Leaching Behavior of Al, Co and W from the Al-Alloying Treated WC-Co Tool as a New Recycling Process for WC Hard Scrap

Lee, Jaeryeong; Lee, Joowung; Kim, Byoungjin; Kim, Young‐Jin

doi:10.3390/met6080174

Cited by 6 publications

(3 citation statements)

References 17 publications

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“…Tungsten is one of the most important metals and is widely used in the aerospace, industrial, and military applications for its excellent toughness and hardness, but it is subject to supply risk due to the limited deposits and increasing demand [ 1 , 2 , 3 ], and will soon be used up at the current consumption speed [ 4 , 5 , 6 ]. Therefore, it is of urgent need to recover tungsten resources.…”

Section: Introductionmentioning

confidence: 99%

Oxidation Behavior of Multilayer Hard Coatings (TiCN/Al2O3/TiN) in Process of Recycling Coated Multicomponent Hardmetal Scrap

Kuang

Tan

et al. 2018

Materials

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The coating is one of the biggest problems in the recycling of coated multicomponent hardmetal scraps. The isothermal oxidation behavior of WC-Co multicomponent cemented carbide inserts with a TiCN/Al2O3/TiN hard coating in the recycling process was investigated. The oxidation rate slowed down as the protective coating blocked element diffusion. A rapid oxidation rate was obtained when they were milled into powders and isothermally oxidized at 900 °C. A rapid path for element diffusion was provided by the defects, which were promoted by stress, expansion, and gas volatilization. Both the TiN and TiCN layers were oxidized to a porous TiO2 scale, while the Al2O3 phase remained and the dense Al2O3 layer acted as a barrier for its good oxidation resistance. Pieces of the Al2O3 layer were obviously seen in the final oxides. This provides critical information to reduce the negative effect of coatings and improve the performance of recycled WC powders and hard alloys.

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Section: Introductionmentioning

confidence: 99%

Oxidation Behavior of Multilayer Hard Coatings (TiCN/Al2O3/TiN) in Process of Recycling Coated Multicomponent Hardmetal Scrap

Kuang

Tan

et al. 2018

Materials

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“…Soft scrap contains more metallic impurities than hard scrap, but does not need to be crushed like hard scrap. To enhance the recycling efficiency and increase the selective recovery of valuable metals, soft scrap should be treated with special care [11].…”

Section: Introductionmentioning

confidence: 99%

A New Recycling Process for Tungsten Carbide Soft Scrap That Employs a Mechanochemical Reaction with Sodium Hydroxide

Lee

Kim

2017

Metals

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WC soft scrap, including Co used as a binder, thermally oxidized at 600 • C, was subjected to grinding with NaOH in a mechanochemical reaction, followed by water leaching to establish an effective recycling process. Na 2 WO 4 was synthesized through a mechanochemical (MC) reaction with oxidized scrap, and Na 2 CO 3 was formed when the mixing ratio of NaOH increased. These as-synthesized compounds were water-soluble. When the weight ratio of soft scrap to NaOH was 1:0.5, 99.2% W was extracted by water leaching, while the extraction yield of Co was limited to 3.57% under the same conditions.

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“…The major pyrometallurgical-based recycling processes are Zn melting [24,25], cold streaming, chemical modification, alkali leaching [26], oxidation roasting followed by leaching [19], chlorination, high-temperature smelting, molten salts electrolysis [27], etc., of which majority involves the use of expensive chemicals (acids, bases, and inorganic salts). A mechano-chemical reaction-based recycling process, in which the scrapes were thermally oxidized at 600 ºC, followed by grinding in NaOH, and water leaching, has also been developed [29].…”

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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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Leaching Behavior of Al, Co and W from the Al-Alloying Treated WC-Co Tool as a New Recycling Process for WC Hard Scrap

Cited by 6 publications

References 17 publications

Oxidation Behavior of Multilayer Hard Coatings (TiCN/Al2O3/TiN) in Process of Recycling Coated Multicomponent Hardmetal Scrap

Oxidation Behavior of Multilayer Hard Coatings (TiCN/Al2O3/TiN) in Process of Recycling Coated Multicomponent Hardmetal Scrap

A New Recycling Process for Tungsten Carbide Soft Scrap That Employs a Mechanochemical Reaction with Sodium Hydroxide

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

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