ヒレ付型攪拌電解槽による連続脱銅電解

抄録

A prototype agitated cell for suspension electrolysis was made and continuous sulphidizing electrolysis was carried out to reduce copper concentration lower than the legal requirement for discharge
The cell consists of a vertical cylindrical agitated compartment with an internal diameter of 40cm, about 50cm height and 4 fin type-electrode compartments vertically attached in radial fashion on the cell wall of the compartment. Each fin compartment is divided with 2 vertical diaphragms of a cation exchange membrane into 2 anode chambersand a cathode chamber, the latter being connected with the agitated compartment through an upper inlet and a lower outlet in the cell wall. The catholyte suspension of 12.9 kg elemental sulphur per 62 dm3 in the agitated compartment is agitated with wings rotating at 800rpm (13.3 S^-1) so as to permit to circulate through the cathode chamber. An acidic sodium sulfate solution is independently circulated through the anode chambers with 4 pumps.
An acidic feed solution containing 1.0 to 1.2g/dm³ Cu was continuously fed to the agitated compartment and the electrolysis was performed stably up to a cell current of 120A at a feed rate of 151dm³/h. The feed rate was controlled so as to maintain the suspension potential at a set value of 0.20V (Pt vs. AgC1 E), at which the residual copper concentration was reduced to 0.2ppm. The current efficiency was about 100% and the power consumption was 2, 970 and 4, 600kWh/t-Cu at 60 and 120 A, respectively. The cell enabled passage of currents up to 180A, but the potential measurement and the feed rate control was disturbed by the high current.
For scale up, the capacity of the cell described can be increased by increasing the number of fins without a reduction of the ratio for (diaphragm area)/(cell volume).