Assessing possibility of technogenic raw material processing using ultra-low concentrations of sodium cyanide

Abstract

The purpose of the study is to conduct experiments in order to determine the possibility of technogenic goldbearing raw material cyanidation using ultra-low concentrations of NaCN. Experiments are carried out on the cyanidation of three samples of technogenic raw materials of different composition. The first sample consists of pyrite cinders (Au – 1.8-2.3 g/t, Ag – 13-22 g/t, Fe – 48.52%, Cu – 0.15-0.30%, Zn – 0.3–0.6%). The second sample is represented by the aged tailings of copper-zinc flotation (sample I) with the content of Au – 0.8 g/t, Ag – 7.0 g/t, Fe – 17.2%, Cu – 0.212%, Zn – 0.207%. The next object is the copper-zinc flotation tailings of a concentration plant (sample II), with the following content of Au – 1.22 g/t, Ag – 15.2 g/t, Cu – 0.13%, Zn – 0.23%. It is recommended to use an aqueous wash from nonferrous metals with subsequent lime treatment as a preliminary processing of pyrite cinders. Cyanidation is carried out at different consumptions of reagent: from 0.075 to 3 kg/t. The experiments have shown that gold recovery in this range of NaCN consumption varies from 42.9 to 44.2%; moreover, a decrease in the reagent consumption allows to reduce the concentration of non-ferrous metal ions in cyanidation solutions. Before cyanidation sample I has also been subjected to aqueous wash to remove acid and non-ferrous metals. NaCN consumption varies from 0.25 to 2.2 kg/t. In this case the extraction of gold amounts to 36.6–46.4%. Cyanidation of tailings (sample II) is carried out in the range of 0.15–1.2 kg/t of NaCN. Gold recovery varies from 24.1 to 30.9%. The cyanidation technology of technogenic raw materials in the field of ultra-low concentrations of sodium cyanide is promising, since it provides acceptable gold recovery under low reagent consumption. For further research in the field of development of an extraction technology of valuable components, the flotation tailings of copper-zinc production (sample II) are chosen as a promising object. It is planned to carry out semiindustrial tests, calculate technical and economic indicators and develop process regulations.