Efficient and Direct Recovery of Germanium from Optical Fiber Solid Waste via Low-Modulus Alkaline Leaching and Customized Meglumine Resin Adsorption

A large amount of germanium-containing waste is generated during optical fiber preform production, representing a critical secondary germanium resource. To address recovery challenges from low germanium content, high silicon content and complex occurrence states in optical fiber solid waste, this study proposes a short-flow clean hydrometallurgical process based on low-modulus alkaline leaching coupled with direct adsorption using customized meglumine resin. Results show that under low-modulus (M = 1) strong alkaline conditions, the system achieved a maximum germanium release concentration of 331.25 mg/L and exhibited excellent anti-gelation stability. The self-synthesized alkali-resistant NMG resin was applied for direct adsorption in raw M = 1 leachate without pH adjustment. The adsorption process follows pseudo-second-order kinetics and the Langmuir isotherm, with a maximum theoretical adsorption capacity of 3.529 mg/g. Spectral analysis indicates that the ortho-cis-diol groups of the resin can specifically chelate with germanate, overcoming competitive interference from strong alkali and high silicon. This process provides a theoretical basis for the green recycling of high-silicon germanium-containing secondary resources.