Recovery of nickel powder from copper bleed electrolyte of an Indian copper smelter by electrolysis

Nickel recovery from electronic waste II electrodeposition of Ni and Ni-Fe alloys from diluted sulfate solutions

This study focuses on the electrodeposition of Ni and Ni-Fe alloys from synthetic solutions similar to those obtained by the dissolution of electron gun (an electrical component of cathode ray tubes) waste. The influence of various parameters (pH, electrolyte composition, Ni(2+)/Fe(2+) ratio, current density) on the electrodeposition process was investigated. Scanning electron microscopy (SEM) and X-ray fluorescence analysis (XRFA) were used to provide information about the obtained deposits' thickness, morphology, and elemental composition. By controlling the experimental parameters, the composition of the Ni-Fe alloys can be tailored towards specific applications. Complementarily, the differences in the nucleation mechanisms for Ni, Fe and Ni-Fe deposition from sulfate solutions have been evaluated and discussed using cyclic voltammetry and potential step chronoamperometry. The obtained results suggest a progressive nucleation mechanism for Ni, while for Fe and Ni-Fe, the obtained data points are best fitted to an instantaneous nucleation model.

Recovery of Precious Metal Material Ni from Nickel Containing Wastewater Using Electrolysis

The recovery of Ni2+ from nickel containing solution is a worthwhile work, owing to its precious value. In the present work, the optimal values of electrolysis (EL) operating parameters were elaborately investigated using Taguchi approach. The effect of Ni2+ initial concentration, boric acid, pH, and voltage were investigated in terms of nickel recovery and energy consumption. The results obtained showed that the influential factors on nickel recovery were voltage > boric acid > pH > concentration. However, in terms of energy consumption the following order of concentration > boric acid > pH > voltage was obtained. A confirmation experiment was carried out with the optimized parameters (boric acid 18g/L, nickel concentration 1000 mg/L, voltage applied 4.0 V, and pH 4). The recovery of Ni2+ yielded about 88%, and the outlet Ni2+ was as low as 119 mg/L. The electrolysis dynamic mode was investagated with flow rate 20 mL/min. The results showed that the outlet nickel concentration was 350 mg/L equal to 65% of Ni2+ recovery and energy consumption of 25.7 kW h/kg. Electrolysis could effectively recover nickel, however the Ni2+ concentration of the residual electrolyte was much higher than the restriction of 1 mg/L, so we used electrodialysis to further treat the residual electrolyte and the nickel concentration has been reduced below 1 mg/L , which will be discussed in other paper.

Recovery of copper and water from copper-electroplating wastewater by the combination process of electrolysis and electrodialysis

In this paper, a laboratory-scale process which combined electrolysis (EL) and electrodialysis (ED) was developed to treat copper-containing wastewater. The feasibility of such process for copper recovery as well as water reuse was determined. Effects of three operating parameters, voltage, initial Cu(2+) concentration and water flux on the recovery of copper and water were investigated and optimized. The results showed that about 82% of copper could be recovered from high concentration wastewater (HCW, >400mg/L) by EL, at the optimal conditions of voltage 2.5 V/cm and water flux 4 L/h; while 50% of diluted water could be recycled from low concentration wastewater (LCW, <200mg/L) by ED, at the optimal conditions of voltage 40 V and water flux 4 L/h. However, because of the limitation of energy consumption (EC), LCW for EL and HCW for ED could not be treated effectively, and the effluent water of EL and concentrated water of ED should be further treated before discharged. Therefore, the combination process of EL and ED was developed to realize the recovery of copper and water simultaneously from both HCW and LCW. The results of the EL-ED process showed that almost 99.5% of copper and 100% of water could be recovered, with the energy consumption of EL ≈ 3 kW h/kg and ED ≈ 2 kW h/m(3). According to SEM and EDX analysis, the purity of recovered copper was as high as 97.9%.