科研之友
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摘要
Mercury is commonly found in hard coals and lignite. It is believed, that mercury occurs in coal both in mineral matter, mainly in pyrite, and also in organic matter, in thiols groups. Nevertheless, there are coals in which mercury occurs in large amounts in silicates and carbonates. Therefore, it could be supposed, that mercury should be correlated with mineral matter and ash content. In literature contradictory information can be found. There are coals, in which mercury content grows, with an increase in ash content. However, examples can also be found where that kind of correlation was not noticed. The aim of this study was to explain the relationship between the occurrence of mercury and sulfur in the mineral matter of Polish hard coals. For this purpose, waste products from the hard coal processing plants were examined. These wastes are characterized by a low organic matter content. The explanation of the mode of occurrence of mercury in mineral matter could be useful for optimizing the method of mercury content reduction in coal and also for optimizing waste products utilization techniques. Mercury content in the examined waste products ranged from 55 to 249 mu g/kg (dry basis). For 11 of the 16 examined samples of waste, the mercury content was higher than in the raw coal. For other cases, the content of mercury was slightly lower. An analysis of various enrichment operations does not allow formulation of general conclusions about the occurrence of mercury in the waste products. Among the examined waste products from any of the analyzed enrichment operations, both low and high mercury content samples were found. However, it was noticed, that the mercury content in waste products for the various mines can vary quite significantly. For example, for one of the analyzed mines, all the samples were characterized by a low mercury content, while for another one by a high mercury content. This should be explained by the different natures of the raw coals derived from these mines. A statistical analysis showed that mercury in the examined waste products was correlated with pyritic, total and sulfate sulfur. The highest determination coefficient was obtained for pyritic sulfur. In view of the results, it can be concluded that the occurrence of mercury and pyrite in coal mineral matter are interrelated. Significant correlations between mercury and mineral matter content as well as between mercury and ash content were not noticed. It could be explained by the fact that in coal mineral matter mercury is bound not only with pyrite, but also with other components, whose presence in mineral matter may be varied. Moreover, it was found that in the waste products containing much more mercury than raw coal (more than 40 mu g/kg), also a high pyritic sulfur content was observed (more than 0.30%). For these hard coals, an effective reduction of the mercury content by coal processing should be expected.
- 出版日期2015-3
