Abstract
The aim: the study and numerically assess the effect of underestimating the results of fire assay analysis of cyanidation tailings of preg-robbing gold bearing products. At present, about 20% of ores submitted for technological research to the Irgiredmet Institute have high preg-robbing activity associated with the presence of carbon in organic form in the raw material. There are some problems with gold grade determination in cyanidation tailings of these ores and concentrates. Fire assay supplies understated results that do not present the actual gold content in the solid phase of tails. In order to quantify this underestimation, experiments were carried out to "contaminate" the cyanidation tailings of carbonaceous gold-bearing concentrates of ores from two Russian deposits as well as coal from one of the deposits in the Irkutsk region and activated carbon produced in China with a known amount of gold from alkaline cyanide solutions simulating cyanide leaching conditions. Products "contaminated" with a known amount of gold were analyzed by fire assay with AAS ending. For the tested products the amount of adsorbed gold calculated by changes of its concentration in the liquid phase was from 1.79 to 34.30 g/t. The 0.39-9.64 g/t, or 18.3-50.7% of this amount,was not determined by fire assay with AAS enduing. Presumably, the underestimation of the results of the fire assay is due to the fact that gold initially in the adsorbed state does not form metal particles with a particle size sufficient to be wetted with molten lead with subsequent extraction to lead alloy and is carried away into borosilicate slags. The results obtained in the work have important practical consequences as they indicate an underestimation of gold losses at industrial plant processing of preg-robbing ores and concentrates and require the development of improved methods of analysis.
Keywords:
gold, cyanidation tailings, preg-robbing activity, carbonaceous matter, fire assay, uncertainty