Currently, gold processing plants produce a large volume of wastewater containing toxic cyanide compounds and heavy metal salts. The presence of these pollutants in water sources produces long-term environmental and ecological impacts. In this work, a combined chemical and electrochemical method was applied on industrial cyanide-leached solutions in order to minimize its environmental impact. Dissolved toxic residues were being precipitated with high yield and selectivity in alkaline solutions at 75-80°C. Atomic absorption spectroscopy analysis has revealed over 90% removal of toxic materials including dissolved gold. The solid precipitate was further treated electrochemically in order to extract the dissolved gold. Approximately, for two liters of the originally waste solutions containing a few ppm gold, a visible thin gold layer could be precipitated on steel electrodes. Results show that the income from the sale of gold is sufficient to cover the cost of the removal of toxic pollutants throughout the whole process.

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