Sorption-atomic-fluorescence determination of gold in ores

摘要

The sorption of gold from hydrochloric acid solutions With polyacrylate sorbents XAD-8, Spheron 1000, and Spheron 100 000 is studied. It is demonstrated that the limiting stage of the metal sorption is diffusion to the sorbent grains for XAD-8 and mass transfer of the metal in solution for Spheron 1000 and Spheron 100000. Kinetic and thermodynamic parameters of sorption are determined. Based on the studies and calculations, 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 sorption--desorption mode. It is demonstrated that 10~(-6)-10~8-fold quantities of Fe, Cu, and Al do not decrease the recovery of gold from solutions. A highly sensitive method is developed for the determination of gold in ores; the method includes the acid decomposition of a sample and the flow sorption--atomic-fluorescence determination of gold in the solution. With preconcentration for 2 rain, 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.