Efficient recycling of WC-Co hardmetal sludge by oxidation followed by alkali and sulfuric acid treatments

Yang, Dong-Hyo; Srivastava, Rajiv Ranjan; Kim, Min-seuk; Nam, Dao Duy; Lee, Jae-chun; Huynh, Hai Trung

doi:10.1007/s12540-016-6060-3

Cited by 16 publications

(10 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Tungsten, a strategically rare metal, is steadily increasing in demand for various high-tech applications, due to its remarkable physical and chemical properties. 1 It is widely used in hard materials, high temperature technology, and communication technologies, especially in armament and aero-space industries. 2 Ammonium tungstate, as the main intermediate product in industrial tungsten extraction, is usually obtained by treating wolframite ((Fe,Mn)WO4), scheelite (CaWO4), and mixed wolframite-scheelite concentrates by either caustic soda or hydrochloric acid.…”

Section: Introductionmentioning

confidence: 99%

Wolframite Conversion in Treating a Mixed Wolframite–Scheelite Concentrate by Sulfuric Acid

Shen

Zhou

et al. 2017

JOM

View full text Add to dashboard Cite

Complete wolframite conversion in sulfuric acid is significant for expanding the applicability of the sulfuric acid method for producing ammonium paratungstate. In this paper, the conversion of wolframite in treating a mixed wolframite-scheelite concentrate by sulfuric acid was studied systematically. The results show that the conversion of wolframite in sulfuric acid is more difficult than that of scheelite, requiring rigorous reaction conditions. A solid H2WO4 layer forms on the surfaces of the wolframite particles and becomes denser with increasing H2SO4 concentration, thus hindering the conversion. Furthermore, the difficulty in wolframite conversion can be mainly attributed to the accumulation of Fe 2+ (and/or Mn 2+) in the H2SO4 solution, which can be solved by reducing Fe 2+ (and/or Mn 2+) concentration through oxidization and/or a two-stage process. Additionally, the solid converted product of the mixed wolframite-scheelite concentrate has an excellent leachability of tungsten in an aqueous ammonium carbonate solution at ambient temperature, with approximately 99% WO3 recovery. This work presents a route for manufacturing ammonium paratungstate by treating the mixed concentrate in sulfuric acid followed by leaching in ammonium carbonate solution.

show abstract

Section: Introductionmentioning

confidence: 99%

Wolframite Conversion in Treating a Mixed Wolframite–Scheelite Concentrate by Sulfuric Acid

Shen

Zhou

et al. 2017

JOM

View full text Add to dashboard Cite

show abstract

“…Although several recycling processes have been globally developed and used, their success would depend on their eco-friendliness and economic feasibility [5]. These processes include pyrometallurgy-based oxidation, carbothermal reduction [7,8] hydrometallurgy [9,10] and electrometallurgy [11][12][13][14][15][16][17][18] routes, or their combination [19][20][21], in order to recover the valuables W and Co materials. Researchers [4] have also studied pyrometallurgy [8], hydrometallurgy [10,22] or pyro/hydrometallurgy [19]) methods, and compared them based on energy consumption, eco-friendliness, equipment cost, emission of toxic gases and recovery of different products (e.g., W and Co) [23].…”

mentioning

confidence: 99%

“…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].…”

mentioning

confidence: 99%

“…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.…”

mentioning

confidence: 99%

“…On the other hand, WC scrap electrodissolution in a NaOH electrolyte has constraints, since this electrolyte recycling is impossible, and further conversion of Na2WO4 into H8N2O4W is very time-consuming. Alternatively, the WC-Co scraps have also been treated in an alkali medium of NH4OH (high pH), because W and Co are highly soluble in it, forming H8N2O4W or APT and Co amine complexes [12,16,19,34]. Further processing of the obtained APT, at high temperatures, under H2 gas, leads to the formation of W powder [38].…”

mentioning

confidence: 99%

See 2 more Smart Citations

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

Katiyar¹,

Randhawa²

2023

Port. Electrochim. Acta

View full text Add to dashboard Cite

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.

show abstract

Reclamation of tungsten from carbide scraps and spent materials

Srivastava¹,

Lee

Bae

et al. 2018

J Mater Sci

View full text Add to dashboard Cite

Efficient recycling of WC-Co hardmetal sludge by oxidation followed by alkali and sulfuric acid treatments

Cited by 16 publications

References 25 publications

Wolframite Conversion in Treating a Mixed Wolframite–Scheelite Concentrate by Sulfuric Acid

Wolframite Conversion in Treating a Mixed Wolframite–Scheelite Concentrate by Sulfuric Acid

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

Reclamation of tungsten from carbide scraps and spent materials

Contact Info

Product

Resources

About