SORPTION-ATOMIC-FLUORESCENCE DETERMINATION OF GOLD IN ORES

The sorption of gold from hydrochloric acid solutions with polyacrylat e sorbents XAD-8, Spheron 1000, and Spheron 100000 is studied. It is d emonstrated that the limiting stage of the metal sorption is diffusion to the sorbent grains for XAD-8 and mass transfer of the metal in sol ution for Spheron 1000 and Spheron 100000. Kinetic and thermodynamic p arameters of sorption are determined. Based on the studies and calcula tions, the XAD-8 polymer is selected as the most efficient sorbent for the preconcentration of gold. A microcolumn with the sorbent is used in a flow-injection system for the preconcentration of gold in the sor ption-desorption mode. It is demonstrated that 10(6)-10(8)-fold quanti ties of Fe, Cu, and Al do not decrease the recovery of gold from solut ions. A highly sensitive method is developed for the determination of gold in ores; the method includes the acid decomposition of a sample a nd the flow sorption-atomic-fluorescence determination of gold in the solution. With preconcentration for 2 min, the detection limit of the metal is 1.2 x 10(-6)%. The method exhibits high precision (RSD = 1-6% in a wide range of determined metal concentrations). High accuracy of gold determination in ores was confirmed by the analysis of standard reference samples of ores.