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Number of results: 6
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Abstract

This study discusses results of experiments on hydrodynamic assessment of gas flow through backbone (skeletal) porous materials with an anisotropic structure. The research was conducted upon materials of diversified petrographic characteristics – cokes. The study was conducted for a variety of hydrodynamic conditions, using air. The basis for assessing hydrodynamics of gas flow through porous material was a gas stream that results from the pressure forcing such flow. The results of measurements indicate a clear impact of the type of material on the gas permeability, and additionally – as a result of their anisotropic internal structure – to a significant effect of the flow direction on the value of gas stream. In aspect of scale transfer problem, a method of mapping the flow geometry of skeletal materials has been developed and usefulness of numerical methods has been evaluated to determine pressure drop and velocity distribution of gas flow. The results indicate the compliance of the used calculation method with the result of experiments.
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Abstract

The paper presents the results of studies on the changes in the PAHs concentration during pre-filtration and ultrafiltration (UF) processes. In the study, biologically treated wastewater (after denitrification and nitrification processes), discharged from the biological treatment plant and used in coke plant, was used. A gas chromatography-mass spectrometry (GC-MS) was used in order to qualify and quantify the PAHs. Sixteen PAHs listed by EPA were determined. The wastewater samples were collected three fold and initially characterized for the concentration of nitrate nitrogen, ammonium nitrogen, COD, TOC and pH. In the first step, wastewater was filtrated on the sand bed. Total concentration of 16 PAHs in the treated wastewater before initial filtration was in the range of 44.8‒53.5 mg/L. During the process the decrease in the concentration of the most studied hydrocarbons was observed. Concentration of PAHs after initial filtration ranged from 21.9 to 38.3 μg/L. After the initial filtration process the wastewater flew to the ultrafiltration module and then was separated on the membrane (type ZW-10). The total concentration of 16 PAHs in the process of ultrafiltration was in the range of 8.9‒19.3 mg/L. The efficiency of removal of PAHs from coke wastewater in the process of ultrafiltration equaled 66.6%. Taking into account the initial filtration, the total degree of removal of PAHs reached 85%. The obtained results indicate the possibility of using the ultrafiltration process with the initial filtration as additional process in the coke wastewater treatment.
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Abstract

The S-7 borehole log from the Sumina area (USCB Poland) revealed the presence of three basaltic veins originating from a basalt dyke. Coal interlayers in the rocks surrounding the basaltic veins have been coked to form natural coke. Photometric measurements revealed that the optical properties of the studied natural coke samples are characteristic of semi-graphite (Rmax > 9%). The natural coke matrix of all of the analyzed samples has a biaxial negative optical character. Vitrinite in the examined natural coke samples is characterized by a lower optical anisotropy than that of the natural matrix and it has a biaxial positive optical character. Vitrinite in almost all samples taken at locations more distant from the intrusion has a biaxial positive optical character. A reversal of the changes of the true maximum vitrinite reflectance and bireflectance with changing distance from the second basaltic vein has been observed. The temperature regime that acted upon the dispersed organic matter located in the immediate vicinity of the intrusion, estimated on the basis of the selected experimental data, is suggested to be higher than 750 °C.
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Abstract

Steel and cast-iron products, due to their low price and beneficial properties, are the most widely used among metals; their consumption has become an indicator of the economic development of countries. The characteristics of iron raw materials, in relation to current metallurgical requirements, are presented in the present this article. The globalization of the trade and development of steelmaking technologies have caused significant changes in the quality of raw materials in the last half-century forcing improvements in processing technologies. In many countries, standard concentrates (at least 60% Fe) are almost twice as rich as those processed in the mid-20th century. Methods of quality assessment have been improved and quality standards tightened. The quality requirements for the most important raw materials ‒ iron ores and concentrates, steel scrap, major alloy metals, coking coal, and coke, as well as gas and other energy media ‒ are reviewed in the present paper. Particular attention is paid to the quality testing methodology. The quality of many raw materials is evaluated multi-parametrically: both chemical and physical characteristics are important. Lower-quality parameters in raw materials equate to significantly lower prices obtained by suppliers in the market. The markets for these raw materials are diversified and governed by separate sets of newly introduced rules. Price benchmarks (e.g. for standard Australian metallurgical coal) or indices (for iron concentrates) apply. Some raw materials are quoted within the framework of the commodity market system (certain alloying components and steel scrap). The abandonment of the long-established system of multi-annual contracts has led to wide fluctuations in prices, which have reached a scale similar to that of other metals.
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Abstract

Over the past two years, coking coal prices have been the most volatile among major bulk commodities. On the supply side, the most important factor determining the movement of coal prices were weather problems affecting the exports of coal from Australia (Queensland), where the production of the best quality coking coals is concentrated. On the demand side, an important factor is the growing role of China on the market, which, being the world’s largest producer and consumer of metallurgical coal, has also become its largest importer. The dominant, about 75% share of China in the global spot market has resulted in their level of activity influencing the periodic price decreases or increases in international trade and prices based on CFR China (along with Australian FOB prices) have become important indicators to monitor market trends and determine levels of negotiated benchmarks. The exceptional volatility on the market led to a change in the quarterly price fixing mechanism for hard-load hard coal contractors in mid–2017 to apply a formula that assumes the valuation of their quarterly volumes based on the average of the basket of spot price indices. This reflects the broader trend of the evolving market, with growing spot market activity. The article describes the current situation on the international coking coal market and presents short-term forecasts for hard coking hard coal prices (PHCC LV), which are a reference point for fixing prices of other types of metallurgical coal (hard standard, semi-soft, PCI).
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Abstract

Studies on the quality of bituminous coal are mainly focused on physico-chemical analysis, examining the ash content, sulphur content, volatile matter content, moisture content, and the Net Calorific Value of coal. Until now, the above mentioned parameters form the basis of the Polish Standard PN-82/87002, on the basis of which individual types of bituminous coal are determined. In addition, an elemental analysis, providing information about the content of primary elements in the organic matter of solids, i.e. coal, hydrogen, nitrogen, oxygen, and sulphur, is carried out for the selected samples. This issue has been studied by many authors, which undoubtedly provide invaluable knowledge due to the huge amount of data, but, as the authors themselves indicate, the knowledge of the petrography of coal, coking properties (Probierz et al. 2012) and finally the coke obtained from individual coal types (based on tests carried out using the Karbotest installation or the so-called „box tests” performed in the coke oven battery) is still very limited. The article discusses the impact of petrographic composition on the quality of metallurgical coke. The analysis was performed using samples of coking coal from the following mines: Pniówek, Zofiówka, Borynia, and Krupiński. The mentioned coal types are used to produce coke mixtures used for the production of coke in the Przyjaźń and Radlin coking plants. Based on the rank of coal and physicochemical parameters, the mentioned coal types were classified according to the Polish classification and the UN/ECE International Classification of In-Seam Coals (UN/ECE 1995). The prediction of thermomechanical properties of coke (CSR and CRI) performed according to the original CCP method were compared with the results obtained using the classical method of Nippon Steel Corporation.
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