Copper cementation on zinc and iron mixtures: Part 2: Fluidized bed configuration

In this study, the cementation of copper ions on iron and zinc as sacrificial metals in a fluidized bed configuration was carried out. A preliminary hydrodynamic study checked the non-segregating behaviour of iron/zinc mixtures during fluidization experiments. The efficiency of the mixtures in copper recovery has been estimated in terms of kinetic and apparent mass transfer coefficients according to operating parameter modifications. The influence of temperature on the kinetics revealed a mass transfer limitation of the reaction, with an activation energy of 19.6 kJ mol−1. Maximum apparent mass transfer (13.6 · 10−5 m s−1) was obtained for a 1.5 pH solution due to the presence of hydrogen bubbles that increase local mass transfer. Acid and sacrificial metal consumptions revealed an over-consumption of zinc compared to iron due to copper catalysed hydrogen evolution. The influence of initial copper concentration in the 50–1000 ppm range shows that kinetic and mass transfer dependence is due to modifications of the copper deposit morphology.

Research Highlights
► Maximum mass transfer is obtained for a 1.5 pH solution due to hydrogen bubbles.
► Kinetic and mass transfer are influenced by copper deposit modification.
► Magnetic stabilization of the bed implies a significant increase in copper recovery.