• 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.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2006.05a
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• pp.86-89
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• 2006

전해 생성된 염소를 이용하여 구리를 침출하는 연구를 수행하였다. 염산농도 $1molL^{-1}$, 반응온도 $25^{\circ}C$, 교반속도 400rpm 조건에서 전류밀도 $10mA/cm^{2}$의 경우 반응온도에 상관없이 구리의 침출속도가 동일하였으나 $Cl_{2}$ 생성량이 충분한 $40mA/cm^{2}$의 경우 온도가 높을수록 구리의 침출속도가 증가하였다. 침출된 구리농도가 6g/L 부근에 도달하면 염소의 공급속도에 상관없이 구리의 침출이 둔화되었다. 이는 구리-염소 착화물의 형성과 관련된 것으로 생각된다.

• Resources Recycling
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• v.25 no.3
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• pp.11-19
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• 2016

A fundamental study to recycle a Si-Sludge and waste copper nitrate solution acid solution generated by domestic electronic industries was carried out. The waste copper nitrate solution was used as the lixiviant to leach the metals like Cu, Ca, Fe, etc. from the sludge leaving Si in the residues. The effect of reaction temperature, time and pup density on the metals leaching from the sludge was investigated. To enhance the extractability of Fe, the effect of HCl, $HNO_3$ and $H_2O_2$ introduced additionally during the leaching was also examined. Considering the leaching efficiency of Fe along with Cu, the leaching conditions comprising of 200 ~ 225 g/L pulp density and $90^{\circ}C$ temperature for 30 min were optimized. Under this condition, 98.27 ~ 99.17% Cu could be dissolved in the leach liquor with the obtained purity of Si in the residues as 98.69 ~ 98.86 %. The study revealed that the leaching of Cu contained in the Si-Sludge with the waste copper nitrate solution is a plausible approach by which the obtained leach liquor can further be treated suitably to recover Cu as the high pure value-added products.

• Resources Recycling
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• v.25 no.5
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• pp.36-43
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• 2016

The leaching behaviors of copper from chalcopyrite were investigated by sulfuric acid. The leaching of copper was examined according to concentration of sulfuric acid, leaching temperature and addition of hydrogen peroxide and ethylene glycol. The concentrations sulfuric acid and hydrogen peroxide in the leaching solution were increased, the leaching efficiencies of Cu were increased. At $30 -60^{\circ}C$, the leaching efficiency of Cu was increased but it was decreased at $70 - 80^{\circ}C$. The results were due to the increasing of hydrogen peroxide decomposition in the solution above $70^{\circ}C$. In the case of ethylene glycol added at $80^{\circ}C$, the decomposition of hydrogen peroxide was decreased and the leaching efficiency was increased. As a result of SEM analysis of leaching residue after leaching, the residue was found to porous form in the case of the ethylene glycol added and then the leaching efficiency of Cu was increased by the increase of surface area under $60^{\circ}C$ with ethylene glycol.

• Resources Recycling
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• v.15 no.6 s.74
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• pp.41-47
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• 2006

A study for recovering of copper and lead from electronic scraps has been carried out using a combination of bioleaching and solvent extraction. It was found that the citric acid generated by Aspergillus niger could be an imporant leaching agent acting in the solubilization of copper, iron, lead and tin from the electronic scrap. Copper could be selectively extracted by 10% LIX84 from the leaching solution and it recoved 99.9% of metallic copper by electrowinning process. Tin and iron were extracted from the remaining solution by 10% Alamine336 and stripped by NaCl solution. Finally, tin could be recovered as a metallic precipitates from the mixed solution of tin and iron by cementation with iron powder.

• Resources Recycling
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• v.18 no.5
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• pp.44-51
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• 2009

Fundamental study has been made on the recovery of copper from the electronic scrap by hydrometallurgical process. Nitric acid was used as a leaching agent to dissolve the metals such as Cu, Sn, Pb, Fe etc. from the crushed electronic scraps. TBP was employed to extract nitric acid from the strong nitric acid leaching solutions and to reclaim nitric acid. From the experimental results, Cu was effectively leached by 3.0-4.0 M nitric acid. And 95% of nitric acid in the leaching solution was extracted by 60% TBP, and 98% of nitric acid was stripped from the loaded organic phase by distilled water and it was possible to reuse as a leaching agent.

• Resources Recycling
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• v.15 no.6 s.74
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• pp.33-40
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• 2006

Leaching behavior of copper using electro-generated chlorine was investigated in hydrochloric acid solutions. When leached copper concentration was lower than 3.6g/L, the utilization efficiency of the electro-generated chlorine was close to 100% at $10mA/cm^2,\;25^{\circ}C$, 400 rpm in 1M HCl solutions. The concentration ot the leached copper over 3.6g/L caused the electrode potential to drop quietly, leading to a change or leaching mechanism. The leaching rate oi copper began to decrease at the concentration of copper 5.2g/L. This is probably due to the formation of a layer of CuCl on Cu metal in 1M HCl solutions. The leaching rate, however, was not retarded in a solution ot high chloride concentration. The high solubility of CuCl in the solution may prevent the formation of CuCl on Cu metal.

• Resources Recycling
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• v.21 no.5
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• pp.3-17
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• 2012

Selective leaching processes for copper, gold, nickel, and cobalt have been investigated because there is an advantage of ammoniacal hydrometallurgy that metal such as copper could be selectively extracted restricting the dissolution of iron or calcium. In the present article, the studies for selective ammoniacal leaching of copper from motor scraps and waste printed circuit boards (PCBs), for ammoniacal leaching of gold to decrease the amount of cyanide used or to substitute cyanide by thiosulfate, and for ammoniacal leaching to recover nickel and cobalt from nickel oxide ore and intermidiate obtained from manganese nodule treatment process were summarized and further studies were proposed for domestic technology development for ammoniacal hydrometallurgy processes.

• Resources Recycling
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• v.20 no.6
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• pp.63-70
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• 2011

Enviromental friendly leaching process for the recovery of cobalt and copper from the cobalt concentrate was investigated by organic acids as a leaching reagent. The experimental parameters, such as organic acid type, concentrations of leachant, time and temperature of the reaction as well as the solid to liquid ratio were tested to obtain the optinum conditions for the leaching of cobalt and copper. The results showed that citric acid was the most effective leaching reagent among the organic acids used in this experiment. About 99% of cobalt, 95% of copper and 70% of nickel was dissolved by 2.0 M of citric acid. Addition of 3.0 vol.% of hydrogen perioxide was effective to enhance the leaching efficiency and the optinum temperature was found to be about $70^{\circ}C$.

• Resources Recycling
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• v.23 no.1
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• pp.64-69
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• 2014

For the recovery of Co and Cu, bioleaching behavior of Co, Cu, Fe, Mg, Al by Aspergillus niger culture from the molasses growth medium was investigated. Series of leaching tests have been conducted by varying Aspergillus niger's type, molasses concentration in the growth medium, pulp density and reaction time. The results showed that increase of the molasses concentration in the growth medium from 1% to 4% increased the leaching percentage of Co and Cu and the optimal molesses concentration was found to be 4% in the growth medium. Maxinum 90% of Co and 70% of Cu were dissolved from the leaching test at the 10 g/L pulp density, 4 % of molasses concentration in the growth medium after 21 days by Aspergillus niger KCTC 6985. But in case of using Aspergillus niger KCTC 6144, the maxium leaching percentage of Co and Cu was reached 90% respectively at a pulp density 5 g/L and 4% of molasses concentration.