Temperature monitoring of electrolytic cells using wireless battery-free harsh environment sensors

Proper control of temperature and electrolyte circulation flow is mandatory in electrolytic cells to produce dense and high-purity cathodes. The electrochemical kinetics of electrolytic processes is inherently dependent on these electrolyte variables. Continuous monitoring of electrolyte condition integrated to operation and housekeeping procedures, allows enhancing cathode quality and electrodeposition time, better utilization of electrolyte additives, and early identification of temperature excursions and electrolyte flow blockages. These abnormal cell conditions can produce excessive evaporation and energy consumption, anode passivation that impair cathode production in copper electrorefining, or safety issues from the production of flammable hydrogen in copper electrowinning. Therefore, the monitoring of changes in temperature and electrolyte flow can give critical indicators of process deviations and providing early warnings to face the wide variability of performance and safety conditions of cells caused by electrolyte condition mismanagement. This paper proposes a non-invasive wireless sensor for the monitoring of the temperature and electrolyte circulation flow estimation through each cell, suitable to highly-corrosive sulfuric acid environments. The condition monitoring sensor design is small size, lightweight, meets battery-free operation and non-sparking safety requirements. It uses an inductive link-based system for powering and a RF link for communicating. The result is a sensor that surpasses the features of standard instrumentation currently used for electrolytic process monitoring.