CuS were mainly temperature and ferric concentration, while redox potential only had a slight positive effect. The present work provides an insight into mineral kinetics to understand this unique bioheapleaching operation and gives further information for optimization of the existing practices.

A novel porous Pb–Ag (0.8wt.%) anode was investigated for zinc electro-winning and six kinds of porous anodes with different controlled pore size and homogeneous pore structure were prepared by negative pressure infiltration. Their electrochemical properties were studied by chrono-potentiometry in the electrolyte of ZnSO4–H2SO4 and ZnSO4–MnSO4–H2SO4, respectively, and the results compared with the traditional flat plate anode. The results show that with the decrease of pore size, the anodic potential first decreases and then increases in ZnSO4–H2SO4 electrolyte. The lowest value was 1.729 V when the pore size was 1.25–1.60 mm, which is 106 mV lower than that of the flat plate anode. The anodic corrosion rate reaches the lowest value at the pore size of 1.60–2.00 mm. In the electrolyte of ZnSO4–MnSO4–H2SO4, the formation of dense PbO2/MnO2 protective layer leads to a further decrease of the anodic potential and corrosion rate while manganese impurity has little effect on cathode current efficiency. Furthermore, the porous anode is beneficial in decreasing the precipitation of Mn2+ from solution as MnO2. Compared with the flat plate anode, the behavior of the porous anode is similar to a flat plate anode operating under a lower current density.

A new anodic material of ternary Pb-0.8%Ag-(0–5.0%)Bi alloy for zinc electrowinning was obtained by doping Bi. The anodic oxygen evolution potential, corrosion rate, surface products after polarization, and microstructures before and after polarization were studied and compared with those of Pb-0.8%Ag anode used in industry. The results show the anodic overpotential decreases with the increase of Bi content in the alloys. When the content of Bi is 1.0% (mass fraction), the anodic overpotential is 40–50 mV lower than that of Pb-0.8%Ag anode. While the corrosion rate decreases and then increases with the increase of Bi content. The Pb-0.8%Ag-0.1%Bi anode has the lowest corrosion rate (0.090 6 mg/(h·cm2). Doping Bi influences the structure of the anodic layer, but does not change the phase. The Pb-0.8%Ag-1.0%Bi anode layer is of a more fine-grained structure compared with Pb-0.8%Ag anode.