Ultrasonic-enhanced selective sulfide precipitation of copper ions from copper smelting dust using monoclinic pyrrhotite

The sulfide passivation film produced on the surface seriously prevents further reaction in the process of using monoclinic pyrrhotite(MPr)to treat heavy metal ions in wastewater.Ultrasonic technology was introduced to assist MPr to recover the copper ions.XPS result proves that CuS products exist on the surface of MPr.XRD and SEM results show that the CuS on the particles’surface is stripped under ultrasonic condition.The kinetics results indicate that the reaction under both conventional and ultrasonic conditions conform to the Avrami model.The reaction process changes from diffusion control to chemical reaction control under the ultrasonic condition as the solid layer is stripped off.The presence of ultrasonic significantly reduces the acidity and temperature required for the reaction and enhances the utilization efficiency of MPr;by controlling the amount of MPr,the removal rates of copper and arsenic in copper smelting dust leachate exceed 99%and 95%,respectively.

Separation of macro amounts of tungsten and molybdenum by precipitation with ferrous salt

In order to develop a low-cost approach for separating macro amounts of Mo and W, the effects of parameters on the separation using FeSO4 as precipitation reagent were studied. The results show that the optimum reaction temperature is 10 °C, and the separation factor does not further improve after a reaction time of 7 h. Moreover, slow dropping speed of the precipitation reagent is beneficial for improving the separation efficiency. When the H＋/W molar ratio is below 1/1, the addition of acid to a neutral solution is favorable to the separation. For the solution with an ammonium concentration below 3 mol/L, the separation factor is high due to the high W-precipitation rate. Furthermore, the method is also effective when it is applied to industrial solution containing some other impurities. All these indicate the ferrous salts have great potential for removing W from Mo on a commercial scale.

Separation and recovery of copper in Cu-As-bearing copper electrorefining black slime by oxidation acid leaching and sulfide precipitation

A new hydrometallurgical route for separation and recovery of Cu from Cu-As-bearing copper electrorefining black slime was developed. The proposed process comprised oxidation acid leaching of Cu-As-bearing slime and selective sulfide precipitation of Cu from the leachate. The effects of various process parameters on the leaching and precipitation of Cu and As were investigated. At the first stage, Cu extraction of 95.2% and As extraction of 97.6% were obtained at 80 ℃ after 4 h with initial H2 SO4 concentration of 1.0 mol/L and liquid-to-solid ratio of 10 mL/g. In addition, the leaching kinetics of Cu and As was successfully reproduced by the Avrami model, and the apparent activation energies were found to be 33.6 and 35.1 kJ/mol for the Cu and As leaching reaction, respectively, suggesting a combination of chemical reaction and diffusion control. During the selective sulfide precipitation, about 99.4% Cu was recovered as CuS, while only 0.1% As was precipitated under the optimal conditions using sulfide-to-copper ratio of 2.4:1, time of 1.5 h and temperature of 25 ℃.

Recycling of mixed cathode lithium-ion batteries for electric vehicles: Current status and future outlook

Worldwide trends in mobile electrification,largely driven by the popularity of electric vehicles(EVs)will skyrocket demands for lithium-ion battery(LIB)production.As such,up to four million metric tons of LIB waste from EV battery packs could be generated from 2015 to 2040.LIB recycling directly addresses concerns over longterm economic strains due to the uneven geographic distribution of resources(especially for Co and Li)and environmental issues associated with both landfilling and raw material extraction.However,LIB recycling infrastructure has not been widely adopted,and current facilities are mostly focused on Co recovery for economic gains.This incentive will decline due to shifting market trends from LiCoO2 toward cobalt-deficient and mixed-metal cathodes(eg,LiNi1/3Mn1/3Co1/3O2).Thus,this review covers recycling strategies to recover metals in mixed-metal LIB cathodes and comingled scrap comprising different chemistries.As such,hydrometallurgical processes can meet this criterion,while also requiring a low environmental footprint and energy consumption compared to pyrometallurgy.Following pretreatment to separate the cathode from other battery components,the active material is dissolved entirely by reductive acid leaching.A complex leachate is generated,comprising cathode metals(Li+,Ni2+,Mn2+,and Co2+)and impurities(Fe3+,Al3+,and Cu2+)from the current collectors and battery casing,which can be separated and purified using a series of selective precipitation and/or solvent extraction steps.Alternatively,the cathode can be resynthesized directly from the leachate.

Thermodynamic analysis for separation of vanadium and chromium in V(Ⅳ)-Cr(Ⅲ)-H_2O system

To recycle vanadium and chromium from the V?Cr-bearing reducing slag,the thermodynamics of separating V(IV)and Cr(III)at 298 K was summarized in the form of potential-pH diagram and activity-pH diagram.The potential-pH diagrams of V-Mn-H2O and Cr-Mn-H2O systems show that the electrode potential of MnO2/Mn2+is higher than that of VO2+/VO2+but lower than that of Cr2O7 2-/Cr3+,which proves that it is feasible to selectively oxidize low valent vanadium using MnO2.The activity-pH diagrams of V(V)-H2O and Cr(III)-H2O systems show that the precipitation pH of V(V)is far lower than that of Cr(III),and therefore V(V)and Cr(III)can be separated through precipitation method.Based on the thermodynamic analysis,the flowsheet of recovery of vanadium and chromium from the V-Cr-bearing reducing slag is designed.

Complexation of uranyl ions by N-(sulfoethyl)-iminodiacetic acid:hydrothermal synthesis, luminescence, and uranyl sequestration

Reported here is a water-soluble ligand, N-（sulfoethyl）-iminodiacetic acid （H3SEIDA）, used for the complexation of uranyl ions. A coordination compound composed of uranyl cation and N-（sulfonatoethyl）-ammoniodiacetate （SEADA2-） zwitterion was synthesized from an acidic aqueous solution. This compound features a 2D undulating fes （4.82） coordination layer that is stacked and linked by hydrogen-bonding interaction to form a 3D supramolecular framework with a 1D larger-cycle channel. Thermal analysis demonstrates the relatively weak bonding between uranyl cation and SEADA2 zwitterion. The monomeric uranyl-based fluorescence emission is red-shifted by about thermal synthesis of this uranyl compound was successfully 5 nm compared to that of uranyl nitrate hexahydrate. The hydro- applied to the sequestration of uranyl ions.

Insight from in situ microscopy into which precipitate morphology can enable high strength in magnesium alloys

Magnesium alloys, while boasting light weight, suffer from a major drawback in their relatively low strength. Identifying the microstructural features that are most effective in strengthening is therefore a pressing challenge. Deformation twinning often mediates plastic yielding in magnesium alloys. Unfortunately, due to the complexity involved in the twinning mechanism and twin-precipitate interactions, the optimal precipitate morphology that can best impede twinning has yet to be singled out. Based on the understanding of twinning mechanism in magnesium alloys, here we propose that the lamellar precipitates or the network of plate-shaped precipitates are most effective in suppressing deformation twinning. This has been verified through quantitative in situ tests inside a transmission electron microscope on a series of magnesium alloys containing precipitates with different morphology. The insight gained is expected to have general implications for strengthening strategies and alloy design. 2018 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.