2LiFe1-xCoxPO4-Li3V2（P04）3/C was synthesized using Fel-2xCo2xVO4 as precursor which was prepared by a simple co-precipitation method. 2LiFej-xCoxPO4-Li3V2（PO4）3/C samples were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electrochemical measurements. All 2LiFel-xCoxPOa-Li3V2（PO4）3/C composites are of the similar crystal structure. The XRD analysis and SEM images show that 2LiFe0.96Co0.04PO4-Li3V2（PO4）3/C sample has the best-ordered structure and the smallest particle size. The charge-discharge tests demonstrate that these powders have the best electrochemical properties with an initial discharge capacity of 144.1 mA.h/g and capacity retention of 95.6% after 100 cycles when cycled at a current density of 0.1C between 2.5 and 4.5 V.
The leaching processes of zinc plant purification residue in sulfuric acid solution were investigated with respect to the effects of sulfuric acid concentration, reaction temperature, and particle size. A particle size of 75？80 μm was required to leach 99.8%cobalt and 91.97%zinc at 70 °C for 20 min when the sulfuric acid concentration was 100 g/L and the ratio of liquid to solid was 50？1 （mL/g）. The leaching kinetics of zinc plant purification residue in sulfuric acid solution system conformed well to the shrinking core model, and the dissolution rates of cobalt and zinc were found to be controlled by diffusion through a porous product layer. The apparent activation energy values of cobalt and zinc reaction were calculated to be 11.6931 kJ/mol and 6.6894 kJ/mol, respectively, according to the Arrhenius formula equation. The results show that diffusion through the inert particle pores is the leaching kinetics rate-controlling step.
The leaching behavior of metals from a pressure-leaching slag was investigated using a desulphurization-leaching-hydrolysis process for the recovery of bismuth and antimony.Various parameters were studied,including the amount of acid added,temperature,time,addition of NaCl and solid-liquid ratio in the leaching process.The experimental results show that the contents of bismuth and antimony are mostly enriched in the process of kerosene desulphurization.More than 98% Sb and 96% Bi are extracted under the determined conditions.In the process of hydrolysis,the precipitation rates of bismuth and antimony are 97.80% and 94.59%,respectively.Under the optimum experimental conditions,the recovery rate of bismuth and antimony can be up to 95.80% and 90.80%,respectively.
