Copper Recovery Using a Tumbled‐Bed Electrochemical Reactor

AbstractThe electrocatalytic nitrogen (N2) reduction reaction (NRR) relies on the development of highly efficient electrocatalysts and electrocatalysis systems. Herein, we report a non-loading electrocatalysis system, where the electrocatalysts are dispersed in aqueous solution rather than loading them on electrode substrates. The system consists of aqueous Ag nanodots (AgNDs) as the catalyst and metallic titanium (Ti) mesh as the current collector for electrocatalytic NRR. The as-synthesized AgNDs, homogeneously dispersed in 0.1 M Na2SO4 solution (pH = 10.5), can achieve an NH3 yield rate of 600.4 ± 23.0 μg h−1 mgAg−1 with a faradaic efficiency (FE) of 10.1 ± 0.7% at −0.25 V (vs. RHE). The FE can be further improved to be 20.1 ± 0.9% at the same potential by using Ti mesh modified with oxygen vacancy-rich TiO2 nanosheets as the current collector. Utilizing the aqueous AgNDs catalyst, a Ti plate based two-electrode configured flow-type electrochemical reactor was developed to achieve an NH3 yield rate of 804.5 ± 30.6 μg h−1 mgAg−1 with a FE of 8.2 ± 0.5% at a voltage of −1.8 V. The designed non-loading electrocatalysis system takes full advantage of the AgNDs’ active sites for N2 adsorption and activation, following an alternative hydrogenation mechanism revealed by theoretical calculations.

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Recovery of Zinc and Silver from Zinc Acid-Leaching Residues with Reduction of Their Environmental Impact Using a Novel Water Leaching-Flotation Process

Minerals ◽

10.3390/min11060586 ◽

2021 ◽

Vol 11 (6) ◽

pp. 586

Author(s):

Yunpeng Du ◽

Xiong Tong ◽

Xian Xie ◽

Wenjie Zhang ◽

Hanxu Yang ◽

...

Keyword(s):

Hazardous Waste ◽

Acid Leaching ◽

Copper Recovery ◽

Water Leaching ◽

Flotation Process ◽

Metal Levels ◽

Valuable Metals ◽

Leaching Experiments ◽

Zinc Hydrometallurgy ◽

Poor Stability

Zinc-leaching residue (ZLR) is a strongly acidic hazardous waste; it has poor stability, high heavy metal levels, and releases toxic elements into the environment. ZLR has potential as a valuable resource, because it contains elevated levels of zinc and silver. In this paper, the recovery of zinc (Zn) and silver (Ag) from ZLR wastes from zinc hydrometallurgy workshops using water leaching followed by flotation was studied. During water leaching experiments, the zinc and copper recovery rates were 38% and 61%, respectively. Thereafter, various flotation testing parameters were optimized and included grinding time, reagent dosages, pulp density, flotation time, and type of adjuster. Experimental results demonstrated this flotation method successfully recycled Ag and Zn. A froth product containing more than 9256.41 g/t Ag and 12.26% Zn was produced from the ZLR with approximately 80.32% Ag and 42.88% Zn recoveries. The toxicity characteristic leaching procedure (TCLP) results indicated the water-leaching flotation process not only recycled valuable metals such as zinc and silver in zinc-containing hazardous wastes but lowered the hazardous waste levels to those of general wastes and recycled wastes in an efficient, economical, and environmentally friendly way.

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Effective Recovery Process of Copper from Waste Printed Circuit Boards Utilizing Recycling of Leachate

JOM ◽

10.1007/s11837-020-04510-z ◽

2020 ◽

Author(s):

Joona Rajahalme ◽

Siiri Perämäki ◽

Roshan Budhathoki ◽

Ari Väisänen

Keyword(s):

Hydrogen Peroxide ◽

Sulfuric Acid ◽

Printed Circuit Boards ◽

Sulfuric Acid Concentration ◽

Recovery Process ◽

Copper Recovery ◽

Circuit Boards ◽

Printed Circuit ◽

Waste Printed Circuit Boards ◽

Acid Consumption

AbstractThis study presents an optimized leaching and electrowinning process for the recovery of copper from waste printed circuit boards including studies of chemical consumption and recirculation of leachate. Optimization of leaching was performed using response surface methodology in diluted sulfuric acid and hydrogen peroxide media. Optimum leaching conditions for copper were found by using 3.6 mol L−1 sulfuric acid, 6 vol.% hydrogen peroxide, pulp density of 75 g L−1 with 186 min leaching time at 20°C resulting in complete leaching of copper followed by over 92% recovery and purity of 99.9% in the electrowinning. Study of chemical consumption showed total decomposition of hydrogen peroxide during leaching, while changes in sulfuric acid concentration were minor. During recirculation of the leachate with up to 5 cycles, copper recovery and product purity remained at high levels while acid consumption was reduced by 60%.

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