Determination of Au in High Grade Gold Deposits by Flame Atomic Absorption Spectrometry
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摘要: 采用经典火试金法测定高品位金，操作流程长，影响因素多，在铅扣灰吹过程中易挥发逸出大量的铅，对实验环境造成严重污染。本文将20.0~100.0 g取样量先分成若干小样量进行焙烧，经50%王水完全分解后分离滤渣，所得若干份滤液定容于同一容量瓶内，分取适量体积进行泡沫塑料富集，将富集金的泡沫塑料灰化后用浓王水复溶，以火焰原子吸收光谱法(FAAS)测定高品位金矿石中金的含量。方法检出限为0.101 μg/g，通过多个国家一级标准物质和分析样品验证，准确度和精密度满足相关要求。此方法测定灵敏度高，取样量为20.0~100.0 g，有效地提高FAAS法取样代表性，同时拓展了FAAS法测定矿石中金的含量范围，针对50.0~550.0 μg/g中高含量段的金结果同样可靠。Abstract: The conventional fire assay method to determine high grade gold has a long chemical procedure with many factors influencing the analysis result. Moreover, the ash blowing process for the Pb button volatilizes a large amount of Pb, causing serious pollution to the environment. In this paper, a method is described whereby the 20.0-100.0 g sample was split into small amounts and calcinated. The products of calcination were dissolved by 50% aqua regia and the residues were filtered. All the clean filtrates were loaded into a volumetric flask. An appropriate volume of solution was selected to extract Au with foam enrichment. After ashing the Au bearing foams, the Au was dissolved again by concentrated aqua regia. Then, the Au was measured by Flame Atomic Absorption Spectrometry (FAAS). The detection limit was 0.101 μg/g. Through verifications for a few national first grade standard materials and the analysis samples, the accuracy and precision met the relevant requirements. The sampling weight was from 20.0 g to 100.0 g which effectively improved the sample representativeness and extended the analysis content range for Au by FAAS. This method is also suitable for samples with Au contents from 50.0 μg/g to 550.0 μg/g.
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Key words:
- high grade of gold deposit /
- Au /
- Flame Atomic Absorption Spectrometry
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表 1 仪器工作参数
Table 1. Working parameters of instrument
工作参数 设定值 波长 242.8 nm 灯电流 5 mA 狭逢宽度 0.4 nm 燃烧器高度 6 mm 燃气流量 45 L/h 积分方式 Repeated mean 积分时间 3 s 延迟时间 10 s 
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表 2 准确度试验
Table 2. Accuracy tests of the method
标准物质
编号w(Au)/(μg·g-1) 相对误差
RE/%标准值(不确定度) 测量值 GBW 07298 32.3(1.4) 32.6 0.93 GBW 07810 92.0(2.0) 92.5 0.54 GBW 07299 53.0(2.4) 52.8 0.38 GBW 07801 57.2(0.9) 57.8 1.05 GBW 07802 37.3(0.9) 37.0 0.80
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表 3 精密度试验
Table 3. Precision tests of the method
样品编号 w(Au)/(μg·g-1) RSD/% 分次测定值 测定平均值 GBW 07810 93.5 92.3 92.7 91.8 92.4 0.73 92.8 91.3 92.8 91.5 92.5 92.3 93.1 Au-1 556 531 550 547 547 1.72 557 550 538 545 537 540 561
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表 4 分析方法对比试验
Table 4. Comparison of analytical results of Au in sample with different methods
测定方法 w(Au)/(μg·g-1) RSD/% 分次测定值 平均值 标准
偏差本法 550 550 540 538 556 547 7.56 1.38 武警黄金地质研究所
测试中心(氰醌容量法)565 561 559 569 552 561 6.42 1.14 沈阳地质矿产研究所
测试中心(氰醌容量法)544 546 544 537 540 542 542 3.25 0.01 北京矿冶研究总院
(火试金重量法)544 543 546 552 549 547 3.70 0.68 国家黄金管理局黄金
测试中心(火试金重量法)555 557 557 554 556 556 1.30 0.23
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