• Journal of Powder Materials
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• v.28 no.2
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• pp.164-172
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• 2021

Titanium is the ninth most abundant element in the Earth's crust and is the fourth most abundant structural metal after aluminum, iron, and magnesium. It exhibits a higher specific strength than steel along with an excellent corrosion resistance, highlighting the promising potential of titanium as a structural metal. However, titanium is difficult to extract from its ore and is classified as a rare metal, despite its abundance. Therefore, the production of titanium is exceedingly low compared to that of common metals. Titanium is conventionally produced as a sponge by the Kroll process. For powder metallurgy (PM), hydrogenation-dehydrogenation (HDH) of the titanium sponge or gas atomization of the titanium bulk is required. Therefore, numerous studies have been conducted on smelting, which replaces the Kroll process and produces powder that can be used directly for PM. In this review, the Kroll process and new smelting technologies of titanium for PM, such as metallothermic, electrolytic, and hydrogen reduction of TiCl₄ and TiO₂ are discussed.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2011.10a
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• pp.101-102
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• 2011

• Resources Recycling
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• v.24 no.3
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• pp.11-15
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• 2015

In order to develop a technology for the recovery of pure tin from the Sn containing industrial wastes (SIWs), a process consisted of high temperature reduction and electrorefining was investigated. The tin which exists as oxide in SIWs was successfully reduced by two consecutive high temperature treatments and 92.7% of the tin was recovered. The purity of the tin thus obtained was increased to 99.87% by electrorefining. By applying the results obtained in this work, a commercial process can be developed to produce pure tin metals from domestic spent resources, which can reduce the amount of tin imported from abroad.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.3
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• pp.260-270
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• 2008

The economics of manganese nodules mining was assessed based on 36 scenarios which reflect recent changes of the metal market. Those scenarios included optimistic/neutral/pessimistic prospect for the cost, 2 production scales(1.5 MT and 3 MT) and 6 assumptional paths of future metal prices. A large part of scenarios, in which optimistic or neutral prospect for the cost and metal prices were assumed, showed good economic feasibility of the project. For example, 37.12% of Internal Rate of Return(IRR) was obtained in the scenario of 3 MT production, neutral cost prospect and present metal price maintained in the future.

• Resources Recycling
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• v.31 no.3
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• pp.27-39
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• 2022

The global demand for lithium-ion batteries (LIBs) has been continuously increasing since the 1990s along with the growth of the portable electronic device market. Of late, the rapid growth of the electric vehicle market has further accelerated the demand for LIBs. The demand for the LIBs is expected to surpass the supply of lithium from natural resources in the near future, posing a risk to the global lithium supply chain. Moreover, the continuous accumulation of end-of-life LIBs is expected to cause serious environmental problems. To solve these problems, recycling the spent LIBs must be viewed as a critical technological challenge that must be urgently addressed. In this study, recycling LIBs using pyrometallurgical processes and post-processes for efficient lithium recovery are briefly reviewed along with the major accomplishments in the field and current challenges.

• Resources Recycling
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• v.18 no.5
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• pp.72-81
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• 2009

The demand for platinum group metals for various advanced industries has been growing due to their excellent physical and chemical properties. Since the deposit of platinum minerals are restricted to few countries, their recovery from various secondary resources has becomes an important issue to related industries for keeping the supply reliably. In this paper, patents on the metallurgical technologies for the platinum group metals were analyzed. The search of patent was limited to the open patents of USA (US), European Union (EP), Japan (IP), and Korea (KR) from 1986 to 2006. Patents were surveyed using key-words searching and selected by filtering criteria. The trend of patents was analyzed by the years, countries, companies, and technologies.

• Journal of Conservation Science
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• v.33 no.4
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• pp.297-312
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• 2017

In the ancient iron-making process, a slag former was often added so that iron and other minerals in the ore could be smoothly separated. However, there are insufficient data for judging whether a slag former was added. Thus, in this study, we conducted a smelting experiment to understand the material characteristics of a steel structure that differed depending on the addition of a slag former. It was found that the steel structure produced in the first experiment had a total Fe content of 39.45-52.94 wt%, which decreased to 34.89-38.92 wt% in the second and third experiments. CaO compounds such as calcite, gehlenite, and hercynite appeared, in addition to iron oxides, after the addition of a slag former. As a result of an assessment of whether a slag former was added by comparing the ratio between the components, it was found that the ratio of $CaO/SiO_2$ was 0.42. From a comparative analysis of $Al_2O_3/SiO_2$ and $CaO/SiO_2$, it was judged that the ratio of $Al_2O_3$ and $SiO_2$ can be utilized as an index to judge similar systems of smelting process (ore, furnace wall, and fuel).

• Korean Journal of Metals and Materials
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• v.47 no.10
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• pp.605-612
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• 2009

The suitability of twin roll strip casting for Ag-27.5%Cu-20.5%Zn-2.5%Mn-0.5%Ni brazing alloy (known as HS-49D) was examined in the present work and the mechanical properties and microstructure of the strip were also investigated. The effect of annealing heat treatment on the properties was also studied. The new manufacturing process has applications in the production of the brazing alloy. XRD and microstructural analyses of the Ag-27.5%Cu-20.5%Zn-2.5%Mn-0.5%Ni strip revealed a eutectic microstructure of an Ag-rich matrix (FCC) and a Cu-rich phase (FCC) regardless of heat treatment. The results of mechanical tests showed tensile strength of 434 MPa and 80% elongation for the twin roll casted strip. Tensile results showed decreasing strengths and increasing elongation with annealing heat treatment. Microstructural evolution and fractography were also investigated and related to the mechanical properties.

• Korean Journal of Heritage: History & Science
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• v.57 no.2
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• pp.6-25
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• 2024

This study concentrated on a report on the results of smelting experiments conducted eight times by the Jungwon National Research Institute of Cultural Heritage, put together the goals and results of the operation, and examined changes in the content of experiments and in the experimental results. First, changes related to operation, such as the ratio of raw materials to fuel and the presence or absence of additives, were reviewed depending on the operation goal. In addition, the results of metallurgical analysis of raw materials, formations, and byproducts were summarized and reviewed by comparing them with materials excavated from the ruins. The operation method varied up to the eighth smelting experiment in terms of iron ore roasting, additives, and raw material/fuel ratio. After reviewing the results again, pure iron with a low carbon content began to be confirmed through metallurgical analysis. As a result, it was confirmed that the charging ratio of raw materials and fuel plays an important role depending on the purpose of production. In addition, most of the products are gray cast iron, and it was deemed that this is due to changes in the internal structure of the pig iron while it was left in the furnace for a long time. The iron was an ingot that was in a molten state even though the carbon content did not reach 4.3%, where the process reaction takes place, and it was deemed to have been caused by excessive operating temperature. Based on the previously reviewed results and the structure and shape of the experimental furnace used in other ironmaking technology restoration experiments, this study finally attempted to restore the structure of an ancient iron smelting furnace, including the furnace's upper structure. By comprehensively referring to the remaining conditions of the excavated iron smelting furnace and the characteristics of the blow pipe, the form of the ancient iron smelting furnace was subdivided into six categories: furnace wall thickness, furnace height, blower height, blow pipe size, furnace inner wall shape, and top shape, and a restoration plan was proposed. To improve the problems of the restoration plan and the Jungwon National Research Institute of Cultural Heritage's experiments that have been conducted through continuous trial and error, an experiment that reflects changes in operating methods by lowering the furnace height and controlling the blowing volume is necessary.

• Journal of Conservation Science
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• v.28 no.4
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• pp.367-376
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• 2012

The ironware production technology is a measure to fathom the society's level of development in time. To understand iron-manufacure methods in the past, various investigations on the fine structures and additions of ironware remains and Iron ingot have been conducted in a way of natural science. This study metallurgically reclassifies remains excavated in iron-manufacture remains located in Beokje, Goyang, which are thought to be in time of Goryeo Dynasty, and draws an inference from the element analysis on the iron-manufacture and smelting technology. Iron ingot samples with a cast iron structure are divided into those with a white cast iron structure and those with a grey cast iron rich in P. The P content of grey cast iron appeared to be the result of adding a flux agent like lime, iron ingot and carbon steel iron ingot with a cast iron structure excavated in the area is regarded as pig iron which was made without a refining process. In this study it seems that two methods of making ironware were used in the area; one is the method of making ironware by pouring cast iron to the casting, and the other is the method of making carbon steel through the refinement of pig iron. It appears that highly even steel structure of carbon steel and a small amount of MnS inclusion are very similar with that of the modern steel to which Mn is artificially added. Nevertheless, these data alone cannot be used to determine the source of Mn in the carbon steel of the excavated from the iron-manufacture remains, which raises the need for further studies on the source and the possibility of carbon steel via the iron-manufacture process of cast iron.