Zeolites, minerals with the formula Mx/n[AlO2]x(SiO2)y] zH2O, are environmentally friendly materials used as water treatment adsorbents, gas adsorbents, and petrochemical catalysts. This study used a mixture of aluminum black dross and waste glass to synthesize zeolites via a hydrothermal synthesis and analyzed the effects of varying reaction time on phase changes under different synthesis conditions. With increased reaction times, a phase change from zeolite Na-P1 to analcime was observed; on employing hydrothermal synthesis at 150°C for 96 h, the majority of the crystalline structures changed into analcime. Heavy metal cation adsorption was tested to assess the applicability of the synthesized analcime to water treatment. Zeolite adsorption of at least 95% was observed for both Pd and Cd ions. Although a higher level of adsorption was observed for Pb ion than Cd ion, Cd ion was demonstrated to undergo relatively faster adsorption when tested under optimal pulp density at the same level of adsorption (95%).

Global tantalum production from mines averages 1800 tons per year and hardly increases, but demand for tantalum in the electronics industry consistently increasing. Globally, 50% of total tantalum produced is being used for tantalum capacitors manufacturing, almost all demand from various industries is mainly met by primary resources only. Tantalum production and supply predominantly dominated by Congo and Rwanda which accounts for > 50%, add disadvantages for the strategic and economic competitiveness of other nations. To address the monopoly dominated by Congo and Rwanda, and the disparity of tantalum primary reserve, exploitation of secondary resources can alternatively address the drawbacks of primary resource distribution. Currently, hardly < 1% of tantalum getting recycled, and the poor recycling rate of tantalum is mainly contributed by the lack of efficient and sustainable valorization technology for recycling tantalum-bearing scraps like electronic capacitors and semiconductor industry tantalum scrap. In the current investigation, a sustainable tantalum extraction process from scrap dominated by hydrometallurgical route has been developed. Tantalum scrap which is passive to leach for tantalum recovery was calcinated for oxidation of TaN content and followed by tantalum has been leached using a mixture of NaF and HCl, a specially developed novel lixiviant for the purpose as an HF substituent. Calcination process parameter like temperature and time requirement for oxidation was optimized varying one parameter at a time. Then, the efficient leaching condition was optimized for quantitative leaching of tantalum. The process can achieve 99.99% efficient leaching, the process can successfully be applied for feasible industrial-scale tantalum scrap recycling. The HF substituent lixiviant can add advantages to overcome occupational and industrial operation safety challenges associated with HF lixiviant. The reported valorization process can be a sustainable tantalum recycling process that simultaneously can address UNO sustainable development goal, WEEE directive, and UNEP E-Waste Management goal.

The electrode in the waste capacitor and capacitor producing semiconductor industry produces a significant amount of tantalum-bearing e-wastes. The lack of proficient technology poses a significant challenge for valorization and the circular economy of tantalum-bearing waste. Currently, we are developing a process for the purification and recovery of metal values from such waste through a combination of hydrometallurgy and pyrometallurgy techniques. In our present investigation, the initiative for the study includes an understanding of rudimentary thermochemistry and thermal characterization of semiconductor industry tantalum scrap for possible pretreatment. Also includes identification of suitable pretreatment conditions for feasible oxidation of semiconductor industry tantalum scrap to generate leachable tantalum oxide. Followed by the possibility for leaching has been investigated through the Pourbaix diagram and selected case studies. Our leaching investigation reasonably indicated that tantalum nitride in the semiconductor industry tantalum scrap can efficiently be oxidized using Na2CO3 (1:1 weight ratio) at 500 degrees C and roasting time of 3 h. Then Ta leaching using concentrated HF and H2SO4 at 50:50 wt% ratio as a lixiviant can be achieved efficiently. As the roasting and leaching process is feasible and scalable, Ta can be successfully extracted from the semiconductor industry tantalum scrap on an industrial scale.

Owing to the increasing ACW generation, asbestos detoxification and recycling technologies are required for environmental and economic reasons. Recently, microwave heat treatment is being considered an efficient method for ACW detoxification. In the present study, ACW is detoxified through a microwave heat treatment involving SiC plates. These plates absorb the microwaves and radiate the heat, thereby enhancing the heat treatment efficiency relative to those of existing methods, in which the microwave heat treatment method requires a temperature higher than 1100 °C. In the present study, thermochemical experiments were conducted by applying chemical additives during the microwave heat treatment. To determine the optimal heat treatment temperature based on the chemical added, the detoxification response of the ACW as a function of heat treatment was investigated for different chemical additives, and the crystal structure and microstructure changes were analyzed using X-ray diffraction and scanning electron microscopy. ACW was then detoxified by applying the optimal temperature derived for each chemical additive in microwave heat treatment involving SiC plates. According to the results, asbestos is eliminated in the ACW at 800 and 900 °C with magnesium chloride and sodium hydroxide, respectively, as the additives.

Studies on detoxification of asbestos and recovery of valuable metals from detoxified asbestos were conducted. First, asbestos was detoxified by a microwave heat treatment that used silicon carbide balls, which are inorganic heating elements that absorb microwaves and release heat at room temperature. For efficient heat treatment, the asbestos containing waste (ACW) was powdered by crushing and grinding processes and then a detoxification heat treatment was performed. Microwave heat treatment temperature and time variables were adjusted to investigate the detoxification properties according to heat treatment conditions. After heat treatment, treated ACW was analyzed for detoxification properties through crystal structure and microstructure analysis using X‐ray diffraction (XRD) and scanning electron microscopy. Complete asbestos detoxification was confirmed when the microwave heat treatment was performed at 1200°C for over 60 min and at 1300°C for over 10 min. Second, recovery of valuable metals from detoxified asbestos was carried out. The main components, Si, Ca, and Mg, of detoxified asbestos‐containing waste (DACW) were separated and recovered in the form of SiO 2 , CaSO 4 , and Mg(OH) 2 . SiO 2 was separated first after treatment of DACW with HCl. Ca in the form of sulfate, CaSO 4 , was recovered when subsequent treatment of remaining aqueous acid solution with H 2 SO 4. The remaining Mg was recovered by precipitation as Mg(OH) 2 form under strong basic conditions. Each separated component was confirmed by XRD and Inductively Coupled Plasma (ICP) analysis.

요 약 생활계에서 발생되는 폐비닐은 토사, 금속, 유리 등의 이물질로 인해 고형연료(SRF, Solid Refuse Fuel)로 사용되었지만 최근 환경문 제로 인해 고형연료의 사용량이 감소하고 있어 재활용이 필요한 실정이다.본 연구에서는 폐비닐 재활용을 위해 우선 생활계 폐비닐로 생 산된 복합 재생원료와 영농폐비닐로 생산된 PE 단일 재생원료에 대해 분석을

Even asbestos-containing waste (ACW) are highly harmful to humans, it continues being produced due to the massive disposal of asbestos-containing products.A development of asbestos detoxification and recycling technologies is required.Heat treatment using microwave is the most efficient method for ACW detoxification.However, microwave heat treatment method has the limitation that asbestos does not absorb microwave at room temperature.That is why, in this study, ACW was detoxified by microwave heat treatment adding the ACW between SiC plates, which are inorganic heating elements that absorb microwaves at room temperature.In order to improove the heat transfer, ACW was crushed and pulverized and then heated using microwave.Microwave heat treatment temperature and time variables were adjusted to investigate the detoxification properties according to heat treatment conditions.After heat treatment, treated ACW was analyzed for detoxification properties through crystal structure and microstructure analysis using X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Asbestos-containing waste has been continuously generated due to the disposal of asbestos-containing products, and the development of asbestos detoxification and recycling technologies are required due to a lack of landfills. In this study, asbestos-containing waste was detoxified by a microwave heat treatment that used silicon carbide balls, which are inorganic heating elements that absorb microwaves and release heat at room temperature. For efficient heat treatment, the asbestos-containing waste was powdered by crushing and grinding processes and then a detoxification heat treatment was performed. The asbestos-containing waste powder particle size, heat treatment temperature, and heat treatment duration were adjusted to investigate the effect of the heat treatment conditions on the detoxification characteristics. After the heat treatment, the detoxification characteristics of asbestos-containing waste were analyzed using X-ray diffraction and scanning electron microscopy. Asbestos was completely removed from the crystal structure and microstructure when the microwave heat treatment was performed at 1200 °C for over 60 min and at 1300 °C for over 30 min. Using silicon carbide balls in the heat treatment enabled fast heat treatments because heating to the target temperature was possible within a short period of time.

In the current investigation, we synthesize zeolite using two different waste streams, such as aluminum dross and waste glass powder, for its potential application in indium and tin recovery from the leach liquor of waste liquid crystal display (LCD) glass. The aluminum dross (Al resource) and waste glass powder (Si resource) were used as raw materials for the synthesis of zeolite. Zeolite was synthesized using different weight ratios of Al dross and waste LCD glass by hydrothermal synthesis route using NaOH. The weight ratio variations of Al dross and waste LCD glass in this study are 0.3:1, 0.5:1, 1:1, 2:1, 3:1, and 4:1 using 2 M NaOH hydroxide by the hydrothermal technique. The synthesized zeolite was analyzed by X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) followed by the possible application for recovery/extraction of indium and tin from leach liquor of waste LCD glasses. The indium extraction of average 93.66%, and tin extraction of 93.10% could be achieved from mixed solution indium and tin chloride. The significant achievement of the current investigation is that it can address two environment problems simultaneously, i.e., waste LCD glass and Al dross, and can be used for value recovery from waste LCD, LCD etching waste like secondary resources.

The current study focuses on the understanding of leaching kinetics of metal in the LTCC in general and silver leaching in particular along with wet chemical reduction involving silver nanoparticle synthesis. Followed by metal leaching, the silver was selectively precipitated using HCl as AgCl. The precipitated AgCl was dissolved in ammonium hydroxide and reduced to pure silver metal nanopowder (NPs) using hydrazine as a reductant. Polyvinylpyrrolidone (PVP) used as a stabilizer and Polyethylene glycol (PEG) used as reducing reagent as well as stabilizing reagent to control size and shape of the Ag NPs. An in-depth investigation indicated a first-order kinetics model fits well with high accuracy among all possible models. Activation energy required for the first order reaction was 21.242 kJ mol(-1) for Silver. PVP and PEG 1% each together provide better size control over silver nanoparticle synthesis using 0.4 M hydrazine as reductant, which provides relatively regular morphology in comparison to their individual application. The investigation revealed that the waste LTCC (an industrial e-waste) can be recycled through the reported process even in industrial scale. The novelty of reported recycling process is simplicity, versatile and eco-efficiency through which waste LTCC recycling can address various issues like; (i) industrial waste disposal (ii) synthesis, of silver nanoparticles from waste LTCC (iii) circulate metal economy within a closed loop cycle in the industrial economies where resources are scarce, altogether. (C) 2017 Elsevier Ltd. All rights reserved.

The effect of ethanol addition during milling on the milling performances of Ta-hydride powders was investigated for hydride and dehydride processes during Ta recycling process. As the Ta-hydride was milled in a conventional dry atmosphere, Ta2O was dominantly formed due to the increased temperature of the Ta-hydride pieces because they were rubbed against each other and crushed by the ring mill system. However, with the addition of ethanol solvent, the ratio of the Ta2H phase increased compared to the Ta2O phase, and the size of the powders reduced and became more uniform. These were attributed to the enhanced hydride formation and reduced contact between the Ta-hydride powders and air by wetting them. Therefore, an optimum amount of ethanol addition and milling time can enhance the formation of additional Ta-hydrides, while preventing oxidation during milling.

This study analysis of environmental and economic value through Life Cycle Assessment(LCA) on recycling technologies for flat panel display devices. Environmental impacts were assessed for the five categories of impacts: global warming, resource depletion, acidification, eutrophication, and photochemical oxide production. When recycling 1kg of waste glass, global warming impact was 1.93E-02 kg CO2-eq., resource depletion impact was 1.26E-04 kg Sb-eq., acidification impact was 3.29E-05 kg SO2-eq., eutrophication impact was 6.13E-06 kg PO43--eq., and the photochemical oxide production impact was 1.64E-05 kg C2H4-eq. When 1kg of recycled glass is produced, the result of analysis of environmental and economic value can be taken as 72 won. When producing 3,800 kg of recycled glass, it is possible to obtain 275,076 won of gain and 3,471,750 won in annual amount of waste glass.

We investigated enhanced tantalum (Ta) hydride formation by using the catalytic effect of tungsten (W) to reduce the hydrogen dissociation energy. Ta turning scrap was hydrated at various temperatures by using a W crucible and conventional Al2O3 crucible, and the structural and chemical properties of the hydrated powders were compared. Structural investigation by X-ray diffraction and chemical analysis using an oxygen-nitrogen-hydrogen determinator showed that the Ta hydride was formed at temperatures lower than 500 degrees C, while the dehydride formation process occurs at temperatures higher than 600 degrees C in conventional Al2O3 crucibles. However, when the W crucible is used, the hydrogen incorporation into the Ta lattice was enhanced at both low and high temperatures. This enhancement was attributed to the reduced energy of dissociation of H-2 into mono-atomic H because of the catalytic effect of W, finally resulting in enhanced Ta hydride formation.

Considering the value of silver metal and silver nanoparticles, the waste generated during manufacturing of low temperature co-fired ceramic (LTCC) were recycled through the simple yet cost effective process by chemical-metallurgy. Followed by leaching optimization, silver was selectively recovered through precipitation. The precipitated silver chloride was valorized though silver nanoparticle synthesis by a simple one-pot greener synthesis route. Through leaching-precipitation optimization, quantitative selective recovery of silver chloride was achieved, followed by homogeneous pure silver nanoparticle about 100 nm size were synthesized. The reported recycling process is a simple process, versatile, easy to implement, requires minimum facilities and no specialty chemicals, through which semiconductor manufacturing industry can treat the waste generated during manufacturing of LTCC and reutilize the valorized silver nanoparticles in manufacturing in a close loop process. Our reported process can address issues like; (i) waste disposal, as well as value-added silver recovery, (ii) brings back the material to production stream and address the circular economy, and (iii) can be part of lower the futuristic carbon economy and cradle-to-cradle technology management, simultaneously.

본 연구에서는 Inconel 713C 스크랩을 원료로 아르곤-산소 탈탄 공정을 이용하여 니켈계 초내열합금을 재활용 하였다. 아르곤-산소 탈탄 공정에서 아르곤은 1,000 sccm으로 지속적으로 주입되었고 산소는 100, 250, 500 sccm의 유량으로 10, 20, 30 분씩 주입되었다. 산소 주입 초기 단계에서는 산소 양이 증가하면서 Al, Cr, 및 Mo 함량은 증가하였고 탄소 함량은 감소하였다. 그리고 Al 함유량은 탄소의 반응이 끝난 후 Al, Cr 등의 원소와 산화가 일어났기 때문에 첨가원소와 탄소의 반응에 의해 감소하였다. 결과적으로, Al 함유량이 감소하였기 때문에 ${\gamma}^{\prime}$상이 줄어들었으며 이는 Al이 ${\gamma}^{\prime}$을 형성하는 주요 원소이기 때문이다. 또한, 탄소의 양이 줄어들면서 탄화물도 줄어들었으며 산소가 과잉 공급된 시료의 기계적인 물성(강도, 경도 등)은 감소하게 된다. In this study, the Ni base superalloy was recycled by Argon oxygen decarburization(AOD) process using an inconel 713C scrap. During AOD process, argon gas was continuously injected 1,000 sccm and oxygen gas was injected into 10, 20 and 30 minutes of 100, 250 and 500 sccm.. In early stage of oxygen injection, the oxygen dose increased with increasing Al, Cr, and Mo content and decreasing C content. And Al content was decreased by carburization with added elements in late stage Because of oxidation was occurred with Al, Cr etc. after the reaction of carbon has been finished. From the results, the ratio of ${\gamma}^{\prime}$ phase reduced due to decreasing of Al content for that reason Al is the main element to form the ${\gamma}^{\prime}$ phase. Also carbide reduced owing to decreasing of C content so the mechanical properties of the specimens excessively injected by excess $O_2$ gas were decreased.

We report on the theoretical and experimental investigations about the Ta-hydride formation depending on the temperature for recycling of Ta scraps. The structural investigations based on scanning electron microscope and X-ray diffraction (XRD) showed that the amount of hydrogen incorporated into the Ta matrix varied with hydridation temperature. The XRD measurement showed that the H/Ta mole ratio in Ta-hydride increased with increasing the hydridation temperature up to 700°C and then decreased with increasing the temperature furthermore. Depending on the hydridation temperature, various phase of Ta-hydride, such as TaH0.93 and Ta2H were formed and this hydride process was verified by thermodynamic analysis.

Glass-ceramics were developed many years ago and have been applied in many fields such as electronics, chemistry, optics, etc. Much is already known about glass-ceramic technology, but many challenges in glass-ceramic research are still unresolved. Recently, large amounts of slag have steadily increased in the steel industry as by-products. To promote recycling of industrial waste, including steel industry slags, many studies have been performed on the fabrication of basalt-based high-strength glass-ceramics. In this study, we have fabricated such ceramics using various slags to replace high performance cast-basalt, which is currently imported. Glass-ceramic material was prepared in similar chemical compositions with commercial cast-basalt through a pyro process using slags and power plant by-product (Fe-Ni slag, converter slag, dephosphorization slag, Fly ash). The properties of the glass-ceramic material were characterized using DTA, XRD, and FE-SEM; measurements of compressive strength, Vicker's hardness, and abrasion were carefully performed. It is found that the prepared glass-ceramic material showed better performance than that of commercial cast-basalt.

Every year 25 million tons of slag is generated as an industrial by-product by the steel-making industry in Korea. Using slag to manufacture high-strength glass-ceramic materials is increasingly becoming a feasible option, and recently several types of slag have been used in combination to manufacture glass-ceramic materials such as basalt-based glass-ceramics. Glass-ceramic materials with two different chemical compositions were prepared using Fe-Ni slag, basic oxygen furnace slag, dephosphorization slag, and fly ash by melting and casting and a subsequent heat treatment. X-ray diffraction analyses confirmed that clinopyroxene and CaAl2SiO8 were the primary phases in the formed glass-ceramics, while thermogravimetry and differential thermal analyses showed that their glass-transition points were 709-724 degrees C and crystallization temperatures were 888-918 degrees C. The morphologies and constituent components were also examined using field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. The stable phases were calculated as functions of the temperature using FactSage. Finally, the compressive strength, Vickers hardness, and wear rate values of the glass-ceramics were evaluated in order to elucidate their physical properties.