Chinmaya Kumar Sarangi

Recovery of copper from a surface altered chalcopyrite contained ball mill spillage through bio-hydrometallurgical route

Bioleaching studies for chalcopyrite contained ball mill spillages are very scarce in the literature. We developed a process flow sheet for the recovery of copper metal from surface activated (600 °C, 15 min) ball mill spillage through bio-hydrometallurgical processing route. Bioleaching of the activated sample using a mixed meso-acidophilic bacterial consortium predominantly A. ferrooxidans strains was found to be effective at a lixiviant flow rate of 1.5 L/h, enabling a maximum 72.36% copper recovery in 20 days. Mineralogical as well as morphological changes over the sample surface were seen to trigger the bioleaching efficiency of meso-acidophiles, thereby contributing towards an enhanced copper recovery from the ball mill spillage. The bio-leach liquor containing 1.84 g/L Cu was purified through solvent extraction using LIX 84I in kerosene prior to the recovery of copper metal by electrowinning. Purity of the copper produced through this process was 99.99%.

Bio-hydrometallurgical processing of low grade chalcopyrite for the recovery of copper metal

A process flowsheet was developed to recover copper metal from the lean sulfide ore of copper available at Malanjkhand, Hindustan Copper Limited (HCL), India. Copper pregnant leach solution (PLS) obtained from bio-heap leaching of chalcopyrite containing 0.3% copper was purified through solvent extraction (SX) and the copper recovered by electrowinning (EW). The copper-free raffinate obtained from SX stripping unit was returned back to the bioleaching circuit. The purity of the electrolytic copper produced at pilot scale was found to be 99.96%. During electrowinning, the effect of flow rate of electrolyte on current efficiency and energy consumption was also studied.

Influence of Synthesis Temperature on the Growth and Surface Morphology of Co3O4 Nanocubes for Supercapacitor Applications

A facile hydrothermal route to control the crystal growth on the synthesis of Co3O4 nanostructures with cube-like morphologies has been reported and tested its suitability for supercapacitor applications. The chemical composition and morphologies of the as-prepared Co3O4 nanoparticles were extensively characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Varying the temperature caused considerable changes in the morphology, the electrochemical performance increased with rising temperature, and the redox reactions become more reversible. The results showed that the Co3O4 synthesized at a higher temperature (180 °C) demonstrated a high specific capacitance of 833 F/g. This is attributed to the optimal temperature and the controlled growth of nanocubes.

Role of hydrazine and hydrogen peroxide in aluminium hydroxide precipitation from sodium aluminate solution

Aluminium hydroxide precipitation from synthetic sodium aluminate solution was studied in the presence of hydrazine or hydrogen peroxide. The addition of low concentration of hydrazine is found to be effective, while higher amount of hydrogen peroxide is required to generate similar effect. XRD data confirm the product phase to be gibbsitic by nature. The scanning electron micrographs (SEM) show that agglomerated products form in the presence of hydrazine while fine discrete particles are produced with hydrogen peroxide. The probable mechanism of precipitation in the presence of hydrazine and hydrogen peroxide is also discussed.

An evaluation of cadmium sorption potential of waste aluminium dross

Abstract The removal of Cd(II) from aqueous solution onto aluminium dross surface was investigated. The influence of pH, contact time, initial metal ion concentration and temperature on the effectiveness of the removal process was studied. The variation of adsorption efficiency with pH indicates that the aluminium dross has residual negative charge on the surface. At low pH, H+ ion gets adsorbed preferentially than Cd(II) ion but at higher pH, Cd(II) ion gets adsorbed in larger numbers. It has been further observed that the adsorption efficiency increases with temperature indicating an increase in kinetic energy of the solute ions or decrease in boundary layer resistance to mass transfer. Kinetic study indicated that in the present work the adsorption process follows mainly pseudo-first-order rate model. The low activation energy (18.3 kJ mol−1) reveals that the process is spontaneous and physical in nature. The value of is negative which further decreases with temperature indicating spontaneity of the ad...

Electro-Crystallization of Antimony from Acidic and Alkaline Baths in Diaphragm-Less Cell

Studies based on electrocrystallization of antimony were carried out to evaluate the effects of current density and antimony concentration in the electrolytic bath on cathodic current efficiency, energy consumption, and quality of the deposits during electrowinning of antimony from Sb2O3-HCl and Sb2S3-NaOH systems. In acidic bath, current efficiency for electrodeposition of antimony increases with the increase in current density till 150 A/m2, beyond which it follows a trend of gradual diminution. On varying antimony concentration in the bath, current efficiency was found to improve significantly and the optimum antimony concentration in Sb2O3-HCl system was evaluated to be about 60 g/L. In alkaline bath, current efficiency was observed to be maximum at 50 A/m2 and further, with the increase in current density it progressively decreases. However, energy consumption for electrowinning of antimony in both of the baths gradually increases with the increase in current density. At a current density less than 150 A/m2, alkaline bath was found to be more current efficient in comparison to the acidic bath. Crystallographic studies by XRD, imaging by optical microscopic technique and morphological studies by SEM were also carried out to differentiate antimony deposits obtained from acidic and alkaline baths.