Studies on mercury occurrence in inorganic constituents of Polish coking coals

Dziok, Tadeusz; Strugała, A.; Włodek, Adam

doi:10.1007/s11356-018-1667-1

Cited by 17 publications

(12 citation statements)

References 29 publications

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“…In general, most of the mercury is found in pyrite and other sulphides. 9,37 Furthermore, there are significant differences in the amount of mercury in pyrite. Extremely high mercury contents are recorded in pyrite derived from hydrothermal solutions, that is, up to 4.7Á10 6 μg/kg.…”

Section: Resultsmentioning

confidence: 99%

“…For finer coal grain sizes, the calorific value of the rejects may exceed 6 MJ/kg. 8 In most coal conversion processes, mineral matter is considered as ballast that deteriorates quality of raw material and increases the amount of harmful components, such as sulfur, mercury 9,10 or other ecotoxic elements. 11 However, in the gasification process, the effect of mineral matter is not unambiguous, since some of its components catalyse the gasification reactions, thus positively affect the process rate.…”

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Experimental evaluation of the dry coal deshaling by pneumatic vibrating FGX separator on the CO₂ gasification process

Czerski

Grzywacz

Dziok

et al. 2020

Intl J of Energy Research

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The dry deshaling process using the FGX method is a modern technique of coal quality enhancing without the use of water. The positive effect of this operation is the increase of calorific value and the removal of contaminants such as sulphur, chlorine, mercury and other heavy metals along with the separated gangue. However, elements such as sodium, potassium or calcium, considered as catalysts in the gasification process, are also partially removed. Consequently, the global effect of the dry deshaling on coal reactivity, being a key parameter determining its suitability for the gasification, is hard to predict. This study aims to determine the impact of dry deshaling of coal by FGX separator on its reactivity. Using TG analysis, 10 samples of coals from Polish mines, before and after the dry deshaling at commercially working FGX separator, were gasified in CO 2 atmosphere under non-isothermal conditions. The effect of deshaling on the basic properties of coals, ash composition and the content of contaminants such as sulphur and mercury, was also determined. The results showed slightly lower reactivity of clean coals. The values of kinetic parameters of gasification reaction were similar, or an increase in the activation energy value was compensated by the higher value of the pre-exponential factor. The basic properties of coals and the content of sulphur and mercury have changed after the deshaling process, and the magnitude of these changes differed significantly among the samples analysed. The changes in the ash composition were insignificant. These results suggest that FGX technology may be an attractive way of coal preparing for the gasification, resulting in a reduction of byproducts and contaminants without adverse effect on coals reactivity. K E Y W O R D S CO 2 gasification, coal, dry deshaling, non-isothermal TGA, upgrading of coal 1 | INTRODUCTION So as to allow efficient and ecological conversion of this fossil fuel, coal can be gasified. 1 Before thermochemical use, however, coal is directed to processing processes aimed at reducing ash content and increasing heating value, this being the first stage of applying Clean Coal Technologies. One such method of coal preparation is the

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Experimental evaluation of the dry coal deshaling by pneumatic vibrating FGX separator on the CO₂ gasification process

Czerski

Grzywacz

Dziok

et al. 2020

Intl J of Energy Research

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“…The content of ecotoxic elements in the bituminous coals is greatly varied and depends on individual properties of each coal, which are determined primarily by coal bed formation conditions. The significant role of the epigenetic and syngenetic processes should be emphasised [11]. The comparison of mercury, arsenic and lead contents in Polish coking coals and foreign coals is given in table 1.…”

Section: Resultsmentioning

confidence: 99%

Contents of Ecotoxic Elements in Polish Coking Bituminous Coals and in Products of Coking

et al. 2019

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Ecotoxic elements include the ones which have a negative impact on human health and the environment, among others, mercury, arsenic and lead. Hard coal is a fuel which contains significant amounts of ecotoxic elements and the processes of coal combustion, coking and gasification are one of the main sources of their anthropogenic emission. In the coking process, individual ecotoxic elements in various proportions remain in coke and are released to the raw coke oven gas. During the cleaning and cooling of coke gas, ecotoxic elements are distributed between purified coke gas and other coking byproducts. In the paper, the measurement results of the contents of selected ecotoxic elements in the Polish coking bituminous coals are presented, i.e. mercury, arsenic and lead. The examination results of their content in the products of the coking process i.e. coke, coal tar, BTX, sulfur, and purified coke oven gas are also shown. Coke is characterized by a much lower content of mercury and lead than coal, and by a similar content of arsenic. Among the coking products, sulfur and tar are characterized by the highest content of mercury. Coal tar also contains a high amount of lead.

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“…For that purpose, the results of an instrumental investigation could be used, i.e. the ones obtained with the usage of the electron probe micro-analyzer -EPMA (Dziok 2016;Dziok et al 2017), or, at least, a statistical analysis of the relationship between the contents of mercury and various forms of sulfur and ash could be performed (Dziok et al 2015a).…”

Section: Discussionmentioning

confidence: 99%

Preliminary assessment of the possibility of mercury removal from hard coal with the use of air concentrating tables

Dziok¹,

Strugała²

2017

Gospodarka Surowcami Mineralnymi

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Mercury is characterized by highly toxic properties. The natural biogeochemical cycle of mercury occurs in the environment, which results in the fact that even a small amount of mercury emitted to the environment is a potential threat to human health. The process of coal combustion is one of the main sources of anthropogenic mercury emissions. For this reason, on 31 July 2017 the European Commission has adopted the mercury emission standards for large combustion plants. The issue of mercury emissions is particularly important for Poland. Forecasts concerning energy consumption in Poland show that coal will be the main source for energy production in the coming decades. Therefore, actions enabling the reduction of mercury emissions from coal-fired power plants will have to be implemented. The mercury emissions from coal-fired power plants may be reduced through the application of a number of methods. These methods can be divided into two main groups: the post-combustion methods which allow for mercury removal from flue gases, and the pre-combustion methods which allow for mercury removal from coal before its combustion. The effectiveness of mercury removal from coal is determined by the mode of its occurrence in coal. In the case of mercury occurrence in the adventitious inorganic constituents of coal, high effectiveness will be obtained in the coal cleaning processes. In the case of mercury occurrence in the organic matter as well as in the inherent inorganic constituents of coal, the effectiveness of this method will be low. Mercury could be removed from such coals through the process of thermal pretreatment at the temperature of 200-400°C (mild pyrolysis). In the paper, the possibility of mercury removal from hard coal through the process of dry deshaling on an air concentrating table was examined. Six raw coals (coal feed), clean coals and the rejects derived from their dry deshaling were analyzed. The mercury content was measured in the examined samples. The content of mercury in raw coals and clean coals were compared. Additionally, the effectiveness of mercury removal from coal with rejects was determined. For the analyzed coals, the effectiveness of mercury removal from coal in the process of dry deshaling on an air concentrating table ranged from 9 to 96%. This effectiveness is similar to the effectiveness of mercury removal from coal in the processes of coal washing. It should be mentioned that, when compared to the coal washing processes, the dry deshaling process is characterized by lower investment and operating costs. Therefore, the dry deshaling process on an air concentrating table should be considered as a competitive method for the coal washing processes. There is also a possibility of an increase in the mercury removal efficiency from coal in the process of dry deshaling as a result of the thermal pretreatment of clean coal derived from dry deshaling. This solution is only recommended for coals in which mercury occurs in the organic matter as well as in the inorganic constituents characterized by a relatively low temperature of mercury release.It should be emphasized that the dry deshaling process allowed for a decrease of mercury content is not suitable for every coal. Although for five of the analyzed coals the mercury content in clean coal was lower in the range from 11 to 53%, for one coal the mercury content was higher by 19%. The effect of decreasing the mercury content in coal is more evident when it is related to the amount of energy contained in coal (i.e. for example to the lower heating value). For five of the analyzed coals mercury content expressed in such a way decreased in the range from 11 to 53 %, and for one coal the mercury content was, however, higher. Nevertheless, the difference was not very significant (ca. 5%).

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Studies on mercury occurrence in inorganic constituents of Polish coking coals

Cited by 17 publications

References 29 publications

Experimental evaluation of the dry coal deshaling by pneumatic vibrating FGX separator on the CO₂ gasification process

Experimental evaluation of the dry coal deshaling by pneumatic vibrating FGX separator on the CO₂ gasification process

Contents of Ecotoxic Elements in Polish Coking Bituminous Coals and in Products of Coking

Preliminary assessment of the possibility of mercury removal from hard coal with the use of air concentrating tables

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Studies on mercury occurrence in inorganic constituents of Polish coking coals

Cited by 17 publications

References 29 publications

Experimental evaluation of the dry coal deshaling by pneumatic vibrating FGX separator on the CO2 gasification process

Experimental evaluation of the dry coal deshaling by pneumatic vibrating FGX separator on the CO2 gasification process

Contents of Ecotoxic Elements in Polish Coking Bituminous Coals and in Products of Coking

Preliminary assessment of the possibility of mercury removal from hard coal with the use of air concentrating tables

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Product

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Experimental evaluation of the dry coal deshaling by pneumatic vibrating FGX separator on the CO₂ gasification process

Experimental evaluation of the dry coal deshaling by pneumatic vibrating FGX separator on the CO₂ gasification process