Carbothermic reduction of scheelite (CaWO4) doped with cobalt or nickel

Palmieri, Elena; Marcucci, Andrea; Marcheselli, Giancarlo; Stefanis, Adriana De; Polini, Riccardo

doi:10.1016/j.ijrmhm.2016.05.018

Cited by 4 publications

(1 citation statement)

References 10 publications

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“…Temuujin et al reported that the reduction of wolframite:carbon mixtures, prepared by 2 h ball milling, showed an endothermic peak at 913 °C that was attributed to reaction : Fe 6 W 6 C then reacted with further carbon to form Fe and WC passing through intermediate Fe 3 W 3 C: The carbothermic reduction of CaWO 4 was extensively studied in the literature. ,,,− The reduction is a two-stage process starting with reaction , namely, the formation of tricalcium tungstate (Ca 3 WO 6 ) and W, followed by reaction , that is, the reduction of tricalcium tungstate to W and CaO: Finally, the carburization of metallic tungsten occurs via the intermediate ditungsten carbide, W 2 C, formation: W → W 2 C → WC . The endothermic peaks associated with reactions and occur typically in the interval 1000–1150 °C. − Therefore, the three endothermic peaks we observed at approximately 900, 1000, and 1100 °C were attributable to reactions , , and , respectively.…”

Section: Resultsmentioning

confidence: 99%

Toward Greener Synthesis of WC Powders for Cemented Tungsten Carbides Manufacturing

Polini

Marcucci

D’Ottavi

et al. 2021

ACS Sustainable Chem. Eng.

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Tungsten carbide (WC) is the most important tungsten compound, and the main component of WC-Co cermet composites. WC-Co are widely used engineering materials due to the combination of high hardness and strength of tungsten carbide with the toughness and plasticity of the metallic binder. The direct synthesis of WC from tungsten concentrate containing ∼70% WO3 has been achieved by carbothermic reduction. Mineral/carbon black mixtures were prepared by planetary ball milling and subjected to annealing at 1150 °C in flowing Ar. Specific leaching treatments have been developed to remove foreign phases and obtain pure WC powders. This new process allows about 50% energy saving, −34% CO2 emissions, and significantly lower amounts of industrial waste, with respect to the classical hydrometallurgical tungsten extraction and subsequent pyrometallurgical WC synthesis, widely used in tungsten industry. WC powders obtained by carbothermic reduction of the mineral were employed to prepare sintered WC-8 wt %Co samples that showed high density (>99%), hardness (1490 HV), and toughness (14.6 MPa·m1/2). These findings demonstrate, for the first time, that the carbothermic reduction of tungsten concentrates does represent a viable process for energy efficient and sustainable synthesis of WC powders to be used in the production of cemented carbides.

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