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. Electrowinning in the presence of Saponin and Tennafroth was 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]

An environmentally friendly and high current efficiency acid mist inhibitor for zinc electrowinning

“…As shown in figure 8(a), the addition of 5 mg l −1 FS-101 acid mist inhibitor made the grain structure of the deposited zinc plate smaller and more closely aligned, this is similar to previous studies [34] where the addition of perfluorocarboxylic acid to an acidic zinc sulfate electrolyte resulted in smaller and more compactly arranged grain structure and better surface morphology of the deposited zinc sheets. However this is in contrast to the previous Dhak [23] study where the grain size of the microstructure of the zinc plate was larger and less densely arranged when 5 ppm SE/Saponin acid mist inhibitor was added to the electrolyte. Furthermore, no fragments and aggregation phenomenon is observed on the zinc surface, obtained in ZnSO 4 electrolyte with 5 mg l −1 FS-101 (figure 8(a)).…”

“…More precisely, Cheng [22] demonstrated that two saponinrich products (Mistop ® and QLZinc ® ) with a commercial licorice product can also play an active role in suppressing the generation of acid mist during the zinc electroposition process while reducing the current efficiency. Dhak [23] studied the influence of saponin, licorice, Dowfroth 250, and Tennafroth 250 on the zinc electrowinning process in industrial waste electrolytes. He deduced that all these surfactants can reduce acid mist.…”

Adsorption Capacity of Organic Compounds Using Activated Carbons in Zinc Electrowinning

“…In the presence of 100 mg/L zinc, with increasing adsorbate from 0-5%, the recovery efficiency of zinc decreased from 100% to 0% and the energy consumption increased from 0.0017-0.003 kwh/kg zinc. Considering the energy consumption and zinc deposit mass, 0.1% of the adsorbate is recommended for zinc electrowinning.The presence of organophosphorus-based extractants decreases metal impurities, including the concentration of Zn [17]. Ivanov's research group focused on Zn impurities through the addition of inhibitors during electrowinning [18,19].…”

“…The presence of organophosphorus-based extractants decreases metal impurities, including the concentration of Zn [17]. Ivanov's research group focused on Zn impurities through the addition of inhibitors during electrowinning [18,19].…”

Nucleation and growth orientation of zinc electrocrystallization in the presence of gelatin in Zn(ii)–NH3–NH4Cl–H2O electrolytes

“…[16][17][18][19] 103) and (112) planes during zinc electrowinning in sulphate system. 20,21 Alvarez and Salinas reported that addition of gelatin caused variation of instantaneous nucleation in sulphate electrolyte without additives. 22 Additionally, nucleation mechanism was also controlled by overpotential, magnetic eld, concentration of electroactive sites and temperature in acidic electrolyte.…”