Leaching Kinetics of Zinc from Metal Oxide Varistors (MOVs) with Sulfuric Acid

Kim, Young‐Jin; Lee, Jaeryeong

doi:10.3390/met6080192

Cited by 10 publications

(2 citation statements)

References 24 publications

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“…As mentioned earlier, when leaching Zn(II) with sulfuric(VI) acid of various concentrations, this is most likely due to the consumption of all the zinc(II) oxide (Equation (3)), leaving only zinc(II) sulphide, which is covered with a passive layer of sulfur (Equation (4)), reducing the leaching of Zn(II). In addition, in works [ 48 , 49 , 50 , 57 , 58 ], where metallurgical dusts, ores and zinc concentrate were studied, the test results indicate that the rate of zinc dissolution slightly increased with increasing temperature. It was found that with the use of H 2 SO 4 and a different range of leaching temperatures, the temperature had no significant effect on the extraction of Zn(II).…”

Section: Resultsmentioning

confidence: 99%

Two-Stage Leaching of PCBs Using Sulfuric and Nitric Acid with the Addition of Hydrogen Peroxide and Ozone

Lisińska,

Wojtal,

Saternus

et al. 2023

Materials

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The paper presents the possibility of recovering metals from printed circuit boards (PCBs) of spent mobile phones using the hydrometallurgical method. Two-stage leaching of Cu(II), Fe(III), Sn(IV), Zn(II), Ni(II) and Pb(II) with H2SO4 (2 and 5 M) and HNO3 (2 M) with the addition of H2O2 (10 and 30%) and O3 (9 or 15 g/h) was conducted at various process conditions (temperature—313, 333 and 353 K, time—60, 120, 240, 300 min, type and concentration of leaching agent, type and concentration of oxidant, solid–liquid ratio (S/L)), allowing for a high or total metals leaching rate. The use of two leaching stages allows for the preservation of selectivity, separation and recovery of metals: in the first stage of Fe(III), Sn(IV) and in the second stage of the remaining tested metal ions, i.e., Cu(II), Zn(II), Ni(II) and Pb(II). Removing Fe from the tested PCBs’ material at the beginning of the process eliminates the need to use magnetic methods, the purpose of which is to separate magnetic metal particles (ferrous) from non-magnetic (non-ferrous) particles; these procedures involve high operating costs. Since the leaching of Cu(II) ions with sulfuric(VI) acid practically does not occur (less than 1%), this allows for almost complete transfer of these ions into the solution in the second stage of leaching. Moreover, to speed up the process and not generate too many waste solutions, oxidants in the form of hydrogen peroxide and ozone were used. The best degree of leaching of all tested metal ions was obtained when 2 M sulfuric(VI) acid at 353 K was used in the 1st research stage, and 2 M nitric(V) acid and 9 g/h O3 at 298 K in the 2nd stage of leaching, which allowed it to be totally leached 100% of Fe(III), Cu(II), Sn(IV), Zn(II), Ni(II) and 90% Pb(II).

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Section: Resultsmentioning

confidence: 99%

Two-Stage Leaching of PCBs Using Sulfuric and Nitric Acid with the Addition of Hydrogen Peroxide and Ozone

Lisińska,

Wojtal,

Saternus

et al. 2023

Materials

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“…The activation energy of the zinc oxide leaching with sulfuric acid was found 17.5 kJ/mol by the Arrhenius plot showing that the reaction rate of zinc oxide leaching was controlled by mass transfer through the liquid boundary layer. Activation energy was also calculated as 20.7 kJ/mol in the temperature range of 313 K to 353 K, for zinc recovery from metal oxide varistors (MOVs) with sulfuric acid [33].…”

Section: Effect Of Roasting Prior To Leachingmentioning

confidence: 99%

Recovery of ZnO from lead-zinc flotation tailings by hydrometallurgical processes: XRD, SEM, and AFM studies

Perek¹,

Benli²,

Arslan³

et al. 2020

J Min & Metal A Mining

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The hydrometallurgical route of zinc hydroxide and synthesis of nanocrystalline ZnO is a particularly attractive method to recover oxidized lead and zinc from lead-zinc flotation tailings. In Turkey, lead-zinc complex/mixed ores along with high iron content are not suitable for conventional mineral processing methods and need hydrometallurgical treatments. Therefore, the control of iron during zinc processes is really important. In this study, hydrometallurgical process route for zinc recovery from Pb-Zn flotation tailings was investigated by considering the effects of H2SO4 concentration, leaching and roasting temperatures on the zinc dissolution considering the Eh-pH variations. The iron and zinc products were also individually examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) images in order to compare before and after leaching, precipitation and roasting steps. 83.1% Zn and 91.6% Cd leaching efficiencies were obtained from Pb-Zn flotation tailing particles with the size range of 50-110 nm from AFM image cross-sections, while lead and iron were not dissolved. Elemental sulfur started to form and produce a layer around the particles or a partially agglomerated particle in the size of 170 nm during the sulphuric acid leaching. However, majority of the particles was determined to be less than 20 microns, and AFM images showed that the size reduction between the leached and unleached particles was over 50%. Selective precipitations of iron and zinc in the form of hydroxide were performed in high recovery efficiencies of 90.1% and 99%, respectively. After the heat treatment, nanocrystalline zincite clusters of 96.6% purity were produced in the ZnO mineral form and nearly 13 nm in size. Zinc can be successfully recovered and a flotation tailings ore can be a good candidate for the production of high technology needs of nanocrystalline ZnO nanoparticles.

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