This study focuses on the fabrication of a WC/Co composite powder from the oxide of WC/Co hardmetal scrap using solid carbon in a hydrogen gas atmosphere for the recycling of WC/Co hardmetal. Mixed powders are manufactured by mechanically milling the oxide powder of WC-13 wt% Co hardmetal scrap and carbon black with varying powder/ball weight ratios. The oxide powder of WC-13 wt% Co hardmetal scrap consists of WO₃ and CoWO₄. The mixed powder mechanically milled at a lower powder/ball weight ratio (high mechanical milling energy) has a more rapid carbothermal reduction reaction in the formation of WC and Co phases compared with that mechanically milled at a higher powder/ball weight ratio (lower mechanical milling energy). The WC/Co composite powder is fabricated at 900°C for 6 h from the oxide of WC/Co hardmetal scrap using solid carbon in a hydrogen gas atmosphere. The fabricated WC/Co composite powder has a particle size of approximately 0.25-0.5 μm.

This study focuses on the development of an alkaline leaching hydrometallurgy process for the recovery of tungsten from WC/Co hardmetal sludge, and an examination of the effect of the process parameters on tungsten recovery. The alkaline leaching hydrometallurgy process has four stages, i.e., oxidation of the sludge, leaching of tungsten by NaOH, refinement of the leaching solution, and precipitation of tungsten. The WC/Co hardmetal sludge oxide consists of WO₃ and CoWO₄. The leaching of tungsten is most affected by the leaching temperature, followed by the NaOH concentration and the leaching time. About 99% of tungsten in the WC/Co hardmetal sludge is leached at temperatures above 90°C and a NaOH concentration above 15%. For refinement of the leaching solution, pH control of the solution using HCl is more effective than the addition of Na₂S·9H₂O. The tungsten is precipitated as high-purity H₂WO₄·H₂O by pH control using HCl. With decreasing pH of the solution, the tungsten recovery rate increases and then decrease. About 93% of tungsten in the WC/Co hardmetal sludge is recovered by the alkaline leaching hydrometallurgy process.

Citations

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• Fabrication of tungsten oxide powder from WC–Co cemented carbide scraps by oxidation behaviour
  Min Soo Park, Jong-Min Gwak, Kyeong-mi Jang, Gook-Hyun Ha
  Powder Metallurgy.2023; 66(5): 688.     CrossRef

This study focuses on fabricating silver flake powder by a mechanical milling process and investigating the formation of flake-shaped particles during milling. The silver flake powder is fabricated by varying the mechanical milling parameters such as the amount of powder, ball size, impeller rotation speed, and milling time of the attrition ballmill. The particle size of the silver flake powder decreases with increasing amount of powder; however, it increases with increasing impeller rotation speed. The change in the particle size of the silver flake powder is analyzed based on elastic collision between the balls, taking energy loss of the balls due to the powder into consideration. The change in the particle size of the silver flake powder with mechanical milling parameters is consistent with the change in the diameter of the elastic deformation contact area of the ball, due to the collision between the balls, with milling parameters. The flake-shaped silver particles are formed at the elastic deformation contact area of the ball due to the collision.

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• Fabrication of WC/Co composite powder from oxide of WC/Co hardmetal scrap by carbothermal reduction process
  Gil-Geun Lee, Young Soo Lim
  journal of Korean Powder Metallurgy Institute.2018; 25(3): 240.     CrossRef

This study is focused on investigating the relation between the particle size of silver flake powder and mechanical milling parameters. Mechanical milling parameters such as ball size, impeller rotation speed and milling time of the attrition ball-mill were controlled to produce silver flake powder. The particle size of the silver flake powder increased with increasing ball size and impeller rotation speed. The change of the particle size of the silver flake powder with mechanical milling parameters was analyzed based on balls motion in the mill container of the attrition ballmill. The silver flake particles were formed at the elastic deformation area of the ball due to the collision between balls. The change of the particle size of the silver flake powder with mechanical milling parameters well consists with the change of the collision energy of ball with parameters mentioned above.

Citations

Citations to this article as recorded by  

• Fabrication of Silver Flake Powder by the Mechanical Milling Process
  Hae-Young Jeong, Gil-Geun Lee
  Journal of Korean Powder Metallurgy Institute.2016; 23(1): 54.     CrossRef

Citations

Citations to this article as recorded by  

• Effects of mechanical milling on the carbothermal reduction of oxide of WC/Co hardmetal scrap
  Gil-Geun Lee, Gook-Hyun Ha
  Metals and Materials International.2016; 22(2): 260.     CrossRef
• Recovery of Tungsten from WC/Co Hardmetal Sludge by Alkaline Leaching Hydrometallurgy Process
  Gil-Geun Lee, Ji-Eun Kwon
  Journal of Korean Powder Metallurgy Institute.2016; 23(5): 372.     CrossRef
• Recovery of tungsten carbide from hard material sludge by oxidation and carbothermal reduction process
  Woo-Gwang Jung
  Journal of Industrial and Engineering Chemistry.2014; 20(4): 2384.     CrossRef
• Trend on the Recycling Technologies for the used Tungsten Carbide(WC) by the Patent and Paper Analysis
  Jin-Ki Jeong, Jae-Chun Lee, Sang-Woo Park, Kyung-Seok Kang
  Journal of the Korean Institute of Resources Recycling.2012; 21(1): 82.     CrossRef