Determination of Gold in Ore Samples by Flame Atomic Absorption Spectrometry of Sealed Dissolution after Adsorption using Polyurethane Foam

Abstract

This is an essay in the field of mineral analysis. After the samples were roasted and digested in 50% aqua regia by sealed dissolution,the gold in ore samples were adsorbed by 0.25g polyurethane foam during the oscillating, the polyurethane foam was washed to removing the slurry and acid, and gold was eluted out from polyurethane foam with 1% thiourea. Thus, a determination method of gold in ore samples by flame atomic absorption spectrometry of sealed dissolution after adsorption with polyurethane foam was established.The roasting method of some special gold ore samples was discussed.The conditions of sealed dissolution time, foam pretreatment, adsorption temperature and solution temperature were optimized, the results showed that when the sealed dissolution for 2 h, the gold was completely decomposed. After the polyurethane foam was treated with 5%HCl, the adsorption recoveries of gold could reach 95% at room temperature, the temperature of solution and standard solution shall be consistent with room temperature during determination. The calibration curve was prepared by foam adsorption and desorption process. Under the selected experimental conditions, the limit of detection was 0.13 μg/g, the limit of quantification was 0.43 μg/g, and the upper limit of determination was 80 μg/g. The standard recoveries were between 98.7% and 101%, the relative standard deviations(RSD, n=5) were between 1.10% and 2.07%. Verified by the determination of gold ore certified reference materials, the results were basically consistent with the certified value.

Keywords

• mineral analysis
• sealed dissolution
• polyurethane foam
• flame atomic absorption spectrometry
• ore samples
• gold