The determination of the content of ecotoxic elements directly in flue gas is important for determining its actual emission from coal combustion. Moreover, in the BAT for large combustion plants conclusions adopted in 2017, apart from tightening of pollutants emission standards, i.e. SO 2, NO x and dusts, and setting emission limits, among others, for mercury, the monitoring of the actual emission of toxic elements has been established with the use of specific analytical methods. The review and comparison of available methods of analyzing the content of elements in flue gases in accordance with American and European standards has been presented in the article. Moreover, the factors influencing the quality of the obtained measurement results were identified.
Węgiel kamienny wydobywany w kopalni (węgiel surowy) tworzy substancja organiczna i mineralna. Przed bezpośrednim wykorzystaniem urobek musi być poddany procesom wzbogacania. Stosowane procesy wzbogacania mają na celu usunięcie skały płonnej, pirytu, a także przerostów. Do wzbogacania węgla kamiennego stosowane mogą być zarówno metody wzbogacania na mokro, jak i na sucho. W pracy przedstawiono wybrane ekologiczne i ekonomiczne aspekty procesu suchego odkamieniania węgla kamiennego przy wykorzystaniu separatora powietrzno-wibracyjnego i separatora optyczno-rentgenowskiego. Zastosowanie nowoczesnych urządzeń do suchego odkamieniania, tj. separatory powietrzno-wibracyjne i separatory optyczno-rentgenowskie, umożliwią obniżenie emisji pierwiastków ekotoksycznych ze spalania węgla kamiennego. Wydzielenie pirytu pozwala na obniżenie zawartości siarki, a także innych pierwiastków ekotoksycznych, m.in. rtęci, arsenu, talu, czy ołowiu. Generalnie pod względem ekonomicznym technologia suchego odkamieniania cechuje się niższymi nakładami inwestycyjnymi i kosztami eksploatacyjnymi w porównaniu do metod wzbogacania na mokro. Instalacje suchego odkamieniania są dobrym rozwiązaniem dla inwestycji o krótkim okresie planowanej eksploatacji i/lub dla instalacji o małej wydajności, a także w przypadku ograniczonej dostępności do wody. Dla instalacji o dłuższym okresie eksploatacji i o wyższych wydajnościach, efektywność inwestycji jest wyższa dla metod wzbogacania na mokro. Istnieje również możliwość suchego odkamieniania węgla na dole w kopalni przy użyciu tzw. kruszarek Bradforda. Wydzielony produkt w postaci grubych kamieni może znaleźć zagospodarowanie na dole kopalni, np. do podsadzania wyrobisk.
The analysis of leaching behavior of harmful substances, such as arsenic, is one of the parameters of risk assessment resulting from the storage or economic use of coal waste. The leachability depends both on the environmental conditions of the storage area as well as on the properties of the waste material itself. There are a number of leaching tests that allow to model specific conditions or measure the specific properties of the leaching process. The conducted research aimed at comparing two methods with different application assumptions. The study of arsenic leaching from waste from the hard coal enrichment process was carried out in accordance with the Polish PN-EN 12457 standard and the US TCLP procedure. The leaching results obtained with both methods did not exceed the limit values of this parameter, defined in the Polish law. Both methods were also characterized by the good repeatability of the results. The use of an acetic acid solution (TCLP method) resulted in three times higher arsenic leaching from the examined waste compared to the use of deionized water as a leaching fluid (method PN-EN 12457). Therefore, the use of organic acid tests for mining waste intended for storage with municipal waste should be considered, as the results of the basic test based on clean water leaching may be inadequate to the actual leaching of arsenic under such environmental conditions.
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.
The economic downturn in Europe and in the world, has affected the traditional branches of industry in a particular way. Development plans of domestic coke plants in terms of main production assets for the next years have been presented. Taking into account the current market situation, the coke plants strategy should aim at risk minimization through application of already known technologies. On the other hand, investments in scope of new and innovative technologies which are connected with a high level of variability, should be seen as an opportunity. Thus, evaluation of investment projects should be done in a different way than so far. The traditional discount analysis, because of its static nature, does not take into account variability and options included in projects with many decision moments - it can prove to be not sufficient. A tool which helps the decision makers in such situations, is the real options analysis. The article presents the findings of the research-development project on coal blend pre-drying implementation, realized by Zdzieszowice Coke Plant and ICHPW in Zabrze. The results achieved so far, as well as the concerns resulting from the project, have been discussed in this article. Further project development plans, aiming at the construction of a semi industrial research installation for analysing the impact of pre-drying on the coke making process have been presented. The article describes premises for the application of real options analysis as a tool to evaluate projects, the results of which are uncertain. The origin and structure of real options as well as the conditions of their application compared to traditional, discount based project evaluation methods, have been presented. The origin and characteristic parameters of real options have been discussed. In the next part, by applying the NPV and real options method, the research-development undertaking of coal blend pre-drying implementation on two coke batteries, has been evaluated. In order to assess the real option's value of the project, which is a classic European call option, the Black-Scholes formula has been used. The achieved results have been compared as well as the flexibility rate of the analyzed research-development project has been defined.