• Journal of Electrochemical Science and Technology
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• v.13 no.2
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• pp.186-198
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• 2022

Heavy metals recovery from Printed Circuit Boards industrial wastewater is crucial because of its cost effectiveness and environmental friendliness. In this study, a copper recovery route combining the sequential processes of acid leaching and LIX 984N extracting with an electrowinning technique from Printed Circuit Boards production's sludge was performed. The used residual sludge was originated from Hanoi Urban Environment One Member Limited Company (URENCO). The extracted solution from the printed circuit boards waste sludge containing a high copper concentration of 19.2 g/L and a small amount of iron (0.575 ppm) was used as electrolyte for the subsequent electrolysis process. By using a simulation model for multi-step current electrolysis, the reasonable current densities for an electrolysis time interval of 30 minutes were determined, to optimize the specific consumption energy for the copper recovery. The mathematical simulation model was built to calculate the important parameters of this process.

• Journal of Powder Materials
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• v.30 no.4
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• pp.332-338
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• 2023

Thermite welding is an exceptional process that does not require additional energy supplies, resulting in welded joints that exhibit mechanical properties and conductivity equivalent to those of the parent materials. The global adoption of thermite welding is growing across various industries. However, in Korea, limited research is being conducted on the core technology of thermite welding. Currently, domestic production of thermite powder in Korea involves recycling copper oxide (CuO). Unfortunately, controlling the particle size of waste CuO poses challenges, leading to the unwanted formation of pores and cracks during thermite welding. In this study, we investigate the influence of powder particle size on thermite welding in the production of Cu-thermite powder using waste CuO. We conduct the ball milling process for 0.5-24 h using recycled CuO. The evolution of the powder shape and size is analyzed using particle size analysis and scanning electron microscopy (SEM). Furthermore, we examine the thermal reaction characteristics through differential scanning calorimetry. Additionally, the microstructures of the welded samples are observed using optical microscopy and SEM to evaluate the impact of powder particle size on weldability. Lastly, hardness measurements are performed to assess the strengths of the welded materials.

• Applied Chemistry for Engineering
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• v.20 no.2
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• pp.223-226
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• 2009

In this study, we investigated the recovery of copper and synthetic fuel from the waste wire by low temperature pyrolysis which can overcome problems of the recent incineration methods. Through thermal decomposition process of waste wire, we achieved the big advantage of getting usable resources as the forms of copper and fuel with a very high value. The TG/DTA and small-scale reaction experiments were carried out to determine an optimum temperature for waste wire pyrolysis. And the pyrolysis was done at 350, 450, and $550^{\circ}C$, respectively, and heating rate of the TG/DTA was $5^{\circ}C/min$ untill $700^{\circ}C$. The result shows that the optimum temperature range for dehydrochlorination of PVC was $280{\sim}350^{\circ}C$, as a lower temperature range than $400{\sim}550^{\circ}C$ of PE and PP. Practically over 95% of copper metal and synthetic fuel, which has the 8027 kcal/kg as a calorific value, were recovered from the waste wire samples.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.2
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• pp.97-103
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• 2017

In this study, variations of hydrogen production were investigated with food waste fermentation in the presence of heavy metals. Hydrogen production was 79.48 mL/g COD with fermentation of food waste. In the presence of 1 mg/L of zinc, the hydrogen production was decreased about 60%. When the copper is present, the production of hydrogen is severely inhibited, while the coexistence of copper with zinc relaxes the inhibition of copper and restores hydrogen production. Butyric acid or acetic acid was observed as the main species during hydrogen production. Klebsiella sp., Clostridium sp., and Dysgonomonas sp. were mainly appeared in the samples not containing heavy metals. However, Enterococcus sp. extremely influenced the hydrogen production activities of samples containing zinc or copper.

• Resources Recycling
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• v.17 no.6
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• pp.24-33
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• 2008

The leaching of Cu from waste PCBs was investigated with electro-generated chlorine as an oxidant. The leaching experiments were carried out according to the design of experiments to analyze quantitatively the effect of parameters on copper leaching. From the analysis of variance (ANOVA) it was suggested that the effective parameters were current density, temperature, concentration of HCl, and the interaction between the concentration of HCl and temperature. Especially, the effect of current density was analyzed to contribute to the interpretation of result for copper leaching up to 95.7%. A multiple regression model obtained from the analysis of effective parameters explained 99% of leaching results. From the model equation, it was found that the effect of HCl concentration on copper leaching increased with temperature.

• Resources Recycling
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• v.23 no.3
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• pp.37-43
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• 2014

A study has been made on the recovery of tin and copper from waste solder stripper by oxalate precipitation. With the increasing of the oxalic acid addition, tin was precipitated effectively and removed above 99.5% of tin when the oxalic acid, in an amount 1.0-1.5 times the stoichometric requirement, was added. But, in this case, only 2.0% of copper was precipitated and lead, iron were not precipitated. So, tin was selectively removed from the waste solution. With the increasing of the reaction temperature, the removal percentage of tin was increased and maximum value at arounf $60^{\circ}C$ and decreased with increase in the temperature any more. After filtering the precipitate and drying in oven, $SnO_2$ was obtained from the precipitate. After removal of tin in stripping solution, above 91% of copper was selectively removed by Cu-oxalate by addition of oxalic acid.

• 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.

• International Journal of Air-Conditioning and Refrigeration
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• v.12 no.1
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• pp.21-29
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• 2004

This paper is to study the heat transfer performance of the copper-water heat pipe with screen wicks. Recently, the semiconductor capacity of an electronic unit becomes larger, but its size becomes much smaller. As a result, a high- performance cooling system is needed. Experimental variables are inclination angles, temperatures of cooling waters and the mesh number of screen wicks. The distilled water was used as a working fluid. Based on the experimental results, when the copper-water heat pipe of 6mm diameter is used at the top heat mode, the heat transfer performance of 100 mesh 2 layers heat pipe is better than that of 150 and 200 mesh. The thermal resistance of the two layers with the 100-mesh screen was 0.7-$0.8^{\circ}C$/W.

• Resources Recycling
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• v.12 no.1
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• pp.25-32
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• 2003

A study on the separation of heavy metals such as iron, copper, zinc and nickel from electroplating waste water has been investigated. The results showed that the PC-88A was more effective extractant for the extraction of zinc and the efficiency of zinc was to be about 100% at pH 2.5. And copper and nickel were extracted about 100% at pH 2 and more than 90% at pH 4～5 with LIX 84, respectively. On the other hand, in the case of solvent extraction of electroplating waste water(Acid-Alkali type) containing heavy metals, the ferric ion was first extracted at pH 2∼2.5 with 20% Naphthenic acid or 10% Versatic acid-10. And then, copper and zinc were extracted at pH 2 with 3% LIX 84 and at pH 2.5∼3 with 20% PC-88A respectively, remaining nickel in the raffinate. In this manner, the heavy metals in electroplating waste water could be effectively separated with solvent extraction method.

• Resources Recycling
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• v.28 no.3
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• pp.21-25
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• 2019

The utilization of incineration ash from municipal waste must be promoted to solve the social problem on the shortage of final disposal site. In this research, metals should be recovered to avoid the damage of the crushing machine during the utilization of incineration ash in cement industry. In fact, incineration bottom ash from municipal waste contains iron in 3-5%. Nonferrous metal and stainless steel in 1% is also included. The research and development on the physical recovery process was performed not only to remove the metals but also to recover high grade products. Metals were separated from incineration ash in Maruya Co. Ltd.. In fact, iron scrap recovered by magnetic separation can be selled. After that, mixed metal was separated from incineration ash using screen. In this research, mixed metal tried to divided copper, aluminum, brass and stainless steel using drum type magnetic separation, eddy current separation and high magnetic separation. As a result, recovered iron had an 80% for the grade. Aluminum was recovered by eddy current separation without copper and brass.