• Economic and Environmental Geology
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• v.22 no.2
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• pp.129-139
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• 1989

The anthracite coalfields of Korea are confined to the areas where sedimentary rocks of Permian and Jurassic are preserved. The Chungnam coalfield lies in the sedimentary rocks of Jurassic which belongs to the Daedong Supergroup (the Nampo group). For the property analysis of each coal seam interbeded in Daedong Supergroup, Seongju area is chosen and twelve coalseams are taken. Many standard tests have been established for optical analysis (maceral analysis, coalification degree measurement), chemical analysis (proximate, ultimate analysis) and physical analysis (ignition temperature, ash fusion temperature, hardgrove grindability index and X-ray diffraction). The Jurassic anthracite mainly consist of vitrinite and macrinite and the range of the reflectance is $R_{max}$ 5.0-6.5 which means metaanthracite rank. By the chemical composition analysis, it shows low H/C and high O/C value compare with international average value. By the physical analysis, it has very high ignition temperature ($531-584^{\circ}C$) and ash fusion temperature ($1510-1700^{\circ}C$) and very low combustion velocity (0.2-1.9 mg/min). The very wide range of the hardgrove grindability index (46-132) means that the grindability controlled mainly by the structural conditions of coal bearing strata.

• Resources Recycling
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• v.2 no.2
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• pp.39-44
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• 1993

This study was carried out to remove the water from low grade anthracite slurry produced at Eoryong coal mine by the oil agglomeration process. 80% of Anthracite as a coal oil mixture (COM) was separated from water by the difference of specific gravity. Then, the amount of kerosene, diesel oil, and heavy oil forming COM was 10% of the amount of sample, respectively. The recovery rate of combustibles and ash content of agglomerated anthracite were affected largely by the amount of added oil, pulp density, particle size, mixing time, and impeller speed. The recovery rate of combustibles was increased to 95% and ash content was decrea-sed from 30% to 13.5% under the optimum conditions.

• Journal of the Korean Society of Safety
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• v.14 no.3
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• pp.84-92
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• 1999

The effects of air velocity and excess air on combustion characteristics were studied in a fluidized bed combustor. The domestic low-grade anthracite coal with heating value of 2010 kcal/kg and the imported bituminous coal from Australia with heating value of 6520 kcal/kg were used as coal samples. The combustion characteristics of mixed fuels in a fluidized bed combustor could be interpreted by pressure fluctuation properties, ash distribution and gas emission. The properties of the pressure fluctuations, such as the standard deviation, cross-correlation function, dominant frequency and the power spectral density function, were obtained from the statistical analysis. From this study, the combustion region increased with increasing air velocity but decreased with excess air due to combustion characteristics of anthracite and bituminous coal.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.580-586
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• 2009

In this study, co-combustion characteristics of Chinese bituminous coal and North Korean anthracite were investigated using a 2 MWe scale circulating fluidized bed power plant. At first, the combustion efficiency of bituminous coal of China and Australia as a function of excess air ratio and temperature were observed. The results showed that the combustion efficiency was influenced by particle size and volatile content of coal, the combustion efficiency of Chinese bituminous coal was over 99.5%. The unburned carbon particles from fly ash and bottom ash were a content 5~7% and 0.3%, respectively. The combustion efficiency with the mixture ratio 20% of bituminous coal and anthracite decreased over 5% because of the increase of entrained particles by a small average particle size of anthracite in the combustor. However, the outlet concentration of $SO_2$ and $NO_x$ was not changed remarkably. The concentrations of the typical air pollutants such as $NO_x$ and $SO_2$ were 200~250 ppm($O_2$ 6%), 100~320 ppm($O_2$ 6%) respectively. The outlet concentration of $NO_x$ was decreased to 30~65% with $NH_3$ supplying rate of 2~13 l/min in SCR process. The $SO_x$ removal efficiency was up to 70% by in-furnace desulfurization using limestone with Ca/S molar of approximately 6.5. With wet scrubbing using $Mg(OH)_2$ as absorbent, the $SO_x$ removal efficiency reached 100% under near pH 5.0 of scrubbing liquid.

• Journal of the Korean Ceramic Society
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• v.15 no.3
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• pp.149-156
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• 1978

The utilization of waste and industrial byproduct materials, such as blast furnace slag, shales, poor coal and anthracite briquet ash, were investigated as a source of calcareous or argillaceous material in the manufacture of Portland cement. As a slag is similar to cement in chemical compoment and contains about 40∼50% of CaO, it's utilization in cement manufacture should be suitable. The burnability was increased and the heat of clinker formation was decreased by using slag. Some consideration should betaken in the use of large quantity because of sticking in suspension preheater kiln. Suitable quantities of colliery shales and poor coal should be useable in cement manufacture as a argillaceous materials and also its combustible materials should be utilized in cement manufacture. Anthracite briquet ash is also usable as a argillaceous source and it gives good burnability.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.108-117
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• 2013

Among the byproducts from thermal power plant using coal combustion, fly ash as mineral admixture is widely utilized in concrete manufacturing for its engineering merits. However residuals including bottom ash are usually reclaimed. This study presents an evaluation of engineering properties in cement mortar with pond ash (PA). For this work, two types of pond ash (anthracite and bituminous coal) are selected from two reclamation sites. Cement mortar specimens considering two w/c (0.385 and 0.485) ratios and three replacement ratio of sand (0%, 30%, and 60%) are prepared and their workability, mechanical, and durability performance are evaluated. Anthracite pond ash has high absorption and smooth surface so that it shows reasonable workability, strength development, and durability performance since it has dense pore structure due to smooth surface and sufficient mixing water inside. Reuse of PA is expected to be feasible since PA cement mortar has reasonable engineering performance compared with normal cement mortar.

• Composites Research
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• v.37 no.3
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• pp.226-231
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• 2024

Coal ash has been used as a sand replacement in the construction industry. Due to the use of bituminous coal as a result of anthracite depletion, and quicklime as an air purifier in the desulfurization process, pop-out defects have recently occurred in concrete using coal ash, severely limiting the recycling of coal ash into concrete. In this study, the components that cause the pop-out problem of the coal ash filled concrete were identified and a pretreatment method to fully expand the expansive components in advance was proposed as a solution to this problem. By treating water twice for 10 min, allowing the CaO mixed in the coal ash to fully expand, the problems of pop-out and reduced compressive strength of the concrete were overcome. The cost and time efficient water treatment method proposed in this study is expected to promote the recycling of coal ash into concrete.

• Plant Journal
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• v.14 no.3
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• pp.35-41
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• 2018

Considering the recent government policy toward North Korea and situation of power facilities in North Korea, it will be necessary to prepare for the consumption of the anthracite coal from Korea in coal-fired power plants. In this study, the anthracite co-fired tests in 500 MW thermal power plants were conducted with varying the main operation conditions, such as anthracite injection position in the boiler, coal fineness and combustion air flow, to investigate the effects on the generation of unburned carbon. It was confirmed that the generation of unburned carbon was remarkably reduced when the anthracite coal was injected into the boiler low burner with a relatively long residence time in the main combustion region, and that the increase of the coal fineness proportional to the combustion reaction surface area also reduces the generation of unburned carbon. An increase in the combustion air flow, which increase the combustion reactivity, also contributes to the reduction of unburned carbon. It is possible to maintain the unburned carbon generation below 5 % of the ash recycling quality by controlling the above operating conditions for the given mixing rate of anthracite, and the priority of changing the operating conditions within the test range is the highest for anthracite coal injection position.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.1
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• pp.10-14
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• 1994

The slowly released potassium fertilizer was developed by mixing fly ash with KOH, anthracite coal powder, KCI, $K_2CO_3$ and $Mg(OH)_2$ as the substances for accelerating calcination. Measuring proper ratios of raw materials, we found that the anthracite coal powder was 12 percent and $Mg(OH)_2$ was two to three percent. The optimal calcination temperature and time were proved to be $850^{\circ}C$ and 30 minutes, respectively, however, the trial product with lower temperature and shorter time in calcination had low quality. The K solubility of the product was very low compared to that of the KCl fertilizer.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.3
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• pp.207-213
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• 1992

In this study, the strength and durability of compacted coal ash with proper mixing ratio of fly ash to bottom ash, such as 5:5 or 6:4, are examined for use of highway embankment and subgrade materials. Right after compaction, the strength of bituminous mixed coal ash is greater than that of anthracite mixed coal ash. The distinguished increase of strength with curing time is observed only in Ho-nam mixed coal ash that contains a lot of free lime, and the strength increase with curing time are not seen or little in the others. The durability in sinking test is good also in Ho-nam mixed coal ash, but satisfactory by adding 2% cement in the others. And it is seen that the effects of the strength increase with adding cement are greater in coal ash with proper mixing ratio than in fly ash or bottom ash respectly.