Effect of solution volume on the rate of metal recovery and its distribution in porous cathode

Electrodeposition on a porous electrode with low initial conductivity: Effect of the oxidant on the dynamics of the cathode deposit mass

“…All the calculations were carried out for the porous cathode with the back current feeder and back solution feed with rather high fixed solution flow rate 1 cm 3 s À1 through 1 cm 2 of the geometric area of the PE cross section. The parameters of the total cathode polarization curve (the side reaction of oxidant reduction and the target reaction of metal dissolution-deposition [6]), as well as the initial PE characteristics remained invariable. The numerical values of parameters were chosen so that under the favourable conditions of electrolysis (direct-flow regime) the effect of AZ was rather strong.…”

“…In the process of non-uniform deposition of the metal inside the PE, we take into account temporal changes of the local values of filament diameters (and therefore the porosity and specific surface) as well as the linear rate of solution flow and the mass transfer coefficient of the electrically active components. For the metal deposition at a PE with low initial conductivity, we additionally took into account changes in the local conductivity of the solid phase, depending on the electric conductivity of the initial filaments and the cathode deposit [17]. All the calculations were carried out for the porous cathode with the back current feeder and back solution feed with rather high fixed solution flow rate 1 cm 3 s À1 through 1 cm 2 of the geometric area of the PE cross section.…”

“…To calculate the dynamics of metal deposition, we used a previously developed model representing a PE as a set of parallel filaments along which the electrolyte solution flows [18,19]. In the process of non-uniform deposition of the metal inside the PE, we take into account temporal changes of the local values of filament diameters (and therefore the porosity and specific surface) as well as the linear rate of solution flow and the mass transfer coefficient of the electrically active components.…”

“…The low initial conductivity of these PE contributes a new important factor into the electrodeposition process: changes of the local conductivity of the solid phase j s (x, t). In the absence of an oxidant in solution, as a rule, this factor leads to good final results: an increase in the final metal mass and better filling of the remote back part of the porous cathode with the deposit [17].…”

“…Previously [6] the effect of an oxidant on the dynamics of metal deposition inside a PE with the high initial conductivity of the porous matrix was considered. We showed that the presence of an oxidant in solution in a concentration comparable with the concentrations of metal ions causes noticeable worsening of the deposition process: a decrease in the rate of metal deposit accumulation and its final mass, and metal localization in a narrow layer near the PE front end which is the closest to the anode.…”