• Title/Summary/Keyword: precious metals

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Electro-refining Characteristics of PCB-based Copper Anode for the Enrichment of Precious Metals (귀금속 농축을 위한 PCB 기반 양극동의 전해정련 특성)

  • Ahn, Nak-Kyoon;Shim, Hyun-Woo;Park, Kyung-Soo;Park, Jeung-Jin
    • Resources Recycling
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    • v.27 no.5
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    • pp.14-22
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    • 2018
  • In this study, scarp of PCB containing copper and precious metals was manufactured as an anode, and electrorefining experiments were conducted on change of $H_2SO_4$ concentration and current density. Through electrolytic refining experiments, the concentration of Cu and slime recovered from each electrode was analyzed, element behavior was confirmed, and current efficiency was also calculated. As the $H_2SO_4$ concentration was increased, the current efficiency and the purity of Cu decreased, but the precious metals in the anode slime were maximally concentrated with 2.0 M $H_2SO_4$. In addition, as the current density was increased, the current efficiency decreased and the purity of Cu showed a tendency to increase, and the precious metals in the anode slime were maximally concentrated with $300A/m^2$. As a result of the pilot scale experiments, the Au content was 8,705 mg/kg, the Ag content was 35,092 mg/kg in the anode slime. As compared with the initial content, Au was concentrated 16 times and Ag concentrated 14 times.

ELECTROLYTIC RECOVERY OF PRECIOUS METALS FROM DILUTED SOLUTIONS

  • Roland Kammel;Lieber, Hans-Wilhelm
    • Journal of the Korean institute of surface engineering
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    • v.14 no.4
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    • pp.209-214
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    • 1981
  • Electrolytic recovery of gold and silver from diluted solutions has at first been applied nearly 100 years ago. Compared with other recovery techniques electrolytic treatment offers several advantages. But to achieve high space-time yields special constructions of electrolytic cells for improved mass transfer are necessary. Ex-tended cathode surface areas and vigorous agitation are important features. Gold and silver recovery by use of newly developed electrolytic cell constructions - rotating tubular bed reactor and impact rod reactor - has been described. Calculations based on industrial application during several years are confirming that electrolytic recovery of precious metalss from diluted solutions has been operated in a very economic way.

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A Study on Specific Qualities of Gold Alloy and its Components (금합금의 특수성질 및 성분에 관한 연구)

  • Shin, Mu-Hak
    • Journal of Technologic Dentistry
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    • v.2 no.1
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    • pp.11-15
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    • 1980
  • This study was aimed at obtaining an ideal gold alloy for dental prothetic. The experiment was on physical characteristics of gold alloy and mixing proportion for proper appliance to living tissues. The most frequently used material in the past for dental prothetic was gold, but recently used are mictures or precious metals and non-precious, which are proved to affect on oral tissues. The experiment was to examine gold alloy over its physical and chemical qualities and to make an ideal type of gold alloy by means of statistic and laboratory research.

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Conversion and Aging Characteristics of Oxidation Catalyst for Natural Gas Vehicle with Lean-burn System (린번 천연가스자동차용 산화촉매의 정화 및 열화특성)

  • 최병철;윤성식;정종우
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.2
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    • pp.134-139
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    • 2003
  • This study was carried out to investigate the aging and conversion characteristics of oxidation catalysts for a natural gas vehicle with lean-bum system. The conversion of $CH_4$ was observed over the various composition ratio of PMs(Precious metals) and washcoating methods. On the fresh catalysts, Pd affected on the activity of $CH_4$ at low temperature more than other PMs in Pd-only and Rh/Pd/Pt catalysts. The activity at low temperature increased as a mount of Pd increases. On the aged catalysts, the $CH_4$ conversion efficiency of Pd-only catalyst with mono-layer washcoat decreased more than that of the other catalysts of $CH_4$ conversion. It was observed that the thermal durability of Rh/Pd/Pt catalysts with double-layer washcoat was better than the single washcoat catalyst.

Studies on the Interaction of Alkyl Thiophosphinate with Precious Metals

  • 김동수
    • Bulletin of the Korean Chemical Society
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    • v.16 no.4
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    • pp.321-325
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    • 1995
  • Adsorption mechanisms of diisobutyl dithiophosphinate (DIBDTPI) and diisobutyl monothiophosphinate (DIBMTPI) on gold and gold-silver alloys (80:20 and 50:50) have been studied. The adsorption mechanisms on gold-silver alloys can be explained by the EC mechanism involving an electron transfer step and a chemical reaction step. Thus, the adsorption should be controlled by the E of the electrochemical oxidation of the electrode involved and the pK of the metal collector complex. Both di- and mono- thiophosphinate adsorb on 50:50 Au-Ag alloy at lower potential than on 80:20 Au-Ag alloy surface. There are no significant differences between the reactivities of DIBDTPI and DIBMTPI with precious metals except that the dithio- compound can be oxidized to dimer on gold at high potentials, while the monothio- homologue cannot. In this regard, DIBDTPI may be a better surface active reagent for pure gold than DIBMTPI.

Study on A Laser-induced Photoredox Reaction for the Extraction of Precious Elements from Aqueous Solutions

  • Kyuseok Song;Hyungki Cha;Lee, Jongmin;Park, Jongsoo;Lee, Yong-Ill
    • Nuclear Engineering and Technology
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    • v.32 no.6
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    • pp.531-536
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    • 2000
  • The extraction of precious metals from aqueous solutions is performed by using a photoredox reaction with a Q-switched Nd:YAG laser. The metallic silver was efficiently precipitated and extracted from the silver nitrate solution by laser photolysis. An optimum reaction condition for silver extraction was determined by adjusting various experimental factors such as type of reducing agent, type of acids and reaction time. The composition of the reaction product was analyzed and it was identified as metallic silver, not other molecular types. The photoreaction of chromium(III) chloride in an acidic aqueous solution was also investigated. The 355 nm laser light was better suited for the reaction of silver nitrate as well as chromium(III) chloride in an acidic solution compared to the 532 nm light.

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Recovery of Valuable Metal from e-Wasted Electronic Devices (폐전자부품에서 유가금속 회수기술)

  • Kim, Yu-Sang
    • Journal of the Korean institute of surface engineering
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    • v.49 no.6
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    • pp.477-485
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    • 2016
  • As expensive and valuable metals being used in electronic and semiconducting industries are abandoned as industrial wastes after use of them, it is required to recover them from e-wasted electronics parts. Gold which is used for printed circuit boards or electronic equipments, accessories, etc., is one of e-Wasted materials and recently indium, gallium, zirconium, cobalt, molybdenum and lithium are bacome valuable metals to be recovered from the e-wastes. Since the amount of precious metals is now being faced with scarcity, lean too much on area and instability of supply, and industrial demands are rapidly increasing every year, it becomes more important to recover the valuable metals from the industrial wastes. In this review, we introduced technologies and research trend of the recovery processes of valuable metals from the e-wastes in high-tech devices over the world.

Biosorption of Chromium by Ca-loaded Laminaria Japonica Biomass

  • Lee, Hak-Sung;Snisarenko, Olga
    • Proceedings of the Korean Environmental Sciences Society Conference
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    • 2006.05a
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    • pp.333-337
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    • 2006
  • Biosorption can be used to eliminate heavy metals from industrial effluents or to recover precious metals from processing solutions. Scanning Electron Microscopedetected a high Cr sorption capacity of L. Japonica biomass almost 45% of its dry weight at pH 4.5. It should be mentioned that adjusting the pH influences on sorption capacity of biomass.

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Precious Metals Extraction Processing in Chloride Media by Using Ionic Liquids as Novel Extractant Systems

  • Kumar, Jyothi Rajesh;Choi, In-Hyeok;Lee, Jin-Young
    • Korean Chemical Engineering Research
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    • v.55 no.4
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    • pp.503-509
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    • 2017
  • The present experimental study proposed two ionic liquids (ILs) namely [Aliquat 336] [$HSO_4$] (prepared and characterized at our laboratory) and Cyphos 101 IL (supplied by Cytec Company) dissolved in two different diluents such as DCM (di-chloro-methane) and toluene applied for PMs extraction. The first IL [Aliquat 336] [$HSO_4$] prepared and confirmed the formation of final product by using FT-IR and TGA studies. The primary experiment in solvent extraction processing is kinetic effect; 0 to 30 time varied for PMs by using two ILs and confirmed the optimized extraction equilibrium time. This study was conducted for PMs (Pt, Rh and Cu) extraction and separation from each other by using proposed ILs. This is the primary study of the utilizing green solvents such as ILs as an extractant system for Pt, Rh and Cu extraction and possible separation.

Effect of concentration of H2SO4 on electrochemical properties of equipped Al sacrificial anode to prevent the corrosion and discolor of silver surface (은의 표면 부식 및 변색을 방지하기 위해 설치된 Al 희생양극의 전기화학적 특성에 미치는 황산 농도의 영향)

  • Shin, Byung-Hyun;Chung, Won-Sub
    • Journal of the Korean institute of surface engineering
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    • v.54 no.1
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    • pp.12-17
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    • 2021
  • Among the various precious metals, silver is used in various fields because of its low price than other precious metals. However, the surface of silver remains after rain in the atmosphere containing sulfur ions and chlorine ions, causing silver corrosion and discoloration. Existing documents have developed a anode to prevent corrosion but that are concentrated on secondary batteries. This study tried to prevent corrosion and discoloration of silver by using an Al sacrificial anode. Sulfuric acid decreased the potential of silver and increased the current density at active polarization and OCP. The amount of corrosion of silver with the Al sacrificial anode was reduced from 0.5 % to 6.5%. When silver is used for decoration outside, corrosion and discoloration of silver can be suppressed by installing an Al anode.