摘要
金的地球化学勘查基于金的准确测定,地球化学样品中金含量通常处于ng/g水平,需先进行分离富集,再采用电感耦合等离子体质谱法(ICP-MS)或石墨炉原子吸收光谱法(GFAAS)进行测定。当前,隐伏矿床勘查是地球化学探测技术的发展前沿,金活动态提取技术是寻找隐伏金矿的有效手段之一。相比于全量分析,金的活动态含量更低,需要解决选择性提取、高效预富集与准确测定等一系列难题。本文采用柠檬酸铵与土壤中黏土矿物及次生矿物作用促使吸附和可交换组分的金进入提取液,以硫脲和硫代硫酸钠络合金使活动态金向提取液中扩散,达到选择性提取的目的,建立了提取液中金的预富集及ICP-MS测定方法。实验确定的分析条件为:采用5g/L柠檬酸铵-2g/L硫脲-5g/L硫代硫酸钠为提取剂,提取时间24h,在酸性硫脲介质下用活性炭富集金,金吸附率可达89.6%~109.2%,灰化解吸温度为650~700℃。本方法检出限为0.05ng/g,相对标准偏差(RSD)为9.4%~10.2%,加标回收率为91.2%~93.4%。与已报道的硫酸铁-硫脲-硫代硫酸钠溶液提取再GFAAS测定的方法相比,本方法具有检出限低、测试线性范围宽、测试速度快的优势;应用于森林覆盖区黑龙江东安金矿区地球化学探测试验,金活动态异常与隐伏金矿位置一致。
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.
作者
王冀艳
胡家祯
丁汉铎
曹立峰
张明炜
张帆
黄杰
姚文生
WANG Ji-yan;HU Jia-zhen;DING Han-duo;CAO Li-feng;ZHANG Ming-wei;ZHANG Fan;HUANG Jie;YAO Wen-sheng(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;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)
出处
《岩矿测试》
CAS
CSCD
北大核心
2020年第4期525-534,共10页
Rock and Mineral Analysis
基金
国家重点研发计划项目(2016YFC0600603)。
关键词
隐伏金矿
金
活动态提取
硫脲
活性炭吸附
电感耦合等离子体质谱法
concealed gold deposit
gold
mobile fraction leaching
thiourea
activated carbon adsorption
inductively coupled plasma-mass spectrometry
