煤中金的研究现状及其展望

煤中金因其可异常聚集而日益受到重视,其潜在的经济价值又为该贵金属来源提供了新的途径.详细分析了前人对煤中金研究的相关文献,就煤中金的丰度、分布、成因及其工业前景进行了较全面的阐述,并重点讨论了煤中金异常聚集的地质机制,认为存在河流或大气降尘带入泥炭沼泽、同沉积过程中有机物质吸附富集和后生成因等3种主要的富集机制,且当煤被灰化后灰分中金会进一步富集,其富集度可以高出原煤的几倍,甚至几十倍,达到工业利用价值.深入揭示金在煤炭加工利用过程中的迁移、聚集的机制,发展煤中金的提取技术是很有必要的、前瞻性的工作,也是进行煤中伴生金地质经济评价的基础.

The Present Status and Future Trend of Research of Gold in Coal

Sources of gold continue to attract great attention because of the value of the metal. Concentration of gold in various geological environment occurs mainly in quartz and quartz-carbonate veins, sulphide-bearing shear zones, carbonate-rich aureoles, hydrothermal systems, carbon-rich sediments, banded iron formations and cherts, alluvial and fanglomerate placers, etc. The anomalous concentration of gold has been discovered in coal, which attracts increasing attention. The potential economic significance of enriched gold in coal suggests another way to obtain gold in industry. Based on detailed analysis of related references about gold in coal, the paper introduces the content, distribution, accumulation cuases and industrial prospect of gold in coal, and specifically discusses the geologic mechanisms of enriched gold in coal. After the studies of gold in coal in the world, it is found that gold has a lower abundance in most coals throughout the world. However, anomalous gold content was found in some coals. Three main mechanisms were proved in the gold accumulation: the gold can be supplied into the peat bog by the fragmental material as suspensions and atmospheric dust falls; the anomalous gold concentrations in coals make it possible to suggest a biogenic-sorptive mechanism of Au concentration; and partly due to the capillary uptake of the ground water and extraction of nutritive matters by plant root system from the underlying soils, it is possible to conclude that ground water is the main source of gold. Plants extract the ionic gold from the underlying water horizons. After the burning of coal residuum, the gold will be secondary enrichment several times more or even tens of times more in the crude coal, and will reach gold production level. Finally, some areas for further research are suggested. The mechanisms of Au migration and concentration will be studied durning the coal processing and utilization. It is necessary and forward-looking work to develop the technology of extracting gold from coal, which is also a basis for geologic and economic evaluation of associated gold in coal. Because gold is a trace element in coal, the determining methods are very importance, which will directly influence the result. The author suggests two determining methods, one being the neutron activation analysis, the other being plasma mass spectrometer. The author also points out that the energy spectrum scanning electronic microscope is playing important role in studying the Au occurring shape in coal.