Gold leaching with elemental sulfur in alkaline solutions under oxygen pressure

1　ＩＮＴＲＯＤＵＣＴＩＯＮＣｙａｎｉｄａｔｉｏｎｐｒｏｃｅｓｓ ,ｃｈａｒａｃｔｅｒｉｚｅｄｂｙｅｆｆｅｃｔｉｖｅｎｅｓｓａｎｄｌｏｗｏｐｅｒａｔｉｎｇｃｏｓｔ,ａｓａｃｏｎｖｅｎｔｉｏｎａｌｔｅｃｈｎｏｌｏｇｙｆｏｒｇｏｌｄｅｘｔｒａｃｔｉｏｎｆｒｏｍｏｒｅｓ ,ｈａｓｂｅｅｎｕｓｅｄｉｎｉｎｄｕｓｔｒｙｆｏｒｏｖｅｒ 10 0ｙｅａｒｓ .Ｈｏｗｅｖｅｒｔｈｅｃｙａｎｉｄｅｉｓａｈｉｇｈｌｙｔｏｘｉｃｃｈｅｍｉｃａｌ,ａｎｄｃｏｍｍｅｒｃｉａｌｃｙａｎｉｄａｔｉｏｎｐｒｏｃｅｓｓｉｓｌｉｍｉｔｅｄｉｎｔ…     

Bioleaching of refractory gold ore （ Ⅲ ）——Fluid leaching Jinya refractory gold concentrate by Thiobacillus ferrooxidans

A novel fluidized-bed reactor was designed and installed for bloleaching in a semi-continuous way, by which a process for biuleaching-cyanidation of Jinya refractory gold arsenical concentrate was studied. The arsenic extraction rate reaches 82.5 % after 4-day batch biooxidation of the concentrate under the optimized condition of pH 2.0, ferric ion concentration 6.Sg/L and pulp concentration 10%. And leached rate of gold in the following cyanida.tion is over 90%. The parameters of three series fluidized-bed reactors exhibit stability during the semi-continuous bioleaching of the concentrate.Armmic in the concentrate can be got rid of 91% after 6-day leaching. Even after 4 days, 82% of arsenic extraction rate was still obtained. The recovery rates of gold are 92 % and 87.5 % respectively in cyaniding the above bioleached residues.The results will provide a base for further commercial production of gold development.     

铜基仿金合金

为了寻找金的代用品,长期以来研究者竞相研制铜基仿金合金以满足制造较大的金色艺术品。文中阐述了研制铜基仿金合金的原理及其金色度和抗变色性的测试方法,分别叙述了铝、锌、锡、铟、硅、镍、稀土等元素对合金金色度和抗变色性的影响。鉴于各研究者得出的合金化学成分相差极大,最后提供了较为合理的铜基仿金合金的化学成分。     

无氰电刷镀金技术在航天工业中的应用

应用FJY-18无氰电刷镀金技术制得的金镀层具有孔隙率低、色泽金黄、光亮、结合力好,镀厚能力大于20μm,显微硬度HV=130～150,施工温度范围宽、无毒等特点,该技术已用于航天工业中某一关键部件的表面减磨密封镀金.     

Manufacturing processes of Atlantic Bronze Age annular gold ornaments—A case study of the Guînes gold hard (Pas-de-Calais,France)

ABSTRACT

The gold work from the Western European Middle and Late Bronze Age (about 1500–700 BC) is characterized by solid ornaments and vessels. This article deals with manufacturing techniques of heavy gold jewelry by presenting a gold hoard found at Guînes, Pas-de-Calais, in Northern France, as a case study. In particular, three ornament types will be taken into consideration: (1) solid penannular neck and arm-rings, plain or with linear or geometric decoration; (2) flange-twisted ornaments that appear in different dimensions, as small as ear rings, as neck rings, up to the large size of a belt; (3) complex, composite ornaments. The technological aspects dealt with in this precious metal working context are manifold, including ingot and lost wax casting, hammering and bending of solid rods, the production of flange-twisted rods, chasing as decoration method, and finally joining techniques such as soldering, riveting and folding, and creasing.     

Graphene-Au nanoparticle based electrochemical immunosensor for fish pathogen Aphanomyces invadans detection

Epizootic ulcerative syndrome (EUS) that is primarily caused by an invasive oomycete fungus Aphanomyces invadans is a devastating fish disease. Rapid diagnosis of EUS is significantly important for the control and treatment of this highly invasive disease. In our study, a label-free immunosensor constructed with G-AuNPs/SAM-Ab-BSA/GCE was proposed for the determination of Aphanomyces invadans. The electrode was prepared by the immobilization of anti-mycelium antibodies on graphene-AuNPs nanocomposite-cysteamine monolayers modified GCE. The optimized parameters were as follows: 90 min as the immersion time of SAM modified electrode in the anti-mycelium solution, 0.20 µg/mL as the concentration of anti-mycelium solution and 10 min as the interaction time of immunoreaction. The immunosensors exhibited low limit detection of 309 ng/mL and good reproducibility.     

Enhancement of Upconverted Fluorescence by Interference Layers

Upconverting nanoparticles show potential applications in the field of photovoltaics and array‐based detection devices. While fluorescence enhancement using interference of incident radiation is well known in Stokes‐shift type systems such as fluorescent dyes; the effect of such interference geometry in nonlinear Anti‐Stokes type emission, such as in upconversion rare earth photophysics is demonstrated for the first time. This work describes in detail the influence of the interference modulation on both the excitation (interion energy transfer) and radiative decay with nonradiative decay processes active between emissive levels. These effects are illustrated in the thickness dependence of the decay rate and rise time. Single particle upconverted spectra and time‐resolved measurements show concurrent optimization of the infrared absorption and emission at 540 and 650 nm, with an average enhanced emission of 20 times at λ = 540 and 45 times at λ = 650 nm, dependent on the interference layer thickness and on the excitation intensity. The experimental results are correlated with finite element modeling. Both experiments and calculations show emission enhancement at an interference layer thickness of about 740 ± 20 nm, where such tolerance and the planar design, leads to ease in implementation in applications.     

High Figure of Merit (FOM) of Bragg Modes in Au‐Coated Nanodisk Arrays for Plasmonic Sensing

Gold‐coated nanodisk arrays of nearly micron periodicity are reported that have high figure of merit (FOM) and sensitivity necessary for plasmonic refractometric sensing, with the added benefit of suitability for surface‐enhanced Raman scattering (SERS), large‐scale microfabrication using standard photolithographic techniques and a simple instrumental setup. Gold nanodisk arrays are covered with a gold layer to excite the Bragg modes (BM), which are the propagative surface plasmons localized by the diffraction from the disk array. This generates surface‐guided modes, localized as standing waves, leading to highly confined fields confirmed by a mapping of the SERS intensity and numerical simulations with 3D finite element method. The optimal gold‐coated nanodisk arrays are applied for refractometric sensing in transmission spectroscopy with better performance than nanohole arrays and they are integrated to a 96‐well plate reader for detection of IgY proteins in the nanometer range in PBS. The potential for sensing in biofluids is assessed with IgG detection in 1:1 diluted urine. The structure exhibits a high FOM of up to 46, exceeding the FOM of structures supporting surface plasmon polaritons and comparable to more complex nanostructures, demonstrating that subwavelength features are not necessary for high‐performance plasmonic sensing.     

A Metal–Polyphenol Network Coated Nanotheranostic System for Metastatic Tumor Treatments

As a characteristic trait of most tumor types, metastasis is the major cause of the death of patients. In this study, a photothermal agent based on gold nanorod is coated with metal (Gd³⁺)‐organic (polyphenol) network to realize combination therapy for metastatic tumors. This nanotheranostic system significantly enhances antitumor therapeutic effects in vitro and in vivo with the combination of photothermal therapy (PTT) and chemotherapy, also can remarkably prevent the invasion and metastasis due to the presence of polyphenol. After the treatment, an 81% decrease in primary tumor volumes and a 58% decrease in lung metastasis are observed. In addition, the good performance in magnetic resonance imaging, computerized tomography, and photothermal imaging of the nanotheranostic system can realize image‐guided therapy. The multifunctional nanotheranostic system will find a great potential in diagnosis and treatment integration in tumor treatments, and broaden the applications of PTT treatment.