• Korean Journal of Heritage: History & Science
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• v.50 no.1
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• pp.4-17
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• 2017

In this research, the chemical composition of the iron artifacts from the late 6th-century to early 7thcentury Baekje remains in Gwanbuk-ri, Buyeo, specifically of the nine iron artifacts including slags, furnace walls and ingot iron excavated in the District "Na", were examined by observing their chemical compounds and microstructures. As a result, GB1 and GB6 were determined to be proto-reduction lumps whereas GB2, GB3, GB4 and GB5 were determined to be tempered slags, respectively. Also, he furnace wall GB7 were containing mullite and cristobalite, which are high temperature index minerals, The extrusion temperature was found out to be about $1200{\sim}1300^{\circ}C$, and it is most likely that the smelting temperature in the furnace was in that temperature range. GB8 ingot iron was determined to be a forged ironware. This ingot iron was an intermediary product for making ironware and its nonmetallic inclusions displayed similar microstructure and contents compared to the forged iron. Because of the existence of proto-reduction lumps and forged iron, the iron making facility located in District "Na" most likely had a small-scale iron making facility that handled iron bloom smelting and refining processes.

• Resources Recycling
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• v.30 no.5
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• pp.25-31
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• 2021

Smelting reduction of spent lithium-ion batteries results in the production of metallic alloys in which reduced cobalt, nickel and copper coexist. In this study, we investigated the leaching of the metallic alloys containing the above three metals together with iron, manganese, and silicon. The mixture of hydrochloric acid and hydrogen peroxide as an oxidizing agent was employed, and the effect of the concentration thereof, the reaction time and temperature, and pulp density was investigated to accomplish the complete leaching of cobalt, nickel, and copper. The effect of the hydrogen peroxide concentration and pulp density on the leaching was prominent, compared to that of reaction time and temperature, especially in the range of 20 to 80℃. The complete leaching of the metals present in metallic alloys, except silicon, was accomplished using 2 M HCl and 5% H₂O₂ with a pulp density of 30 g/L for 150 min at 60℃.

• Journal of Energy Engineering
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• v.11 no.3
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• pp.269-275
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• 2002

Experimental studies are carried out to find the behavior of sulfur compounds which are evolved during high temperature pyrolysis of coals at the smelting reduction process for iron ore. Three kinds of bituminous coals, such as Hunter & Mt. Thorley (Australia), and Ensham (South Africa) are used. And forms of sulfur compound and their amounts are analyzed at the temperature ranges of 800~110$0^{\circ}C$. Then H$_2$S is the major gas, but CS$_2$ and COS are minor gases. Sulfur compounds in three coals are distributed into the volatiles (gas & tar) and coal char as the ratio of approximately 50%：50%, respectively.

• Journal of Technology Innovation
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• v.10 no.1
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• pp.174-200
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• 2002

Technological capabilities of POSCO (Pohang Iron & Steel Co.) have been developed through acquisition, catch-up, and generation stage. In 1970s standardized operation technologies were acquired based on Japan's technological cooperation. The prime route of technological acquisition was overseas training and operation technologies were articulated by mock and real operation. In 1980s POSCO focused to catch-up advanced technologies through in-house R&D activities. Technological informations were broadly accumulated, task force teams were constructed for important technological tasks, and the scope of technological innovation covered nearly all fields. In 1990s POSCO launched long-term projects based on the large-scale investment and challenged the new fronts of steel technologies. Frontier technologies such as smelting reduction and thin slab casting were early commercialized and new technological concepts were emerged. In conclusion, this article suggests some implications on the development of technological capabilities in Korea.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.71-74
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• 2008

In order to resolve the problems which appear after the clean large ingot production process, the impurities which are involved in the steel smelting process should be removed by developing cleaner materials. Through the rationalization of cogging process that is the first forging process of large ingot the quality is to be improved. For the sake of the optimization of an open die forging process and the improvement of the subject matter frequency ratio, a hazard precise die forging process must be developed and a Near Net Shape Forming accomplished. As a result, energy can be reduced by minimizing an after control process. In order to produce large axes and other forming parts, processing techniques are to be developed. In this context, this paper is a study about a reduction ratio, dies width ratio and rotary angles, the amount of overlap, and intends to analysis cogging processes, utilizing Deform-3D cogging module

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.719-726
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• 2021

Through the process of chemical vapor deposition, Tungsten Hexafluoride (WF₆) is widely used by the semiconductor industry to form tungsten films. Tungsten Hexafluoride (WF₆) is produced through manufacturing processes such as pulverization, wet smelting, calcination and reduction of tungsten ores. The manufacturing process of Tungsten Hexafluoride (WF₆) is required thorough quality control to improve productivity. In this paper, a real-time detection system for oxidation defects that occur in the manufacturing process of Tungsten Hexafluoride (WF₆) is proposed. The proposed system is implemented by applying YOLOv5 based on Convolutional Neural Network (CNN); it is expected to enable more stable management than existing management, which relies on skilled workers. The implementation method of the proposed system and the results of performance comparison are presented to prove the feasibility of the method for improving the efficiency of the WF₆ manufacturing process in this paper. The proposed system applying YOLOv5s, which is the most suitable material in the actual production environment, demonstrates high accuracy (mAP@0.5 99.4 %) and real-time detection speed (FPS 46).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.649-653
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• 1999

A magnetic fluid separation technology was confirmed to be very effective to remove the suspended solids (SS) from aquacultural recirculating water, In this study, the effects of operating variables on the characteristics of SS removal were investigated through the test runs using magnetite of 2 $\mu$m mean diameter as magnetic powder. Magnetic flocculation here formed by adsorbing fine magnetites on the surface of suspended solid was observed. The strength of magnet was of significance in determining the SS removal efficiency as well as the capacity of the equipment. In addition, the SS removal efficiency decreased with an increase in the superficial liquid velocity, but the effect became negligible when the mass ratio of magnetite to the suspended solids was higher than 1.0.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.9-18
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• 2001

1. EAF Dust in Japan - Generation and Characteristics. The quantity of dust generated from EAF shops in Japan was estimated to be 520,000 tons/year in 1999. Extremely fine dust (or fume) is formed in the EAF by metal vaporization. Its characteristics such as chemical compositions, phases, particle size, leaching of heavy metal are mentioned. 2. EAF Dust Treatment Methods in Japan. In 1999, 61% of EAF dust was treated by regional zinc recovery processing routes, 25% went to landfill disposal, 4% was reused as cement material, and 10% was treated by on-site processing routes. The problems of EAF dust treatment methods in Japan are: (1) very high treatment cost, and (2) heavy environmental load (leaching of heavy metal, emission of dioxins, depletion of disposal sites, etc). It has been much hoped for that new dust management technology would be developed. 3. New technology of EAF dust treatment in Japan. In Japan, some new technologies of EAF dust treatment have been developed, and some others are in the developing stages. Following five processes are mentioned:. (1) Smelting reduction process by Kawasaki Steel, (2) DSM process by Daido Steel, (3) VHR process by Aichi Steel, (4) On-site dust direct recycling technology, and (5) Process technology of direct separation and recovery of iron and zinc metals contained in high temperature EAF off gas by the Japan Research and Development Center fur Metals.

• Resources Recycling
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• v.30 no.6
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• pp.36-42
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• 2021

Spent lithium-ion batteries are treated by reduction-smelting at high temperatures to recover valuable metals. Solvent extraction and precipitation of the HCl leaching solution of reduction-smelted metallic alloys resulted in a filtrate containing Ni(II) and a small amount of Si(IV). Adsorption and precipitation experiments were conducted to recover pure Ni(II) compounds from the filtrate. Si(IV) was selectively loaded onto polyacrylamide, but this method did not efficiently filter the solution due to an increase in viscosity. The addition of Na₂CO₃ as a precipitant to the filtrate led to the simultaneous precipitation of Ni(II) and Si(IV). However, it was possible to recover nickel oxalate with a purity higher than 99.99% by selectively precipitating Ni(II) with the addition of Na₂C₂O₄ as a precipitant.

• Resources Recycling
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• v.31 no.1
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• pp.12-20
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• 2022

The smelting reduction of spent lithium-ion batteries results in metallic alloys containing Co, Cu, Fe, Mn, Ni, and Si. A process to separate metal ions from the sulfuric acid leaching solution of these metallic alloys has been reported. In this process, ionic liquids are employed to separate Fe(III) and Cu(II). In this study, D2EHPA and Cyanex 301 were employed to replace these ionic liquids. Fe(III) and Cu(II) from the sulfate solution were sequentially extracted using 0.5 M D2EHPA with three stages of cross-current and 0.3 M Cyanex 301. The stripping of Fe(III) and Cu(II) from the loaded phases was performed using 50% (v/v) and 60% (v/v) aqua regia solutions, respectively. The mass balance results from this process indicated that the recovery and purity percentages of the metals were greater than 99%.