Co-recovery of tungsten and lanthanum from photovoltaic tungsten-based busbars scrap by molten salt electrolysis

Abstract

As a rare-earth reinforced tungsten alloy, photovoltaic tungsten-based busbars have been extensively employed in silicon production in recent years. The urgent issue at hand is the need to achieve the co-recovery of tungsten and lanthanum from photovoltaic tungsten wire scrap. In this study, the complete recycling of photovoltaic tungsten scrap is achieved for the first time through a brief molten salt electrolysis process, utilizing Na₂WO₄ as the electrolyte and tungsten wire scrap as the anode. The process involves a graphite crucible as the cathode, ensuring continuous contact with the product to prevent the oxidation of tungsten powder (W) to sodium tungsten bronze (Na_xWO₃) by Na₂WO₄ electrolyte. The corundum anode basket promotes the dissolution of La₂O₃ in the electrolyte to form La₂(WO₄)₃. This compound actively participates in electrochemical reactions to facilitate the simultaneous production of W and La₂O₃. The regenerated tungsten powder possesses a uniform distribution of La₂O₃, making it a suitable raw material for the manufacture of photovoltaic tungsten-based busbars. Overall, this approach establishes a sustainable and environmentally friendly tungsten resource recycling ecosystem.