Distribution Characteristics of Total Mercury in Imported Coals at Shanghai Port
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摘要:
随着我国从煤炭净出口国向世界第一大煤炭进口国转变，进口煤炭中汞成为大气汞污染一个不可忽视的来源，研究进口煤炭中总汞含量的分布特征，对科学评估进口煤炭中汞的迁入性风险和保护环境安全具有重要意义。本文借鉴美国环境保护总署分析固体和液体（包括土壤、沉积物、沉淀物及废水或地下水等）中汞含量的方法（EPA 7473），运用直接测汞仪法测定了上海口岸123批进口印度尼西亚、加拿大、俄罗斯、澳大利亚煤炭的总汞含量。进口煤炭中总汞含量的稳健统计描述表明，上海口岸进口煤炭总汞含量中位值为0.043 mg/kg，标准化四分位距为0.025 mg/kg。依据我国煤炭行业标准MT/T 963—2005《煤中汞含量分级》，上海口岸进口煤炭主要为特低汞煤和低汞煤，其中印度尼西亚煤炭中存在高汞煤和中汞煤。进口煤炭汞含量与灰分含量、全硫含量的相关分析表明，印度尼西亚、俄罗斯煤炭总汞含量与灰分含量不相关，与全硫含量正相关，推断汞的赋存形态主要为硫化物结合态；进口加拿大煤炭总汞含量与灰分含量呈负相关，与全硫含量呈正相关，推断煤炭中存在一定的有机结合态汞；进口澳大利亚煤炭总汞含量与灰分含量呈正相关，与全硫含量呈负相关，推断煤炭中汞的赋存形态主要为铝硅酸盐结合态。本文建立的固体进样-直接测汞仪测定煤炭中总汞含量的方法，省去了消解样品前处理操作，较冷原子吸收光谱法、氢化物发生-原子荧光光谱法等传统分析方法大幅缩短了检验流程，提高了分析效率，值得推广应用；运用该方法可准确评价进口煤炭中汞的赋存形态特征，针对性提出高汞煤炭的处理方法和燃煤电厂汞排放量控制的有效途径。
Abstract:As China swings from being a net coal exporter into the world's largest coal importer, mercury in imported coals has become an increasingly significant source of atmospheric mercury pollution. The research of distribution characteristics of total mercury in imported coals could be a significant initiative for scientific assessment of the immigration risk of mercury in coal imports and protecting environment security. Based on the American Environmental Protection Agency method 7473, which is suitable for soil samples, sediments, sludge, wastewater and groundwater, total mercury concentrations in 123 imported coal samples at Shanghai Port were determined using a direct mercury analyzer. The robust statistical description of total mercury content in imported coals shows that the median of mercury concentrations in 123 imported coals is 0.043 mg/kg and the Norm IQR is 0.025 mg/kg. On the basis of Chinese coal industry standard MT/T 963—2005, the imported coals at Shanghai Port are mainly special low mercury coal and low mercury coal. It is worthy of attention that medium mercury coal and high mercury coal were found in Indonesian coals. The occurrence modes of mercury in coal affect its final emissions, which has a guiding significance on mercury removal technology. The correlation analysis of ash, sulfur and mercury content shows that the occurrence modes of mercury are mainly sulfide form in Indonesian coals and Russian coals based on the relationship between total mercury and sulfur content instead of ash content. According to the positive relationship between total mercury and sulfur content and the negative relationship between total mercury and ash content, the mercury was contained in organic matter in Canadian coals. According to the negative relationship between total mercury and sulfur content and the positive relationship between total mercury and ash content, the mercury was contained in aluminum silicate form in Australian coals. Compared to cold atomic absorption spectrometry, hydride generation atomic fluorescence spectrometry and other traditional analysis methods, the direct mercury analyzer method for determination of mercury in coal established in this paper shorten the inspection process, improve work efficiency, and is worthy of popularization and application. The research of distribution characteristics of total mercury in imported coals could provide reference for scientific assessment of the immigration risk of mercury in imported coals and comprehensive utilization of imported coals.
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Key words:
- imported coal /
- mercury /
- distribution characteristics /
- occurrence mode
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表 1 采集样品统计
Table 1. Statistics of the samples
进口国家 进口批次 进口国家 进口批次 印度尼西亚 51 澳大利亚 9 俄罗斯 46 南非 3 加拿大 13 新西兰 1 
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表 2 直接测汞仪工作条件
Table 2. Operating conditions of direct mercury analyzer
工作参数 设定条件 工作参数 设定条件 干燥温度 200℃ 等待时间 60 s 干燥时间 60 s 记录时间 30 s 分解温度 650℃ 汞齐化管加热时间 12 s 分解时间 90 s 氧气压力 0.4 MPa
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表 3 煤炭有证标准物质中总汞的分析结果
Table 3. Analytical results of total mercury concentrations in certified reference materials
标准物质编号 总汞含量(mg/kg) 测定值(n=6) 标准值 SARM19 0.210±0.005 0.21±0.02 SARM20 0.255±0.005 0.25(95%置信区间为0.18~0.27) 注：总汞含量的数据为“平均值±标准偏差”。
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表 4 不同国家进口煤炭的总汞含量比较
Table 4. Comparisons of total mercury concentrations in different national coals
进口国 样品数量(个) 总汞含量(mg/kg) 数据来源 含量范围 算术平均值 印度尼西亚 51 0.011~0.922 0.10 本次研究 俄罗斯 46 0.017~0.098 0.040 本次研究 加拿大 13 0.019~0.074 0.037 本次研究 澳大利亚 9 0.014~0.164 0.056 本次研究 印度尼西亚 8 0.022~0.19 0.10 Belkin等[21] 俄罗斯 - 0.02~0.9 - Mukherjee等[22] 加拿大 286 0.02~1.3 - Goodarzi等[23] 澳大利亚 - 0.01~0.14 0.06 Dale等[24] 美国 7649 0~10 0.17 Finkelman等[25] 中国 1413 0.003~10.5 0.195 任德贻等[9] 世界 - 0.02~1.0 0.10 Swaine等[26]
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表 5 上海口岸进口煤炭汞含量分级
Table 5. Classification for mercury concentrations in imported coals of Shanghai Port
进口煤炭汞含量分级 煤炭进口国 印度尼西亚 俄罗斯 加拿大 澳大利亚 评定的总批次 51 46 13 9 特低汞煤( < 0.150 mg/kg) 41 46 13 8 低汞煤(0.150~0.250 mg/kg) 7 0 0 1 中汞煤(0.251~0.400 mg/kg) 1 0 0 0 高汞煤( > 0.400 mg/kg) 2 0 0 0
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[20] GB/T 212—2008. 煤的工业分析方法[S].
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