• Journal of Korea Foundry Society
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• v.41 no.1
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• pp.11-15
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• 2021

Scrap steel used as a charge material in melting process of cast iron foundry is mostly press scrap. The press scrap usually causes several problems including energy loss, workability, safety, and so on. By charging the shredded scrap instead of the press scrap, it is expected that the above-mentioned problems can be solved. In this study, the power basic units to produce cast iron by using the press and shredded scrap are compared in 3t/h medium-frequency induction melting furnace. Charging the shredded scrap instead of the press scrap was confirmed that the power basic unit is improved by about 15%. The characteristics and restrictions of the usage according to the shape and size of scrap steel were considered.

• Journal of Environmental Health Sciences
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• v.39 no.3
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• pp.248-255
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• 2013

Objectives: The purpose of this paper is to define the level of recycling standards and its process in paper scrap. As pollution is increased by improperly treated paper scrap, the government has recently strengthened the management of the paper scrap. Methods: In this study, the current status of paper scrap recycling was investigated through a 2012 field survey, and the classification and recycling standards for paper scrap in developed countries and institutions were also investigated through a literature review in order to introduce optimal recycling standards. Results: As a result, the contents of contaminants were identified as the most important recycling standard, and the contents of contaminants in paper scrap was measured at less than 1.0% at most companies. The recycling standard for paper scrap was determined to be below 3% contaminants in the case of paper and 5% in the case of board. In this study, recycling stage was determined by considering regulations on resources and practices in the field. Conclusions: The recycling standard for paper scrap was determined to be below 3% and 5% contaminants for paper and board, respectively.

• Korean Journal of Materials Research
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• v.21 no.12
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• pp.673-678
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• 2011

With an increased production of Printed Circuit Boards (PCBs) in electronic equipment, the consumption of solder alloys is growing globally. Recently, increasing importance of recycling solder scrap has been recognized. Generally, solder scrap contains many impurities such as plastics and other metals. Hazardous components must be eliminated for recycling solder scrap. The present work studied pretreatment for reuse of solder scrap alloys. An experiment was conducted to enhance the cleanliness of solder scrap melt and eliminate impurities, especially lead. Physical separation with sieving and magnetic force was made along with pyrometallurgical methods. A small decrease in lead concentration was found by high temperature treatment of solder scrap melt. The impurities were removed by filtration of the solder scrap melt, which resulted in improvement of the melt cleanliness. A very low concentration of lead was achieved by a zone melting treatment with repeated passage. This study reports on a pretreatment process for the reuse of solder scrap that is lead free.

• Journal of Korea Foundry Society
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• v.41 no.2
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• pp.132-138
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• 2021

In this study, the power basic units to produce cast iron by using the press and shredded scrap are compared in 16t/h low-frequency induction melting furnace. Charging the shredded scrap instead of the press scrap was confirmed that the power basic unit is improved by about 5%. The energy characteristics according to the shape and size of scrap steel and the effect of the furnace size were investigated. Finally, the strategy to improve the utilization of this technology was proposed.

• Journal of the Korean institute of surface engineering
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• v.53 no.6
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• pp.322-329
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• 2020

The utilization of aluminum scrap is a subject of great importance in terms of reducing energy consumption and environmental protection. However, aluminum scrap contains impurities, which can degrade the properties of aluminum alloy, especially corrosion resistance. This study examines the effect of scrap charge rate of aluminum alloys about microstructures and corrosion characteristics. According to the metallographic examinations, Mg2Si tended to become coarser and its uniformity was decreased by increasing aluminum scrap charge rate. The immersion test exhibited corrosion progressed through the eutectic areas due to micro-galvanic interactions. Electrochemical measurements revealed that excess aluminum scrap could reduce the intergranular corrosion resistance of aluminum alloys. Results showed that the scrap charge rate is important factor in the design of corrosion resistance of aluminum die casting alloys.

• Journal of Korea Foundry Society
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• v.36 no.3
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• pp.81-87
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• 2016

In this study, the effect of scrap ratio on the mechanical properties of Zr alloys was studied. Oxygen content in the ingot cake increased rapidly with increasing fraction of scrap, which can be attributed to the surface oxide of scrap including small pieces of turning, chips, etc. Iron content did not increase much with the increasing addition of scrap, suggesting scrap materials was well reserved in the iron-free container. As-cast structure of Zr alloy with the scrap:sponge ratio displayed plate/or needle ${\alpha}$ phase and no appreciable change of the cast structure was observed with change of scrap fraction. The strength increases with increasing fraction of scrap, which can be attributed to the increase of oxygen content. The ductility decreased slightly with increase of scrap fraction. Dislocation-oxygen interaction is known to increase the strength at the expense of ductility. Ingot cake with intentionally added $Fe_2O_3$ exhibited the drastic decrease of the formability, even exhibited the brittle fracture behavior during rolling. The oxidation resistance, however, increased with the increase of scrap fraction because of high oxygen content, which may prevent more penetration and diffusion of oxygen into matrix.

• Korean Journal of Materials Research
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• v.13 no.4
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• pp.239-245
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• 2003

In order to explore the possibility to extract precious metals from PCB(Printed Circuit Board) scrap by gravity separation, a high temperature melting process was adopted, from the recycling view point, to investigate the influence of viscosity on A1$_2$$O_3$-CaO$-SiO_2$ slag system composed of PCB scrap. For optimizing the pre-treatment process of PCB scrap, an experimental condition for the complete calcination and oxidation of organic materials in PCB scrap was established and a quantitative analysis of oxidized PCB scrap was also carrie out. It was found that 6 hours were enough for the complete oxidation of PCB scrap at 1273 K in an atmosphere condition. A slag, l5wt%$A1_2$$O_3$-45wt%CaO-40wt%SiO$_2$, was chosen as a basic slag composition which is determined based on the quantitative analysis of PCB scrap. Viscosities were measured in slag systems both made from pure fluxes and from PCB scrap with additional fluxes. Slag viscosities composed of pure fluxes were measured to be 5.29 poise and 30.52 poise at temperatures of 1773 and 1573 K, whereas that of PCB scrap with additional fluxes were 3.37 poise and 69.89 poise, respectively.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.34
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• pp.155-159
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• 1995

For the relationship between conformance cost and the individual elements of non-conformance, an analysis was made of the relationship between inspection cost and training cost and scrap cost. As a result it was explained that there was all a positive correlation between training cost and scrap cost, and between inspection cost and scrap cost. Like this, training and inspection cost and scrap cost have a positive correlation. Judging from the fact that the coefficient of inspection cost is lower than that of training cost in the comparison of the coefficient of each cost, it can be analyzed that the change in scrap cost is influenced by the change in training cost more greatly than the change in inspection cost. If doing so, it can be interpreted that scrap cost and rework cost do not still decrease in spite of increasing in education and training cost and prevention cost. This result may represent the problem as to whether education and training cost is effectively expended for prevention activity. Accordingly, to cope with this situation, it is thought that scrap cost should be cut by establishing the effective prevention measure for causing the increase of scrap cost.

• Journal of Environmental Science International
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• v.22 no.9
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• pp.1105-1113
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• 2013

This paper attempted to estimate the emissions of HFC-134a from scrap truck as a result of measuring the residual quantities of HFC-134a in air conditioner of scrap truck. We measured the residual amounts in the scrap truck of 138 by applying commercial recover for refrigerants. The average residual rate(disposal-phase emission factor) is reported to be $44.3{\pm}3.3%$ within a confidence interval of 95%. Recent year model trucks exhibit the higher residual rates. Little variation, however, is observed in regard to vehicle size. The HFC-134a emission quantity from scrap truck in 2011 is estimated to be 55,908 $tCO_2$-eq that demonstrates 21.4% increase to compare with that in 2007. As the numbers of truck have increased dramatically during the last two decades, the emissions of HFC-134a from scrap truck would increase sharply in the next coming years. HFC-134a is a very high GWP greenhouse gas. therefore have to reduce the emissions from the scrap truck and need to find ways to recycle. The chemical compositions of refrigerants from scrap truck are quite similar to those of new refrigerants, suggesting that the refrigerants from scrap truck could be reused as refrigerant.

• Journal of Korea Foundry Society
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• v.41 no.4
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• pp.342-348
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• 2021

Almost all ferrous foundries use press scrap as the main charge material. In this study, we tried to reduce the melting energy by optimizing the shape and size of press scrap. The experiment was conducted using 3t/h medium frequency induction melting furnaces at two foundries. In the case of the improved condition, customized press scrap was used for initial charging, and small press scrap was used for additional charging. The energy reduction effect of the improved condition was enhanced by reinforcing the cleaning process of the return scrap surface. The reduction ratios of the melting energy basic unit by the improved condition at the two foundries were almost the same (23.3 and 23.9%). The improved condition was very effective in both foundries with different basic unit levels. The reasons for energy reduction and the economic effects of the improved condition were described.