Solvothermal synthesis of high value copper powder from copper bleed solution of an Indian copper smelter

Recovery of copper powder from copper bleed solution (CBS) of a copper smelter by solvothermal route has been investigated. After removing sulphuric acid by solvent extraction with tri-iso-octyl-amine, copper from the acid depleted CBS was recovered by using Versatic 10 acid as an extractant in kerosene. In 1.5 M Versatic 10 acid 29.8 g/L copper was loaded at an equilibrium pH of 4.25. During the hydrogen stripping, a 97% copper powder was recovered from the loaded Versatic 10 acid solution at 20 bar hydrogen pressure and 403 K temperature. The solvothermal synthesis of copper powder followed nucleation and growth kinetic model with activation energy value of 145 kJ/mol. Stripping of copper powder could also follow the chemical control kinetic model with lower value of activation energy (66 kJ/mol). The copper powder as characterized by SEM exhibited globular particles of 0.25–0.5 μm size and was found to be suitable for P/M applications.