• 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.

• Journal of Environmental Science International
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• v.24 no.2
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• pp.245-251
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• 2015

The main objective of this study is to recovery valuable metals with metal particle size distributions in waste cell phone PCBs(Printed Circuit Boards) by means of pulverization and nitric acid process. The particle size classifier also was evaluated by specific metal contents. The PCBs were pulverized by a fine pulverizer. The particle sizes were classified by 5 different sizes which were PcS1(0.2 mm below), PcS2(0.20~0.51 mm), PcS3(0.51~1.09 mm), PcS4(1.09~2.00 mm) and PcS5(2.00 mm above). Non-magnetic metals in the grinding particles were separated by a hand magnetic. And then, Cu, Co and Ni were separated by 3M nitric acid. Particle diameter of PCBs were 0.388~0.402 mm after the fine pulverizer. The sorting coefficient were 0.403~0.481. The highest metal content in PcS1. And the bigger particle diameter, the lower the valuable metals exist. The recovery rate of the valuable metals increases in smaller particle diameter with same leaching conditions. For further work, it could improve to recovery of the valuable metals effectively by means of individual treatment, multistage leaching and different leaching solvents.

• Resources Recycling
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• v.29 no.2
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• pp.48-54
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• 2020

Korea, one of the manufacturing-oriented countries, consumes a large amount of metals in various industrial areas, but should depend on import of most of the metals from foreign countries. Also, global metal consumption amounts are increasing in relation to those of the world's reserve and production. Some metals are limitedly produced from only several centuries, which might lead to instability of the future supply of those metals. In addition, when such metals are hazardous, those may result in various environmental troubles with contamination. To resolve those issues, the recovery and the recycling of hazardous but valuable metals in industrial waste are desirable. However, there are overwhelming numbers of the metal types, waste generators, and amounts of wastes containing the metals, so it can be troublesome even to implement a preliminary status analysis to screen proper metals, wastes with the metals, and waste producers. Therefore, this study introduces the valuable metals for Korean industry, announced by public institutions, Also, a flow chart is suggested to facilitate a preliminary status analysis, using the domestic PRTR (Pollutant Release and Transfer Register) database, to screen proper waste producers containing some of hazardous but valuable metals such as nickel, cobalt, and manganese.

• Journal of Powder Materials
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• v.20 no.2
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• pp.107-113
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• 2013

In this study, the microstructure and valuable metals dissolution properties of PDP waste panel powders were investigated as a function of milling parameters such as ball diameter size, milling time, and rotational speed during high-energy milling process. The complete refinement of powder could achieved at the ball diameter size of 5 mm due to sufficient impact energy and the number of collisions. With increasing milling time, the average particle size was rapidly decreased until the first 30 seconds, then decreased gradually about $3{\mu}m$ at 3 minutes and finally, increased with presence of agglomerated particles of $35{\mu}m$ at 5 minutes. Although there was no significant difference on the size of the particle according to the rotational speed from 900 to 1,100 rpm, the total valuable metals dissolution amount was most excellent at 1,100 rpm. As a result, the best milling conditions for maximum dissolving amount of valuable metals (Mg: 375 ppm, Ag 135 ppm, In: 17 ppm) in this research were achieved with 5 mm of ball diameter size, 3min of milling time, and 1,100 rpm of rotational speed.

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.121-125
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• 2015

Distribution of rare earth metals (REMs) and rare valuable metals (RVMs) contents in coal ashes (fly ash, bottom ash, and pond ash) and leachate from 11 coal-fired power plants in Korea were investigated. Coal ashes and leachates were found to contain important REMs and RVMs such as Yttrium (Y) and Neodymium (Nd), which was in the range of 23~75 mg/kg. However, it still requires developing effective recovery and separation methods in order to utilize REMs and RVMs in ash and leachate. Recovery of valuable elements (Y and Nd) from various and extensive ash sources (8.21 million tons/year in 2013) can provide the existing power plants with additional profit; therefore, it can significantly improve economics of the power plants.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.26-40
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• 2000

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.183-187
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• 2001

Present states on reutilization of metal-bearing solid wastes in China including metal-containing gangue, red mud, nonferrous metallurgical slag or residue, arsenical slag, steel - iron slag, waste batteries, were described in detail. The wastes pile up at a large quantity, resulting in seriously potential harm to environment. Most of these wastes, however, contain valuable metals, which are regarded as important secondary resources for extracting metals. Waste slag and batteries with a high grade of metals are treated by a hydro-based and / or pyre-based method for extracting valuable metals. While gangue and waste slag with a low grade are as a raw material in architecture field. In the future, a novel technology, such as high-grads magnetization separation technique and biological technique, will be designed to treat these wastes for protecting environment and recycling valuable components. These wastes, furthermore, are synthetically reutilized to produce various architectural materials, including glass and ceramics.

• Resources Recycling
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• v.18 no.4
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• pp.14-23
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• 2009

In terms of resources recycling and resolving waste disposal problems, it is very important to recover precious metals like Au, Ag and Pd and valuable metals like Cu, Sn and Ni from the scraps of waste electrical and electronic equipment(WEEE) that consists of detective electrical and electronic parts discarded during manufacturing electrical and electronic equipments and waste electrical and electronic parts generated during disassembling them. In general, the scraps of WEEE are composed of various metals and alloys as well as refractory oxides and plastic components. Precious and valuable metals from the scraps of WEEE can be recovered by gas-phase-volatilization, hydrometallurgical, or pyrometallurgical processes. However, the gas-phase-volatilization and hydrometallurgical processes have been suggested but not yet commercialized. At the present time, most of the commercial plants for recovering precious and valuable metals from the scraps of WEEE adopt pyrometallurgical processes. Therefore, in this paper, the technical and environmental aspects on the important pyrometallurgical processes through literature survey are reviewed, and the scale-up result of a new pyrometallurgical process for recovering the precious and valuable metals contained in the scraps of WEEE using waste copper slag is presented.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.478-481
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• 2001

The spent petrochemical catalyst used in the manufacturing process of terephthalic-acid contains valuable metals such as cobalt and manganese. To recover these metals, sulfuric acid leaching was performed with hydrogen peroxide as a reducing agent. Low extractions of Mn, Co and Fe were obtained by sulfuric acid leaching without reducing agent. With adding hydrogen peroxide as a reducing agent, the high extraction of these metals could be obtained. Different from general leaching experiment, the extraction rates of metal components were decreased with increasing reaction temperature in this case. Under the optimum condition, the extraction rates of Mn, Co and Fe were 93.0%, 87.0% and 100% respectively.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.563-568
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• 2003

Recently, the recycled amount of electric, mechanical parts, and appliances in artifacts has increased. These products use valuable rare metals such as platinum group metals and gold, which are included occasionally as additives. Rare metals are maldistributed in the world and most of them are produced in small quantities. A small amount of rare metals used in the appliances causes a large loss of rare metal resources because of the lack of an economically recycling method. The present recycling technologies including physical and chemical separation methods that are considered for recycling of electric, mechanical parts and appliances.