AN EVALUATION OF ATOMIC SPECTROSCOPY METHODS IN-PROCESS CONTROL FOR RECOVERING AND RECONCENTRATING GOLD FROM RAW-MATERIALS AND WASTE PRODUCTS

The analytical performance of atomic spectroscopy techniques was evalu ated with regard to the control of solvent extraction processes used f or gold recovery from waste products and raw materials. A comparison w as made between flame atomic absorption spectrometry (FAAS), graphite furnace AAS (GFAAS), and inductively coupled plasma-atomic emission sp ectrometry (ICP-AES). The solutions derived from different extraction processes were prepared for analysis by extracting the gold with Aliqu ot 336-diisobutil ketone solution, volatilizing the organic layer, and dissolving the gold with aqua regia. Recoveries of known amounts of g old added exceeded 99%. This procedure avoids interferences produced i n the presence of different concentrations of cyanide or residues of o rganic reagents and allows use of aqueous standard solutions for calib ration. The detection limits (DL) were 30 ng/mL with FAAS, 0.1 ng/mL ( sample volume 20 muL) with GFAAS, and 4.5 ng/mL with ICP-AES. The cali bration curves were linear up to 10 mug/mL for FAAS, up to 0. 5 ng for GFAAS, and over a broad working range for ICP-AES. The coefficients o f variation (n=6), at concentration levels five times higher than the corresponding detection limits, were 3% with FAAS, 5% with GFAAS, and 0.85% with ICP-AES.