ammonia

The presence of copper oxide next to gold increases the consumption of cyanide in the cyanidation process, reduces the absorption of gold on carbon, and causes many problems in the downstream processes of elution, electrowinning, and smelting. In the current research, increasing the recovery of gold dissolution and its selective adsorption on activated carbon using ammonia additive and the effect of different factors such as the type of ammonia additive, changing the system of contact of gold with carbon from CIL to CIC, and adding hydrogen peroxide and cyanide to the filtered solution were studied. The findings showed that adding ammonium chloride or liquid ammonia to the cyanidation solution, in the sample with high copper grade (1% copper), and in the sample with medium copper grade (0.5% copper), increased the dissolution recovery by 60% and 30%, respectively. Also, the recovery of gold adsorption on activated carbon in sample with a grade of 0.5% copper increased from about 25% during the normal CIL process to about 100% during the ammonia cyanidation process in the form of CIC. Results showed that liquid ammonia provides up to 10% higher dissolution recovery and up to 3% higher absorption recovery compared to ammonium chloride, while reduces the consumption of cyanide by half and the amount of copper absorption on carbon by a third.

Chalcopyrite dissolution rate in atmospheric pressure in sulphate media is slower than the leaching of copper oxides and secondary sulfides due to the formation of passive layer on the particles. So the use of sulphate media in industrial scale is faced with serious problems. Due to the high recovery in chalcopyrite leaching with Ammonia and ammonium salts in atmospheric pressure، this media are considered. In this study experiments performed to investigate the parameters affecting the leaching of Sarcheshmeh chalcopyrite copper concentrate with 53. 029% chalcopyrite and 25% Cu at atmospheric pressure with ammonia and ammonium carbonate. The findings of this research showed that parameters of the concentration of ammonia، ammonium carbonate، solid to liquid ratio، stirring rate، oxygen flow rate and leaching time are the most important factors in the leaching of chalcopyrite. Under optimal conditions، 5 mol of ammonia، 0. 3 M ammonium bicarbonate، liquid to solid ratio of 20/1، stirring speed 1000 rpm، 60 ° C، oxygen flow rate of 1 liter per minute and 240 minutes of leaching time، the copper recovery was obtained more than 71%.