A New Approach and Efficient Solvent Extraction/Recovery of Gold and Copper from Waste Electrical Equipment Using Tri-n-Octylamine as Extractant

Publish Year: 1398
نوع سند: مقاله کنفرانسی
زبان: English
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NSCEI09_061

تاریخ نمایه سازی: 19 آبان 1398

Abstract:

By extensive exploitation of gold and copper from their resources, the obtaining of these precious metals from the corresponding ores has begun to be exhausted. This is because of the insufficient amount of raw materials to afford the increasing need to these metals of electric and electronic industries. Moreover, the continuous production of waste electrical and electronic equipment results in severe environmental issues as it is disposed in landfills, because of their precarious and harmful content [1]. These economic and environmental aspects motivated many research groups around the world to be focused on the recovery of gold and copper from the mentioned wastes [2].The metallic parts of electronic circuits (80 g) were demounted and were dissolved in aqua-regia (1000 mL) to analysis the metallic contents (Au, Cu, Ni, Al, Cd, Co, Cr, Fe, Pb and Zn), by using inductively coupled plasma. The selective extraction of the gold and copper contents from the leached solution was studied by optimization of the parameters affecting the process included the initial aqueous gold (copper contents were varies with the gold concentration) concentration, extractant and hydrochloric acid concentration and aqueous to organic phases, and contact time using the RSM. The selection of the organic diluent performed via a univariate optimization process. This was the same optimization used for the optimization of the back-extraction process. The back-extraction of the gold and copper extracted to the organic phase were stripped with a solution of sodium hydroxide [3].Under the optimized extraction conditions, i.e. aqueous phase 5 mL (90 mg L-1 Au, 32600 mg L-1 Cu) adjusted to 4 M HCl, 10 mL organic phase (0.048 M tri-n-octylamine in o-xylene), and contact time 15 min, the mount of the extracted gold and copper into the organic phase were ~90 and ~2400 mg L-1, respectively. A quantitative back-extraction of copper and gold was realized by using a solution of 0.1 M NaOH. The copper was precipitated in its hydroxide form, and chloro-complex of gold was found in the aqueous phase. This study showed that the gold in the leached solutions of spent electronic circuits can quantitatively and selectively recovered by using a solvent extraction method based on tri-n-octylamine extractant, followed by applying a back-extraction step with sodium hydroxide. The co-extraction of copper with gold did not interfere for the recovery of gold. Moreover, the co-extracted copper was completely separated from the gold content by a selective back-extraction process by sodium hydroxide.

Authors

Z Raeisi,

Department of Chemistry, Faculty of Science, The University of Zanjan, ۴۵۳۷۱–۳۸۷۹, Zanjan

M.R Yaftian

Department of Chemistry, Faculty of Science, The University of Zanjan, ۴۵۳۷۱–۳۸۷۹, Zanjan

B Farajmand

Department of Chemistry, Faculty of Science, The University of Zanjan, ۴۵۳۷۱–۳۸۷۹, Zanjan

P NakhostinPanahi

Department of Chemistry, Faculty of Science, The University of Zanjan, ۴۵۳۷۱–۳۸۷۹, Zanjan