A series of activated carbons were prepared from coconut shells and coal-tar pitch binder by physical activation with steam in this study. The effect of variable processes such as activation temperature, activation time and ratio of mixing was investigated for optimizing those preparation parameters. The activation processes were carried out continuously. The nitrogen adsorption isotherms at 77 K on pellet-shaped activated carbons show the same trend of Type I by IUPAC classification. The average pore sizes were about 19-21a. The specific surface areas (SBET) of pellet typed ACs increased with increasing the activation temperature and time. Specific surface area of AC treated for 90 min at temperature 900℃ was 1082 m2/g. The methylene blue numbers continuously increased with increasing the activation temperature and time. On the other hand, iodine numbers highly increased till activation time of 60 min, but the rate of increase of iodine numbers decreased after that time. This indicates that new micropores were created and the existing micropores turned into mesopores and macropores because of increased reactivity of carbon surface and H2O.

저가형 TiO2 광촉매의 개발과 광촉매의 활용범위를 확대하고자, 석탄회를 지지체로 이용하여 TiO2 광촉매를 제조하였다. 석탄회 표면에 TiO2 입자의 피복은 침전법에 의해서 수행되었다. TiO2의 공급원으로는 TiCl4수용액과 침전제로는 NH4HCO3가 사용되었다. 이들의 중화반응에 의해 석탄회 표면에 생성되는 Ti(OH)44는 300~700˚C의 열처리 과정에서 산화되었다. 여기서 생성된 TiO2의 결정구조는 anatase형을 나타내었다. 피복 TiO2의 결정립 크기는 열처리 온도의 상승에 따라 증가하였으나, NO가스의 제거능은 감소하는 경향을 보였다. TiO2피복 석탄회를 300~400˚C의 온도 범위에서 2시간 동안 열처리할 경우, TiO2의 결정립 크기는 약 9nm이었고, 질소산화물 제거율은 85~92%이었다. 또한, TiO2피복 석탄회의 백색도는 TiO2의 피복량이 증가할수록 열처리 온도가 증가할수록 상승하는 경향을 나타내었다.

Ash ball 배지의 이화학적특성과 사용배지의 염류집적 및 제거효과를 펄라이트 및 입상암면과 비교하였다. ash ball의 가비중, 진비중, 공극율은 각각 0.93 g.cm-3, 2.29 g.cm-3, 40.6%, 59.4%로서 그중 가비중은 펄라이트 및 입상암면에 비해 현저히 높았고 가공율은 낮았다. 배지의 포화수분함량(saturation moisture capacity)은 ash ball이 52%, 펄라이트가 71%, 입상암면이 90%로 나타났고, 배수 1시간 후 수분율은 ahs ball이가 21%, 펄라이트가 27%, 입상암면이 80%로 낮아졌다. Ash ball의 입도별 수분율은 소립(3~5 mm)이 대립 (7~15mm)에 비해 5% 정도 높았다. Ash ball의 배드내 수분율은 수직 및 수평방향의 분포가 균일하여 수분확산성이 좋은 것으로 나타났다. ash ball의 pH는 7.6으로 약염기성을 나타내었다. 배지를 침지한 배양액의 pH는 7.6으로 약염기성을 나타내었다. 배지를 침지한 배양액의 pH는 다소 증가하는 경향을 보였으며 EC는 거의 변호가 없었으며, 배지내 무기이온의 흡착은 ash ball과 입상암면은 인산의 흡착이 비교적 많았다. 토마토 재배에 사용된 ash ball의 염류집적은 펄라이트와 비슷하였고 8회 정도의 침수처리로 배지표면에 흡착된 무기염을 대부분 제거할 수 있었다. 위의 결과로부터, ash ball 배지는 보수력은 다소 낮지만 통기성 및 수분확산성이 우수하여 배지내의 수분조절이 용이한 배지임을 알 수 있었다.

Raman spectroscopy has been used to investigate the structure of coal tar pitch heat-treated up to 3000℃ by using 514.5 run Ar ion laser line. Four critical temperature ranges were found on pyrolyzing coal tar pitch, which correspond to four distinct processes from disordered carbons to the well-ordered graphite structure. The range of heat treat temperature (HTT) below 1000℃ corresponds to gas evolution during the pyrolysis of coal tar pitch. Above the HTT are correlated to rearrangements of enlarged molecules, growth of the molecules along the direction of plane, finally stacking in the normal direction of the plane, in the respective HTT ranges of 1000-2000, above 2000 and 2500-3000℃.

Coal tar pitch was chemically modified with 10 wt% benzoquinone (BQ) to raise the softening point of isotropic pitch precursor and the precursor was melt-spun into pitch fibers, stabilized, carbonized and activated with steam at 900℃. The weight loss of carbon fiber-benzoquinone (CF-BQ) increased with the increase of activation time like other fibers, but was lower than those of Kureha fiber at the same activation time in spite of larger geometric surface area. Those adsorption isotherms fitted into 'Type I' according to Brunauer, Deming, Deming and Teller classification. However, there was very thin low-pressure hysteresis that lower closure points of the hysteresis are about 0.42-0.45. From the pore size distribution curves, there might be some micropores having narrow-necked bottle; a series of interconnected pore is more likely than discrete bottles. FT-IR studies showed that the functional groups such as carboxyl, quinone, and phenol were introduced to ACFs-BQ surface after steam activation. Methylene blue decolorization and iodine adsorption capacity of ACF-BQ increased linearly with the increase of specific surface area and was larger than that of ACF-Kureha at the same specific surface area.

This study was carried out to synthesis the zeolite using the bituminous coal fly ash emitted from power plant that occurs several environmental problems. In spite of fly ash has contained high content of SiO2 and Al2O3, it disposed mainly landfill. If the effective methods to recover the SiO2 and Al2O3 were developed, the fly ash could be utilized valuable raw materials. In this study, fly ash was used as raw material to synthesize the zeolite by pressurized hydrothermal reaction. Also, experimental parameters included temperature(70~110℃, and pressure(140~200 psi) of crystallization were investigated. The more crystallization pressure was increased, the more Zeolite 4A was synthesized at 70 and 90℃. Zeolite 4A of metastable phase tend to be transformed into sodalite of stable phase at 110℃.

석탄계 핏치의 열처리 온도 및 압력에 따른 결정화도와 기공도 그리고 산화저항성 등을 관찰하였으며, hexagonal type 4D 탄소/탄소 복합재를 석탄계 핏치로 가압함침 및 탄화시킨 다음 가해준 압력이 고밀도화에 미치는 영향을 관찰하였다. 석탄계 핏치의 가압탄화 압력이 흑연화도에 크게 영향을 미치지 않았으며, 기공면적비에 있어서는 압력을 600bar로 상승시켜 줌으로써 상압 처리한 경우 보다 1.5배 정도 감소 하였다. 650˚C까지 열처리하여 얻은 코우크스의 산화반응 개시온도는 처리압력이 증가함에 따라서 지연되었다. 탄소/탄소 복합재의 함침압력을 100bar에서 600bar로 상승시켜 줄 경우 밀도 증가율이 크게 향상 되었으며 기공도는 감소하였다.

본 연구에서는 원료 석탄 핏치와 흑연화성이 우수한 THF 가용성분만을 추출한 핏치 결합재에 8H/Satin woven fabric 프리프레그 및 고탄성 및 고강도계 연속 탄소섬유 등을 보강하여 가압열성형법으로 green body 를 제조한 다음 탄화, 함침, 재탄화 및 흑연화 공정을 거쳐 열적 미 기계적물성이 우수한 CFRC를 제조하였으며, 주사전자현미경, 편광현미경, X선회절분석,열중량분석, 굴곡강도, 굴곡탄성률, 충간전단강도 등을 시험하였다. THFSP결합재를 2300˚C까지 열처리 한 다음 X선회절분석을 한 결과, 결정성이 가장 우수하여 (002) 면에서 C0/2인 값이 3.380Å였으며, 2θ값도 26.276˚로 천연흑연의 Bragg angle에 거의 접근하였으며 공기산화 반응특성을 시험하기 위하여 등온 열중량분석을 한 결과 2300˚C까지 흑연화 한 THFSP결합재가 산화에 대하여 가장 우수한 저항성을 나타내었다. 섬유용적률이 증가됨에 따라 65~70%까지는 기계적 물성이 중가하는 경향을 보였지만 그이상 섬유가 보강된 CFRC는 결합재의 부족으로 인하여 오히려 기계적 물성이 감소하였다. 또한 굴곡강도 시험후 주사전자현미경으로 파괴 단면을 관찰한 결과 THFSP결합재가 흑연화성이 우수하여 파괴시 결합재가 외력에 대한 흡수가 양호하여 보강재의 파괴를 억제했기 때문에 기계적 물성도 우수하게 나타났다.

The physical properties of sedimentary rocks in the coal fields were studied. Sandstones and shales are major samples among the core samples from Samchuck and Boeun coal fields. The measured properties were seismic velocities (P and S-wave), electrical resistivity, density and porosity. The relationships between physical properties were analyzed by using the cross plots. Summarized results are as follows : 1. Compressional wave velocity is approximately linearly related to shear wave velocity and the velocity ratio Vp/Vs of shales has slightly larger value than that of sandstone. And with increasing Vp, the velocity ratio Vp/Vs decreases because the effect of porosity and clay content on Vs is larger than on Vp. 2. In the case of sandstones, as porosity increases, P-wave velocity decreases slowly, but effect on the density is not apparent. In the case of shales, as porosity increases, both P-wave velocity and density decrease. 3. The values and variation range of density of sandstones are relatively small as compared to those of shales. But the range of elastic wave velocities of both rocks are appeared to be similar. 4. Seismic velocity is power-functionally related to electrical resistivity, and the value of the power is appeared to be larger for sandstones than for shales. 5. Because samples from Boeun field are slightly metamorphosed, the values of electrical resistivity are larger than those of samples from Samchuk field.

A zeolite material (ZCH) was synthesized from coal fly ash in an HD thermal power plant using a fusion/hydrothermal method. ZCH with high crystallinity could be synthesized at the NaOH/CFA ratio of 0.9. Ion-exchanged ZCH adsorbents for ammonia removal were prepared by ion-exchanging various cation (Cu2+, Co2+, Fe3+, and Mn2+) on the ZCH. They were used to evaluate the ammonia adsorption breakthrough curves and adsorption capacities. The ammonia adsorption capacities of the ZCH and ion-exchanged ZCHs were high in the order of Mn-ZCH > Cu-ZCH ≅ Co-ZCH > Fe-ZCH > ZCH according to NH3-TPD measurements. Mn-ZCH ion-exchanged with Mn has more Brønsted acid sites than other adsorbents. The ion-exchanged Cu2+, Co2+, Fe3+, or Mn2+ ions uniformly distributed on the surface or in the pores of the ZCH, and the number of acidic sites increased on the alumina sites to form the crystal structure of zeolite material. Therefore, when the ion-exchanged ZCH was used, the adsorption capacity for ammonia gas increased.

The objective of this study was to develop a management strategy for the recovery of carbon storage capacity of abandoned coal mine forest rehabilitation area. For the purpose, the biomass and stand carbon storage over time after the forest rehabilitation by tree type for Betula platyphylla, Pinus densiflora, and Alnus hirsuta trees which are major tree species widely planted for the forest rehabilitation in the abandoned coal mine were calculated, and compared them with general forest. The carbon storage in abandoned coal mine forest rehabilitation areas was lower than that in general forests, and based on tree species, Pinus densiflora stored 48.9%, Alnus hirsuta 41.1%, and Betula platyphylla 27.0%. This low carbon storage is thought to be caused by poor growth because soil chemical properties, such as low TOC and total nitrogen content, in the soil of abandoned coal mine forest rehabilitation areas, were adverse to vegetation growth compared to those in general forests. DBH, stand biomass, and stand carbon storage tended to increase after forest rehabilitation over time, whereas stand density decreased. Stand' biomass and carbon storage increased as DBH and stand density increased, but there was a negative correlation between stand density and DBH. Therefore, after forest rehabilitation, growth status should be monitored, an appropriate growth space for trees should be maintained by thinning and pruning, and the soil chemical properties such as fertilization must be managed. It is expected that the carbon storage capacity the forest rehabilitation area could be restored to a level similar to that of general forests.

A zeolite material with a Si/Al molar ratio of 1.2 was synthesized by changing the NaOH/CFA ratio of coal fly ash (CFA) via a fusion/hydrothermal reaction in the HD thermal power plant. The change in the crystal structure of the zeolite was confirmed using XRD and SEM, and the ammonia adsorption capacities of the synthesized zeolitic materials and a commercial zeolite (Na-A zeolite) were analyzed via an ammonia temperature-programmed desorption (NH3-TPD) process. The SEM and XRD results revealed out the zeolitic materials from the coal fly ash maintained a hexagonal Linde-type crystal structure similar to that of Na-A zeolite, but the crystallinity of the synthesized zeolitic material was reduced due to impurities. The NH3 adsorption capacity, determined from the NH3-TPD analysis of was 1.122 mmol/g of the synthesized zeolitic material, which was lower than the NH3 adsorption capacity of the Na-A zeolite.

광산배수에서 일어나는 철광물의 침전과 상전이는 배수 내 미량 원소의 거동에 매우 중요한 영향을 미친다. 그러나 주로 침전되는 철광물 중 하나인 페리하이드라이트의 침전과 이와 연관된 배수 내 미량원소의 거동은 거의 연구된 적이 없다. 본 연구는 문경 석탄광에서 발생하는 광산배수에서 pH 변화와 시간에 따른 광물침전 특성을 알아보고 이러한 광물의 침전과 연관된 미량원소의 거동 변화를 연구하였다. 침전되는 광물의 경우 pH 4에서는 침철석이 관찰되었고 pH 6 이상에서는 일부 6-line 페리하이드라이트가 혼재하는 2-line 페 리하이드라이트가 주로 동정되었다. 또한 pH 6 이상의 시료에서는 pH가 증가할수록 방해석의 침전이 추가적 으로 증가하는 것이 관찰되었다. 침철석의 경우 초기에 배수 내에서 페리하이드라이트로 침전된 후 낮은 pH의 영향으로 이 광물이 짧은 시간 내에 침철석으로 상전이 되었을 것으로 생각된다. 배수 내 미량 원소의 농도는 pH와 시간에 큰 영향을 받고 있음을 보여준다. 시간에 따라 배수 내의 Fe는 철광물의 침전에 의하여 급격한 농도의 감소를 보였는데 배수 내 산화음이온으로 존재하는 As의 경우도 pH 값에 상관없이 Fe와 같이 급격 한 농도의 감소를 보였다. 이러한 As의 농도 감소는 주로 페리하이드라이트와의 공침에 의한 것으로 여겨지며 낮은 pH의 배수에서는 침철석의 표면 흡착에 의한 것으로 생각된다. 이와는 달리 Cd, Co, Zn, Ni 등의 미량 원소의 농도는 광물의 종류에 상관없이 pH에 큰 영향을 받으며 pH 값이 낮을수록 배수 내 높은 농도로 존 재하였고 pH가 증가할수록 그 농도는 낮아졌다. 이러한 결과는 양이온으로 존재하는 미량원소의 거동의 경우 광물의 종류보다 pH에 따른 광물 표면의 전하 값에 더 큰 영향을 받고 있음을 지시한다.

Zeolitic material, Z-Y3, was synthesized from coal fly ash (CFA) under low-alkaline conditions (NaOH/CFA ratio = 0.3 and NaOH solution concentrations of 0.0, 0.5, and 1.0 M) using a fusion/hydrothermal method. The adsorption capacities of the fabricated Z-Y3 samples for Cs and Sr ions and the desorption capacity of Na ions were evaluated. The XRD patterns of the Z-Y3 sample fabricated using a 1.0 M NaOH solution (Z-Y3 (1.0 M)) indicated the successful synthesis of a zeolitic material, because the diffraction peaks of Z-Y3 coincided with those of the Na-A zeolite in the 2θ range of 7.18-34.18. Moreover, the SEM images revealed that morphology of the Z-Y3 (1.0 M) sample, which presented zeolitic materials characteristics, consisted of sharp-edged cubes. The adsorption isotherms of Cs and Sr ions on all the fabricated Z-Y3 samples were described using the Langmuir model, and the maximum adsorption capacities of Cs and Sr were calculated to be 0.14-0.94 mmol/g and 0.19-0.78 mmol/g, respectively. The desorption of Na ions from the Cs and Sr ions adsorbed Z-Y3 samples followed the Langmuir desorption model. The maximum desorption capacities of Na ions from the Cs and Sr ions adsorbed Z-Y3 (1.0 M) samples were 1.28 and 1.49 mmol/g, respectively.

This objective of this study is to enrich the literature by the debt ratio and enterprise performance of Joint stock companies of Vietnam National Coal and Mineral Industries Holding Corporation Limited (Vinacomin). The debt ratio is an important index of capital structure, and it influences and decides the enterprise performance. Therefore, the determination of reasonable debt ratio level is beneficial to the stable operation of Vinacomin’s enterprises. Based on the research conclusion about the effect on capital structure of debt ratio from domestic and foreign scholar, collecting data from 2014-2018 of Vinacomin’s enterprises as a research sample, the article conducts research on the relationship between debt ratio and business performance of Vinacomin, as measured by return on total Assets. In addition, the study uses free cash flow, company size , growth opportunity, investment opportunities, operating costs to sales ratio as control variables.The study shows the debt ratio of Joint stock companies of Vietnam National Coal and Mineral Industries Holding Corporation Limited has a negative effect on the enterprise performance. Furthermore, the research results of the article are references for Vinacomin’ enterprises in the course of production and business activities, determining a reasonable debt ratio, and improving the operational performance of enterprises.

The study investigates the impact of globalization on coal consumption in Vietnam. This study employs an autoregressed distributed lag approach on time series data for the period of 1990 to 2017. The study tests the stationary, cointegration of time series data and utilizes autoregressed distributed lag modeling technique to determine the short-run and long-run relationship among coal consumption, globalization, income, population, and CO2 emissions. The results show that globalization increases coal consumption in Vietnam in the long run. The results also show that rapid economic growth promotes more coal consumption in the short run as well as in the long run. Moreover, higher population reduces coal consumption, and CO2 emissions decrease coal consumption both in the short run and the long run. The findings of the study suggest that globalization increases coal consumption in Vietnam in the long run. This result suggests that the increase in globalization level in Vietnam increases coal consumption. An interesting finding is that higher population reduces coal consumption, and population is an important factor towards the lessening in coal consumption. The findings confirm that environmental pollution decreases coal consumption in the short run and the long run. This implies that coal consumption may be green consumption in Vietnam.

항만의 주요 정책 및 향후 운영계획 수립 시 정확한 물동량 예측에 관한 연구는 매우 중요하며 이러한 중요성으로 인해 관련 연구가 활발히 수행되고 있다. 본 논문에서는 국내 최대 석탄 및 철광석 처리 항만인 광양항을 대상으로 단계적 회귀분석과 인공신경망모형을 활용하여 모형간 예측력을 비교하였다. 2009년 1월부터 2019년 1월까지 총 121개월의 월별자료를 활용하였으며 석탄 및 철광석 물동량에 영향을 주는 요인을 선정하여 공급관련요인과 시장·경제관련요인으로 분류하였다. 단계적 회귀분석 결과, 광양항 석탄 물동량 예측모형의 경우, 입항선박 톤수, 석탄가격 및 대미환율이 최종변수로 선정되었고 철광석 물동량 예측모형의 경우, 입항선박 톤수, 철광석가격이 최종변수로 선정되었다. 인공신경망모형의 경우, 모델 성능에 영향을 미치는 다양한 Hyper-parameters를 조정하며 최적 모델을 선정하는 시행착오법을 사용하였다. 분석결과 인공신경망모형이 단계적 회귀분석에 비해 우수한 예측성능을 나타내었으며 예측 모형별 예측값과 실측값을 그래프 상 비교 시에도 인공신경망모형이 단계적 회귀분석에 비해 고·저점을 유사하게 나타냈다.

본 연구는 사회적 현안이 되는 미세먼지 저감 및 대기정화를 위해 석탄화력 발전산업에서 발생되는 부산물을 활용하여 미세먼지를 포집·분해하는 건설재료에 대한 기술 개발로서 자원재활용과 대기오염 저감 기술에 해당된다. 미세먼지를 석탄화력 발전소 애시 기반 다공성 활성탄의 표면에 흡착하고, 고기능성 광분해 나노섬유를 통해 분해하여 미세먼지 제거효율을 극대화 하고자 한다. 본 연구를 통해 개발되는 미세먼지 흡착·분해 다공체 기술은 방음벽, 보도블록 등 대기오염 농도가 높은 도로시설분야에 활용할 수 있을것으로 판단된다.