• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.95-96
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• 2006

Stainless steel sludge is generated as a waste in the grinding process, and the possibility of recycling stainless steel is considered here. In this study, we considered the possibility of using the stainless steel sludge as metal powder for MIM or raw material for metal foam. For the MIM process, the metal powder will need some improvement, and flotation and spheroidizing processes of the sludge are necessary. For fabrication of the metal foam, untreated sludge can be used, and steel foam about 90% porosity is produced.

• Resources Recycling
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• v.30 no.6
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• pp.76-82
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• 2021

The separation of palladium from crude metal, which is obtained from electronic waste using pyrometallurgy was achieved through electrolysis. This was done to recover high-purity copper. The oxidation potentials of these metals are a fundamental part of the analysis of electrolytic separation of palladium and impurity metals. To achieve this, copper, iron, and nickel were dissolved in the electrolyte, and palladium and aluminum were found to be recoverable from anode slime. During the electrolysis for palladium separation, palladium was present in the anode slime and was obtained with a recovery of 97.46 % indicating almost no loss. 4N-grade copper was recovered from the electrodeposition layer at the cathode.

• Journal of Soil and Groundwater Environment
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• v.15 no.3
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• pp.52-60
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• 2010

The stone-dust is an unavoidable by-product of aggregate production, which is produced about 0.8~1.0 million $m^3$ annually. The stone-dust is currently regarded as a hazard material on environment because it is classified as an industrial waste in the Waste Management Law of Korea. At present, the stone-dust is considered as a environmentally hazardous material, and is classified as an industrial waste according to the Waste Management Law of Korea. In this study, we assessed the heavy-metal contamination of the stone-dust on surrounding environments by various leaching tests. Leaching experiments (such as Korea Standard Leaching Procedure (KSLP), Soil Environment Preservation Act of Korea (SEPAK), Toxicity Characteristic Leaching Procedure (TCLP), and Synthetic Precipitation Leaching Procedure (SPLP)) show that very low heavy metals (As, Cd, Cu, Pb, Zn, Hg) and CN are leached out, or much less than each regulatory thresholds. The resuts of the leaching test with time in acidic solution (initial pH 5 and 3) indicate that pH-buffering minerals are present in the stone-dust. These results suggest that the stone-dust can not potentially affect adverse impact on surrounding environments such as surface water, groundwater and soil etc..

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.157-160
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• 2014

We examined and compared the feasibility of vegetable oils with synthetic thermal conductive oils to recover highly purified copper metal from waste jelly-filled communication cables. While polydimethylsiloxane shows relatively poor separation efficiency under entire operating conditions, dibenzyltoluene and waste vegetable oil show the high separation efficiency if the appropriate operating temperature and time were given. By running 50 kg-class equipment with waste vegetable oils, we obtained 100% copper metal recovery with 99.2% purity at $300^{\circ}C$ for 60 min.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.69-74
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• 2002

Incineration method of municipal solid waste is the general method for reduction it's quantity and weight. Municipal solid waste incineration ash is classified two general types of ash : fly ash((MWFA) and bottom ash(MWBA)). MWFA containing a high degree heavy-metal may give rise to a serious environmental trouble. Therefore, this study was carried out to examine utilization of fly ash. In this study, we tried to find the recycling method of fly ash as a environmental-friendly artificial aggregate. The artificial aggregate using fly ash was tested for the various aspects, including physical properties and environmental stability. The qualities of artificial aggregate are similar to it of lightweight aggregate, and the heavy metal leaching concentration are very lower than a limitation of KSLT and EP.

• Carbon letters
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• v.7 no.3
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• pp.180-187
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• 2006

The treatment of piggery wastes was carried out at pilot scale using a multilayered metal-activated carbon system followed by carbon bed filtration. The physicochemical properties were obtained from treated samples with aqueous solutions containing metallic ions such as $Ag^+$, $Cu^{2+}$, $Na^+$, $K^+$ and $Mn^{2+}$, which main obsevations are subjected to inspect surface properties, color removal properties by Uv/Vis and EDX. Multilayered metal-activated carbons were contacted with waste water to investigation of the simultaneous catalytic effect for the COD, BOD, T-N and T-P removal. The removal results for the piggery waste using multilayered metal-activated carbon bed was achieved the satisfactory removal performance under permitted values of Ministry of Environment of Korea. The high efficiency of the multilayered metal-activated carbon bed was determined by the performance of this material for trapping, catalytic effect and adsorption of organic solid particles.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.259-263
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• 2001

There are several steps such as slicing, lapping, chemical etching and mechanical polishing in the silicon wafer production process. The chemical etching step is necessary to remove damaged layer caused In the slicing and lapping steps. The typical etching liquor is the acid mixture comprising nitric acid, acetic acid and hydrofluoric acid. At present, the waste acid is treated by a neutralization method with a high alkali cost and balky solid residue. A solvent extraction method is applicable to separate and recover each acid. Acetic acid is first separated from the waste liquor using 2-ethlyhexyl alcohols as an extractant. Then, nitric acid is recovered using TBP(Tri-butyl phosphate) as an extractant. Finally hydrofluoric acid is separated with the TBP solvent extraction. The expected recovered acids in this process are 2㏖/l acetic acid, 6㏖/1 nitric acid and 6㏖/l hydrofluoric acid. The yields of this process are almost 100% for acetic acid and nitric acid. On the other hand, it is important to recover and reuse the metal values contained in various industrial wastes in a viewpoint of environmental preservation. Most of industrial products are made through the processes to separate impurities in raw materials, solid and liquid wastes being necessarily discharged as industrial wastes. Chemical methods such as solvent extraction, ion exchange and membrane, and physical methods such as heavy media separation, magnetic separation and electrostatic separation are considered as the methods for separation and recovery of the metal values from the wastes. Some examples of the application of solvent extraction to the treatment of wastes such as Ni-Co alloy scrap, Sm-Co alloy scrap, fly ash and flue dust, and liquid wastes such as plating solution, the rinse solution, etching solution and pickling solution are introduced.

• Carbon letters
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• v.7 no.2
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• pp.105-113
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• 2006

The electro-chemical removal (ECR) of water pollutants by metal-ACF electrodes from wastewater was investigated over wide range of ECR time. The ECR capacities of metallic ACF electrodes were related to physical properties such as adsorption isotherm, surface area and pore size and to reaction time. Surface morphologies and elemental analysis for the metal supported ACFs after electro-catalytic reaction were investigated by scanning electron microscopy (SEM) and energy disperse X-ray (EDX) to explain the changes in adsorption properties. The IR spectra of metallic ACFs for the investigation of functional groups show that the electro-catalytic treatment is consequently associated with the removal of pollutants with the increasing surface reactivity of the activated carbon fibers. The metal-ACFs were electro-catalytically reacted to waste water to investigate the removal efficiency for the COD, T-N, $NH_4$-N, $NO_3$-N and $NO_2$-N. From these removal results of the piggery waste using metallic ACFs substrate, satisfactory removal performance was achieved. The removal efficiency of the metallic ACFs substrate was mainly determined by the properties of the material for adsorption and trapping of organics, and catalytic effects.

• Journal of Soil and Groundwater Environment
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• v.29 no.2
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• pp.1-10
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• 2024

With industrial development, the inevitable increase in both organic and inorganic waste necessitates the exploration of waste treatment and utilization methods. This study focuses on co-pyrolyzing lignin and red mud to generate metalbiochar, aiming to demonstrate their potential as effective adsorbents for water pollutant removal. Thermogravimetric analysis revealed mass loss of lignin below 660℃, with additional mass loss occurring (>660℃) due to the phase change of metals (i.e., Fe) in red mud. Characterization of the metal-biochar indicated porous structure embedded with zero-valent iron/magnetite and specific functional groups. The adsorption experiments with 2,4-dichlorophenol and Cd(II) revealed the removal efficiency of the two pollutants reached its maximum at the initial pH of 2.8. These findings suggest that copyrolysis of lignin and red mud can transform waste into valuable materials, serving as effective adsorbents for diverse water pollutants.

• Resources Recycling
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• v.20 no.3
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• pp.12-27
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• 2011

DOWA group has been working on metal recycling applying the smelting and refining process of KOSAKA Smelter. DOWA has developed it's metal recycling technologies through the treatment of black ore(complex sulfide ores) that contain many kinds of non-ferrous metals. In addition to these special technologies, DOWA has strengthened its hydrometallurgical process of precious metals and ability to deal with low-grade materials such as used electrical appliances or vehicles. On the other hand, JX Nippon Mining & Metals Corporation(JX-NMMC) carries out its metal recycling and industrial waste treatment businesses employing advanced separation, extraction and refining technologies developed through its extensive experience in the smelting of non-ferrous metals. JX-NMMC collects approximately 100,000t/y of copper and precious metal scraps from waste sources such as electronic parts, mobile phones, catalytic converters, print circuit boards and gold plated parts. These items are recycled through the smelting and refining operations of Saganoseki smelter and Hitachi Metal-recycling complex(HMC). In this like, metal recycling industries combined with environmental business service in Japan have been developed through excellent technologies for mineral processing and non-ferrous smelting. Also, both group, Dowa and JX-NMMC, were contributed to establish Japan's recycling-oriented society as the typical leading company of non-ferrous smelting. Now. it is an important issue to set up the collection system for e-waste.