Preparation and performance of 3D-Pb anodes for nonferrous metals electrowinning in H2SO4 aqueous solution

The effects of Pb^2+concentration,current density,deposition time and temperature on Pb deposit structure were investigated.In lower Pb^2+concentration(~0.15 mol/L),carambola-like 3D-Pb structure was constructed,while in higher Pb2+concentration(≥0.30 mol/L),Pb deposits exhibited pyramid-like structure.Furthermore,the oxide layer and anodic potential of carambola-shaped 3D-Pb(Cara-Pb)and pyramid-shaped 3D-Pb(Pyra-Pb)anodes were investigated and compared with those of fresh Pb anode.After 72 h galvanostatic electrolysis(50 mA/cm2)in 160 g/L H2SO4 solution,the oxide layer on Pyra-Pb was much thicker than that on Cara-Pb and Pb anodes,which remarkably relieved intercrystalline corrosion of the metallic substrate.Additionally,the oxide layer on Pyra-Pb anode presented a larger surface area and higher PbO2 content.Hence,Pyra-Pb anode showed a 40 m V lower anodic potential compared to Cara-Pb and Pb anodes.In sum,Pyra-Pb anode had a potential to decrease energy consumption and prolong the life span of traditional Pb anode.

Effects of Phenyl Content and Molecular Structure on the Refractive Index of Organic Silicon Polymer

The effects of phenyl content and group distribution on the refractive index of phenyl silicone oil were investigated by synthesis and characterization of silicone oils of different molecular structures.A group contribution function model was established to predict the refractive index. The results showed that refractive index of phenyl silicone oil increased as its phenyl content increased. A linear equation had been established to describe the quantitative relationship between the refractive index and phenyl content.Refractive index values from the group contribution function model showed good consistency with experimental results.

Oxygen pressure leaching-flotation joint process for Jinbaoshan platinum group minerals

An oxygen pressure leaching-flotation joint process was proposed to treat Jinbaoshan platinum group minerals to produce a desired concentrate. The result demonstrates that leaching parameters which include particle size, stirring speed, liquid-solid ratio, and the dosage of calcium lignosulfonate, simultaneously affect the leaching rates of base metals and the recovery of platinum group metals (PGMs). The complete dissolution of base metals sulfides leads to a reduction in the amount of flotation carrier for enriching PGMs, decreasing the recovery of PGMs. The optimum leaching conditions are determined as follows: liquid-solid ratio of 10 mL/g, 73% occupancy of ore particle size below 0.043 mm, stirring speed of 400 r/min, and 0.6 g dosage of calcium lignosulfonate. Under optimal conditions, the leaching rates of Cu, Ni and Fe are 87.6%, 87.6% and 90.3%, respectively. The grade of PGMs enriched in the flotation concentrate is 420 g/t through the flotation technology.

Microstructure improvement related coercivity enhancement for sintered NdFeB magnets after optimized additional heat treatment

The micro structure, especially the Nd-rich phase and the grain boundary, in sintered NdFeB magnets plays an important role in magnetic reversal and coercivity mechanism. To better understand the effects of the microstructure on the coercivity, we investigated the microstructure and properties improvements of a commercial sintered NdFeB magnet after optimized additional heat treatment. The coercivity is enhanced from 1399 to 1560 kA/m. This enhancement has been explained in terms of the evolution of the grain boundary structure, and the formation of continuous thin layers of Nd-rich phase is important for high coercivity. The micromagnetic simulation together with the numerical analysis based on the nucleation model suggest that the reversed magnetic domains nucleate mainly at the interface of multijunctions of Nd_2 Fe_（14）B grains with high stray fields during the demagnetization process. Both improved anisotropy fields at grain boundaries and reduced stray fields at multi-junction Nd-rich phases contribute to the coercivity enhancement. This work has importance in understanding the crucial micro structure parameters and enhancing the obtainable properties for sintered NdFeB magnets.