Spin-off pyroprocessing technology and inert anode materials to replace the conventional carbon-based smelting process for critical materials were introduced. Efforts to select inert anode materials through numerical analysis and selected experimental results were devised for the high-throughput reduction of oxide feedstocks. The electrochemical properties of the inert anode material were evaluated, and stable electrolysis behavior and CaCu generation were observed during molten salt recycling. Thereafter, CuTi was prepared by reacting rutile (TiO2) with CaCu in a Ti crucible. The formation of CuTi was confirmed when the concentration of CaO in the molten salt was controlled at 7.5mol%. A laboratory-scale electrorefining study was conducted using CuTi(Zr, Hf) alloys as the anodes, with a Ti electrodeposit conforming to the ASTM B299 standard recovered using a pilot-scale electrorefining device.

Because of its unique properties, tungsten is a strategic and rare metal used in various industrial applications. However, the world's annual production of tungsten is only 84000 t. Ammonium paratungstate (APT), which is used as the main intermediate in industrial tungsten production, is usually obtained from tungsten concentrates of wolframite and scheelite by hydrometallurgical treatment. Intermediates such as tungsten trioxide, tungsten blue oxide, tungstic acid, and ammonium metatungstate can be derived from APT by thermal decomposition or chemical attack. Tungsten metal powder is produced through the hydrogen reduction of high-purity tungsten oxides, and tungsten carbide powder is produced by the reaction of tungsten powder and carbon black powder at 1300–1700oC in a hydrogen atmosphere. Tungsten scrap can be divided into hard and soft scrap based on shape (bulk or powder). It can also be divided into new scrap generated during the production of tungsten-bearing goods and old scrap collected at the end of life. Recycling technologies for tungsten can be divided into four main groups: direct, chemical, and semi-direct recycling, and melting metallurgy. In this review, the current status of tungsten smelting and recycling technologies is discussed.

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.

전기⋅전자산업이 급격하게 발전함에 따라 유가금속 및 희소금속의 수요가 급증하고 있다. 유가금속들은 주로 제련산업 공정에서 다량 방출되며, 회수기술 부족으로 중화, 치환, 흡착을 통해 폐기되어 큰 비용으로 경제적이지 못하다. 이에 분리막을 통한 유가금속회수 소재개발의 필요성이 강조되고 있다. 유가금속이 포함된 습식제련 공정 침출액(15% 황산 용액, 온도 60°C)은 다량의 다가이온과 1가이온을 포함하고 있기 때문에 이온별 분리가 가능해야 하며, 특히 구리와 같은 2가 유가금속 분리성능이 우수해야 한다. 또한, 지속적인 분리/농축을 위해 산에 대한 안정성이 중요하다. 따라서 본 연구를 통해 2가 금속 배제율 98%, 유량 33GFD 성능을 1개월 이상 유지하는 나노분리막 제조 연구 개발을 수행하고 있다.

본 연구에서는 제련 공정에서 발생되는 희소금속 및 유가금속 회수를 위하여 상용화 된 나노여과막인 NE40, 70, 90 (Toray Chemical Korea) 와 내산성 분리막인 NP030 (Nadir), Duracid (GE), NanoPro (AMS)를 선정 하였으며, 습식 제련 공정을 모사하기 위해 황산 15% 용액에 침지한 시간 (0 ~ 63일)에 따라 투과 특성을 평가하였다. 공급 용액으로는 대표적인 1가 이온으로 NaCl을, 2가 이온으로는 MgSO4를 2,000 ppm 사용하여, 황산 15% 용액에 63일 동안 노출하였을 때의 투과 성능 변화를 측정 하였다. 이러한 투과 특성 평가를 이용하여, 제련 공정에서 발생되는 희소금속 및 유가금속 회수를 위한 최적의 분리막을 선정 할 수 있었다.

본 연구에서는 제련 공정에서 발생되는 희소금속 및 유가금속 회수를 위한 나노여과막으로 도레이 케미칼에서 생산되는 NE40, 70, 90을 선정하였으며, 습식 제련 공정을 모사하기 위해 황산 15% 용액에 침지하여 시간에 따라 표면 특성을 분석하였다. 황산 노출 전/후의 표면 특성 분석을 위해, 주사전자현미경(SEM), 원자간력현미경 (AFM), 감쇠전반사-푸리에변환 적외선분광기 (ATR-FTIR), 광전자분광기 (XPS)를 이용하여 분석하였다. 이를 바탕으로 Piperazine 기반의 NE40, 70의 분리막이 m-Phenylenediamine (MPD) 기반의 NE90 분리막과 비교하여 산에 대한 영향이 많음을 알 수 있었으며, 내산성을 가지는 분리막을 위해 MPD 기반의 분리막이 유리함을 보여주었다.

V2O5-TiO2 catalysts were prepared by various methods. V2O5-TiO2 were prepared by sol-gel method with different drying conditions (aerogel and xerogel), and V2O5 supported on TiO2 obtained by sol-gel method with precipitation-deposition method and impregnation method. The performance of the V2O5-TiO2 catalysts was investigated for the selective oxidation of hydrogen sulfide in the stream containing both ammonia and excess water. All the catalysts showed good dispersion of vanadium and they had high H2S conversion with no or little production of sulfur dioxide. The V2O5-TiO2 aerogel catalyst prepared by sol-gel method with drying under super critical condition had the highest surface area which led to better catalytic activity compared to those by other synthesis methods.

Recycling technology research in the copper smelting industry is necessary because the recovery of valuable metals from generated waste can offset the cost of raw materials. The cost of imported raw materials, can exert a significant impact on profitability. In order to perform this research review of previous studies about the base characteristics of the target waste was needed. In this study, copper slag and copper alloy smelting slag generated in the process, along with slag, ash, and sludge, were analyzed for particle size, distribution of the waste, physical characteristics, chemical composition, and inclusion of heavy metals. Copper slag and copper alloy particle separation results were able to remove most of the metal pieces that were at least 1 mm in size. In this waste, zinc, copper-containing metal were less than 80%. toxic substances, such as cadmium, arsenic and mercury, were removed by utilizing a hydrometallurgical process. The data suggests that this industry should be able to take advantage of new technologies the recover valuable metals from copper smelting waste.

The aim of this study is to evaluate the environmental impacts of recovery of valuable metals from the desulfurizing spent catalyst. Molybdenum, vanadium and nickel widely used in the area of catalysis. But the demand of these metals is full filled by industries. Every year, more than 18,000 tons spent catalysts are discarded. In most countries, spent catalyst is classified as a harmful waste. Thus, metal recovery from spent catalyst has been processed. The recovery process of molybdenum, vanadium and nickel from spent catalyst was mainly carried out wet process. However, this process are not suitable for economics and environmental aspects. Because environmental costs for removal of sulfur in the spent catalyst is high and huge amount of industrial wastewater occurs. Thus, it is necessary to develop a process which is efficient and does not cause pollution than the wet process. Thus, we have studied life cycle assessment about the dry process for the recovery of valuable metals.