As和MgO的加入对铜冶炼渣中砷玻璃化的影响

研究FeO−SiO_(2)−Fe_(2)O_(3)−B_(2)O_(3)−CaO−Al_(2)O_(3)−(MgO)体系铜冶炼渣中砷(As)的玻璃化。通过XRD、SEM、FTIR和XPS分析手段系统地研究As玻璃化机制。结果表明,As与铁硅酸盐炉渣表现出良好的相容性。FTIR和XPS分析结果表明,As可以部分替代硅形成Si—O—As结构,从而提高熔体的聚合度。[BO_(3)]^(3−)结构单元随着As含量的增加而趋于减少,而加入MgO后则观察到相反的行为。此外,MgO增加了熔体的非桥氧数量(NBO)。TCLP、SPLP和pH依赖性测试结果表明,As的浸出毒性随着As含量的增加而增加,但随着MgO的加入而降低。DSC分析结果表明,As和MgO的加入均可以改善含As玻璃的热稳定性。

加压氧化过程中胡敏酸结构和吸附特性的变化

从碳质加压氧化金矿中提取胡敏酸。采用元素分析、傅里叶转换红外光谱、紫外-可见光光谱、拉曼光谱和X射线光电子能谱分析胡敏酸的结构。建立胡敏酸吸附金的动力学和等温线模型,计算热力学参数和等量吸附热。结果表明,受加压氧化的影响,胡敏酸的脂肪族结构、C=O键及其他含氧基团被破坏。更重要地,胡敏酸结构中有新化学键形成,如C—O—Cl_(x)、C—Cl_(x)和Me_(4)N—Cl。吸附实验结果显示,加压氧化对胡敏酸的金吸附性能具有极大影响。加压氧化后,胡敏酸对纯金溶液的吸附率下降至(42.78±1.05)%,对金浸出液的吸附率下降至(28.63±1.11)%。吸附数据表明,胡敏酸对金吸附行为符合伪二级动力学和Langmuir等温线模型。胡敏酸的等量吸附热随吸附量的增加而增加。

Epalrestat protects against diabetic peripheral neuropathy by alleviating oxidative stress and inhibiting polyol pathway

Epalrestat is a noncompetitive and reversible aldose reductase inhibitor used for the treatment of diabetic neuropathy. This study assumed that epalrestat had a protective effect on diabetic peripheral nerve injury by suppressing the expression of aldose reductase in peripheral nerves of diabetes mellitus rats. The high-fat and high-carbohydrate model rats were established by intraperitoneal injection of streptozotocin. Peripheral neuropathy occurred in these rats after sustaining high blood glucose for 8 weeks. At 12 weeks after streptozotocin injection, rats were intragastrically administered epalrestat 100 mg/kg daily for 6 weeks. Transmission electron microscope revealed that the injuries to myelinated nerve fibers, non-myelinated nerve fibers and Schwann cells of rat sciatic nerves had reduced compared to rats without epalrestat administuation. Western blot assay and immunohistochemical results demonstrated that after intervention with epalrestat, the activities of antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase gradually increased, but aldose reductase protein expression gradually diminished. Results confirmed that epalrestat could protect against diabetic peripheral neuropathy by relieving oxidative stress and suppressing the polyol pathway.

Leaching kinetics of selenium from copper anode slimes by nitric acid-sulfuric acid mixture

The leaching kinetics of selenium from copper anode slimes was studied in a nitric acid?sulfuric acid mixture.The effects of main parameters on selenium leaching showed that the leaching rate of selenium was practically independent of stirring speed,while dependent on temperature and the concentrations of HNO3and H2SO4.The leaching of selenium includes two stages.The activation energy in the first stage is103.5kJ/mol,and the chemical reaction is the rate controlling step.It was almost independent of H2SO4concentration and dependent on HNO3concentration since the empirical reaction order with respect to HNO3concentration is0.5613.In the second stage,the activation energy is30.6kJ/mol,and the process is controlled by a mixture of diffusion and chemical reaction.The leaching of selenium was almost independent of HNO3concentration.

Agglomeration−aggregation and leaching properties of mechanically activated chalcopyrite

The effect of mechanical activation on the granulometric parameters,microstructure,and leaching efficiency of chalcopyrite was evaluated,and the occurrence/transition of agglomeration and aggregation was discussed.The results showed that in 8 h of milling treatment,the agglomeration and the microstructure did not affect each other.However,with prolonging milling time,the crystallite size tended to reach a saturation value,and the stagnating microstructural changes led to the replacement of agglomeration by aggregation.The leaching results indicated that the mechanical activation can strongly enhance the reactivity of chalcopyrite and the hindering effect of aggregation on leaching was considerably greater than that of agglomeration.Consequently,after 8 h of milling,the maximum Cu leaching rate of 80.13%was achieved after 4 h of acid leaching.

New insights into the extraction of invisible gold in a low-grade high-sulfur Carlin-type gold concentrate by bio-pretreatment

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.

Biooxidation-thiosulfate leaching of refractory gold concentrate

A process of biooxidation followed by thiosulfate leaching of gold from refractory gold concentrate was investigated.Mineralogical studies on the concentrate showed that very fine gold grains(<10μm)were encapsulated in pyrite and arsenopyrite,while the proportion of monomer gold was only 21%.The gold-bearing sample was identified as a high-sulfur fine-sized wrapped-type refractory gold concentrate.The gold leaching efficiency obtained by direct cyanidation was only 59.86%.After biooxidation pretreatment,the sulfide minerals were almost completely decomposed,92 wt%of the mineral particles of the biooxidation residue were decreased to<38μm,and the proportion of monomer gold in the biooxidation residue was over 86%.Meanwhile,the gold content in the biooxidation residue was enriched to 55.60 g/t,and the S,Fe,and As contents were reduced to approximately 19.8 wt%,6.97 wt%,and 0.13 wt%,respectively.Ammoniacal thiosulfate was used for gold extraction from the biooxidation residue of the refractory gold concentrate.The results showed that the optimal reagent conditions were 0.18 M thiosulfate,0.02 M copper(II),1.0 M ammonia,and 0.24 M sulfite.Under these conditions,a maximum gold leaching efficiency of 85.05%was obtained.

Effect of temperature on leaching behavior of copper minerals with different occurrence states in complex copper oxide ores

The effect of temperature on leaching behavior of copper minerals with different occurrence states in complex copper oxide ores was carried out by phase analysis means of XRD, optical microscopy and SEM-EDS. The results indicated that at ambient temperature, the easily leached copper oxide minerals were completely dissolved, while the bonded copper minerals were insoluble. At lukewarm temperature of 40℃, it was mainly the dissolution of copper in isomorphism state. With increasing temperature to 60℃, the copper leaching rate in the adsorbed state was significantly accelerated. In addition, when the temperature increased to 80℃, the isomorphic copper was completely leached, leaving 11.2% adsorbed copper un-leached. However, the copper in feldspar-quartz-copper-iron colloid state was not dissolved throughout the leaching process. Overall, the leaching rates of copper in different copper minerals decreased in the order: malachite, pseudo-malachite > chrysocolla > copper-bearing chlorite > copper-bearing muscovite > copper-bearing biotite > copper-bearing limonite > feldspar-quartz-copper-iron colloid.

Study on the mechanical activation of malachite and the leaching of complex copper ore in the Luanshya mining area, Zambia

Mechanical activation(MA) of malachite was carried out by dry planetary grinding(DPG) and wet Isa grinding(WIG) methods. When the rotational speed was increased to 400 r/min in DPG, the specific surface area of malachite reached the maximum and the particle size reached the minimum of 0.7–100 μm. Agglomeration occurred between mineral particles when the rotational speed was increased to 580 r/min in DPG.However, no agglomeration was observed among particles with sizes 0.4–3 μm in WIG. X-ray diffraction analysis showed that, at a 580 r/min rotational speed in DPG, the amorphization degree of malachite was 53.12%, whereas that in WIG was 71.40%, indicating that MA led to amorphization and distortion of crystal structures. In addition, in the Fourier transform infrared(FT-IR) spectra of activated malachite, the bands associated with –OH, CO_3^(2-)and metal lattice vibrations of Cu–O and Cu–OH were weakened, and a new H–O–H bending mode and peaks of gaseous CO_2 appeared, indicating that MA decreased the band energy, enhanced dihydroxylation, and increased the chemical reactivity of the malachite.Furthermore, the leaching behavior of copper ore was greatly improved by MA.

Cyanide removal for ultrafine gold cyanide residues by chemical oxidation methods

Because of the highly toxic cyanide in the gold cyanide residues,cyanide must be removed for environmental protection.The process mineralogy of residues was studied firstly,and then cyanide removal was carried out by three chemical methods.The results showed that the residue mainly contained Si,S and Fe.Pyrite was the main metallic mineral,and the iron-complex cyanides make cyanide removal difficult.The minerals in residues were in ultrafine particle size with high monomer dissociation degrees.In H_(2)O_(2)oxidation process,the self-decomposition and side reactions resulted in high consumption of H_(2)O_(2).In Na_(2)S_(2)O_(5)-air oxidation process,the time for complete process was long because of the reactions between Na_(2)S_(2)O_(5)and O_(2).Na_(2)SO_(3)oxidation method was found to be a new method for cyanide removal without air inflation device.The cyanide content was reduced to the national standard level in 90 min at pH 9.0 with optimum Na_(2)SO_(3)dose of 2.0 g/L.

Bio-dissolution of pyrite by Phanerochaete chrysosporium

The dissolution of pyrite was studied with Phanerochaete chrysosporium(P.chrysosporium).This fungus resulted in the dissolution of 18%iron and 33%sulfur.The oxidization layer was formed on the pyrite surface,which probably consisted of iron oxide,iron oxy-hydroxide,iron sulfate,elemental sulfur and mycelia.The electrochemical characteristics of pyrite were studied in the systems without and with P.chrysosporium.P.chrysosporium could accelerate the dissolution of pyrite by decreasing pitting potential and polarization resistance plus improving polarization current,corrosion potential and corrosion current density.The dissolution of pyrite is the combined effect of enzymes,hydrogen peroxide,ferric iron and organic acids.Enzymes attack the chemical bonds by free radicals.Organic acids dissolve pyrite by acidolysis and complexolysis.Enzymes and hydrogen peroxide play an essential role in this process.

Ultra fast microwave-assisted leaching for the recovery of copper and tellurium from copper anode slime

The decomposition of copper anode slime heated by microwave energy in a sulfuric acid medium was investigated. Leaching experiments were carried out in a multi-mode cavity with microwave assistance. The leaching process parameters were optimized using response surface methodology（RSM）. Under the optimized conditions, the leaching efficiencies of copper and tellurium were 99.56% ± 0.16% and 98.68% ± 0.12%, respectively. Meanwhile, a conventional leaching experiment was performed in order to evaluate the influence of microwave radiation. The mechanism of microwave-assisted leaching of copper anode slime was also investigated. In the results, the microwave technology is demonstrated to have a great potential to improve the leaching efficiency and reduce the leaching time. The enhanced recoveries of copper and tellurium are believed to result from the presence of a temperature gradient due to the shallow microwave penetration depth and the superheating at the solid-liquid interface.

Effect of the CaO/SiO2 mass ratio and FeO content on the viscosity of CaO–SiO2–“FeO”–12wt%ZnO–3wt%Al2O3 slags

An effective process for recycling lead from hazardous waste cathode ray tubes（CRTs） funnel glass through traditional lead smelting has been presented previously. The viscous behavior of the molten high lead slag, which is affected by the addition of funnel glass, plays a critical role in determining the production efficiency. Therefore, the viscosities of the CaO–SiO_2–＂FeO＂–12wt%ZnO–3wt%Al_2O_3 slags were measured in the current study using the rotating spindle method. The slag viscosity decreases as the CaO/SiO_2 mass ratio is increased from 0.8 to 1.2 and also as the FeO content is increased from 8wt% to 20wt%. The breaking temperature of the slag is lowered substantially by the addition of FeO, whereas the influence of the CaO/SiO_2 mass ratio on the breaking temperature is complex. The structural analysis of quenched slags using Fourier transform infrared（FTIR） spectroscopy and Raman spectroscopy reveals that the silicate network structure is depolymerized with increasing CaO/SiO_2 mass ratio or increasing FeO content. The [FeO_6]-octahedra in the slag melt increase as the CaO/SiO_2 mass ratio or the FeO content increases. This increase can further decrease the degree of polymerization（DOP） of the slag. Furthermore, the activation energy for viscous flow decreases both with increasing CaO/SiO_2 mass ratio and increasing FeO content.

Corrosion mechanism of magnesia-chromite refractories by ZnO-containing fayalite slags: Effect of funnel glass addition

An efficient approach for lead extraction from waste funnel glass through the lead smelting process has been proposed. To clarify the effect of funnel glass addition on the degradation of magnesia-chromite refractories by ZnO-containing fayalite slag, the corrosion behavior of magnesia-chromite refractories in lead smelting slags with different funnel glass additions from 0wt% to 40wt% was tested. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) was used to acquire the microstructural information of the worn refractory samples. Experimental results showed that the corrosion of magnesia-chromite refractory consisted predominantly of the dissolution of MgO into slag. ZnO and FeO reacted with periclase and chromite to form (Zn,Fe,Mg)O solid solution and (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel, respectively. With the addition of funnel glass, the solubility of MgO increased whereas ZnO levels remained stable, thereby resulting in a reduced Mg content and an elevated Zn and Fe content in the (Zn,Fe,Mg)O solid solution and the (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel. Considering the stability of the (Zn,Fe,Mg)O solid solution layer and the penetration depth of the slag, the optimal funnel glass addition for lead smelting was found to be 20wt%.

In situ characterization of natural pyrite bioleaching using electrochemical noise technique

An in situ characterization technique called electrochemical noise（ECN） was used to investigate the bioleaching of natural pyrite.ECN experiments were conducted in four active systems（sulfuric acid,ferric-ion,9k culture medium,and bioleaching solutions）.The ECN data were analyzed in both the time and frequency domains.Spectral noise impedance spectra obtained from power spectral density（PSD）plots for different systems were compared.A reaction mechanism was also proposed on the basis of the experimental data analysis.The bioleaching system exhibits the lowest noise resistance of 0.101 MΩ The bioleaching of natural pyrite is considered to be a bio-battery reaction,which distinguishes it from chemical oxidation reactions in ferric-ion and culture-medium（9k） solutions.The corrosion of pyrite becomes more severe over time after the long-term testing of bioleaching.

Pharmacokinetic behavior of 16-dehydropregnenolone after intramuscular administration in rats

The pharmacokinetics of 16-dehydropregnenolone （16-DHP）, a sterols compound isolated from Solanum lyratum Thunb., was investigated in rats following a single intramuscular administration （40 mg/kg）. The concentration of 16-DHP in rat plasma was determined by a high performance liquid chromatography （HPLC） method with UV detection. Levonorgestrel was used as the internal standard （IS）. The pharmacokinetic parameters of 16-DHP were derived by non-compartmental method. After a single intramuscular administration, the maximum plasma concentration （Cmax） was （289±25）ng/mL, time to reach Cmax（tmax） was （0.38±0.14） h, the elimination half-life （t1/z） was （2.5±1.1）h, the area under the plasma concentration-time curve from time zero to the time of the last measurable concentration （AUC（0-t）） was （544± 73）ng· h/mL. The results indicated that 16-DHP was absorbed quickly and eliminated rapidly in rats after the intramuscular injection.

Optimal quantum parameter estimation of two-qutrit Heisenberg XY chain under decoherence

Adopting the Milburn decoherence model, we investigate the performance of quantum Fisher information of the twoqutrit isotropic Heisenberg XY chain under decoherence. We find that the quantum Fisher information with respect to the decoherence rate and the magnetic field decreases exponentially in the long-time limit, which significantly reduces the precision of optimal quantum estimation. We also show that with the increase of the decoherence rate or the magnetic field,the QFIs go down considerably. Furthermore, we find that the precision of optimal quantum estimation can be enhanced by the entanglement in the input state.

Chlorajaponins A—Q,Lindenane-Related Sesquiterpenoid Dimers from Chloranthus japonicus and Their Biological Activities

Seventeen undescribed lindenane-related sesquiterpenoid dimers,chlorajaponins A—Q(1—17),and 13 reported analogs(18—30)were isolated from Chloranthus japonicus Sieb.Compound 1 possesses an unprecedented 3/5/7/5/5/6/5/3 fused octacyclic scaffold,featuring a 6(5→4)-abeo-lindenane monomer,while 2 exhibits a 3/5/6/6/5/6/5/3 fused octacyclic scaffold.Their structures were determined through a combination of spectroscopic analyses and X-ray crystallography.Compounds 1,2,and 18 demonstrated significant inhibitory effects on lipid accumulation and effectively reduced the levels of triglycerides and total cholesterol,as well as the levels of aspartate aminotransferase and alanine aminotransferase in a HepG2 cell model.In addition,compounds 1,2,and 18 significantly suppressed the protein expression of the fatty acid synthase(FASN)and the sterol regulatory element-binding protein 1(SREBP1).Moreover,the anti-inflammatory assay showed that compounds 19—22 and 25 inhibited the NO production induced by lipopolysaccharide in RAW 264.7 macrophages with IC50 values of 7.89±0.44,6.25±0.46,2.98±0.29,10.77±0.60,and 3.60±0.28μmol/L.

Intensified bioleaching of low-grade molybdenite concentrate by ferrous sulfate and pyrite

Intensifying effects of ferrous sulfate and pyrite on bioleaching of low-grade molybdenite concentrate were studied in this paper. The experimental results show that the oxidation dissolution of molybdenite can be accelerated with the addition of either ferrous sulfate or pyrite in bi- oleaching medium. Pyrite has better enhancing effect than ferrous sulfate, and the highest molybdenum leaching rate in pyrite-added solutions is 20.85 %, increasing by 12.64 % compared with that in 9 K leaching system. Molybdenum leaching rate does not increase linearly with the increase of the addition of either ferrous sulfate or pyrite in each type solution. Great amounts of [NH4Fe3（SO4）2（OH）6] and [KFe3（SO4）2（OH）6] with different morphologies will be deposited on molybdenite ores when the additions of Fe from ferrous sulfate or pyrite exceed that from 9 K leaching system by 0.5 times, and these deposits hinder the oxidation dissolution of molybdenite to some extent.

Mechanism of aluminum complexation in oxidative activity of leaching bacteria in a fluoride-containing bioleaching system

Accumulation of toxic ions in leachate is one factor limiting bioleaching applications. The effect of fluoride ions on the growth of bioleaching microorganisms has been extensively emphasized. In this study, HF is found to be the toxic form of fluoride that affects the bacterial activity under acidic conditions. The added aluminum could compete with H^+ to complex with F-, thus significantly decrease the concentration of HF and finally reduce the toxicity of fluoride to bacteria. When F^-/Al^(3+)concentration ratio is 0.5:1.0, Fe^(2+) oxidation rate could reach 0.167 g·L^(-1)·h^(-1), close to that of the biotic control group(0.195 g·L^(-1)·h^(-1)). The competitive complexation mechanism of fluoride by AlF_n^(3-n) results in stability constants of AlF_n^(3-n) complex(7.00) that are larger than those of HF(3.18). The F^-/Al^(3+) concentration ratio in the medium could affect the speciation of AlF_n^(3-n) complex.With the decrease in F^-/Al^(3+) concentration ratio, the coordination numbers of AlF_n^(3-n) decrease. Finally, the feasibility of fluoride detoxification by aluminum ion is verified. This work has meaningful implications for fluoride-containing bacterial bioleaching systems.