Separation of cobalt and tungsten carbide by anodic dissolution of solid alloys in phosphoric acid

Малышев, В. В.; Hab, A. I.

doi:10.1007/s11003-005-0078-x

Cited by 11 publications

(4 citation statements)

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“…A close-knit group of papers describes attempts to implement controlled corrosion for HM recovery in acidic electrolyte [45][46][47][48][49][50][51][52][53][54][55]. Co from the binder is efficiently dissolved and electrodeposited on the cathode surface, while WC remain undissolved.…”

Section: Introductionmentioning

confidence: 99%

“…Instead, alkaline electrolytes [56][57][58][59][60][61] dissolve WC readily at the anode, that can be recovered later as tungstic acid, while Co, again, is electroplated on the cathode. Potentiostatic [45,47,49,[51][52][53]60,61] and galvanostatic [45,48,50,56,58] approaches have been explored with both acidic and alkaline electrolytes, but no industrially viable process resulted from these studies [23,62]. In the literature on electrochemical recovery processes, the pseudopassivation layer phenomenon is observed but not well studied.…”

Section: Introductionmentioning

confidence: 99%

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In-Depth Understanding of Hardmetal Corrosion Performance Reveals a Path to the Electrochemical Demolition of Scrap

Bozzini,

Tavola,

Travella

et al. 2023

Metals

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Recycling of hardmetal scrap is strategic for critical raw materials recovery. Available recycling processes are polluting and have a large carbon footprint. Attempts to exploit controlled corrosion failed in industrial practice, owing to self-limiting processes. We revisit the corrosion route, in view of gaining the fundamental knowledge enabling high-throughput recovery. We selected the worst-case approach of highly corrosion-resistant CoNiWC-based hardmetal grades and neutral aqueous electrolyte at room temperature. Systematic electrochemical measurements, UV–Vis spectroscopy and SEM microscopy disclosed that, even though there is no hope to overcome the self-limiting corrosion rate, nevertheless, by exploiting the mechanical action of anodic O2 evolution acting precisely at the interface between the residual active material and the corrosion film, the latter can be efficiently removed, periodically reactivating the hardmetal corrosion in a way that results in an ultra-high scrap destruction rate, of interest for real-life industrial processes.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

In-Depth Understanding of Hardmetal Corrosion Performance Reveals a Path to the Electrochemical Demolition of Scrap

Bozzini,

Tavola,

Travella

et al. 2023

Metals

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“…The application of such technique has been employed in processing of metallic materials containing Fe, Cu, Ni, Co, W, Al, etc. [15][16][17][18][19]. The above reported studies were performed by taking either metal alone or its alloy using different acid/alkali solution.…”

Section: Introductionmentioning

confidence: 99%

Process for recovery of metal values from alnico scarps by electro-chemical leaching technique

Prabaharan

Barik

2016

Separation and Purification Technology

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“…Two different types of electrochemical recycling techniques based on HCl, HNO3, H2SO4, H3PO4 and alkali electrolytes (NaOH and NH3) have been adopted in the WC-Co scrap electrodissolution. It has been found that W and Co effective recovery depend on the selective phase dissolution and deposition mechanisms [6,15,16,19,28,[31][32][33][34][35][36][37]. However, in an acidic medium, Co is dissolved and goes into the electrolyte, and a significant fraction of it is deposited on the cathode, leaving behind the WC skeleton as an anode residue, which is further processed.…”

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confidence: 99%

Recovery of Strategic Metals from Tungsten Carbide-Cobalt Bonded Waste by Electrochemical Processing

Katiyar¹,

Randhawa²

2023

Port. Electrochim. Acta

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Scraped or end-of-life WC-Co bonded makes it an attractive resource. The conventional technologies to recover these metals entail energy-intensive pre-treatment steps, followed by their dissolution in a high volume of concentrated acids/alkali reagents. Recently, much attention has been given to the development of energy-efficient and environmentally friendly routes based on WC-Co direct electrochemical dissolution as anodes. However, the metals have a retarded dissolution, in NaOH alkali media, due to the formation of passive oxide layers, in the acidic electrolytes, and of hydroxides, on the anodic surface. The present study investigated WC and Co dissolution fundamentals in aqueous NH3, in order to develop a greener process, by the suitable addition of (NH4)2CO3, (NH4)2SO4 and NH4Cl Preliminary PDP studies revealed the necessary concentration of NH3 and additives, and their effect on the metals passivation tendency, for obtaining the best anodic dissolution parameters. The electrodissolution experiments in a specially designed cell achieved the maximum values, by adjusting those parameters. The highest dissolution of W and Co occurred under optimum conditions (10 V, 150 g/L NH3 and 15% w/v NH4Cl). Co was deposited at the cathode, while H8N2O4W remained in the electrolyte and was recovered as H2WO4 or YTO. Topographical analysis of the polarized surface by AFM has confirmed the pitting corrosion mechanism responsible for W and Co dissolution. A process flow chart for the newly developed single-step direct recycling methods of WC scraps has also been proposed. This process has produced pure saleable WO3 powder and Co.

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Separation of cobalt and tungsten carbide by anodic dissolution of solid alloys in phosphoric acid

Cited by 11 publications

References 1 publication

In-Depth Understanding of Hardmetal Corrosion Performance Reveals a Path to the Electrochemical Demolition of Scrap

In-Depth Understanding of Hardmetal Corrosion Performance Reveals a Path to the Electrochemical Demolition of Scrap

Process for recovery of metal values from alnico scarps by electro-chemical leaching technique

Recovery of Strategic Metals from Tungsten Carbide-Cobalt Bonded Waste by Electrochemical Processing

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