Preparation of ammonium jarosite from clinker digestion solution of nickel oxide ore roasted using(NH_4 )_2SO_4

To obtain the appropriate conditions for eliminating Fe3＋from NiSO4 solution, the digestion solution of the clinker was used as raw material, which was obtained from roasting the nickel oxide ore with （NH4）2SO4. The ammonium jarosite was successfully synthesized from the solution with analytic grade NH4HCO3. The effects of reaction temperature, reaction time, end pH value of reaction on the removal rate of iron were investigated, and the effect of the initial concentration of Fe3＋was also discussed. All of those factors had significant effects on the removal rate of Fe3＋, among which the reaction temperature was the most prominent. The appropriate reaction conditions were concluded as follows： reaction temperature 95 ℃ reaction time 3.5 h, end pH value of reaction 2.5 at initial concentration of Fe3＋19.36 g/L. The physical aspect of （NH4）2Fe6（SO4）4（OH）12 was cluster figure composed of sheet or prismatic particles with smooth surface.

Synthesis and characterization of Co_3O_4 prepared from atmospheric pressure acid leach liquors of nickel laterite ores

A chemical precipitation-thermal decomposition method was developed to synthesize Co3O4 nanoparticles using cobalt liquor obtained from the atmospheric pressure acid leaching process of nickel laterite ores. The effects of the precursor reaction temperature, the concentration of Co2＋, and the calcination temperature on the specific surface area, morphology, and the electrochemical behavior of the ob- tained Co304 particles were investigated. The precursor basic cobaltous carbonate and cobaltosic oxide products were characterized and ana- lyzed by Fourier transform infrared spectroscopy, thermogravimetric differential thermal analysis, X-ray diffraction, field-emission scanning electron microscopy, specific surface area analysis, and electrochemical analysis. The results indicate that the specific surface area of the Co3O4particles with a diameter of 30 rim, which were obtained under the optimum conditions of a precursor reaction temperature of 30℃, 0.25 mol/L Co2＋, and a calcination temperature of 350℃, was 48.89 m2/g. Electrodes fabricated using Co3O4 nanoparticles exhibited good electrochemical properties, with a specific capacitance of 216.3 F/g at a scan rate of 100 mV/s.