Proceedings of the international symposium on electrochemistry in mineral and metal processing

Doyle, Fiona M.; Hanson, James S.

doi:10.1016/0301-7516(86)90065-7

Cited by 15 publications

(19 citation statements)

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Section: Introductionsupporting

confidence: 53%

“…Analogous behavior was found (1,2) for the deposition of sulfur on platinum and gold from sulfide ion solutions, systems that also display potential dependence of wettability. In contrast, for sulfur deposition on silver and oxygen adsorption on platinum, the EQCM measures mass changes accurately because these surfaces remain hydrophilic during potential excursions (1,2). Further research has now been carried out on the ethyl xanthate/silver system, in order to elucidate the processes occurring at the EQCM electrode/electrolyte interface during hydrophilic/hydrophobic transitions.…”

Section: Introductionsupporting

confidence: 53%

“…At the International Symposium on Electrochemistry in Mineral and Metal Processing V, the present authors reported studies (1) with the electrochemical quartz crystal microbalance (EQCM) of systems that undergo a change in the electrode surface between a hydrophilic and hydrophobic condition during potential excursions. A significant shift in frequency was observed when linear potential sweeps were applied to a silver EQCM electrode in a solution of ethyl xanthate (1,2). In this system, charge transfer adsorption of a monolayer of ethyl xanthate occurs at an underpotenial to silver ethyl xanthate formation.…”

Section: Introductionmentioning

confidence: 99%

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Frequency Changes Observed with the EQCM Resulting from Hydrophilic/Hydrophobic Transitions

Woods¹,

Jeffrey²

2006

ECS Trans.

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The processes responsible for the altered frequency response of the EQCM when the electrode surface changes from a hydrophilic to a hydrophobic condition have been investigated using silver electrodes in ethyl xanthate solution. The frequency accurately tracks the voltammetric charge when silver ethyl xanthate is formed, but moves in the opposite direction when xanthate is chemisorbed; chemisorption is known to result in the surface becoming hydrophobic. The characteristics of the EQCM in a xanthate solution that had been completely degassed was the same as that in one deaerated with nitrogen. This is inconsistent with nanobubbles being formed at a hydrophobic surface, but is in agreement with slippage occurring as a result of a change in water structure. Similar voltammograms were observed for smooth silver surfaces to those for electrodeposited ones, but the alteration in frequency response during the change in wettability was much greater. This is also explained in terms of water structure.

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Section: Introductionsupporting

confidence: 53%

Section: Introductionsupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

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Frequency Changes Observed with the EQCM Resulting from Hydrophilic/Hydrophobic Transitions

Woods¹,

Jeffrey²

2006

ECS Trans.

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“…It is known that chloride ion promotes the crystallinity of elemental sulphur. 37 Little work has been carried out on the electrochemical behaviour of pure Ni 3 S 2 in the presence of Cu(II), although there is no doubt a reaction between Cu(II) and nickel sulphide to form CuS or Cu 2 S on the surface 38,27 Chen et al 39 found that the reaction rate was controlled by both solid diffusion and electron charge transfer. At 40uC, the Ni 3 S 2 electrode quickly passivated at 0 .…”

Section: Electrochemistry Of Nickel Sulphidesmentioning

confidence: 99%

Process review and electrochemistry of nickel sulphides and nickel mattes in acidic sulphate and chloride media

Muir¹,

Ho²

2006

Mineral Processing and Extractive Metallurgy

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Analysis of several nickel mattes from around the world shows a significant variation in their nickel and copper content. Typically, matte contains an alloy, heazlewoodite (Ni 3 S 2 ) and a copper sulphide phase. The various commercial methods of processing these mattes are reviewed and some of the fundamental factors that determine the choice of leaching system are discussed. Electrochemical studies on pure heazlewoodite and millerite (NiS) in sulphate and chloride media are compared which show that nickel sulphides react via a series of nickel deficient sulphides and exhibit passivation as nickel is removed. The electrochemistry of mattes differs owing to the presence of alloy and copper. Copper in the matte modifies the potential for alloy dissolution and the rate of anodic dissolution of nickel. Differences in the electrochemical behaviour of matte in chloride media relative to sulphate media are attributed to greater crystallinity of sulphur and less formation of intermediate NiS 2 which oxidises to form thiosulphate and sulphate in solution. At elevated temperatures, Cu(II) in solution exchanges with NiS and completes the leaching of nickel at relatively low potentials without significant oxidation of sulphur to sulphate. It is concluded that there are fundamental advantages to leaching nickel sulphides and nickel matte in the presence of Cu(II) and chloride ion to minimise the production of sulphate ion via NiS 2 formation.

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“…In the present study, the different metallic ions (Pd, Pt and Au) are diluted in artificial acidic leach liquors, composed of HCl (concentration up to 0.1 mol/L) and thiourea, (concentration up to 10 mmol/L) at pH = 1. They are assumed to complex with chloride ions and thiourea due to their high affinity binding (log K = 11.5 and 30.1 with Pd(II) ,for chloride and thiourea respectively, at 25°C and 1 mol/L ionic strength [21], log K = 14.0 for chloride with Pt(II) [21], and log K = 29.6 for chloride with Au(III) [21] and 5.76 for thiourea with Au(I) [22]). Furthermore, they can exist under different forms, according to their oxidation state.…”

Section: Resultsmentioning

confidence: 99%

Speciation and quantitation of precious metals in model acidic leach liquors, theoretical and practical aspects of recycling

Gouyon

d’Orlyé²,

Zimmerman³

et al. 2020

Anal Bioanal Chem

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Waste printed circuits boards are a major source of strategic materials such as platinum group metals since they are used for the fabrication of technological devices, such as hard drive discs, capacitors, diodes, etc. Because of the high cost of platinum, palladium and gold (> 25k€ / kg), an economic and environmental challenge is their recycling from printed circuit boards, that represent around 2% weight of electronic equipment. Hydrometallurgical treatments allow to recover these metals in solution, with a high recovery rate for a leaching liquor made of thiourea in hydrochloric acid. So as to develop an efficient recycling process from this leach liquor, one requires the speciation of these strategic metals, as well as their extraction and quantitation in the mixture. For this purpose, platinum, palladium and gold were dissolved in model leach liquors made of hydrochloric acid and thiourea at low concentration. The identification of metal complexes was determined in function of thiourea concentration (between 10 µmol/L and 10 mmol/L) by the combination of UV-Visible spectrometry, cyclic voltammetry and for the first time capillary electrophoresis. The electrokinetic method was then applied for the quantitation of trace metal analyses in leach samples from waste printed circuit boards reprocessing, demonstrating its applicability for industrializable recycling applications.

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Proceedings of the international symposium on electrochemistry in mineral and metal processing

Cited by 15 publications

References 0 publications

Frequency Changes Observed with the EQCM Resulting from Hydrophilic/Hydrophobic Transitions

Frequency Changes Observed with the EQCM Resulting from Hydrophilic/Hydrophobic Transitions

Process review and electrochemistry of nickel sulphides and nickel mattes in acidic sulphate and chloride media

Speciation and quantitation of precious metals in model acidic leach liquors, theoretical and practical aspects of recycling

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