In this work, aiming to recover copper from AMD, we studied a surfactant-assisted cementation by iron. We tested the use of polyvinylpyrrolidone (PVP-K30) through a factorial design of experiments. The factorial design was implemented to study the effects of surfactant concentration (1, 2 and 4 mM) and temperature (25, 50 and 75°C) on cementation kinetics, copper recovery and copper particle size. The activation energies of cementation with and without surfactant were also assessed by fitting the experimental data with the Arrhenius equation. The concentration of the dissolved copper was determined by inductively-coupled plasma spectrometry (ICP/AES). The cemented product was characterized by X-ray fluorescence (XRF) and X-ray diffraction (XRD) to determine the product purity and phase composition and by scansion electron microscopy (FE-SEM) to estimate the product morphology and size distribution. Without using any surfactant, the copper recovery yield ranged from 75% at low temperature to 98% at high temperature while the purity of copper accounted for a maximum of 98%. The cementation reaction was found to follow a first order kinetic and the activation energy was estimated as 23.8 kJ/mol, thus suggesting the occurrence of a diffusion controlled process. Furthermore, the cemented product aggregated into micro-sized clusters of about 2-3 m diameter. The use of PVP as surfactant did not affect the recovery yield but it determined an increase of copper purity above 99% due to the templating action that protects the metal surface from the oxidation. This templating action determined a dramatic decrease of particle size at high temperature: while at 25°C the cemented copper still aggregated into 3 m clusters, by increasing the temperature the average grain size decreased up to 300-400 nm. Even in the presence of PVP, the cementation reaction was found to follow a first order kinetic in a diffusion controlled process.
|出版ステータス||Published - 2017 1 1|
|イベント||14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017 - Sapporo, Hokkaido, Japan|
継続期間: 2017 9 26 → 2017 9 29
|Conference||14th International Symposium on East Asian Resources Recycling Technology, EARTH 2017|
|Period||17/9/26 → 17/9/29|
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