Hydrogen Reduction of Tellurium Oxide in a Rotary Kiln, Initial Approaches for a Sustainable Process

In the recycling of semiconductor materials like Bi<sub>2</sub>Te<sub>3</sub> or CdTe, TeO<sub>2</sub> may form as a by-product that can be directly reduced to recover metallic Te. The hydrogen reduction of TeO<sub>2</sub> offers an eco-friendly altern...

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Bibliographic Details
Main Authors: Hanwen Chung, Semiramis Friedrich, Mengqi Qu, Bernd Friedrich
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Crystals
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Online Access:https://www.mdpi.com/2073-4352/15/5/478
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Summary:In the recycling of semiconductor materials like Bi<sub>2</sub>Te<sub>3</sub> or CdTe, TeO<sub>2</sub> may form as a by-product that can be directly reduced to recover metallic Te. The hydrogen reduction of TeO<sub>2</sub> offers an eco-friendly alternative to conventional carbothermic reduction by avoiding CO by-products. This study investigates the reduction of 99.99 wt.% purity level TeO<sub>2</sub> using hydrogen in an oscillating kiln furnace (200–800 °C, 2–7 h), with phase composition and microstructure analysed via XRD and SEM. Results demonstrate conversions of up to 89% (solid–gas) and 100% (liquid–gas), revealing that kinetics dominate over thermodynamics in controlling reaction progress. The work proposes a reaction mechanism based on morphological evolution observed in SEM images, suggesting that further parameter optimisation could enhance scalability. As the first lab-scale demonstration of hydrogen-assisted TeO<sub>2</sub> reduction, this study establishes a preliminary process window (temperature/time) and underscores the potential for industrial adoption. Future work should verify the proposed mechanism and refine operational parameters to maximize efficiency.
ISSN:2073-4352