Technology GRAVIMELT and possibilities of their application in preparation of Slovak brown coal

The results of alkaline treatment tests on Slovak brown coal (from Nováky, Handlová and Cíge¾ localities) using the MCL procedure (Gravimelt) are presented in this paper. On the basis of conclusions of an optimal variant of the technology, the samples were pre-treated and submitted to a subsequent test at the NAOH/coal ratio = 1.0. The recovery of chemically treated coal, effectiveness of desulphurization and ash removal were assessed. This treatment procedure is less suitable for Slovak brown coal

The geology, petrography and mineralogy composition of coal from the Nováky deposit

Na území regiónu Vtáènik - Horná Nitra sa vyskytujú významné zdroje energetických surovín na Slovensku. Patrí k nim aj loisko Nováky. Hlbie podloie je reprezentované horninami veporika a to vápencami, slieòmi a dolomitmi kriòanského príkrovu, ktoré sú prekryté hronikom, reprezentovaným maluickým súvrstvím (perm-trias) melafýrových hornín. Najstaria èas neogénnej výplne panvy je reprezen-tovaná èausianskym súvrstvím (egenburg), prièom naò diskordantne nasadá kamenské súvrstvie (báden), reprezentované pestrým súborom hornín, tvorených redeponovanými produktami vulkanizmu vo forme konglomerátov, ktoré tvorí priame podloie produktívneho nováckeho súvrstvia. V nadloí nováckeho súvrstvia sú vyvinuté "nadloné íly" koianskeho súvrstvia. Na denudovaný reliéf územia boli uloené sedi-menty lehotského súvrstvia.Vzorky lignitu z loiska Nováky sú budované prevane xylitickým detritom, s hrubími xylitickými vlokami. V macerálovej skupine huminitu má pomerne výrazné zastúpenie denzinit, ulminit B (svetlá varieta), korpohuminit, gelinit a textinit A (tmavá varieta). Macerálová skupina liptinitu je zastúpená suberinitom, rezinitom, sporinitom, kutinitom, liptodetrinitom, bituminitom a identifikovaný bol aj fluorinit. Minerálna prímes je tvorená najmä ílovým materiálom a pyritom. Auripigment a realgár vytvára jemné nálety na vrstevných plochách a tieto minerály vystupujú v spojitosti s rôznymi modifikáciami kremeòa a podie¾ajú na vysokom obsahu As v nováckom uhlí. Okrem týchto minerá-lov sa v uhlí nachadzájú aj sekundárne sírany (sádrovec, anhydrid, melanterit)

The geology and petrography composition of coal from Handlová deposit

In some countries, including the Slovak Republic caustobioliths have been and for the foreseeable future will continue to be the most important source of energy.During the geological development of the territory of Slovak Republic, suitable conditions for the formation of coal-bearing formations were created. Within the stratigraphical span, it presents the period from the Carboniferous to the Pliocene. The West Carpathians as a part of the Alpine mobile zone are characterised by a complex tectonic development with an intensive manifestation within a relatively small space. Frequent vertical motions of the Earth`s crust precluded the formation of a more extensive flat and shallow basin enabling a greater concentration of plant detritus, and hence the formation of greater, extensive accumulation spaces with the coal-bearing sedimentation.Handlová coal deposit represents one of the most important accumulation of caustobioliths in the Slovak Republic. The deposit is situated in the Prievidza district.In the geological structure of the region are incorporated crystalline, Late Paleozoic, Mesozoic, Paleogene, Neogene sedimentary and volcanic rocks and Quaternary deposits.The sample examined were lignitic humites with variable xylite, detrite and mineral contents. Huminite reflectance (R0=0,33%) corresponding to the lignitic orthotype. Huminite concentration (86,6%) is the most abundant maceral group. The maceral ulminite, textinite and densinite contributes to the high huminite content. The concentration of attrinite and gelinite is substantially lower, i. e. 2,4 %. Corpohuminite contents does not exceed 3,2 %.Liptinite is formed by waxy and resinous substances. The maceral composition of liptinite was determined by a fluorescence measurement. The remaining liptinite macerals, i.e. cutinite, sporinite, resinite, suberinite, and fluorinite are accessory.The content of inertinite (sklerotinite) is low (0,7%).The mineral admixture of the coal seams in Handlová basin is mainly formed by clayey and tuffogenic material, also by pyrite, marcasite, realgar, orpiment, various modifications of qartz and gypsum.Coal mined in the Handlová mine is used for the power industry. The aim of our work was to evaluate the geology and petrography composition of Handlová mine

Utilisation of chemically treated coal

The numerous application of coal with high content of humic substances are known. They are used in many branches of industry. The complex study of the composition of coal from upper Nitra mines has directed research to its application in the field of ecology and agriculture. The effective sorption layers of this coal and their humic acids can to trap a broad spectrum of toxic harmful substances present in industrial wastes, particularly heavy metals. A major source of humic acids is coal - the most abundant and predominant product of plant residue coalification. All ranks of coal containt humic acids but lignite from Nováky deposit represents the most easily available and concentrated form of humic acids. Deep oxidation of coal by HNO3 oxidation - degradation has been performed to produce water-soluble-organic acids. The possibilities of utilisation of oxidised coal and humic acids to remove heavy metals from waste waters was studied. The residual concentrations of the investigated metals in the aqueous phase were determined by AAs. From the results follows that the samples of oxidised coal and theirs humic acids can be used for the heavy metal removal from metal solutions and the real acid mine water.Oxidised coal with a high content of humic acids and nitrogen is used in agriculture a fertilizer. Humic acids are active component in coal and help to utilize almost quantitatively nitrogen in soil. The humic substances block and stabiliz toxic metal residues already present in soil

Petrographical and mineralogical analysis of coal after biological leaching

For coal utilization the sulphur content is a decisive parameter for the quality of the coal. In many countries clean coal technologies have to be applied on the basis of regulations concerning fuel quality and emission standards for dust, CO, SO2 and NOx in the flue gas. It becomes quite obvious that it is always preferable to keep the sulphur levels in coal at a minimum. Bacterial oxidation of the sulphur present in coal could well be thought of as an effective alternative.Desulphurization by bacteria Thiobacillus ferrooxidans was applied to coal sample from Sokolov mine. Bacteria growing in batch culture on ferrous iron at initial pH 1.6 were harvested at the later growth phase. The ferric iron precipitates were separated from the cells by centrifugation and the rest medium by membrane filtration. Cell pellet captured on the filter was washed by hydrochloric acid and distilled water and finally suspended in fresh Waksmann & Joffe medium. The medium was previously acidified by 5M H2SO4 to pH 2. Initial concentration of sulphates in medium was 1.8 g L-1. Desulphurization of coal was studied in a stirred batch reactor at 10% w/v pulp density in diluted H2SO4 at pH = 2.The effect of bacterial leaching on mineral and organic matter of coal was followed by optical microscopy. Petrographic evaluation of the coal matter samples consisted of the determination of reflectance of gelified huminite macerals (R0), determination of maceral group contents of huminite, liptinite, inertinite and determination of the mineral content with emphasis on the various forms of iron sulphides. The sample examined were brown coal with higher liptinite and pyrite contents. The huminite reflectance of 0,33 % is corresponding to the lignitic metatype. Huminite concentration is 65,7 % and is the most abundant maceral group. The maceral ulminite and densinite contributes to the high huminite content. The concentration of attrinite, who be pass to liptodetrinite, textinite, gelinite and corpohuminite contents does not exceed 5 %. The maceral composition of liptinite was determined by a fluorescence measurement. The remaining liptinite macerals, i.e. liptodetrinite and bituminite, resinite, cutinite and fluorinite are accessories. The content of inertinite (fusinite, sklerotinite and inertodetrinite) is low (4,5 %).Coal contains sulphur in inorganic form (mainly pyrite and marcasite) and sulphur in organic form. Biological lixiviation has caused relatively significant change in FeS2, in some cases full or part elimination of dispersed framboids at mineralised detrite as well as at huminite macerals resulting in empty holes and hudge FeS2 grains were slightly disintegrated at the surface or dike - pyrite was relased irregularly after lixiviation

Environmental aspect of chemical pretreatment of slovak brown coal with nitric acid

With the aim to produce a low-sulphur coal by the nitric acid pretreatment, a research was undertaken on the influence of the different process parameters, such as temperature, time, acid concentration, particle size and physical pretreatment on the sulphur decrease, nitrification of the product and the variation in the ash composition for Slovak brown coal