Study of hydrogen depolarization anodes for zinc electrowinning of hydrogen-participated hydrometallurgy and their evaluation under industrial conditions

Abstract

Development of highly efficient electrochemical devices is as a desirable approach to hydrogen industries. Hydrogen depolarization anode (HDA), is considered as an advanced approach to dramatically reducing the high energy consumption for hydrometallurgy. To evaluate the feasibility of HDA technology in zinc electrowinning and its technical features, we prepare two kinds of HDAs. After 48 h operation in industrial electrolyte, the low cell voltage (below 1.5 V), low power consumption (below 1320 kWh/t) and high Faraday efficiency (above 95%) confirm the good technical prospect of this hydrogen-participated hydrometallurgy. Besides, the anode degradation should also be paid attentions. The lower hydrophobicities (i.e., PVDF-bonded HDA), leading a better electrolyte wettability, make a better initial electrocatalysis performance but a faster degradation. Through the structural changes of electrodes before and after electrowinning operations, the degradation behaviors seem different on their corrosion regions of PVDF-bonded HDA (mainly on platinum-carbon interface) and PTFE-bonded HDA (carbon supports). Whereas, we also provide some insights into materials selections, structural states, and operation conditions for the future development of using HDA technologies for hydrometallurgies, with the expectation of increasing ability to design and tailor highly efficient electrochemical devices.