• Resources Recycling
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• v.21 no.4
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• pp.60-68
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• 2012

Silicon wafer for making semiconductor devices and solar cell is used in the semiconductor and solar industry, respectively. Silicon wafer is produced by cutting with silicon ingot and sludge contains silicon occurs from cutting process. Generation of silicon sludge is increasing on developing all industry sectors which have need of semiconductor device. These days it has been widely studied for the recycling technologies of the silicon sludge from view points of economy and efficiency. In this paper, patents and paper on the recycling technologies of the silicon sludge were analyzed. The range of search was limited in the open patents of USA (US), European Union (EU), Japan (JP), Korea (KR) and SCI journals from 1982 to 2011. Patents and journals were collected using key-words searching and filtered by filtering criteria. The trends of the patents and journals was analyzed by the years, countries, companies, and technologies.

• Resources Recycling
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• v.14 no.5 s.67
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• pp.24-31
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• 2005

In order to recover valuable metals from fine-grained electronic waste, bioleaching of Cu, Zn, Al, Co, Ni, Fe, Sn and Pb were carried out using Aspergillus niger as a leaching microorganism in a shaking flask. Aspergillus niger was able to grow in the presence of electronic scrap. The formation of organic acids(citric and oxalic acid) from Aspergillus niger caused the mobilization of metals from waste electronic scrap. In a preliminary study, in order to obtain the data on the leaching of Cu, Zn, Al, Fe, Co and Ni from electronic scrap, chemical leaching using organic acid(Citric acid and Oxalic acid) was accomplished. At the electronic scrap concentration of 50 g/L, Aspergillus niger were able to leach more than 95% of the available Cu, Co. But Al, Zn, Pb and Sn were leached about 15-35%. Ni and Fe were detected in the leachate less than 10%.

• Resources Recycling
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• v.1 no.1
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• pp.23-28
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• 1992

The process for recovery of acids and valuable metals such as nickel and chromium from the stainless-steel pickling acids has been developed vased on the use of solvent extraction technique. Until now, several processes for the treatment of waste acids were already developed in such countries as Japan, Swden and Canada. Those methods are, however, forcussed on the recovery of acids from them discarding the metals included in them as the hydroxides sludge. In the present work, the recovery of nickel and chromium in addition to nitric acid and hydrofluoric acid has been aimed so as to recycle them to the stainless-steel pickling lines and also to minimize the amount of sludge generated during the treatment of waste acids. The establishment of the process to recover the acids has been carried out based on the solvent extraction with TBP. The iron was eliminated from the waste solutions by precipitating in the form of hydroxide through the adjustment of pH with calcined limestone and the selective extration of chromium and nickel from the resultant solutions has been conducted by using D2EHPA as extractant.

• Resources Recycling
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• v.13 no.5
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• pp.3-16
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• 2004

There are over 190,000 tons per year of the sludge containing heavy metals (SHM) generated from industries in Korea. The SHM is so hazardous waste, it needs proper intermediate treatment before final disposal. At present, the common intermediate treatment and final disposal technologies of SHM are solidification and landfill. However, the future treatment and disposal technologies of SHM will be carry out to fulfill in both the environmental aspect and resource recycling. Thus, how to reduce the generation of SHM and recycle the valuable metal from SHM become the major subjects in the global world. In this article, in order to prospect the effective processing of SHM, the generation and processing of the sludge from plating wastewater, the research and development of valuable metal recycling technology and problems were summarized.

• Journal of Electrochemical Science and Technology
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• v.10 no.1
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• pp.14-21
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• 2019

Supported liquid membrane process usually is used for recovering or enrichment of valuable metals in the industrial wastewater. But, even if the metals in the wastewater was separated with high chemical selectivity, it cannot be enough concentrated since separation performance of supported liquid membrane (SLM) process is limited by concentration gradient between feed solution and stripping solution. If metal concentration in the stripping solution to be enough low, transport of metal through membrane can be accomplishment constantly. Therefore, Electrodialysis (ED) has been placed after SLM process and the stripping solution of SLM was used as the feed solution for the ED process. Transport of ions in the solutions is successfully performed by ED process. Thus, the metal concentration in the stripping solution does not rise as to stop ion transport. Besides, valuable metals easily are concentrated by ED process for re-use. In this study, effects of operation parameters like initial Cd(II) concentration, HCl concentration in the feed solution of SLM and applied voltage are investigated on separation efficiency, flux and permeability of the both processes. As the feed solution concentration increased, all performance values has increased. When initial concentration of 100 mg/L is used, separation performances (SP) are 55% and 70%, for SLM and consecutive process, respectively. The best HCl concentration in the feed solution of SLM has determined as 2 M, in this conditions SP are 64% and 72%, for SLM and consecutive process, respectively. With increased of applied voltage on ED process, SP of the consecutive process has been raised from 72% to 83%. According to the obtained experimental data, consecutive process has better separation performance than SLM. When the separation performances of both processes were compared for the same operating conditions, it was determined higher the separation efficiency, permeability and flux values of the consecutive process, 8%, 9% and %10.6, respectively. Consequently, the use of the consecutive process increases the performance efficiency of both processes. The consecutive process studied has quite a good chemical separation efficiency, and enrichment capability. Moreover, this process requires few water and energy.

• Resources Recycling
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• v.12 no.2
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• pp.21-27
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• 2003

Smelting reduction technique in arc furnace was applied for the recovery of valuable metal such as V from LD slag. In the present study, the parameters for increasing the reduction rate and the reduction efficiency were selected by changing the oxide additives, melting temperature and basicity. The optimum condition for LD-slag reduction was achieved by $Al_2$$O_3$ addition. The reduction ratio of V was increased in increasing the basicity.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.249-251
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• 2001

A novel technology for recycling valuable metals contained in waste dry-battery by vacuum metallurgy was devised by theoretical analysis. On the condition of the total chamber pressure of 1.013$\upsilon$10$^1$Pa, Hg, Cd and Zn are distilled in the temperature range of 773~973K, Pb is volatilized in the range of 1173~1273K while Mn, Cu, Fe and C are remained in residual. MnO$_2$and ZnO are reduced by carbon in waste dry-battery in 773~1273K. Pure metals including Zn, Cd, Hg and Pb can be recovered respectively from their mixed vapor by fractional condensation. Metal Cu and MnO$_2$can be obtained from the residual by hydrometallguical method. The technology can eliminate the pollution of Cd, Hg and Pb to environment.

• Journal of Magnetics
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• v.18 no.3
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• pp.365-369
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• 2013

Coal ash is known to contain a noticeable amount of valuable elements, including transition metals and lanthanides. Therefore it is quite actual problem to extract them for metallurgy and other applications. This paper presents the results of high gradient magnetic and mechanical separation, microscopy, element analyses and optical spectroscopy of brown coal ash taken from the combustion camera and chimney-stalk of Angren thermal power station. The separated magnetic fraction was 3.4 wt.%, where the content of Fe in ferrospheres increased to 58 wt.%. The highest contents of Fe and rare earth elements were found in the fine fractions of $50-100{\mu}m$. Optical absorption spectroscopy of water solutions of the magnetic fractions revealed $Fe^{2+}$ and $Fe^{3+}$ ions in the ratio of ~1:1. The separated coal ash could be used for cleaning of technological liquid waste by means of the high gradient magnetic field.

• Biomedical Science Letters
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• v.16 no.4
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• pp.323-330
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• 2010

Although copper and zinc are essential metals for human health, excessive level of these metals is toxic. Besides, aluminum is known to induce various adverse health effects including neurological disorders. Therefore, monitoring the human body burden of these metals is important in preventing adverse health effects. In this study, we assessed the exposure to copper, zinc, and aluminum among an adult population residing in Daegu and Kyungbuk areas. Based on data from 171 participants, we found that the geometric mean copper, zinc, and aluminum concentrations in hair were $15.1\;{\mu}g/g$ [95% confidence interval (CI): 13.1~17.5], 76.9 (95% CI: 70.4~84.1), and $1.11\;{\mu}g/g$ (95% CI: 0.81~1.51), respectively. The copper concentrations in hair were significantly related to age, education, and residence area. In addition, zinc concentrations in hair were significantly related to age, whereas higher hair aluminum concentrations were related to alcohol drinking. Correlations between copper and zinc in hair had a significant positive correlation. Our findings suggest that the body burden of copper, zinc, and aluminum varies according to demographic factors, and hair could be used as a valuable biological medium for metal exposure.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.659-663
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• 2001

In Japan, the municipal solid waste, which amounts to 50 million tons, is generated every year and most of it is incinerated. The bottom and fly ashes are disposed to the registered disposal areas under the provisions of The Waste Disposal and Public Cleaning Law. Especially, as the fly ash from the municipal waste incineration (the primary fly ash) contains heavy metals (lead, zinc, etc) and dioxins, it cannot be disposed directly without decontamination, such as moiling, cementation, chelating and dissolving processes provided in the law. However, these procedures for decontamination, except melting, are not enough for dioxins. Even in case of melting, the fly ash from the process (the secondary fly ash) contains high concentration of heavy metals (e.g., Zn; 1-20%, Pb; 1-10%). For these reasons, Metal Mining Agency of Japan (MMAJ), a governmental organization, started a four-year project to develop the treatment technologies of these fly ashes in 1999. The purpose of the project is to establish the integrated technologies to recover the valuable metals from, and to decontaminate, the primary and secondary fly-ashes in the practical scale by utilizing the existing metallurgical processes and facilities, along with the energy saving and the reduction of the environmental impact.