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Precipitation of high pure Cu powders through H2 gas reduction of copper sulphate solutions containing Ni and Fe have bben investigated.
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Presence of trace amount ( 50–100ppm) of ferrous ion found to affect the reduction kinetics of Cu2.
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Agglomeration of precipitated Cu powders could be controlled by addition of a surfactant.
Selective reduction of Cu from aqueous solutions containing Ni and Fe to produce Cu powders was investigated through hydrogen gas reduction. The reduction kinetics was found to depend on temperature, hydrogen gas pressure as well as trace amount of iron. Under optimum precipitation condition (solution pH: 3.5, temperature: 180°C, time: 90min., and hydrogen pressure: 30kg/cm2), copper powders (purity>99.9%) was obtained with more than 99% precipitation efficiency. The SEM images revealed that the precipitated Cu particles have irregular shapes at lower precipitation temperatures, while spherical Cu particles form at higher reduction temperature. Addition of a surfactant modified the morphology of copper powders and also prevented their coating on the reactor's surface. Precipitated Cu powders are fine sized (more than 80% particles below 45μm) and have lose and green densities of 3.28g/cm3 and 8.45g/cm3, respectively.