A procedure for preparing carbonaceous cyanidation tailings for gold fire assay

The aim is to develop a procedure for gold analysis of carbonaceous ore cyanidation tailings bearing gold in an adsorbed form. The proposed procedure includes high-temperature washing of the solid phase of tailings using a filter followed by transferring the adsorbed gold to the washing solution. The filtrate is analyzed separately, the solid phase undergoes standard fire assay, and the total gold grade is calculated by summing the gold in the solution and that in the solid phase. Using the proposed procedure, the proportion of adsorbed gold not detected by standard fire assay decreased by 4.1 times, from 38.2% to 9.3%. The studies were conducted using additions of gold solutions with a gold balance estimation. This additionally allowed gold adsorption isotherms to be studied by natural carbonaceous matter under cyanidation conditions. It was shown that at a gold concentration of 0.01–0.05 mg/dm³ typical of industrial cyanidation tailings, the adsorbed gold value was significant at the level of 0.1–1.1 g/t. These gold losses are directly determined by the preg-robbing activity of the raw material. The K constant of Freundlich isotherms plotted as the Au loading of organic carbon, g/t vs Au concentration, mg/dm³ was 303–3037 g/t, which is only an order of magnitude lower than that for commercial activated carbons. However, the greater mass of natural carbonaceous matter and its extended surface result in substantial gold losses with cyanidation tailings. The developed analytical procedure can be used to refine the actual gold losses with cyanidation tailings of carbonaceous raw materials.