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The contribution describes some aspects about possible revitalisation of iron ores mining with attention to attainable quality of Fe-concentrate as exemplified by analysing and upgrading of siderite from the Nižná Slaná deposit. These considerations were caused by new trends of EU authorities in Mineral Policy. Generally, iron ore mining and processing have a long-lasting tradition in Slovakia. The Slovak Ore Mts. belongs to the main source of iron spathic ores with several deposits. Lastly exploited deposit Nižná Slaná was closed in 2008 due to unfavourable running costs, above all gas used in ore roasting and concentrate pelletizing. Detailed study and analysis of ore and its upgrading process showed that final quality of Fe-concentrate is limited by siderite composition and occurrence of accompanying mineral such as ankerite. [ABSTRACT FROM AUTHOR]

The contribution deals with the dry low-intensity high-gradient magnetic separation of caustic magnesia prepared from raw magnesite coming from the Mútnik deposit (Eastern Slovakia). Namely, the grain size classes of 0-0.5 mm and 0.5-1.0 mm have been upgraded using universal laboratory magnetic separator JONES at the magnetic field induction of 0.1T, 0.2T and 0.3T. Thus, selected samples of magnetic and nonmagnetic products were subjected to XRD study. As to a grain size of 0.5-1.0 mm the magnetic products at the mass yields of 69-79 % containing 84.79-86.56 % MgO, 5.79-5.95 % Fe2O3, 3.10-3.60 % SiO2, 1.94-2.74 % CaO and 0.56-0.57 % Al2O3 were won from the feed with 74.53-75.80 % MgO, 5.13- 5.41 Fe2O3, 6.25-6.74% SiO2, 6.57-7.35% CaO and 0.94-0.97 Al2O3. The recoveries of observed components into magnetic products were as follows: MgO 80.14-89.14 %, Fe2O3 77.93-86.85 %, SiO2 31.76-44.32 %, CaO 18.22-30.47 % and Al2O3 40.75- 46.80 %. Subsequently, at the separation of 0-0.5 mm class the magnetic products at the mass yields of 85.39-89.64 % with 81.29-83.23 % MgO, 5.09-5.24 % Fe2O3, 4.10-4.39 % SiO2, 2.57-2.92 % CaO, and 0.83-0.93 % Al2O3 were prepared from the feed with 77.17-79.09 % MgO, 4.90-5.07 % Fe2O3, 5.35-5.84 % SiO2, 4.42-4.76 % CaO and 1.03-1.06 % Al2O3. The recoveries into magnetic product attained the following values: MgO 91.32-93.66 %, Fe2O3 89.52-92.61 %, SiO2 59.93-73.56 %, CaO 46.15-58.79 % and Al2O3 67.09-80.59 %. The results of XRD study can be summarized as follows. Periclase as a dominant mineral accompanied by talc, magnesioferrite and magnesiowüstite was identified in magnetic product. On the other hand talc and periclase as dominant minerals accompanied by sericite and quartz were determined in non-magnetic product. An occurrence of chlorite and magnesite in this product is questionable. [ABSTRACT FROM AUTHOR]

The paper presents the explanation of the effect of activation grinding in the attrition mill in order to achieve favorable technological results of decreasing the alkaline leaching agent amount. The effect of mechanochemical leaching of brown coal using GACL (Grinding Aqueous Caustic Leaching) has been assessed on the basis of free and total humic acid distribution in the liquid and treated solid coal product. In order to improve the filtration parameters of fine-dispersed brown coal, the effect of concentration of alkaline agent was studied within the range of 1 - 0.05 % in weight. The effect of leaching agent concentration within the range under study is inessential, even in mild alkaline leaching conditions using 0.05 % NaOH it is possible to achieve a 3.46-fold increase in the content of humic acids. Unlike the mechanochemical leaching of brown coal in solutions of higher concentration, the solid coal product treated by this procedure contains more humic acids than the liquid semi-product. [ABSTRACT FROM AUTHOR]

The paper deals with the study on pyrite liberation from talc raw material. The material comes from deposit nearby Gemerska Poloma village (Eastern Slovakia). A lumpy material was subjected to crushing, grain size and float-sink analyses. Heavy and light products were also assayed. XRD study of selected products of float-sink analysis was carried out. Thus, it was found that iron and sulphur concentrate in a grain size classes of 0.5-3mm, above all in 1-2mm. The highest mass yield of heavy product was attained in a class of 1-2mm, namely 15%. This product contains 44.62% S and 37.06% Fe. Talc was identified in light products. Pyrite as a dominant mineral was detected in heavy products. It is accompanied magnesite, dolomite and talc. [ABSTRACT FROM AUTHOR]

This paper presents a new approach to evaluation of coal with implementation microwave extraction. It is know from literature that coal is a chemically and physically extremely complex and heterogeneous material, consisting of organic (carbon) and inorganic (minerals) constituents. Our attention was intent on the study of influence of Soxhlet and microwave-assisted extraction in the open-vessel and closed-vessel system, respectively. The microwave extraction (MAE) was realised in microwave furnace with using different solvent (methanol, toluene, dichloromethane). The presence of organic compounds with carbon numbers C15, C20 and C19 was confirmed in coal extract after the Soxhlet extraction in dichloromethane for 72 hours. All analyzed compounds belong to group of polycyclic aromatic hydrocarbons. During microwave-assisted extraction in the open-vessel system the extraction time was shorten to 30 minutes at power 500 W and frequency 2.45 GHz. The following organic compounds were identified by GC-MS method: naphthalene and its derivates with the carbon numbers 14 and 15 (m/z = 184, 198), phenanthrene derivates with the carbon number 20 (m/z = 274, 276). The microwave-assisted extraction in closed-vessel system was realized by pressure 1.8 - 2 bar for 20 minutes. The growing of other organic compounds was confirmed. The solvent temperature has the essential influence on number of extracted substances. The temperature is higher by microwave heating in comparison with Soxhlet extraction. Microwave-induced heating is mostly used for extraction and pyrolysis in biomass and waste treatment. Analytical significant concentrations of PAHs (naphthalene, acenaphthene, phenanthrene, fluoranthene, pyrene, chrysene) in the sample of biomass were confirmed with HPLC-FLD method in the experiments of microwave-assisted extraction of biomass. [ABSTRACT FROM AUTHOR]