Sustainable Oxygen-Free Copper Powder Production Method from Wastes

The oxygen content of the copper powders significantly affects the properties of copper, particularly its morphology and electric conductivity. Moreover, the oxygen content depends on the chosen synthesis method and variation of the process parameters. In this study, a sustainable oxygen-free copper powder electrolysis method was exploited to synthesize the copper powder by using wastes as initial materials. The anode and cathode copper scrap plates were used as raw materials. To accomplish this, the effect of the variation of the process parameters including current density, concentration of sulfuric acid, and copper ions was studied. Heat treatment was carried out at 600 degrees C for 90 min under H2 atmosphere for deoxidization. Additionally, the effect of the mechanical reduction through carbon bed on deoxidization (carbothermic reduction) was evaluated prior to the heat treatment under a hydrogen atmosphere. The oxygen content of achieved powders was measured by using the ONH analysis method based on the ASTM E 2575 standard method. The minimum measured oxygen content was found to be 179 ppm in the optimized condition of 0.3 A.cm-2, 140 g.l-1 of concentration of acid sulfuric, and 5 g.l-1 concentration of copper ions. This low oxygen content is attributed to the spherical and flake-shaped morphology of obtained copper powders. The size, morphology, and crystallization of the obtained copper powders were evaluated by scanning electron microscopy (SEM) and EDS. Results revealed that with the variation of the process parameters, the size of the powders was changed between 4.03 and 11.18 mu m.