Search

The recovery of gold from copper anode slime has been paid increasing attention by researchers at home and abroad. To realize the higher reduction rate of gold and purity of gold powder, a novel technology is proposed for reducing gold chloride solution by controlling potential in this work. First, the effects of excess coefficient of Na2SO3, reaction temperature, reaction time and initial H+ concentration on the reduction rate of gold were investigated. The optimized conditions were determined as 30°C for the reaction temperature with an excess coefficient of Na2SO3 of 1.43 and an initial H+ concentration of 1.0 mol/L for a reaction time of 15 min. Under the optimal conditions, the purity of gold powder can reach 99.9%. Then, the relationship among solution potential, concentration of gold ion and reduction rate of gold were explored, indicating that the concentration of gold ion can be reduced to 99.7% when the solution potential is

This study reports the fabrication of micro-sized spherical Mn3O4 particles using a precipitation conversion-roasting method. Morphological evolution of the product and mechanism of formation have been investigated. The results showed that the amount of alkali used in the precipitation conversion step had a significant effect on the morphology and particle size of the product. When mole ratio of the alkali to manganese increased from 1.6 to 4.0, morphology of the Mn3O4 precursor gradually evolved from an irregular cubic shape to a regular spherical shape, and finally, a regular cubic shape with uniform particle size. According to transmission electron microscopy (TEM) and selected area electron diffraction (SAED), morphological evolution of the Mn3O4 precursor was caused by the preferred orientation of crystal planes and supersaturation of the reaction system. Scanning electron microscopy (SEM) images of samples before and after calcination showed that morphology of precursor was inherited by the product obtained after calcination. Thus, spherical Mn3O4 particles, with uniform size and no agglomeration, could be prepared by precipitation conversion-roasting method.

A fundamental theory on pyrometallurgic direct smelting of waste printed circuit boards was investigated in this work. First, the effects of the Fe/SiO2 (mass ratio) and CaO/SiO2 (mass ratio) on the liquidus temperature and viscosity of slag were systematically analyzed at a PO2 value of 10–12 atm. Then, a verification experiment was carried out. Thermodynamic calculation results showed that the liquidus temperature of slag first decreased then increased as Fe/SiO2 and CaO/SiO2 were increased. At 1250°C, the viscosity of slag is lower than 0.5 Pa s in the Fe/SiO2 range of (0.8–1.2):1 and CaO/SiO2 range of (0.25–0.85):1. The verification experiment indicated that an alloy with high content copper can be obtained. Microanalysis of the alloy and slag demonstrated that the distinguishable crystal phase in the alloy mainly contained metallic copper, metallic iron, and a small amount of intermetallic compounds such as (Fe, Ni) and Ni3Sn2. The slag was mainly composed of fayalite (Fe2SiO4), calcium silicate (Ca2SiO4, CaSiO3), and gehlenite (Ca2Al2SiO7).

The oxidization of As(III) to As(V) is necessary for both the detoxification of arsenic and the removal of arsenic by solidification. In order to achieve high efficiency and low cost As(III) oxidation, a novel process of catalytic aerial oxidation of As(III) is proposed, using air as oxidant and Mn-loaded diatomite as a catalyst. Through systematic characterization of the reaction products, the catalytic oxidation reaction law of Mn-loaded diatomite for As(III) was found out, and its reaction mechanism was revealed. Results show that Mn-loaded diatomite achieved a good catalytic effect for aerial oxidation of As(III) and maintained high performance over multiple cycles of reuse, which was directly related to the structure of diatomite and the behavior of manganese. Under the conditions of a catalyst concentration of 20 g/L, an air flow rate of 0.3 m

Graphene as a new type of carbon material has drawn much attention recently. The remarkable properties such as low density, large specific surface area and unique electrochemical properties have attracted extensive research interests for their application in the energy storage area including metal ion batteries, metal-sulfur cells, metal-air cells, etc. For the applications in these areas, two-dimensional (2D) graphene sheets need to be assembled into three-dimensional (3D) graphene structures to control the electrochemical, mechanical and optical properties. In this feature article, the research status, application areas and drawbacks are reviewed. Fabricating graphene by the template, self-assembly and other newly developed methods, e.g., 3D printing, is discussed. The related research on 3D graphene-based materials in the energy storage area is also included. Finally, problems existing in the current fabricating method and future development directions are discussed.

An efficient synthesis of ODM-201's diastereomers has been developed from (R)-methyl 3-hydroxybutanoate or (S)-methyl 3-hydroxybutanoate, respectively, with high overall yield and excellent diastereomeric purity. The key step in this synthesis is the preparation of the key intermediate (R)-5-(1-((tert-butyldimethylsilyl)oxy)ethyl)-1H-pyrazole-3-carboxylic acid or (S)-5-(1-((tert-butyldimethylsilyl)oxy)ethyl)-1H-pyrazole-3-carboxylic acid through intramolecular 1,3-dipolar cycloaddition of the vinyl diazo carbonyl compounds.