Technical note Recovery of copper powder from copper bleed electrolyte of an Indian copper smelter by electrolysis Archana Agrawal * , Sarita Kumari, D. Bagchi, V. Kumar, B.D. Pandey Metal Extraction and Forming Division, National Metallurgical Laboratory, Burmamines, Jamshedpur, Jharkhand 831 007, India Received 25 January 2006; accepted 4 May 2006 Available online 30 June 2006 Abstract Copper bleed solution generated from an Indian Copper smelter contains high amount of copper and nickel along with several impu- rities. Attempts have been made to develop a new process for the production of pure copper powder from such streams. The purity of the electrolytic copper powder produced from such bleed streams was found to be 99.93%. Properties such as compact density of the annealed copper powder, flow-ability, particle size, etc. were evaluated and were found to be suitable for the powder metallurgical applications. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Electrowinning; Hydrometallurgy; Pollution; Reclamation; Wasteprocessing 1. Introduction A large part of the total metal powders (Pavlovic et al., 2001) is produced by electrorefining, electrowinning and electrodeposition (Popov and Pavlovic, 1993) process world over. Properties of metal powder deposited on the cathode depend on various parameters such as concentra- tion of ions, pH, bath temperature, current density, pres- ence of additives in the electrolyte, etc. A number of studies on the effects of various parameters on the electro- winning of copper from their sulphate solutions have been reported (Price and Davenport, 1980, 1981; Pavlovic et al., 2000; Fabian et al., 2003). With an aim to recover copper powder from copper bleed stream (CBS) containing high concentration of copper and nickel besides several other impurities, gener- ated from a copper smelter, we report here a new process comprising of decopperisation–crystallization–SX–electro- winning steps. This paper presents the effect of various parameters on the electrowinning of copper powder from the actual and synthetic CBS. Properties of the electrowon copper powders have also been evaluated. 2. Experimental The copper bleed solution obtained from an Indian copper smelter contains 39.86 g/L Cu, 9.58 g/L Ni, 0.26 g/L Fe, 0.108 g/L Bi, 0.007 g/L As, 0.055 g/L Sb, 198.04 g/L H 2 SO 4 . To optimise the experimental conditions a synthetic solution containing (g/L): 38.42 Cu, 19.37 Ni, 171.5 H 2 SO 4 was prepared. Partially decopperised CBS, containing equal amounts of copper and nickel was evapo- rated in two stages to crystallize mixed crystal of copper– nickel sulphate. The crystals obtained in the second stage was washed with water, and dissolved. The solution was neutralized with NaOH to raise the pH to 3.5–4.0, aerated for 24 h to precipitate iron as hydroxide and filtered. The filtrate was subjected to solvent extraction using LIX 84 and CYANEX 272 to separate copper from nickel. Copper from the loaded organic was stripped with H 2 SO 4 and was electrolysed to give pure copper powder. Raffinate that con- tains nickel was further treated for the synthesis of nickel powder. 0892-6875/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.mineng.2006.05.001 * Corresponding author. Tel.: +0657 2271709; fax: +0657 2270527. E-mail address: archana_nml03@yahoo.com (A. Agrawal). This article is also available online at: www.elsevier.com/locate/mineng Minerals Engineering 20 (2007) 95–97