This paper presents the results of the investigation associated with the determination of mercury content in Polish hard coal and lignite samples. Those coals are major fuels used for electricity generation in Poland. The results indicated that the average content of mercury in the coal samples was roughly about 100 ng/g. Apart from the determination of the mercury contents a detailed ultimate and proximate analysis of the coal samples was also carried out. The relationships between the mercury content and ash, as well as fixed carbon, volatile matter, sulfur, and high heating value of the coal samples were also established. Furthermore, the effect of coal enrichment was also investigated, and it was found that the enrichment process enabled the removal of up to 75% of the coal mercury from the samples.

Nowadays, actions allowing for a reduction of anthropogenic mercury emission are taken worldwide. Great emphasis is placed on reducing mercury emission from the processes of energochemical coal conversion, mainly from the coal combustion processes. One of the methods which enable a reduction of anthropogenic mercury emission is the removal of mercury from coal before its conversion. It should be pointed out that mercury in hard coal may occur both in the organic and mineral matter. Therefore, a universal method should allow for the removal of mercury, combined in both ways, from coal. In the paper, a concept of the hybrid mercury removal process from hard coal was presented. The idea of the process is based on the combination of the coal cleaning process using wet or dry methods (first stage) and the thermal pretreatment process at a temperature in the range from 200 to 400 °C (second stage). In the first stage, a part of mercury occurring in the mineral matter is removed. In the second stage, a part of mercury occurring in the organic matter as well as in some inorganic constituents characterized by a relatively low temperature of mercury release is removed. Based on the results of the preliminary research, the effectiveness of the decrease in mercury content in coal in the hybrid process was estimated in the range from 36 to 75% with the average at the level of 58%. The effect of the decrease in mercury content in coal is much more significant when mercury content is referred to a low heating value of coal. So determined, the effectiveness was estimated in the range from 36 to 75% with the average at the level of 58%.

Work is being carried out on possibilities of limiting the content of mercury in hard coal products by gravity concentration of run-of-mine coal in the Branch of the Institute of Mechanized Construction and Rock Mining in Katowice and on the Faculty of Energy and Fuels of the AGH University of Science and Technology in Krakow. Under domestic industrial conditions, gravity concentration is carried out with heavy medium liquids and in jigs. Preliminary - pilot studies have shown the possibility of mercury removal also by using the dry deshaling method involving vibratory air separators. Mercury is mainly found in the pyrite and the rubble formed by the mineral carbon, but also in the organic carbon. Some of it is located in layers of coal roof fields, which in the course of their exploitation go to coal. The mercury removal efficiency during the gravity concentration process will depend on the decomposition of the listed components in the density fractions. The paper presents the results of investigations of total mercury and total sulphur content in the separated coal fractions from four mines. These contents were determined in fractions: –1.5 g/cm3 (conventionally clean coal – concentrate), 1.5–1.8 g/cm3 (conventionally middlings) and +1.8 g/cm3 (conventionally rock – waste). The results are summarized in Tables 3–5 and in Charts 1–4. Conversely, graphs 5-8 show the relationship between mercury content and total sulphur content in the tested coal samples. The study, which can be called a preliminary analysis of the susceptibility of the coals to gravity concentration, showed that the dry deshaling method on the vibratory air separators would allow significant amounts of mercury accumulated in the middlings and waste fractions to be removed.

Mercury emissions have become one of the problems in the energy sector in recent years. The currently used mercury removal techniques include: primary, secondary and preliminary methods. However, due to the large variation in the mercury content in hard and brown coal and the different characteristics of power plants, these methods are often not effective enough to meet the new requirements set by BREF/BAT which requires a search for new, high-efficiency solutions. The proposal for a new technology has been developed in the project “Hybrid Adsorption Systems to Reduce Mercury Emissions Using Highly Effective Polymer Components” (HYBREM). The project was implemented by the consortium of SBB Energy SA and ZEPAK Pątnów II Power Plant. An innovative, high-efficiency hybrid technology for purifying exhaust gases from mercury was developed. GORE polymer modules were used as a technology base where, in combination with the injection of solid sorbents, a hybrid technology was developed. To assess the economic efficiency of the similar case as in the HYBREM project model based on OPEX and CAPEX, each method was selected separately. The article focused on the substitution of solid sorbents used in the HYBREM project by zeolite based materials. Modified zeolite X, applied in the project, was derived from fly ash. Preliminary analysis shows that the system of proposed technologies is very cost-competitive compared only to GORE technology. The basic factors are the possibility of recovering zeolites from ash, combined with low investment outlays.