• Resources Recycling
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• v.17 no.1
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• pp.29-37
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• 2008

Recently, domestically and internationally, the occurrences of Waste Glass are on the increase. Most of scrap glass are either reused of recycled. However, glass not recycled is buriedand is causing secondary environmental problem. With 5% mixture of Waste Glass, the average paste viscosity (rheology) decreased by 22.3% and 28-day compressive strength of mortar's flow and aging decreased by 1.5% and 6% respectively. Also, as Waste Glass mixture ratio of un-hardened elf-compacting concrete increased, fluidity increased and compressive strength decreased. In consideration of adequate compressive strength and fluidity that meets the 2nd class JSCE regulations; optimum mixture ratio of Waste Glass can be concluded as 20%.

• Resources Recycling
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• v.26 no.5
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• pp.22-28
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• 2017

In-Bi-Sn alloy sheet has been used as a thermal fusible parts of secondary battery safety system. This study offers a simple process to make In-Bi-Sn alloy fusible parts. The process consists of two procedures, melting and sheeting by tape casting. 62.5 wt%-In 20.0 wt%-Bi 17.5 wt%-Sn (M.P. $92.4^{\circ}C$) alloy sheet obtained by tape casting was used as the thermal fusible sheet of thermal fuse system for mobile telephone. The performance test of the system was carried out in oil bath, and the fusible alloy sheet was melted and cut off at $95^{\circ}C$. This results confirmed the possibility that the alloy sheet obtained by tape casting can be usable as a thermal fusible parts of battery safety system. And this process can be applied as a simple process to recycle the In-Bi-Sn alloy scrap separated from the used thermal fuse system.

• Resources Recycling
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• v.31 no.1
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• pp.46-55
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• 2022

The recycling of coated cemented carbide scraps is becoming increasingly significant for the recovery of rare metals. However, coatings consisting of Group IV and V transition metal nitrides are one of the challenging factors in obtaining high-purity materials. We investigated the structural, elastic, and mechanical properties of Group IV and V transition-metal nitrides (TiN, VN, ZrN, NbN, HfN, and TaN) using first-principle calculations. Convergence tests were performed to obtain reliable calculated results. The equilibrium structures of the nitrides were in good agreement with those of a previous study, indicating the reliability of the data. Group IV transition metal nitrides show a higher covalent bonding nature. Thus, they exhibit a higher degree of brittleness than that of Group V transition metal nitrides. In contrast, Group V transition metal nitrides show weaker resistance to shear loading and more ductile behavior than Group IV transition metal nitrides because of the metallic bonds characterized by valence electron concentration. The results of the crystal orbital Hamilton population analysis showed good agreement with the shear resistance tendencies of all transition metal nitrides.

• Journal of Powder Materials
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• v.29 no.1
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• pp.47-55
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• 2022

Tungsten carbide is widely used in carbide tools. However, its production process generates a significant number of end-of-life products and by-products. Therefore, it is necessary to develop efficient recycling methods and investigate the remanufacturing of tungsten carbide using recycled materials. Herein, we have recovered 99.9% of the tungsten in cemented carbide hard scrap as tungsten oxide via an alkali leaching process. Subsequently, using the recovered tungsten oxide as a starting material, tungsten carbide has been produced by employing a self-propagating high-temperature synthesis (SHS) method. SHS is advantageous as it reduces the reaction time and is energy-efficient. Tungsten carbide with a carbon content of 6.18 wt % and a particle size of 116 nm has been successfully synthesized by optimizing the SHS process parameters, pulverization, and mixing. In this study, a series of processes for the high-efficiency recycling and quality improvement of tungsten-based materials have been developed.

• Journal of Environmental Impact Assessment
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• v.17 no.5
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• pp.263-270
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• 2008

The purpose of this study was to investigate the characteristics of the temple wastes and suggest the waste management guidelines for temples in natural parks. Study results revealed four important findings. First, it was found that the average quantity of the total temple wastes was 85,786g/day which was composed of general wastes(44,617g/day), food wastes(20,292g/day), recycling wastes(20.825g/day), and buddhist service wastes(60g/day). The average generation per capita of the temple wastes was 1,511g/capita day and the average bulk density was 0.102kg/l. Second, the food scrap was of small quantity(72.5g/day) because the traditional buddhist eating method, "Baru meal(鉢盂供養)" prohibits food abuse. This amount is very little compared to that produced in the general household in Korea. Third, the average quantity of the buddhist service wastes was 300-1,650g/one time. This wastes occupied 0.07% of the total temple wastes. Fourth, the average waste generated by visitors was 182.8g/person, which occupied 87.1% of the total temple wastes and costed 52,100,000 Wons to treat.

• Journal of Powder Materials
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• v.21 no.2
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• pp.131-136
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• 2014

Cathode materials and their precursors are prepared with transition metal solutions recycled from the the waste lithium-ion batteries containing NCM (nickel-cobalt-manganese) cathodes by a $H_2$ and C-reduction process. The recycled transition metal sulfate solutions are used in a co-precipitation process in a CSTR reactor to obtain the transition metal hydroxide. The NCM cathode materials (Ni:Mn:Co=5:3:2) are prepared from the transition metal hydroxide by calcining with lithium carbonate. X-ray diffraction and scanning electron microscopy analyses show that the cathode material has a layered structure and particle size of about 10 ${\mu}m$. The cathode materials also exhibited a capacity of about 160 mAh/g with a retention rate of 93~96% after 100 cycles.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.140-143
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• 2001

A study has been made on the recovery of nitric acid and valuable metals such as Cu, Sn, Pb from the spent nitric etching solutions. The nitric acid was extracted effectively by TBP but the heavy metals such as Fe, Cu, Sn, Pb were not extracted by TBP from the spent nitric etching solutions. From the experimental results, 95% of nitric acid in spent etching solution was extracted at O:A ratio of 3:1 with five stage by 60% TBP and 98% of nitric acid was stripped from the loaded organic phase at O:A ratio of 1:1 with four stages by distilled water. After extracting nitric acid, Cu was recovered as a metal by electrowinning effectively and Sn was successfully removed by precipitation method by adjusting the pH of raffinate solution. Finally, Pb was recovered by cementation with iron scrap at $65^{\circ}C$. Parameters controlling the cementation process, such as temperature, pH and the effect of the additives were investigated.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.3-8
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• 2001

The mineral industry of the United States is going through a challenging time. The US as an industrial nation faces with increasing demand in raw materials to fuel various industrial sectors but, at the same time, meeting environmental constraints associated with excavating and extracting these raw materials. In addition, gradual depletion of material resources. and the necessity of handling more complex forms of resources of primary origin have led to a decline in her resource productivity, once a strategic advantage of the U.S. As a result. the United States currently relies heavily upon foreign importation of various materials such as precious and strategic metals. However, since the US is the major consumer of most of these materials, the recovery of these values from scrap would help renew her position as a resource-producing nation, and ultimately help spur its domestic economy. Furthermore. recycling would also help maintain a clean environment and reduce energy consumption. In this paper. the author attempts to discuss opportunities and challenges lied ahead of the US mineral in relation to recovering their much-needed resources from secondary sources. The need and demand in various metals in the US will be reviewed and discussed. The implication of resource recovery from secondary sources will also be discussed. Extraction methods treating secondary sources are inherently different from those for primary sources. There is a need for new technologies which are metallurgically efficient and environmentally benign in treating secondary sources. Ways to meet such a need will be examined and key factors to be considered in approaching these challenges will be discussed.

• Korean Journal of Materials Research
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• v.13 no.9
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• pp.619-624
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• 2003

This paper describes a method to control Mn and Fe contents in recycled AZ91D ingots, based on the mutual solubility of Mn and Fe in AZ91 alloy melts. For this purpose, Fe solubility with the change of Mn content and temperature was investigated in the homogenized and re-precipitated liquid AZ91 alloy. The increase of the amount of Mn added to the melt resulted in the decrease of Fe content. The data obtained in this study was adopted to the pilot plant for recycling of the scrap. As a result, Mn and Fe contents measured in the recycled ingot were in good agreement with ASTM B93 standard.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1756-1767
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• 2008

Recently, a global trend has been established to facilitate the use of waste materials in geotechnical engineering applications. In Korea, where there is the need to save natural resources as these may become scare in the near future and to prevent excessive ground excavation for natural aggregates. The annual production of scrap tire and bottom ash has sharply increased in recent years. Therefore, it will be good waste resource recycling, if we can utilize the above wastes as fill materials in soft ground. In this study, based on the proven feasibility of bottom ash and tire shred-soil mixtures as lightweight fill materials, tire shred-bottom ash mixtures were suggested as a new lightweight fill material to replace the conventional construction material(soil) with bottom ash. Therefore, the main objective of this research is to investigate the feasibility of tire shred-bottom ash mixtures in order to estimate their suitability for the use of lightweight fill materials. So we carried out the performance tests of 2 large scale embankment which were made with tire shred-bottom ash mixture and the conventional fill material(weathered soil) respectively.