| WANG Ji-yan,HU Jia-zhen,DING Han-duo,CAO Li-feng,ZHANG Ming-wei,ZHANG Fan,HUANG Jie,YAO Wen-sheng.Determination of Gold Mobile Fraction in Deep-penetrating Geochemical Samples by ICP-MS with Pre-extraction[J].Rock and Mineral Analysis,2020,39(4):525-534 |
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| Determination of Gold Mobile Fraction in Deep-penetrating Geochemical Samples by ICP-MS with Pre-extraction |
| Received:September 23, 2019 Revised:January 30, 2020 |
| DOI：10.15898/j.cnki.11-2131/td.201909300142 |
| Key words: concealed gold deposit gold mobile fraction leaching thiourea activated carbon adsorption inductively coupled plasma-mass spectrometry |
| Author Name | Affiliation | E-mail | | WANG Ji-yan | Henan Province Rock and Mineral Testing Centre, Zhengzhou 450012, China
Key Laboratory of Precious Metals Analysis and Exploration Technology, Ministry of Land and Resources, Zhengzhou 450012, China | | | HU Jia-zhen | Henan Province Rock and Mineral Testing Centre, Zhengzhou 450012, China | | | DING Han-duo | Henan Province Rock and Mineral Testing Centre, Zhengzhou 450012, China | | | CAO Li-feng | Henan Province Rock and Mineral Testing Centre, Zhengzhou 450012, China | | | ZHANG Ming-wei | Henan Province Rock and Mineral Testing Centre, Zhengzhou 450012, China | | | ZHANG Fan | Henan Province Rock and Mineral Testing Centre, Zhengzhou 450012, China | | | HUANG Jie | Henan Province Rock and Mineral Testing Centre, Zhengzhou 450012, China | | | YAO Wen-sheng | Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geologcial Sciences, Langfang 065000, China
Key Laboratory of Geochemical Exploration, Ministry of National Resources, Langfang 065000, China | yaowensheng@igge.cn |
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| Abstract: |
BACKGROUND: The geochemical exploration for gold deposits is based on the accurate determination of gold. The content of gold in geochemical samples is usually at the level of ng/g, which needs to be preconcentrated before determination by inductively coupled plasma-mass spectrometry (ICP-MS) or graphite furnace absorption spectroscopy (GFAAS). At present, the exploration of buried deposits is the frontier of geochemical exploration technology and the extraction of gold mobile fraction is one of the most effective approaches to find concealed gold deposits. Compared with whole rock gold analysis, the gold mobile fraction content is much lower, which requires specific leaching, efficient preconcentration and accurate determination.
OBJECTIVES: To selectively extract gold mobile fraction and find surface secondary anomaly information for exploring concealed ore bodies.
METHODS: Experiments were carried out on the extraction agent and determination of gold mobile fraction by ICP-MS. Ammonium citrate was used to promote the disassociation of the adsorption of exchangeable form gold from the surface of clay minerals and secondary minerals in the soil. The complexation of thiourea and sodium thiosulfate was applied to diffuse the extracted gold into the solution to achieve the purpose of selective extraction. The procedure for gold preconcentration from extraction solution and the ICP-MS determination method were established.
RESULTS: The experiments determined that the extractant was composed of 5g/L ammonium citrate, 2g/L thiourea, and 5g/L sodium thiosulfate. The extraction time was 24h, and the active carbon was used to preconcentrate gold in the acidic thiourea medium. The gold adsorption rates were 89.6%-109.2%, and the ashing temperature of the concentration materials were 650-700℃. The detection limit of the method was 0.05ng/g, the relative standard deviations (RSDs) ranged from 9.4% to 10.2%, and the recoveries were from 91.2% to 93.4%.
CONCLUSIONS: Compared with the published method, extraction with ferric sulfate-thiourea-sodium thiosulfate solution and determination by GFAAS, this method has the advantages of low detection limit, wide linear range and fast analysis. This method has been successfully applied in the geochemical exploration of gold deposits in the forest swamp landscape area of Dongan, Heilongjiang Province. Gold anomaly delineated is consistent with the location of the concealed gold deposit. |
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