• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.95-100
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• 2005

The using amount of preservative-treated wood equipments has been increased. Specially, chromate copper arsenate (CCA) has been widely used to exterior wood. We are faced to the disposal problem after service period of CCA treated wood due to its toxic heavy metals. For the disposal of end-used treated wood, land-filling and incinerating methods are mainly applied. The essential problem of incinerating is an arsenic release into atmosphere. Low pyrolysis is suggested as the methods of protecting arsenic release during incineration. The heavy metals were recovered after combustion of the treated wood at the low temperature which arsenic can not released. The recovery amounts of effectiveness compounds was determined in various solvents (citric acid, nitric acid, sulfuric acid, acetic acid, phosphoric acid) and different temperature (300, 400, $500^{\circ}C$). The higher temperature was applied, the more copper was recovered. The chromium was difficult to be recovered on the carbonized CCA treated wood at 0.5% acid concentration. The recovery mass of arsenic decreased on the higher combustion treated wood. The recovery of chromium was difficult due to the chemical change of the chromium arsenate during pyrolysis.

• Membrane Journal
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• v.32 no.6
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• pp.486-495
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• 2022

This study presents the improved recovery efficiency of rare metal ions through the modified separation membrane wettability and hydrogen ion permeation in the anion exchange membrane (AEM) under the recovery process of combined electrodialysis and solvent extraction. Specifically, the wettability of the separator was enhanced by hydrophilic modification on one separator surface through polydopamine (PDA) and lipophilic modification on the other surface through SiO₂ or graphene oxide (GO). In addition, the modified surface of AEM with polyethyleneimine (PEI), PDA, poly(vinylidene fluoride) (PVDF), etc. reduces the water uptake and modify the pore structure for proton ions generation. The suppressed transport resulted in the reduced hydrogen ion permeation. In the characterization, the surface morphology, chemical properties and composition of membrane or AEM were analyzed with Scanning Electron Microscopy (SEM) and Fourier Transform-Infrared Spectroscopy (FT-IR). Based on the analyses, improved extraction and stripping and hydrogen ion transport inhibition were demonstrated for the copper ion recovery system.

• Journal of the Mineralogical Society of Korea
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• v.27 no.4
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• pp.207-222
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• 2014

In order to recover the metallic copper powder from the mine-waste rock, heap bioleaching, Fe removal and electrowinning experiments were carried out. The results of heap leaching with the mine-waste rock sample containing 0.034% Cu showed that, the leaching rate of Cu were 61% and 62% in the bacteria leaching and sulfuric acid leaching solution, respectively. Sodium hydroxide (NaOH), hydrogen peroxide ($H_2O_2$) and calcium hydroxide ($Ca(OH)_2$) were applied to effectively remov Fe from the heap leaching solution, and then $H_2O_2$ was selected for the most effective removing Fe agent. In order to prepare the electrolytic solution, $H_2O_2$ were again treated in the heap leaching, and Fe removal rates were 99% and 60%, whereas Cu removal rates were 5% and 7% in the bacteria and sulfuric acid leaching solutions, respectively. After electrowinning was examined in these leaching solution, the recovery rates of Cu were obtained 98% in bacteria and obtained 76% in the sulfuric leaching solution. The dendritic form of metallic copper powder was recovered in both leaching solutions.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.10a
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• pp.289-297
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• 2005

• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.8-11
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• 1994

Disposal of hazardous ions in the aqueous streams is a significant industrial waste problem.. Waste streams from electronics, electroplating, and photographic industries contain metal ions such as copper, nickel, zinc, chromium(IV), cadmium, aluminum, silver, and gold, amongst others in various aqueous solutions such as sulfates, chlorides, fluorocarbons, and cyanides. Typical plating solutions having similar compositions are listed in Table 1. Spent process streams in catalyst manufacturing facilities also contain precious metals such as Ag, Pt, and Pd. Developing an effective recovery process of these metal ions for reuse is important.

• Transactions on Electrical and Electronic Materials
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• v.14 no.1
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• pp.20-23
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• 2013

When applying superconducting wire to power machines, an investigation needs to be carried out on the characteristics of wire phase changes in connection with the insulating layer. This study examined trends in the increase of the wire's resistance and the characteristics of its recovery from quenching by a current-applied cycle at temperatures of 90 K, 180 K, and 250 K. The procedure was conducted based on the thickness and presence (or absence) of the insulating wire layers. To achieve this, YBCO thin-film wires with the same critical temperatures were prepared with copper and stainless steel stabilizing layers. At levels (-one, three, and five-), with superior performance, polyimide pressure-sensitive adhesive tape was attached to the wires at a very low temperature. The eight prepared test samples were wound around the linear frames. The wire's voltage and current created from the phase change characteristics were measured at the wire's prescribed temperature, using the four-point probe method. The wire's resistance and recovery characteristics were examined for each cycle at temperatures of 90 K, 180 K, and 250 K.

• Environmental Engineering Research
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• v.24 no.4
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• pp.646-653
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• 2019

Recovery of valuable metals in the industrial wastewater and sludge has attracted an attention owing to limited metallic resources in the earth. In this study, we firstly fabricated Ti/Ir-Ru electrodes by spin coating technique for effective recovery of Cu in electrowinning process. Two different Ti/Ir-Ru electrodes were fabricated using 100 and 500 mM of precursors (i.e., Ir-Ru). SEM-EDX and AFM revealed that Ir and Ru were homogenously distributed on the surface of Ti plate by the spin coating, in particular the electrode prepared by 500 mM showed distinct boundary line between Ir-Ru layer and Ti substrate. XRD, XPS, and cyclic voltammetry also revealed that characteristics of IrO₂, RuO₂, and TiO₂ and its electrocatalytic property increased as the concentration of coating precursor increased. Finally, we carried out Cu recovery experiments using two Ti/Ir-Ru as anodes in electrowinning process, showing that both anodes showed a complete removal of Cu (1 and 10 g/L) within 6 h reaction, but much higher kinetic rate constant was obtained by the anode prepared by 500 mM. The findings in this study can provide a fundamental knowledge for surface characteristics of Ti/Ir-Ru electrode prepared by spin coating method and its potential feasibility for effective electrowinning process.

• Resources Recycling
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• v.20 no.6
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• pp.63-70
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• 2011

Enviromental friendly leaching process for the recovery of cobalt and copper from the cobalt concentrate was investigated by organic acids as a leaching reagent. The experimental parameters, such as organic acid type, concentrations of leachant, time and temperature of the reaction as well as the solid to liquid ratio were tested to obtain the optinum conditions for the leaching of cobalt and copper. The results showed that citric acid was the most effective leaching reagent among the organic acids used in this experiment. About 99% of cobalt, 95% of copper and 70% of nickel was dissolved by 2.0 M of citric acid. Addition of 3.0 vol.% of hydrogen perioxide was effective to enhance the leaching efficiency and the optinum temperature was found to be about $70^{\circ}C$.

• Resources Recycling
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• v.27 no.1
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• pp.55-63
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• 2018

Physical property changes of printed circuit board (PCB) according to heat treatment conditions were investigated. The heat treatment was carried out in air and nitrogen atmosphere at temperature range from $200^{\circ}C$ to $325^{\circ}C$. Thermogravimetric analysis showed that the PCB was pyrolyzed in two steps. The thickness of PCB expanded by 11~28% at about $300^{\circ}C$ in both air and nitrogen atmosphere as layer disintegration occurred. Mechanical strength of PCB decreased from 338.4 MPa to 20.3~40.2 MPa due to the delamination caused by the heat treatment. The heated printed circuit boards were crushed and sieved for analysis of density distribution and liberation degree of copper according to particle size. As a result of the density distribution measurement, non metallic particles and copper particles were concentrated into different size range, respectively. The liberation degree of copper was improved from 9.3% to 100% at size range of $1,400{\sim}2,000{\mu}m$ by heat treatment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1729-1734
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• 2009

About 40 million automotive vehicles all over the world and 0.55 million in Korea were retired from use annually. Every nation is desperate to decrease environmental pollution by ELVs(End of Life Vehicles) and try to tighten the regulations. Europe passed laws requiring OEMs to increase vehicles' recovery and reuse rate to 95% by 2015 from current 84%. The ferrous parts, 75% of total automobile weight, are almost recycled whereas the remaining 25% of the non-metal -predominantly plastics as well as form, glass and rubber- and the non-ferrous materials -copper, nickel and aluminium- end up in landfills. The recycling status of non-ferrous materials represented by copper and nickel is reviewed and how much the recycling rate will be improved is calculated.