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Number of results: 6
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Abstract

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.
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Abstract

The purpose of the research was mapping, inventorization, and valorization of coal mining waste dumps from the mines of JSW SA company, for the needs of recovery of coal from the dump material as well as the reclamation and management of examined facilities. The valorization of post-mining waste dumps has been carried out using a methodology which considers the problems of reclamation, management, accessibility of the dumps as well as environmental hazards connected with disposing of mining and preparation wastes on the ground surface. An inventorization of 10 coal mining waste dumps coming from 6 mines of JSW SA including in their range 7 deposits: Borynia, Jastrzębie, Zofiówka, Budryk, Knurów, Szczygłowice and Pniówek was carried out. The source material within the localization of particular dumps was obtained from archival materials coming from coal mines and municipalities where the dumps are located. Verified data has been drawn on topographical map, which results in the map of coal mining waste dumps. The results of the valorization of the dumps comprise the defining of: the name of the dump, state of the dump, surface of the dump, accessibility, name of the coal mine from where the wastes come from, type of technical and biological reclamation and possibilities of coal recovery, which have been brought on the drawn map. Basing on collected and elaborated data, an attempt of defining of potential possibilities of recovery of coal from the dumps and connection of coal quality in the deposits of JSW SA and in waste material was made. The results of the research showed that in spite of preliminary information that a majority of the investigated dumps may be considered as potential facilities for coal recovery, ultimately the recovery is economically justified only in several cases (5 facilities).
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Abstract

The new legislative provisions, regulating the trade in solid fuels in our country, draw attention to the need to develop and improve methods and methods of managing hard coal sludge. The aim of the work was to show whether filtration parameters (mainly the permeability coefficient) of hard coal sludge are sufficient for construction of insulating layers in landfills at the stage of their closing and what is the demand for material in the case of such a procedure. The analysis was carried out for landfills for municipal waste in the Opolskie, Śląskie and Małopolskie provinces. For hard coal sludge, the permeability coefficient values are in the range of 10–8–10–11 m/s, with the average value of 3.16 × 10–9 m/s. It can be concluded that this material generally meets the criteria of tightness for horizontal and often vertical flows. When compaction, increasing load or mixing with fly ash from hard coal combustion and clays, the achieved permeability coefficient often lowers its values. Based on the analysis, it can be assumed that hard coal sludge can be used to build mineral insulating barriers. At the end of 2016, 50 municipal landfills were open in the Opolskie, Śląskie and Małopolskie Provinces. Only 36 of them have obtained the status of a regional installation, close to 1/3 of the municipal landfill are within the Major Groundwater Basin (MGB) range. The remaining storage sites will be designated for closure. Assuming the necessity to close all currently active municipal waste landfills, the demand for hard coal sludge amounts to a total of 1,779,000 m3 which, given the assumptions, gives a mass of 2,704,080 Mg. The total amount of hard coal sludge production is very high in Poland. Only two basic mining groups annually produce a total of about 1,500,000 Mg of coal sludge. The construction of insulating layers in landfills of inert, hazardous and non-hazardous and inert wastes is an interesting solution. Such an application is prospective, but it will not solve the problem related to the production and management of this waste material as a whole. It is important to look for further solutions.
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Abstract

Significant quantities of coal sludge are created during the coal enrichment processes in the mechanical processing plants of hard coal mines (waste group 01). These are the smallest grain classes with a grain size below 1 mm, in which the classes below 0.035 mm constitute up to 60% of their composition and the heat of combustion is at the level of 10 MJ/kg. The high moisture of coal sludge is characteristic, which after dewatering on filter presses reaches the value of 16–28% (Wtot r) (archival paper PG SILESIA). The fine-grained nature and high moisture of the material cause great difficulties at the stage of transport, loading and unloading of the material. The paper presents the results of pelletizing (granulating) grinding of coal sludge by itself and the piling of coal sludge with additional material, which is to improve the sludge energy properties. The piling process itself is primarily intended to improve transport possibilities. Initial tests have been undertaken to show changes in parameters by preparing coal sludge mixtures (PG SILESIA) with lignite coal dusts (LEAG). The process of piling sludge and their mixtures on an AGH laboratory vibratory grinder construction was carried out. As a result of the tests, it can be concluded that all mixtures are susceptible to granulation. This process undoubtedly broadens the transport possibilities of the material. The grain composition of the obtained material after granulation is satisfactory. Up to 2 to 20 mm granules make up 90–95% of the product weight. The strength of the fresh pellets is satisfactory and comparable for all mixtures. Fresh lumps subjected to a test for discharges from a height of 700 mm can withstand from 7 to 14 discharges. The strength of the pellets after longer seasoning, from the height of 500 mm, shows different values for the analyzed samples. The values obtained for hard coal sludge and their blends with brown coal dust are at the level from 4 to 5 discharges. The strength obtained is sufficient to determine the possibility of their transport. At this stage of the work it can be stated that the addition of coal dust from lignite does not cause the deterioration of the material’s strength with respect to clean coal sludge. Therefore, there is no negative impact on the transportability of the granulated material. As a result of mixing with coal dusts, it is possible to increase their energy value (Klojzy-Karczmarczyk at al. 2018). The cost analysis of the analyzed project was not carried out.
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Abstract

The research involved coal from 11 coal mines in the USCB in Poland, intended for combustion in power plants and for home furnaces. It has been stated that the content of As, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb and Zn in the ash of coal fines from the USCB with a density of <1.30 × 103 kg/m3 is the largest, and in the ash fraction with a density >2.00 × 103 kg/m3 is the smallest The fraction ash of coal fine with a density> 2.00 × 103 kg/m3 has the greatest impact on the content of As, Cd, Co, Cr, Mo, Pb and Zn in whole coal fines from the USCB. In turn, the largest impact on the content of Cu, Ni and Sb in whole fine coal ash has the fraction of coal fine having a density of 1.60–2.00 × 103 kg/m3 (for Cu) and fraction with a density <1.35 × 103 kg/m3 (Ni and Sb). The main carriers of elements in fine coal ash, thus in future furnace waste, are the grains of aluminosilicates and iron oxides resulting from the combustion of probably fusinite and semifusinite and the combustion of adhesions of these macerals with dolomite, ankerite and pyrite. The purification of fine coal from the matter with a density >2.00 × 103 kg/m3 may reduce the sulfur content (by 40%), the content of main element oxides (from 33% to 85%) and the content of ecotoxic elements (from 7% to 59%) in fine coal ash, i.e. in potential furnace wastes. Due to the small content of mineral matter, ash and sulfur in coal, small content of Al, Fe, Ca, Mg, Na, K, P oxides and high content of SiO2 in coal ash, low value of the Rogi sinterability index, small inclination of coal fine to slag the furnaces and boiler fouling by sludge, the investigated coal was favorable for technological reasons, fuel in power plants and for home furnaces
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Abstract

In this study, non-sintered ceramsite was prepared using coal gasification coarse slag obtained from a methanol plant. The basic performance and heavy metal leaching toxicity were analyzed. The results showed that seven out of nine non-sintered ceramsite groups were in accordance with the national standard of compressive strength (5 MPa), while only three groups met the national standard of water absorption index of less than 22%. The heavy metal concentrations in these three groups were found to be lower than that specified in National Class IV of surface water environment standards. The concentration of Cr was found to be 16.45 μg/L, which represents only 1% of the IV standard. The optimum mixing ratio, which showed high compressive strength (6.76 MPa) and low water absorption (20.12%), was found to be 73% coal gasification coarse slag, 15% cement, and 12% quartz sand. The characterization using Fourier transform infrared spectroscopy showed that the formation of gelatin in ceramsite enhances the performance of the ceramsite base and increases the immobilization of heavy metal. The study proved that the preparation of non-sintered ceramsite using coal gasification coarse slag reduces its environmental risk and achieves efficient utilization of the slag. Therefore, it can be concluded that it is a feasible and environmental friendly method for the disposal of coal slag.
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