Comparative, real-time in situ monitoring of passivation phenomenon in the copper electrorefining process based on wavelet series

•Using high frequency domain data to compare the start of passivation in electrorefining of copper.•An estimation of passivation tendency using wavelet series.•A wavelet series was used to transform voltage time series to frequency.•Testing the proposed method at industrial current densities. Electrochemical noise signals can be analyzed to predict the passivation tendency of anodes in electrorefining. An industrial case study began with the sampling of six different casting anodes. Potentiostat/Galvanostat analysis was used to record voltage-time changes through electrorefining at intensified current density (220 mA.cm−2). Wavelet series were used to analyze electrochemical noise signals. Those samples with a higher average contribution of low-frequency signals, with average values of 0.172, 0.173, and 0.173, had long passivation times of 3451, 3693, and 4640 s, respectively. Experimental measurements were carried out using the copper refinery's industrial current density (30 mA.cm−2) as a test bed, and excellent matching was obtained by registering the data. [Display omitted]