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2011-Sustainable Industrial Processing Summit
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| Editors: | Florian K |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2012 |
| Pages: | 764 pages |
| ISBN: | 978-0-9879917-5-1 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
Treatment Of Gold-Silver Ore With High Copper Content
Enrique Elorza Rodriguez1; Veronica Garcia Torres1; Ricardo Corona Corona1; Enrique Elorza-Rodriguez1;1UNIVERSIDAD DE GUANAJUATO, Guanajuato, Mexico;
Type of Paper: Regular
Id Paper: 95
Topic: 14
Abstract:
A mining company, located in the southwest of Mexico, produces gold from an ore with 5.5 g of Au/t. Besides the gold, the ore contains also 0.2 – 0.33 % copper. Although the proportion of copper oxides is not so high, the leaching solution becomes saturated with copper (the process operates with zero discharges) and it is necessary to bleed part of the solution to the tailings pond in order to maintain the efficiency of the process.Approximately 5 % of the copper dissolves in the cyanide solution, resulting in a gold precipitate with high copper content (an average of 14 kg Cu/kg Au). In order to purify and commercialize the precipitate, it is smelt, but only 40 % of the copper can be removed by this method, the remaining copper being eliminated by nitric acid digestion. The silver values dissolved during the latter stage must be further recovered by a chemical precipitation using NaCl as a precipitating agent.Today´s high prices on precious metals have allowed the economic operation of this process; nevertheless, there exist some strong environmental issues related to this practice, among them the following could be mentioned: a) great amount of gases generated, b) corrosive and irritating atmosphere, c) long times of treatment (20 hours per lot of 800 kg) and d) high quantity of silver values in the solution that requires to be recovered.