SPOUTED BED ELECTROWINNING OF ZINC .1. LABORATORY-SCALE ELECTROWINNING EXPERIMENTS

Two types of laboratory cells have been constructed to electrowin zinc from sulfate electrolytes: one cell was cylindrical while the other h ad a rectangular (flat) geometry. Cells were operated on industrial or synthetic electrolytes to electrodeposit zinc onto a spouted bed of z inc particles in the range of 0.75 to 1.45 mm. Current efficiencies an d cell voltages have been measured during the course of batch experime nts, enabling the calculation of the energy consumption per kilogram o f zinc deposited. Electrolyte samples have been analyzed. Current dens ities (current per unit of cell cross-sectional area) were in the rang e of 1380 to 6200 A/m(2). Most catholytes were initially neutral and c ontained on the order of 150 g/L of zinc. Final acid contents were in the range of 39 to 114 g/L of sulfuric acid. The performance of the ce lls (particularly with respect to current efficiency) was superior to prior work on fluidized bed electrowinning from similar electrolytes. The flat cell was superior to the cylindrical cell and showed energy c onsumptions of less than 3 kWh/kg zinc at current densities up to 3500 A/m(2) when used to take the zinc content from 150 to 100 g/L zinc. C urrent efficiencies in this application ranged from 91 to 92 pct.