Determination of Trace Au in Minerals by Bismuth Fire Assay with Enrichment-high Resolution Continuum Source Flame Atomic Absorption Spectrometry

This is an article in the field of analytical testing. As a green and environmentally friendly fire gold test method for efficient separation and enrichment of trace precious metals in ore, bismuth gold test effectively avoids the problem of toxic pollution of lead test gold. In this article, Bi₂O₃ with low toxicity is used as the fire test gold trap of Au element, and Bi₂O₃ is reduced to Bi by the reducing agent flour in the test ingredient during the high-temperature melting process, and Au₂Bi alloy is formed with Au in the samples, and the Ag protective ash blowing method is used to make Au and Ag form about 1mg of Ag zygote. The Ag zygoteum is heated and dissolved by acid solution method to completely enter the solution of Au. In this test, the Au element content in the national standard material GBW 07205 was used as a reference, and the effective pixels of the CCD detector of the continuous light source flame atomic absorption spectrometer were optimized, and 7 were selected as the effective pixels of the CCD detector based on their sensitivity and stability. In the mass concentration range of 0～20 μg/mL, the corresponding absorbance was fitted by the quadratic equation least squares method, the fitting coefficient of the calibration curve was 0.999 8, the characteristic concentration was 0.069 97 μg/mL, and the detection limit of the method was 0.012 7 g/mL. According to the selected experimental method and optimized instrument parameters, Au in the national standard material was determined, and the measured value was in good agreement with the standard value, and the relative standard deviation (RSD, n=6) was 2.23%～4.54%. The established method was applied to the test of Au in actual ore samples, and the recovery rate of spiked was 92.6%～106%. The relative standard deviation (n=6) was 2.53%～4.70%, which met the requirements of the National Geological and Mineral Resources Industry Standard DZ/T 0130-2006.