• Resources Recycling
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• v.13 no.6
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• pp.43-48
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• 2004

For the separation of neodymium from NdFeB permanent magnet scrap, the scrap was roasted for oxidizing, and leached with acetic acid followed by fractional crystallization for selective separation. From the analysis results of the leached solution, the optimum condition for the recovery of neodymium was found that leaching temperature, leaching time and pulp density are 80$^{\circ}C$, 3 hours, and 35%, respectively. At this optimum condition, more than 90% of neodymium could be recovered. Concentration of neodymium acetate in acetic acid. The optimum condition for the recovery of neodymium acetate crystal from the leached solution was that the initial leaching solution was evaporated until the remaining volume was about 1/5 of the initial volume. At this condition, 67.5% of neodymium was recovered from the leached solution. The neodymium remaining in the concentrated solution was recovered by reacting it with oxalic acid.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.1
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• pp.1-8
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• 2017

Fe-9.8Si-6.0Al mother alloy was manufactured using by Fe-3.5Si recycled scrap and Si powder. And then, soft magnetic alloy powder of $D_{50}$ size and sphere type were prepared by gas atomization process. To obtain the soft magnetic powder of a high aspect ratio, in the first, we conducted the ball milling process for 8 hours. And heat treatment was performed under $650^{\circ}C$, 2 hours and $N_2$ atmosphere condition for reducing the residual stress of the powder. Based on these process, we made around $50{\mu}m$ diameter Fe-9.8Si-6.0Al powder, which morphology and shape was a similar to the commercial Fe-Si-Al powder. Finally, the soft magnetic sheets were prepared by tape casting process using by those powders. The permeability of the tape casting sheet was measured, and we confirmed the possibility of reusing to the soft magnetic materials of Fe-Si electric sheet scrap.

• Resources Recycling
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• v.3 no.1
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• pp.9-16
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• 1994

Fine cobalt metal powders was produced from domestic Stellite scrap by decomposing it with molten sodium hydroxide. Complete decomposition of the scrap could be obtained with the weigth ratio of sodium hydroxide to Stellite being about 2 at the temperature ranges of $750~800^{\circ}C$ for an hour. The cobalt-bearing compound was identified as $Co_2O_3{\dot}H_2O$ by X-ray analysis and D.T.-T.G.a.. The compound was then digested in HCI to form cobalt chloride, and after iron removal by adjusting the pH of the solution, cobaltous or cobaltic hydroxide was precipitated at the pH of about 13 or 4, respectively. The precipitates were reduced by hydrogen in the temperatures of $400~500^{\circ}C$ to fine cobalt powders of high purity with the size of 1.0 to $1.5\mu\textrm{m}$. The recovery of cobalt from Stellite scrap was about 75~86% by weight.

• Resources Recycling
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• v.28 no.5
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• pp.30-41
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• 2019

Global production of zinc is about 13 million tons and zinc is the fourth-most widely used primary metal in the world following iron, aluminum and copper. When zinc is recycled to produce secondary zinc, it can save about 75 % of the total energy that is needed to produce the primary zinc from ore, and in therms of $CO_2$ emissions reduced by about 40 %. However, since zinc is mainly used for galvanizing of steel, the recycling rate of zinc is about 25 %, which is lower than other metals. The raw materials for recycling of zinc include dusts generated in the production of steel and brass, sludge in the production process of non-ferrous metals, dross in the melting of zinc ingots or hot dip galvanizing, waste batteries, and metallic scrap. Among them, steelmaking dust and waste batteries are most actively recycled up to now. Most of the recycling process uses pyrometallurgical methods. Recently, however, much attention has been given to a combined process of pyrometallurgical and hydrometallurgical processes.

• Resources Recycling
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• v.28 no.1
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• pp.3-14
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• 2019

Copper is used in many electronic components and construction parts due to its excellent electrical conductivity and heat transfer characteristics, and also used for pre-plating for double layer coating such as nickel, so that copper is an essential material in modern industry. Despite the expected increase of usage and importance on wiring, sensors and data equipment in the next generation industries, it is hard for securing stable copper supply and resource management resulting from the copper prices are fluctuating owing to the economic crisis in Europe, the low economic growth trend in China, and President Trump's commitment to public industrial facilities investment in U.S.. Since most of the domestic copper consumption is used by electrolytic copper cathode, we studied not only copper recycling technology which is being commercialized but also current research trend under the research stage. This study aims to examine the characteristics of each process and the areas where future recycling technology development is required.

• Journal of the Korea Organic Resources Recycling Association
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• v.6 no.1
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• pp.1-12
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• 1998

To examine the possibility of protein recycling of shaving scraps containing chromium generated from manufacturing process of leather, the optimum hydrolysis conditions and the withdrawal methods of low molecular weight protein for using the liquid fertilizer sources by investigation of solubilities of hydrolyzed protein, inorganic nutrients contents and molecular weight distributions of hydrolyzed protein from shaving scraps treated with mixed alkaline inducing agents and mixed alkaline proteolytic enzymes including MgO were investigated. In hydrolysis of shaving scraps treated with mixed alkaline inducing agents, the solubility of shaving scraps were clearly different with 65~85% according to the sorts of the inducing agents, and the degree of hydrolysis was high in the order of NaOH, $Ca(OH)_2$ and KOH. The average molecular weights of withdrawal hydrolyzed protein were 10, 40 and 80 KD treated with NaOH, $Ca(OH)_2$ and KOH, respectively. And the chromium contents was about 15 ppm. In hydrolysis of shaving scraps treated with mixed alkaline proteolytic enzymes, the bility of shaving scraps were high in the order of alcalase, esperase and savinase. In c of treating 0.5% alcalase, the low molecular weight of hydrolyzed protein could be withdrawn. The solubility of the hydrolyzed protein was about 85%, the average molecular weight of the protein was below 1 KD and chrome content of the protein was below 10 ppm.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.3
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• pp.98-109
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• 2002

Each kinds of the leather process wastes which is occurred in the leather making process is almost more than 50% on the basis of the raw hide. The emitted process wastes are important oil and fats and protein resources because they are composed of animal oil and fats and fibrous protein. But most of them are incinerate or filled up simply as the industrial wastes without applying to recycling into the other use. Thus the problems of environmental pollution are becoming more critical and the processing cost of the leather process wastes (40,000~60,000 won) is a heavy burden on the production cost. Because the organic wastes such as fleshing scrap, pelt scrap are high fetid, its unlawful abandonment without being processed properly causes the occurrence of secondary pollution by an offensive odor and leakage of waste water. Thus we made the re-resource experiments in order to resolve this problems. The principal contents of this study are to process the collected leather waste scrape through separate the oil and fat ingredients with various propert by processing various chemicals and enzymes on the next effector. The re-resource application of separated oil and fat ingredients produced chemical for leather applicable to manufacturing process of leather through chemical transformation process(sulphation reaction, sulphitation reaction etc.) of oil and fats.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.65-70
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• 2001

Six recycling plants have started operation for recycling scrap home appliances since the spring of 2000 in Taiwan. The performance of the plants has not yet been measured during the 18-month period. The performance measurement, however, can be looked in several aspects. Because of the nature of these recycling plants, at least three aspects, namely government (representing general public), appliance manufacturers and owners of the recycling plants themselves should be considered in the performance evaluation. This study proposes various performance indices categorized in four groups: profitability, recyclability, automation and environment. The indices are different from the productivity and cost measures that are used in conventional manufacturing plants. Performances of three existing plants in Taiwan are evaluated as illustrative examples to demonstrate the use of the proposed measures. The practical implications of the performance indices are also discussed.

• Korean Journal of Materials Research
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• v.19 no.7
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• pp.397-402
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• 2009

In this study, Ti powder was fabricated from Ti scrap by the Hydrogenation-Dehydrogenation (HDH) method. Hydrogenation reactions of Ti scrap occurred at near 450 $^{\circ}C$ with a sudden increase in the reaction temperature and the decreasing pressure of hydrogen gas during the hydrogenation process in the furnace. The dehydrogenation process was also carried out at 750 $^{\circ}C$ for 2hrs in a vacuum of $10^{-4}$ torr. After the HDH process, a deoxidation treatment was carried out with the Ca(purity: 99.5) at 700 $^{\circ}C$ for 2hrs in the vacuum system. It was found that the oxidation content of Ti powder that was deoxidized with Ca showed noticeably lower values, compared to the content obtained by HDH process. In order to fabricate Ti compacts, Ti powder was sintered at $1100\sim1400^{\circ}C$ for 2hrs under a vacuum of $10^{-4}$ torr. The relative density of compact was 94.9% at 1300 $^{\circ}C$. After sintering, all of the Ti compacts showed brittle fracture behavior, which occurred in an elastic range with short plastic yielding up to a peak stress.

• Elastomers and Composites
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• v.33 no.4
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• pp.290-296
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• 1998

Recycling of waste tire has been limited and very simple, few applications have been observed. This study introduces a new elastic and permeable pavement made of scrap tire. Experimental results showed that key factors affecting the compressive strength were the size of scrap tire, size of aggregate, amounts and property of binder. Also, the water permeability depended on the size of aggregate and scrap tire. The compressive strength and water permeability of the samples were 1.4 and 116 times higher than those of the conventional porous cement concrete, respectively.