Adsorption of aurocyanide complexes onto carbonaceous matter from preg-robbing Goldstrike ore

Aurocyanide complex adsorption by naturally occurring carbon in Goldstrike ore has been implicated in a form of gold refractoriness known as "preg-rob bing". The aim of this work was to establish a relationship between the aur ocyanide uptake capacity of Goldstrike ore carbonaceous matter and the preg -robbing behavior of the parent ore. The effect of varying contact time bet ween the aqueous gold-cyanide and the carbonaceous matter on the uptake of aurocyanide complexes was also investigated. In column adsorption experimen ts, the adsorbed gold concentration from 100 mL of a gold-cyanide solution depended on the flow rate of the solution. The concentration of adsorbed go ld increased with solution flow rate, reaching a maximum concentration at a flow rate of approximately 0.05 mL/min. As solution flow rate increased to more than 0.05 mL/min, the concentration of gold adsorbed on the carbon de creased. Desorption of adsorbed gold into 75-mL sodium cyanide solution als o depended on solution flow rate. Maximum desorption of gold occurred at a flow rate of approximately 0.14 mL/min. The gold adsorbed at the lowest and highest flow rates was more slowly desorbed than the additional gold adsor bed at the intermediate flow rates. The concentration of gold remaining on the carbon after desorption at 0.14 mL/min correlated to the amount of gold adsorbed at the highest and lowest flow rates in the adsorption experiment s. This amount of slowly desorbed gold correlated to the preg-robbing behav ior of the ore, whereas the amount of additional adsorbed gold (i.e., gold adsorbed at intermediate flow rates) was similar for all of the ores. For a ll of the carbonaceous matters studied, the concentration of gold sorbed in both batch and column experiments increased after autoclaving. (C) 2001 El sevier Science B.V. All rights reserved.