• Tunnel and Underground Space
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• v.4 no.3
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• pp.297-304
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• 1994

This study aimed at analysis of induced stress and deformation behavior in rock mass around coal seams of Sam Chuck coal mine. For this study Vibrating Wire Stressmeters and Multi-point Borehole Extensometers were installed in the area of coal shale near coal seams. Induced stress and displacement in this area were coutinuously increased for 6 days from the begining of measurement, and then converged. But induced stress and displacement occurred when there were another openings by tunnelling and mining. The value of final induced stress was 21.8kgf/$\textrm{cm}^2$, displacement of rod extensometer was 1.3 mm at arch. Especially, over 1 mm of displacement between E2 and E3 in rod extensometer was measured.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.389-392
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• 2003

Coalfields in Korea have been grouped into thirteen based on mainly geographycal and geological structure, ten out of which have been developed. To classify the phisico-chemical characteristics of mine drainage from each coalfield and, if possible, to clarify the intrinsic reasons of them. Sampling of waters from 59 mines in eight coalfields has been carried out. Higher pH of drainage water from the mines of the Cungchung coalfield belong to the Beading system, Mesozoic era than those belong to the Pyungan system, Proterozoic era is due to the low content of sulfides of neighboring strata. The drainage from coal beds overlying limestone bed mostly show high pH. Waters from the Gangrung and Samchuck coalfields coal beds are located within black shale formation which contains a lot of sulfides showed mostly very high metal and S $O_{4}$$^{2-}$ concentrations.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.6
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• pp.266-273
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• 2011

Foamed glass was fabricated by using glass powder and foaming agents. For the glass powder, we used sodalime glass which's manufactured by using refused coal ore obtained as by-product from Dogye coal mine in Samcheok. And for the foaming agents, we used Calcium carbonate, Calcium phosphate and powder of shale type refused coal ore itself which has high content of carbon materials. We additionally used liquid binder for forming, and mixed together. And we formed rectangular shape and treated $800^{\circ}C$ for 20 min in an electrical furnace. The various kinds of foam glass samples were fabricated according to the kinds of foaming agents. The physical properties of samples, as specific gravity and compressive strength, were measured. Pore structure of each samples were investigated too. Foam glass with specific gravity of 0.4~0.7 and compressive strength of 30~72 kg/$cm^2$. Especially we get satisfying foam glass sample with low specific gravity of 0.47 and high compressive strength of 72 kg/$cm^2$ by the use of liquid calcium phosphate as foaming agent. It also had small and even shape of pore structure. Therefore, it is concluded that refused coal ore can be used for raw materials to manufacture secondary glass products such as a foamed glass panel for construction and industrial materials.

• Economic and Environmental Geology
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• v.35 no.1
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• pp.55-66
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• 2002

There are several abandoned coal mines around Donghae mine area in the Taebaek coal field. Two major creeks, Soro and Sanae, are contaminated with the colored precipitates formed from the coal mine drainages. Bed rocks of the study area consist of limestone, shale, and sandstone. Limestone consisted mainly of calcite and dolomite, and shale of quartz, pyropyllite and chlorite, and sandstone of quatz and illite. Coal coal spoil dumps composed mainly of pyrite and chlorite. The oxidative dissolution of sulfide minerals leads to acid mine drainage and adds the metal ions in the stream water. The ion concentrations of Fe, Ca, Mg, Al, Si, SO$_{4}$in the stream polluted by AMD are generally higher than those in the unpolluted stream water. High concentrations of Ca and Mg, Al and Si can be resulted from dissolution of carbonate minerals such as calcite, dolomite and aluminosilicates such as chlorite, pyrophyllite. Although the Fe, Al, Si, SO$_{4}$ contents are considerbly high in the acid water released from the mine adits, they become decreased downstream due to dilution of unpolluted water and precipitation of oxide/hydroxide and sulfate minerals on the bottom of stream.

• Journal of Industrial Technology
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• v.7
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• pp.27-47
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• 1987

Fine anthracite is very difficult to upgrade by conventional processes such as gravity concentration or froth flotation, because large quantities of fine coals are generated at the mining and preparation stages and a significant portion of these fine coals are mixed with gangue minerals. This study, therefore, was carried out for the purpose of improving recovery of low ash clean coal, effective beneficiation of low-grade coking coal and removal of sulphur from high-sulphur coals by employing the method of selective agglomeration using oil or polystrene flocculants, for coals which are generally hydrophobic in nature will be extracted by using flocculants. Studies were performed by varying solid concentration, concetration of bridging liquid, mixing speed and mixing time, balling speed and balling time, dispersant dosage, flocculant dosage, pulp pH, and particle size. The results were : when the methods of the oil agglomeration and selective flocculation were employ(in the two process the sample was ground to the size of -74 micron), 1) ash content of the agglomerated coal was 9.85, 7.83%, 2) combustibel recovery of it was 98.5%, 93.5%, respectively. It was observed in selective flocculation that polystyrene is an effective flocculant for coal, De-entrapment of shale from the concentrate flocculated by mechanical agitation was necessary for substantional reductions in final ash content.

• Korean Journal of Plant Resources
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• v.18 no.2
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• pp.251-259
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• 2005

Three different floras(M. sinsinsis, A. vulgaris, Robinia pseudo-acacia) were collected from the granite(GR) and coal bearing shale area(CB) and analysed for their heavy metal elements with the representative soils. Regardless of the flora species, the CB were high in average contents. Among the correlation relationships, the CB were more distinctive than the GR, and the A. vulgaris showed higher correlations than the M. sinsinsis. In the same soils, the A. vutgaris showed high contents than the M. sinsinsis and Robinia pseudo-acacia, and the M. sinsinsis were high relative to the Robinia pseudo-acacia. In the comparisons of the flora, root parts were high in most of the elements except for Zn. In the soils, the CB were high in most of elements while As and Mo showed different contents between the GR and CB. In the comparison between soil and flora, soils of the GR were high in the V and Sc contents and low in Zn and Cu, while those of the CR were high in the Cr, V and Sc contents, and low in the Zn contents, Comparing with the soil contents, the M, sinsinsis in the GR were similar to Co and V contents while, in the CB, the M. sinsinsis were similar to the Ni, Cr, Co, Zn, Mo contents, and the Robinia pseudo-acacia were similar to the Ni, Zn, Cu contents. Overall results suggested that the M. sinsinsis and A. vulgaris should be eligible for the bioremediation of the soils polluted by heavy metal such as the CB.

• Economic and Environmental Geology
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• v.13 no.4
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• pp.241-246
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• 1980

Some components in uranium-bearing formations which consist mainly of black shale, slate. and low grade coal-bearing formation of Ogcheon Belt were processed statistically in order to find out the geochemical correlations with uranium. Geochemical enrichment of uranium, vanadium and molybdenum in low grade coal-bearing formations and surrounding rocks is remarkable in the studied area. Geochemical correlation coefficient of uranium and molybdenum in the rocks displays about 0.6, and that of uranium and fixed carbon about 0.4. Uranium and vanadium in uranium-bearing low grade coals denote very high correlation with fixed carbon, which is considered to be responsible for enrichment of metallic elements, especially molybdenum. Close geochemical correlation of uranium-molybdenum couple in the rocks can be applied as a competent exploration guide to low grade uranium deposits of this area.

• Journal of the Korean Ceramic Society
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• v.18 no.4
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• pp.219-228
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• 1981

To clarify influences of silicious raw materials on mineralogcal and petrological properties in clinkering process clay, shale, quartzite, sand and coal ash have been used as silicious raw materials. The tests on thermal properties, reactivity and burnability of raw mixtures which have different silicious raw materials respectively have been made by means of X-ray diffractometry, differential thermal analysis, optical microscopy and transmission electron microscopy. Limestone contains coarse crystalline grains which show 0.1-1.0mm and its decarbonation temperature is 86$0^{\circ}C$. Reaction temperatures among raw mixtures have been determined by X-ray diffractometry and their results are as follows; clay minerals under 1, 00$0^{\circ}C$, mica group, 100$0^{\circ}C$-110$0^{\circ}C$, feldspar group, 1, 10$0^{\circ}C$-1, 20$0^{\circ}C$ and quartz 1, 20$0^{\circ}C$-1, 30$0^{\circ}C$. Burnabilities of raw mixtures of different temperatures have been found that they mainly depend upon their mineral contents in silicious raw materials and their order is as follows; $clay\geq shale\gg quartzite \geq sand$.

• Geomechanics and Engineering
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• v.3 no.3
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• pp.219-231
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• 2011

Waste fills resulting from coal mining should consist of large, free-draining sedimentary rocks fragments. The successful performance of these fills is related to the strength and durability of the individual rock fragments. When fills are made of shale fragments, some fragments will be durable and some will degrade into soil particles resulting from slaking and inter-particle point loads. The degraded material fills the voids between the intact fragments, and results in settlement. A laboratory program with point load and slake durability tests as well as thin section examination of sixty-eight shale samples from the Appalachian region of the United States revealed that pore micro-geometry has a major influence on degradation. Under saturated and unsaturated conditions, the shales absorb water, and the air in their pores is compressed, breaking the shales. This breakage was more pronounced in shales with smooth pore boundaries and having a diameter equal to or smaller than 0.060 mm. If the pore walls were rough, the air-pressure breaking mechanism was not effective. However, pore roughness (measured by the fractal dimension) had a detrimental effect on point load resistance. This study indicated that the optimum shales to resist both slaking as well as point loads are those that have pores with a fractal dimension equal to 1.425 and a diameter equal to or smaller than 0.06 mm.

• Korean Journal of Materials Research
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• v.32 no.1
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• pp.23-29
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• 2022

Fly ash is a by-product of coal fired electrical power plants and used as a material for cement and concrete; particularly, imported fly ash is mainly applied for cement production. Main objectives of this article are to replace domestic fly ash with an imported source. To verify the possibility of domestic fly ash as a material for cement from the aspect of chemical composition and physical properties, we manufactured various kinds of cement, such as using only natural raw material, shale, and partial replacement with domestic and imported fly ash. When we used the domestic and imported fly ash, there were no specific problems in terms of clinker synthesis or cement manufacturing in relation to the natural material, shale. In conclusion, domestic fly ash has been confirmed as an alternative raw material for cement because 7 days and 28 days compressive strength values were better than those of reference cement using natural raw material, on top of the process issue.