The handling of degraded hydrated alumina should be determined based on the degree of material degradation and its future use. The core principles are safety, compliance, and resource recovery.
Assessment and Classification: First, the degraded material should be assessed for its condition, including whether it has agglomerated, its moisture content, impurities, and changes in crystal phase. If only slight moisture absorption has occurred and no phase change has taken place, partial performance can be restored through drying regeneration (e.g., drying at 110–150℃ for 4–6 hours), suitable for applications with low activity requirements. If severe agglomeration or crystal transformation has occurred, it is not suitable for high-precision processes.
Recycling Methods:
Heat Activation Regeneration: For hydrated alumina that is saturated with adsorption or has surface contamination, heat desorption can be used. For example, heating at around 350℃ under oxygen-deficient conditions desorbs the adsorbate, restoring the pore structure and specific surface area, enabling recycling.
Chemical Regeneration Treatment: For materials with specific functional failures (such as decreased defluorination capacity), soaking in sodium hydroxide solution followed by water washing until neutral, and then acidification treatment can restore surface activity.
Downgrading and Reuse (Low-Cost Disposal): For non-regenerable failed materials, they can be used as non-functional fillers in building materials, coatings, or plastic products; they can also be used for acidic soil improvement or wastewater pH adjustment, but the dosage must be controlled and the impact of heavy metals and other impurities must be monitored.
Final Disposal: If the material contains harmful pollutants or has completely lost its utilization value, it should be disposed of according to general industrial solid waste standards to avoid indiscriminate dumping. Integration into a circular economy model and its inclusion in an aluminum-based solid waste co-treatment system is encouraged.
