• Resources Recycling
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• v.19 no.6
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• pp.11-26
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• 2010

In order to review the recycling status of urban mine resources in Japan, metal consumption, metal recycling rate and metal recycling industry such as iron scrap, end of life vehiclcs(ELV), waste home appliances and spent IT equipments were surveyed. Japan took rank of top class in the world on the metal consumption and urban mine stock reserve. Metal recycling industries in Japan have been developed through excellent technologies for mineral processing and non-ferrous smelting. On the other hand, the technologies for recycling of rare metals are being developed now. Recycling rate of EL V, waste home appliances and personal computer are higher than the guidelines of the legislative standard.

• Resources Recycling
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• v.21 no.1
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• pp.3-16
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• 2012

In order to review the technological modulus of the recycling of urban mine resources and non-ferrous smelting process in Korea, key point of recycling process, physical separation, non-ferrous smelting process, unit operation for the recycling technology, recycling process of LS-Nikko Copper and Korea Zinc were studied. Finally, metal recycling processes of the typical non-ferrous smelters in Japan such sa DOWA Holdings and JX Holdings were compared with those of LS-Nikko Copper and Korea Zinc.

• Resources Recycling
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• v.25 no.5
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• pp.3-13
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• 2016

Statistics on the urban mining industry is the essential information to develop the urban mining industry systematically and the prerequisite way to understand its related trends. Status on domestic urban mining industry was thus investigated through the integrated method which uses both the top-down way based on the national statistics utilization and the bottom-up way based on field data gathering. Results indicated that the scale of metal resources produced through domestic urban mine was 19.6 trillion won, which corresponds to approximately 22 percent of metal demand in korea. The number of firms for urban mining was 917, and they are mostly placed in metropolitan area and Gyeongsang province. It was also found that about 58 percent of urban mining firms was in small business level less than 10 employees. Compared to the results in 2009, the number of urban mining companies in 2014 generally increased, and that of rare metal companies grew up significantly. This study is particularly different from the conventional statistics investigation on the point of the actual scale findings of metal resources based on the field data.

• Resources Recycling
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• v.30 no.4
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• pp.3-10
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• 2021

The field of recycling for waste electronic components, which is the typical example of an urban mine, requires the development of useful sorting techniques. In this study, a sorter based on image identification by deep learning was developed to select electronic components into four groups. They were recovered from waste printed circuit boards and should be separated to depend on the difference after treatment. The sorter consists of a workstation with GPU, camera, belt conveyor, air compressor. A small piece (less than 3.5 cm) of electronic components on the belt conveyor (belt speed: 6 cm/s) was taken and learned as teaching data. The accuracy of the image identification was 96% as kinds and 99% as groups. The optimum condition of sorting was determined by evaluating accuracies of image identification and recovery rates by blowdown when changing the operating condition such as belt speed and blowdown time of compressed air. Under the optimum condition, the accuracy of image classification in groups was 98.7%. The sorting rate was more than 70%.

• Resources Recycling
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• v.24 no.4
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• pp.32-37
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• 2015

Cobalt is abundant only in some countries including Democratic Republic of the Congo. It would be necessary to secure overseas Co ores and Co extraction technology. Two kinds of matte varying the sulfur content were manufactured by smelting reduction of Co concentrate containing ~8 wt% Co, ~19 wt% Cu, and ~3 wt% Fe. The amount of Co, Cu and Fe was concentrated to 19~21 wt%, 39~41 wt%, and 7~9 wt% respectively in the resulting matte. High-pressure leaching of matte was performed in an autoclave with considering the effect of oxidizing agent, $H_2SO_4$ concentration as a lixiviant, and the amount of sulfur added to the matte. An oxidizing agent (oxygen) is necessary to improve Co leaching efficiency enabling usage of a dilute $H_2SO_4$ leaching agent. An increase in $H_2SO_4$ concentration prevents selective leaching of Co, and the sulfur content in matte has a minor influence on the Co leaching efficiency.

• Resources Recycling
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• v.24 no.6
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• pp.9-16
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• 2015

In a recycling scheme of spent lithium ion batteries, a co-precipitation process for the re-synthesis of precursor is essential after the leaching of lithium ion battery scraps. In this study, the effect of ammonia as impurity during the co-precipitation process was investigated in order to re-synthesize a precursor of Ni-rich cathode active material $LiNi_{0.6}Co_{0.2}Mn_{0.2}O_2$ (NCM 622). As ammonia concentration increases from 1 M (the optimum condition for synthesis of the precursors based on 2 M of metal salt solution) to 4 M, the composition of obtained precursors deviates from the designed composition, most notably for Ni. The Ni co-precipitation efficiency gradually decreases from 100% to 87% when the concentration of ammonia solution increases from 1 M to 4 M. Meanwhile, the morphological properties of the obtained precursors such as sphericity, homogeneity and size distribution of particles were also investigated.

• Tunnel and Underground Space
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• v.29 no.1
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• pp.1-11
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• 2019

This study investigated use cases of machine learning technology in domestic medical, manufacturing, finance, automobile, urban sectors and those in overseas mining industry. Through a literature survey, it was found that the machine learning technology has been widely utilized for developing medical image information system, real-time monitoring and fault diagnosis system, security level of information system, autonomous vehicle and integrated city management system. Until now, the use cases have not found in the domestic mining industry, however, several overseas projects have found that introduce the machine learning technology to the mining industry for improving the productivity and safety of mineral exploration or mine development. In the future, the introduction of the machine learning technology to the mining industry is expected to spread gradually.

• Economic and Environmental Geology
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• v.38 no.2 s.171
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• pp.101-111
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• 2005

The objectives of this study we to assess the extent and degree of environmental contamination and to draw general conclusions on the fate of toxic elements derived from mining activities in Korea. 인t abandoned mines with four base-metal mines and four Au-Ag mines were selected and the results of environmental surveys in those areas were discussed. In the base-metal mining areas, the Sambo Pb-Zn-barite, the Shinyemi Pb-Zn-Fe, the Geodo Cu-Fe and the Shiheung Cu-Pb-Zn mine, significant levels of Cd, Cu, Pb and Zn were found in mine dump soils developed over mine waste materials, tailings and slag. Furthermore, agricultural soils, stream sediments and stream water near the mines were severely contaminated by the metals mainly due to the continuing dispersion downstream and downslope from the sites, which was controlled by the feature of geography, prevailing wind directions and the distance from the mine. In e Au-Ag mining areas, the Kubong, the Samkwang, the Keumwang and the Kilkok mines, elevated levels of As, Cd, Cu, Pb and Zn were found in tailings and mine dump soils. These levels may have caused increased concentrations of those elements in stream sediments and waters due to direct dis-charge downstream from tailings and mine dumps. In the Au-Ag mines, As would be the most characteristic contaminant in the nearby environment. Arsenic and heavy metals were found to be mainly associated with sulfide gangue minerals, and mobility of these metals would be enhanced by the effect of oxidation. According to sequential extraction of metals in soils, most heavy metals were identified as non-residual chemical forms, and those are very susceptible to the change of ambient conditions of a nearby environment. As application of pollution index (PI), giving data on multi-element contamination in soils, over 1.0 value of the PI was found in soils sampled at and around the mining areas.

• Journal of the Korean Society of Mineral and Energy Resources Engineers
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• v.56 no.4
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• pp.359-366
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• 2019

This article aims to summarize the recycling status of scrap gold, silver, platinum, and palladium by regions and industries in order to utilize the data for securing raw materials of the domestic urban mining industry. The amount of gold from scrap has shown a tendency to decrease in countries other than China over the last ten years, which is attributed to the increase in scrap containing gold in China. The industry demand for gold is the highest in electronic products, but it is decreasing. The amount of scrap recycling for silver has declined but total silver production has increased by increasing mine products. As production and demand from platinum and palladium scrap are mostly for catalysts, their demand could be affected by the electric vehicle industry.

• Resources Recycling
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• v.24 no.4
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• pp.67-75
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• 2015

The content distributions of some rare metals and rare earthe metals in coal ash (fly ash, bottom ash and pond ash) and leachate from coal-fired power plants were investigated. In case of Yttrium (Y) and Neodymium (Nd) which were strategic critical elements, their contents were ranged from about 23 ~ 75 mg/kg and it is shown they are worth to be developed for the recovery and separation method. Considering the annual amount of fly ash and bottom ash and pond ash, coal-fired power plants have great value of about 1,670 billion KRW and it is regards they are worthy as urban mines.