Recovery Potential of Gold and Silver from anode slimes by cyanidation and adsorption

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Chilumbu, Delax
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Tine cyanidation process for extracting precious metals (gold and silver) from the anode slimes was investigated. The recovery of these metals from cyanidation solution by adsorption on activated cai-bon has been studied. Ttiis was to assess the cyanidation and adsorption process as a potential alternative recovery process to the conventional metallurgical.presented in the report. From the cyanidation tests, the recovery of silver was found to increase with an increase in cyanide concentration. Recoveries of 82% and 77% of silver and gold respectively were achieved.Adsorption isotherms of gold, silver and copper have been generated. From these isotherms, an approximation of the loading capacity of gold and silver on activated carbon has been obtained. The typical results of loading capacity on the activated carbon show that the amount of go I'd and silver adsorbed per unit weight of carbon depends upon the amount of activated carbon, the retention time and the concentration of these metals in solution.Zadra desoption system was used to desorb the loaded activated carbon. From the foregoing studies a flowsheet has been proposed. Information on the nature of adsorbed species (gold and silver) on the activated carbon was obtained by XRF and XRD studies. The loaded and free regions of the activated carbon viewed under SEM, show that the adsorbate appears to adsorb selectively on specific features.
Mettallurgy , Mineral processing