• Resources Recycling
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• v.20 no.4
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• pp.23-35
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• 2011

In order to review the recycling status of urban mine resources in Taiwan, background and history of recycling industries, system of the recovery fund management committee(RFMC), copper recycling with non-ferrous metals, recycling of ELV(end of life vehicles) and recycling of EAF dust were surveyed. Taiwan is a leading country of the world in the metal consumption per capita. Therefore, a lot of waste metals were generated. In other words, urban mine resources are abundant in Taiwan and have some advantages in recycling. There are more than thou-sand recycling plants in Taiwan. Half of them are non-ferrous metal recyclers.

• Journal of the Korean Vacuum Society
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• v.12 no.S1
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• pp.67-69
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• 2003

The magnetic properties of single- and poly-crystalline $La_{0.7}Sr_{0.3}MnO_3/Pr_{0.65}Ca_{0.35}MnO_3$ multilayered (ML) films, and composite (CP) $(La_{0.7}Sr_{0.3})_{0.5}(Pr_{0.65}Ca_{0.35}_{0.5}MnO_3$ films, prepared by laser ablation, have been investigated in a wide temperature range. It was shown that the transformation from an incoherent to a coherent interface in the ML films leads to an enhancement of the ferromagnetic coupling between layers and to a single-phase magnetic transition. The amorphous CP films demonstrate a paramagnetic behavior of the magnetization with a sharp peak at $T_{G}\approx$45 K, which was interpreted as the formation of Griffiths phase. A short-term annealing at $750^{\circ}C$ induced the complete crystallization of film, and a recovery of the ferromagnetic and the metal-insulator transitions.

• Analytical Science and Technology
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• v.9 no.4
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• pp.373-381
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• 1996

Algal biomass was used in our study in order to remove some metals. After packing of 40~60 mesh algae powder into column for use of metal adsorbent, the metal solution of 1mL/min of flow rate was eluted to adsorb in algae. More amount of Cu(II) or Zn(II) ion in green algae, Ulva pertusa Kjellman than in brown algae, Sargassum horneri (Turner) C. Agarch were adsorbed and Cu(II) ion was more adsorbed in both algae than Zn(II) ion. Recovery of metal from algae is showing higher in acidic or neutral than in alkalic conditions. Cu(II) ion is recovered relatively higher than Zn(II) ion in our system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.8-15
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• 2021

Cold forging is a method in which molding is performed at room temperature. It has a high material recovery rate and dimensional precision and produces excellent surface quality, and it is mainly used for the production of bolted or housing products. The lifespan of cold forging molds is generally determined by the wear of the mold, plastic deformation of the mold, and fatigue strength. Cold forging molds are frequently damaged due to fatigue destruction rather than wear and plastic deformation in a high-temperature environment as it is molded at room temperature without preheating the raw material and mold. Based on the results analyzed through FEM, an effective mold structure design method was proposed by analyzing the changes in tensile and compressive stresses on molds according to the number of molds and reinforcement rings and comparing the product geometry and mold stress using three existing mold models.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.438-445
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• 2017

Tanzania has abundant copper deposits, but copper-metal extraction remains low there, owing to the lack of suitable copper recovery processes and insufficient funds for developing mining technologies. Accordingly, leaching and solvent extraction methods for the extraction of copper from copper ore were studied with a particular emphasis on developing a simple processing method for small-scale copper mining. Chrysocolla ore was used as the copper-bearing mineral and sulfuric acid was used as the leaching reagent. A maximum copper recovery of 95.1% was obtained when the particles in the sample were smaller than $53{\mu}m$, the concentration of 98%(w/w) sulfuric acid in the leaching solution was 5.0 g/L and the stirring rate was between 60 and 80 rpm. The highest selectivity of $Cu^2+$ in the solvent extraction was obtained using 15% LIX-70 in kerosene. In the pH range from 0.5 to 3.0, the efficiency of $Cu^2+$ extraction increased with increasing pH. However, at pH values higher than 3.0, other metal ions were extracted into the organic phase more readily than $Cu^2+$. The highest solvent extraction rate obtained was 96.5% at pH values of 2.0 and 3.0 using 15% LIX-70.

• Journal of Environmental Science International
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• v.7 no.6
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• pp.803-809
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• 1998

Heavy metal ions in water were removed using algal biomass as adsorbents. Absorbents were dried for 3 days, ground them by 40~60 mesh and then were swelled in a buffer solution for 1hr. After being packed in the column, commercially available standard solution of Cd(II) and Pb(II) ions were diluted to get the suitable concentration and then it was eluted with the rate of 1mι/min. Heavy metals on the adsorbents were recovered with nitric acid. More amounts of Cd(II) or Pb(II) ions in green algae, Ulva pertusa, than in brown algae, Sargassum horneri, were adsorbed. Pb(II) ion was adsorbed more than Cd(II) ion in both algae. The pH effect of adsorbed amounts of Cd(II), Pb(II) ions on the biomass was shown the following order ; pH 10.5 ＞ 8.5 ＞ 7.0 ＞ 5.5 ＞ 3.5. Recovery ratio of metal ions front algae is shown higher in acidic or neutral conditions than it in alkalic ones. Pb(II) ion is recovered relatively more than Cd(II) ion in our system.

• Journal of Environmental Science International
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• v.20 no.12
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• pp.1607-1615
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• 2011

The adsorption performance of cupper and zinc ions($Cu^{2+}$ and $Zn^{2+}$) in aqueous solution was investigated by an adsorption process on reagent grade Na-A zeolite(Z-WK) and Na-A zeolite (Z-C1) prepared from coal fly ash. Z-C1 was synthesized by a fusion method with coal fly ash from a thermal power plant. Batch adsorption experiment with Z-C1 was employed to study the kinetics and equilibrium parameters such as initial metal ions concentration and adsorption time of the solution on the adsorption process. Adsorption rate of metal ions occurred rapidly and adsorption equilibrium reached at less than 120 minutes. The kinetics data of $Cu^{2+}$ and $Zn^{2+}$ ions were well fitted by a pseudo-second-order kinetics model more than a pseudo-first-order kinetics model. The equilibrium data were well fitted by a Langmuir model and this result showed $Cu^{2+}$ and $Zn^{2+}$ adsorption on Z-C1 would be occupied by a monolayer adsorption. The maximum adsorption capacity($q_{max}$) by the Langmuir model was determined as $Cu^{2+}$ 99.8 mg/g and $Zn^{2+}$ 108.3 mg/g, respectively. It appeared that the synthetic zeolite, Z-C1, has potential application as absorbents in metal ion recovery and mining wastewater.

• Analytical Science and Technology
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• v.24 no.6
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• pp.443-450
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• 2011

Quantitative analytical condition for nickel in ceramic, metal and plastic materials using complexation and solvent extraction followed by inductively coupled plasma-atomic emission spectrometry (ICP-AES) and atomic absorption spectrophotometry (AAS) was studied. Ceramic, metal and plastic samples were dissolved by acid digestion. Nickel was determined by ICP-AES and AAS after extraction of Ni $(DMG)_2$ in $CHCl_3$. Recovery efficiency of nickel was satisfactory, and most of matrix elements causing interference could be effectively eliminated by the separation. Nickel in the certified reference materials (BAM-376 and PACS-2) were quantitatively determined without influence of sample matrix.

• Nuclear Engineering and Technology
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• v.43 no.4
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• pp.329-334
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• 2011

Two conceptual flowsheets were developed for recycling used nuclear fuel. One flowsheet was developed for recycling used oxide nuclear fuel from light water reactors while the other was developed for recycling used metal fuel from fast spectrum reactors. Both flowsheets were developed from a set of design principles including efficient actinide recovery, nonproliferation, waste minimization and commercial viability. Process chemistry is discussed for each unit operation in the flowsheet.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.2
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• pp.243-257
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• 2003

The purpose of this study was to search the influences of the increase of the contents of sodium alginate in the experimental alginates on the some mechanical properties. 3 commercial alginates were selected for the purpose of comparison of the results of experiments. 7 experimental alginates were manufactured with the rise of contents of sodium alginate from 8.8% to 18.3% with the decrease of contents of diatomaceous earth and with the constant contents of calcium sulfate 12.5%. sodium phosphate 2.2%, zinc fluoride 2.0%. Splitable metal mold with 12.5mm diameter and 20.0mm height was filled with mixed alginate to prepare the cylinder shaped specimens. Strain in compression, elastic recovery, compressive strength were tested using the ISO specification number 1563, alginate impression material. Experimental groups were 7, and 10 specimens were used for each test items and each groups. Following results were obtained ; 1. Strain in compression was decreased with the increase of sodium alginate contents (p=0.0077, r2 = 0.6302). 2. Elastic recovery was decreased with the increase of sodium alginate contents but was not significant(p=0.0639, r2=0.7449). 3. Compressive strength was increased with the increase of sodium alginate contents (p<0.0001, r2 = 0.9617). These results mean that the increase of sodium alginate contents make alginate harder but may result the increased permanent deformation.