A consideration of circulating bed electrodes for the recovery of metal from dilute solutions

A comparison is made of three types of circulating particulate electrodes: spouted (circulating) bed (SBE), vortex bed (VBE) and moving bed (MBE). In applications such as metal recovery, all electrodes perform similarly in terms of current efficiency. On the basis of scale-up, it appears that the spouted bed electrode is the preferred system.Nomenclature I cell current (A) - F Faraday constant (94487 C mol^–1) - C dimensionless concentration - C_F friction factor - C₀ Initial concentration (mol m^–3) - D pipe equivalent diameter (m) - e_b bed voidage - e_c voidage of conveying section - L bed length (m) - S_b cross section area of bed (m²) - S_T cross section area of conveying section (m²) - T dimensionless time=It/nFVC₀ - U_f superficial liquid velocity in conveying (m s^–1) - U_i particle terminal velocity corrected for wall effects (m s^–1) - U_s particle velocity in transport (m s^–1) - U_SL slip velocity (m s^–1) - t time (s) - V electrolyte volume (m³) - V_f liquid velocity in the bed (m s^–1) - V_mf minimum fluidization velocity (m s^–1) - V_s particle velocity in the bed (m s^–1) - P pressure drop (NM^–2) - fluid density (kg m^–3) - _s particle density (kg m^–3) - Re Reynolds number