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A hydrometallurgical process for the recovery of copper metal and nickel hydroxide from the aqua regia leaching solutions of printed circuit boards

Nguyen Thi Nhan Hau, Wen Jiangxian, Lee Man Seung

Physicochemical Problems of Mineral Processing

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2024

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Vol. 60, iss. 4

art. no. 191551

EN

Leaching solutions of printed circuit boards (PCBs) contain noble and base metal ions. The precious metal ions present in the leaching solutions of PCBs could be separated by cementation with copper metal. After recovery of precious metal ions by cementation, the filtrate contains Cu(II) together with base metal ions like Al(III), Fe(III), Fe(II), Ni(II), Sn(II), and Zn(II). In this work, separation experiments were conducted to recover Cu(II) and Ni(II) from the filtrate. First, copper ions were completely separated from the filtrate by chemical reduction with hydrazine at the following conditions: a molar ratio of 8 for hydrazine to Cu(II), 20°C, 500 rpm, and 20 mins. By adding sodium oxalate to the solution after separation of Cu(II), most of the Ni(II) and 38% of the Zn(II) were co-precipitated at 20°C, 60 mins, 500 rpm, and a molar ratio of 20 for sodium oxalate to nickel. After dissolving the coprecipitates of Ni(II) and Zn(II) oxalates in a 0.5 M HCl solution, the Zn(II) was completely removed from the solution by a five-stage cross-current extraction with 2.5 M Cyanex 272. Nickel hydroxides were then recovered from the raffinate by precipitation with NaOH. The purity of the copper metal and nickel hydroxides was higher than 99%. A process was proposed to recover Au(III), Pd(II), Cu(II), and Ni(II) from the leaching solutions of PCBs.

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Synthesis, morphology, electrical conductivity and electrochemical properties of α-Ni(OH)2 and its composites with carbon

Khemii O. M., Budzuliak I. M., Kotsyubynsky V. O., Yablon L. S., Ilnytskyi R. V., Boychuk V. M., Morushko O. V., Bandura K. V., Khemii M. M.

Materials Science Poland

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2019

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Vol. 37, No. 4

547--553

EN

A simple and effective hydrothermal synthesis of spherical α-Ni(OH) )2 particles and α-Ni(OH)2/carbon composites was proposed. The mechanism of ultrafine α-Ni(OH) )2 phase forming and correlations between synthesis conditions, morphology, electrical conductivity were analyzed. It was found that carbon nanoparticles form an electric conductive cover on nickel hydroxide microparticles during synthesis which increases overall electronic conductivity of the composite material. α-Ni(OH)2 and α-Ni(OH) )2/C samples were tested as electrodes for hybrid supercapacitors. It was found that carbon coverings stabilize α-Ni(OH) )2 phase in the alkaline medium. The comparison of the influence of laser irradiation and ultrasonic treatment on the electrochemical performance of the obtained materials was made.

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Admixturing of waste nickel hydroxide to ceramical building materials

Osińska M., Stefanowicz T.

Polish Journal of Applied Chemistry

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2001

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Vol. 45, nr 3-4

109-116

EN

Clay destined for bricks production was admixtured with 1, 2, 3 and 10% (d.s.) of nickel hydroxide (the often electroplating sludge component). The burnt-out ceramic brick samples were examined for physical and mechanical properties and for nickel leaching. Samples admixtured within the range of 1-3% did not differ by physical and mechanical properties, while those admixtured with 10% of Ni(OH)2 (non-washed of salts) lost approx. 50% of their initial compressive strength. Nickel concentrations in leachates at water-to-ceramics ratio 10:1 with ceramics admixtured with 10% of Ni(OH)2 (at leaching time 48 h) were below the permissible level. Nickel hydroxide stabilization in ceramics within 1-10% admixtures is considered to be effective and in line with law requirements.

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Comparative study of electrochemical behaviour of nickel carriers for nickel hydroxide positive electrodes in alkaline batteries

Młynarek G., Wójcik G., Kopczyk M., Dmochowska M., Grdeń M., Żelazowska-Zakrent M., Czerwiński A., Skowroński J. M.

Polish Journal of Applied Chemistry

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2000

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Vol. 44, nr 1

7-17

EN

The electrochemical performance of nickel foam, sintered nickel and nickel deposited on Reticulated Vitreous Carbon (RVCŽ) in KOH solutions has been investigated. The results indicate that the foam nickel is a very good carrier for redox couple Ni(OH)2/NiOOH which is used in alkaline rechargeable batteries as an electrode material. Also RVC covered with nickel is a good matrix for nickel hydroxide and it can be used as a positive electrode in secondary alkaline batteries. Foam nickel saturated with Ni(OH)2 has the best weight capacities in comparison to sintered nickel and nickel deposited on RVC. Sintered nickel saturated with Ni(OH)2 has the best volume capacity. However, Ni/RVC-NiOOH electrode has much better weight specific energy than that typical for sintered nickel saturated with NiOOH. The influence of additives (derivatives of cellulose) on sizes of pores and their distribution in sintered nickel and power capacity of positive electrode has been also studied.