• Journal of the Korean Chemical Society
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• v.30 no.1
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• pp.118-125
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• 1986

A small scale combustion unit was built to evaluate the CO suppression effects by various chemical additives added to coal briquettes. Among the additives tested comprising various transition metal compounds with catalytic activities, natural minerals and oxidizing agents, the copper component has shown the best CO suppression effect, and in particular, copper oxide dispersed on porous supports such as ${\gamma}-Al_2O_3$ was most effective. For instance, 0.5% of copper added to coal briquettes in this way bas exhibited 1.4 % CO in the combustion gas at the ignition and beginning stage of combustion and 0.3 % CO at the final stage. The effects of calcium compounds on the fixation of sulfur in coal were also evaluated to reduce the contents of sulfur compounds in the combustion gases.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.149-156
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• 2003

The development and maintenance of a sound bond are essential requirements of concrete repair and replacement. The bond property of a overlay to its substrate concrete during the lifetime is one of the most important performance requirements which should be quantified. A standard or a verified bond strength measurement method is required at field for screening, selecting materials and quality control for overlay or repair materials, but no test method has been adopted as a standard. In this study, a concrete pull off bond strength measurement method for field application is proposed and evaluated. This study compares the splitting tensile test, slant shear test, nipple pipe direct tensile test, flexural adhesion test, briquette tensile test, jumbo nail pull-out test and core pull-off test with their test procedures. From these comparison and investigation, core pull-off test is selected as a main topic of this study because of it's suitability for in situ testing, simplicities in field application and clearness at interface boundary condition. Thus, the proposed core pull off test is evaluated to be the most appropriate method for field application in a simple manner. The fracture surface and fracture mode could be easily determined by visual observation of failure surface of the field specimen. The core pull off test was found to be sensitive to surface condition and latex contents at latex modified concrete.

• Resources Recycling
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• v.9 no.4
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• pp.3-15
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• 2000

Reduction of Electric Arc Furnace dust with carbon (graphite) was studied at the temperature range of $800^{\circ}C$ to $1100^{\circ}C$ in Ar gas atmosphere. The briquetted dust with graphite powder was heated in a vertical tube furnace for given reaction time and Quenched in Ar gas atmosphere. It was found that initially the reduction of Zn was chemically controlled and the activation energy was about 120 KJ/mole. Because the almost all of Pb was removed with Cl in the form of $PbCl_2$, it is considered that Pb is removed by chloride reduction. Cu was vaporized as a chloride up to 30% of its original content, but the remaining of Cu would be accumulated with the reduced iron. and also, Cd was removed completely within 15 min. at $1000^{\circ}C$.

• YAKHAK HOEJI
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• v.24 no.2
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• pp.79-86
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• 1980

CO-intoxication is a serious problem in public health since the coal briquette has been used as one of fuels from 1950's. It has been discussed that the treatment with acetic acid vapor may be effective for CO-intoxication. This study was undertaken to investigate the action of acetic acid therapy, comparing with the spontaneous air treatment The acetic acid vapor was introduced to the blood combined with CO (in vivo and in vitro). The dissociation of COHb, the production of COHb, the levels of Hb and adrenaline and nor-adrenaline were measured. The effect of acetic acid vapor on dissociation of COHb was about 7-9% more effective than the spontaneous air treatment. The acetic acid vapor treatment for the dissociation of COHb was similar effect to the spontaneous air treatment. In an experiment of the combining CO gas with blood, the acetic acid vapor treatment was less effective in the production of COHb than that of spontaneous air treatment. Treatment with the acetic acid vapor to rabbit intoxicated with CO gas induced a little amount of Hb in blood comparing with the spontaneous air treatment. But, it is not a significant increment statistically. By the acetic acid vapor treatment after CO gas intoxication the adrenaline was increased and noradrenaline was decreased. With these results, it is assumed that the effect of acetic acid therapy on CO-gas intoxication would be caused by inductions of Hb and adrenaline and to be reduction of nor-adrenaline.

• Geomechanics and Engineering
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• v.17 no.4
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• pp.355-365
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• 2019

It is normal to observe the presence of numerous cracks in coal body. And it has significantly effective on the mechanical characteristics and realistic failure models of coal mass. Therefore, this paper is to investigate the influence of crack parameters on coal body by comprehensive using theoretical analysis, laboratory experiments and numerical simulation through prepared briquette specimens. Different from intact coal body possessing single peak in stress-strain curve, other specimens with crack angle can be illustrated to own double peaks. Moreover, the unconfined compressive strength (UCS) of specimens decreases and follow by increasing with the increase of crack angle. It seems to like a parabolic shape with an upward opening. And it can be demonstrated that the minimum UCS is obtained in crack angle $45^{\circ}$. In terms of failure types, it is interesting to note that there is a changing trend from tensile failure to tensile-shear mixing failure with tension dominant follow by shear dominant with the increase of crack angle. However, the changing characteristics of UCS and failure forms can be explained by elastic-plastic and fracture mechanics. Lastly, the results of numerical simulations are good consistent with the experimental results. It provides experimental and theoretical foundations to reveal fracture mechanism of coal body with non-penetrating single crack further.

• Particle and aerosol research
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• v.17 no.1
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• pp.1-8
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• 2021

The purpose of this study is to assess respirable crystalline silica (RCS) exposure levels in workers who collect and dispose used coal briquette ash (CBA) in sanitation companies that are subcontracted by one medium-sized local government on the collection of municipal household waste (MHW), and to analyze the quartz content in CBA. When the CBA powder that undergone specialized pretreatment in several steps were subjected to mineral identification and quantitative analysis using X-ray diffraction (XRD), it was found that quartz represented 18%, and in addition, mullite, and plagioclase were included. For two CBA collectors, samples were collected by the personal sampling evaluation method. After respirable dust was collected in accordance with the National Institute for Occupational Safety and Health 7500 method, the concentration of quartz was analyzed using XRD. Meanwhile, a portable real-time dust monitor (Sidepak AM520, TSI Inc., USA) was also used to observe the dust exposure level for each time zone and job task. The RCS exposure level of one worker was as high as 0.024 mg/㎥, which was the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLV) level. The other worker also exhibited a concentration of 0.013 mg/㎥, which was more than half of TLV. The Sidepak results revealed that the work of collecting CBA and loading it onto a vehicle was hardly exposed to the dust of a significant level. It was found, however, that the work of transferring the collected CBA to a container through a conveyor belt was exposed to a very high average respirable dust concentration of 2.238 mg/㎥. The results of this study confirmed that quartz, which is crystalline silica and a carcinogen, is contained in CBA, one of municipal household waste (MHW), in high concentration. It was also confirmed that workers are exposed to high RCS concentrations while transferring collected CBA into a container. Although each local government in South Korea handles CBA in different ways, it is imperative to investigate the CBA exposure level of sanitation workers and improve their working conditions.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.1
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• pp.22-32
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• 2023

In general, when scrap is dissolved in an electric arc furnace, the amount of electric furnace steel dust (EAFD) generated is about 1.5% of the scrap charge amount, and the electric furnace steel dust collected by the bag filter is charged into the Rotary Kiln or Rotary Hearth Furnace (RHF), and the zinc component is recovered as crude zinc oxide, at which time a clinker of Fe-Base is generated. In this research, first, for the efficient resource conversion of electric furnace steel dust, a reduction and roasting experiment was conducted and the reaction kinetics was examined. As a result of the experiment, it was observed that the reduction and roasting reaction was actively conducted in the range of 1100~1150℃, and melting occurred in the range of 1250℃. In the past, this clinker was widely used as a roadbed material for road construction and an Fe-Source for cement production, but in recent years, it has been mainly reclaimed due to strengthening environmental standards. However, landfill treatment is by no means a desirable treatment method due to environmental pollution caused by leachate, expensive landfill costs, and waste of Fe resources. Therefore, in order to more actively recycle the Fe component in the clinker, first of all the clinker was pulverized into an optimal particle size, and anthracite and binder (starch) were added to the magnetic material obtained by specific gravity and magnetic separation for briquet. As a experimental results, it was possible to efficiently separate clinker as Fe component and other slag component by specific gravity and magnetic force. As a results of loading and dissolving the manufactured briquet clinker in an electric arc furnace, it was observed that the unit of power and production yield were clearly improved and the carbon addition effect in molten metal was also somewhat.

• Journal of Preventive Medicine and Public Health
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• v.19 no.1 s.19
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• pp.31-44
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• 1986

For many years, $NO_2$ has been regarded as one of the elements among indoor air pollutants of urban homes, leading to increased public concerns on this gas. For the purpose of preparing the fundamental data for the evaluation and control of health effect relevant to $NO_2$ levels, authors measured the indoor (kitchen, living room, bed room) and outdoor $NO_2$ levels categorized by the type of house(apartment, detached dwelling) and cooking fuel(L.P.G., briquette) in the winter and summer, and surveyed the variables(kitchen ventilation, family size, parental smoking) may effect the indoor $NO_2$ levels. The level of $NO_2$ was measured by Palmes tube, and this survey was carried out at 110 homes in the Pusan area from October 1984 to September 1985. The obtained results were as follows: 1) The mean indoor and outdoor $NO_2$ level in winter and summer, respectively, was $0.029{\pm}0.012$ ppm and $0.022{\pm}0.012$ ppm in the kitchen, $0.022{\pm}0.009$ ppm and $0.018{\pm}0.010$ ppm in the living room, $0.017{\pm}0.008$ ppm and $0.016{\pm}0.010$ ppm in the bed room, and $0.021{\pm}0.007$ ppm and $0.016{\pm}0.007$ ppm outdoors. 2) In the category of the type of house and cooking fuel, the highest mean indoor and outdoor $NO_2$ level in the winter was in apartments using briquettes, and in the summer. the highest level was in apartments using L.P.G. 3) In the category of the type of house, the mean indoor and outdoor $NO_2$ level in the winter and summer was higher in the apartment group compared to detached dwelling. 4) In the category of the type of cooking fuel, the mean indoor and outdoor $NO_2$ level in the winter was higher in the briquette group, and in the summer, the L.P.G. group was higher. 5) In the category of the kitchen ventilation, family size, parental smoking and asthma attack history of children, there was an insignificant difference in the indoor $NO_2$ levels.

• Resources Recycling
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• v.32 no.1
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• pp.50-59
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• 2023

The amount of dust generated during the dissolution of scrap in an electric arc furnace is approximately 1.5% of the scrap metal input, and it is primarily collected in a bag filter. Electric arc furnace dust primarily consists of zinc and ion. The processing of zinc starts with its conversion into pellet form by the addition of a carbon-based reducing agent(coke, anthracite) and limestone (C/S control). These pellets then undergo reduction, volatilization, and re-oxidation in rotary kiln or RHF reactor to recover crude zinc oxide (60%w/w). Next, iron is discharged from the electric arc furnace dust as a solid called Fe clinker (secondary by-product of the Fe-base). Several methods are then used to treat the Fe clinker, which vary depending on the country, including landfilling and recycling (e.g., subbase course material, aggregate for concrete, Fe-source for cement manufacturing). However, landfilling has several drawbacks, including environmental pollution due to leaching, high landfill costs, and wastage of iron resources. To improve Fe recovery in the clinker, we pulverized it into optimal -sized particles and employed specific gravity and magnetic force selection methods to isolate this metal. A carbon-based reducing agent and a binding material were added to the separated coarse powder (>10㎛) to prepare briquette clinker. A small amount (1-3%w/w) of the briquette clinker was charged with the scrap in an electric arc furnace to evaluate its feasibility as an additives (carbonaceous material, heat-generating material, and Fe source).

• Journal of the Korean Wood Science and Technology
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• v.48 no.2
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• pp.253-266
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• 2020

This study selected three types of agglomerated wood charcoal (Agglomerated wood charcoal with charcoal powder, Carbonized wood briquette, Ignition-type of perforated charcoal) that are in circulation in Korea among fuel-type wood products and analyzed the fuel characteristics, harmful substance content, and emissions of air pollutants generated by combustion. The first results showed that charcoal-grilled carbon, which is the raw material of charcoal, produced higher CO than saw-billed carbon. The second result is that the emission standards of air pollutants generated by the combustion of molded wood coal are not up to the emission standards of nitrogen oxides and sulfur oxides in the entire product, compared with the emission criteria of the atmospheric environment preservation method (based on 2019, carbon monoxide: 200 ppm, nitrogen oxides, 150 ppm sulfur oxides: 100 ppm), but the carbon dioxide moulding and carbon dioxide levels were not up. Based on the analysis of combustion gas generated during combustion derived from this study, future research is needed for comparing with the emission standards of pellets, which are wood products for fuel, among the existing biomass burning standards and for reducing carbon monoxide generated during incomplete combustion of agglomerated wood charcoal.