An Investigation on the Effects of Organic Additives on Zinc Electrowinning from Industrial Electrolyte

Abstract

The influence of Saponin, Licorice, Tennafroth 250, and Dowfroth 250 at different concentration levels (0, 5, 10, and 15 ppm) were investigated during zinc electrowinning from industrially supplied spent electrolyte. Acid mist suppression efficiency, polarization behavior, current efficiency and energy consumption were investigated for a current density of 500 A.m-2. Surface tension measurements were used to find a correlation between the concentration of the different additives and the acid mist suppression efficiencies. Morphological and crystallographic orientation studies indicated dense and well defined crystalline grains with homogeneous distribution mostly at the 5 ppm level of suppressant. The electrowinning in presence of Saponin and Tennafroth were found to have high current efficiencies of 90% each with low energy consumptions of 2641 and 2675 kWh/t, respectively and the deposited crystals were found to be oriented preferably in the [101], [102], [103] and [112] planes for both.