• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.1
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• pp.39-45
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• 2018

Research on FA(Fly ash) is actively carried out, while the research on BA(Bottom ash) is not so, and research on BA recycling field is urgently required. Therefore, in this study, we investigated the lightweight and thermal insulation characteristics of BA mortar by comparing BA mortar made with porous dry BA(air-cooled) and general mortar. To investigate the lightweight of BA, density test, unit volume mass test and SEM(Scanning Electron Microscope) test were performed. BA mortar and general mortar molds were prepared for the thermal insulation test at room temperature and humidity environment determined by KS A 0006 and they were dried at the temperature of $105{\pm}2^{\circ}C$ until the weight became constant. As a result of the lightweight test, the lightweight of BA mortar is about 30% lighter than the general mortar. Therefore, BA is expected to contribute to reduce the building load when used as building material. As a result of thermal insulation test, the thermal conductivity of BA mortar is about 30% better than that of general mortar.

• Resources Recycling
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• v.6 no.1
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• pp.29-34
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• 1997

The feasibility of using the industrial inorganic waste materials such as l~mestone sludge. Soundly sand. coal fly 'ash, and chemical glasses as a raw material for cement clinker by melting treatmeut was iovestigated. The slag wh~ch is obtained from thc melts of the mixtnres of waste materials is composed of P-C,S(ZCaO - SIOJ and C,AS(ZCaO . AI,O, . SiO,) phases. The effect of melting tempcrabre, coaling condition and CIS ratio on the fo~mation of P-C,S phasc was examed. In order to obtain thc P-CiS phase which is useful in thc utilhtion as a clinkcr malcrid, it B found that sudl considerations as low melting temperature as possible of the wastc mixhire, quenching the melts and law CIS ratio of the mlxhlre are necessary.

• Resources Recycling
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• v.25 no.3
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• pp.20-28
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• 2016

Assessment on adequate dosage of superplasticizer in eco-friendly ultra-high performance concrete (UHPC) containing industrial by-products was carried out from the standpoint of workability. Various types of industrial by-products, including blast-furnace slag, coal bottom ash and rapid-cooled electric arc furnace oxidizing slag, were utilized, and the effects of dosage of superplasticizer on the workability and strength of UHPC containing the by-products were evaluated. By utilizing the by-products, the workability of UHPC was improved and required dosage of superplasticizer was reduced. In addition, the material cost for UHPC with by-products was decreased due to reduced dosage of superplasticizer.

• Resources Recycling
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• v.25 no.5
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• pp.44-49
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• 2016

Flue gas desulfurization(FGD) is an effective technique to remove $SO_2$ gases of coal-fired plants. Limestone is usually used as desulfurizing agent. In this study, we use the limestone sludge which is a by-product of steel industry in order to replace desulfurizing agent of FGD process. Physical and chemical characteristics analysis of desulfurizing agent was conducted. Desulfurizing agent using limestone sludge was fabricated by pre-treatment process and, then the agent was used on FGD process. Consequently, the tendency on the $SO_2$ concentration did not appear. And limestone sludge was considered as possible alternative agent for flue gas desulfurization process through absorber control system.

• Resources Recycling
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• v.26 no.1
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• pp.11-15
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• 2017

The amount of the wood chip ash is expected to increase continuously as demand of wood chip-based heat and electricity increase. Thus, there is increased interest in wood chip ash utilization. In this study, as a program of utilization in wood chip ash, the physical and chemical properties of wood chip ashes generated from a combined heat and power plant were investigated. The chemical analysis showed that the main contents of wood chip ash are composed of silica, alumina and alkali. A possibility of reuse as secondary cementitious materials was investigated by the analysis of strength activity index, and compared with coal ash. The highest value for Strength activity index of wood chip fly ash was 78% at 90 days curing time. This result revealed that wood chip fly ash has the potential to be utilized as the admixture for cementitious material.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.888-888
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• 2012

본 연구는 3년(2008~2011년)간의 연구기간동안 저탄장에서 발생하는 유량과 수질농도를 분석하여 저탄장의 비점오염 유출특성을 파악하고자 하였다. 연구지점은 강원도 태백시에 위치한 가행 광산으로써 광산작업으로 인해 생산되는 비축탄(석탄과 광재)을 저장하는 대규모 저탄시설이다. 저탄장에는 강우로 인해 발생하는 강우유출수의 오염물질 배출량을 줄이기 위해 콘크리트 배수로와 침사지 시설이 설치되어 있다. 침사지를 거쳐 하천으로 유입되기 전에 강우유출수의 모니터링을 위해 모니터링 시설(유량계, 자동수질시료채취기, 강우량계)을 설치하여 유량과 농도를 측정하였다. 또한 정확한 강우량 측정을 위해 자기우량계를 설치하였다. 연구결과 강우에 의해 유출이 발생한 최저 강우량은 6.0 mm 인 것으로 나타났으며, 강우사상의 강우량은 6.0~248.4 mm의 범위로 나타났다. 이때 평균 강우강도는 0.6~13.1 mm/hr 인 것으로 나타났으며, 강우에 발생한 강우유출수의 유출률은 0.02~0.40으로 나타났다. 저탄장의 경우 저탄장의 표면을 비닐 캔버스로 덮어두기 때문에 불투수층이 많아 6.0 mm 정도의 적은양의 강우가 발생해도 유출이 발생하는 것으로 나타났다. 각 강우사상의 EMC 농도는 SS 6.5~712.3 mg/L, $COD_{Cr}$ 11.6~263.9 mg/L, $COD_{Mn}$ 3.4~106.8 mg/L, $BOD_5$ 1.0~56.0 mg/L, TN 0.145~5.600 mg/L, TP 0.101~2.526 mg/L, DOC 0.6~22.0 mg/L로 나타났다. 저탄장에서 측정된 수질농도는 기존 가행 광산에 관한 연구에 비해 SS 농도가 낮게 산정 되었으며, 이는 저탄장에 설치되어 있는 침사지 시설의 영향인 것으로 판단된다. 본 연구의 결과는 저탄장에서 발생하는 비점오염원의 유출특성을 파악하고, 모델링이나 환경정책에 필요한 기초자료로 활용할 수 있을 것으로 판단된다. 그러나 강우량, 면적, 피복율 또는 침사지 시설 등의 영향에 대한 추가적인 모니터링을 통한 다각적인 분석의 연구가 진행되어야 할 것으로 판단된다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.514-519
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• 2020

In this study, cement clinkers were sintered at each temperature by replacing some of the clay components of cement clinkers with coal materials. The mineral phase change of sintered cement clinker was quantitatively analyzed by XRD-Rietveld method. As the sintering temperature of cement clinker increased, the amount of belite decreased, the amount of alite increased, and the amount of free-CaO decreased. The form of alite and belite could be distinguished at sintering temperature of 1450℃ or higher. The crystal size was greatly increased at 1500℃ sintering. It was confirmed that the excessive sintering was progressed. Free-CaO decreased with the increase of sintering temperature. At 1450 ℃ or higher, it was less than 0.5%. In 1450℃ or greater, it is determined that enough sintering is included. Therefore, the application of fly ash as a raw material of cement clinker was judged to be usable as a source of chemical components of alumina and iron raw materials.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.3
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• pp.276-281
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• 2023

Water pipes manufactured using existing Portland cement suffer from the problem of rapid deterioration and reduced durability due to the hydration product of cement being vulnerable to acids. Therefore, in this study, water pipes were manufactured using slag and fly ash, which are industrial by-products from various industries, and their characteristics were analyzed. As a result of the experiment, slump in unhardened concrete tended to increase due to the ball bearing action of fly ash, and the amount of air was reduced due to unburned coal, indicating that measures for frost resistance were needed. In addition, the initial strength of the compressive strength was increased through steam curing, and the results were equal to or better than OPC when mixing more than 50 % of slag. The acid resistance results showed that the mass reduction rate was less than 5 %, showing excellent durability performance, and the bending failure load of the water pipe also exceeded the KS standards, so it is judged to be commercializable.

• Journal of Korean Society of Forest Science
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• v.29 no.1
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• pp.1-19
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• 1976

This study has been made to make an observation regarding present status of the coal mine props which is desperately needed for coal production, despite of great shortage of the timber resources in this country, and investigate the effects of diffusion process on the decay resistances of the mine props as applied preservatives of Malenit and chromated zinc chloride. The results are as follows. 1. Present status of the coal mine props Total demand of coal mine props in the year of 1975 was approximately 456 thousand cubic meters. The main species used for mine props are conifer (mainly Pinus densiflora) and hardwood (mainly Quercus). Portions between them are half and half. With non fixed specification, wide varieties of timber in size and form are used. And volume of wood used per ton-of coal production shows also wide range from 0.017 cubic meter to 0.03 cubic meter. 2. Decay resistance test a) The oven dry weight decreased between untreated specimen and treated specimen has not shown any significantly, although it has shown some differences in average values between them. It may be caused by the shorter length of the test. b) The strength of compression test between untreated specimen and treated specimen has also shown the same results as shown in case of weight decrease. Reasons assumed are the same. c) The amounts of the extractives in one percent of sodium hydroxide (NaOH) between untreated and treated specimen have shown the large value in case of untreated specimen than that of treated. 3. The economical benifit between untreated and treated wood when applied in field has seen better in long term base in case of treated wood, although the primary cost of treated wood add a little bit more cost than that of the untreated wood.

• Environmental and Resource Economics Review
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• v.15 no.4
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• pp.673-692
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• 2006

In order to test for the dynamic optimality condition for the use of nonrenewable resource, it is necessary to estimate the shadow value of the resource in situ. In the previous literatures, a time series for in situ price has been derived either as the difference between marginal revenue and marginal cost or by differentiating with respect to the quantity of ore extracted the restricted cost function in which the quantity of ore is quasi-fixed. However, not only inconsistent estimates are likely to be generated due to the nonmalleability of capital, but the estimate of marginal revenue will be affected by market power. Since firms will likely fail to minimize the cost of the reproducible inputs subject to market prices under realistic circumstances where imperfect factor markets, strikes, or government regulations are present, the shadow in situ values obtained by estimating the restricted cost function can be biased. This paper provides a valid methodology for checking the dynamic optimality condition for a nonrenewable resource by using the input distance function. Our methodology has some advantages over previous ones: only data on quantities of inputs and outputs are required; nor is the maintained hypothesis of cost minimization required; adoption of linear programming enables us to circumvent autocorrelated errors problem caused by use of time series or panel data. The dynamic optimality condition for domestic coal mining does not hold for constant discount rates ranging from 2 to 20 percent over the period 1970~1993. The dynamic optimality condition also does not hold for variable rates ranging from fourth to four times the real interest rate.