Study on the Purification Process of Pharmaceutical Grade High-Purity Montmorillonite

This study focuses on the development of a process for producing high-purity montmorillonite that meets pharmaceutical standards using natural calcium-based bentonite as raw material. Based on an in-depth analysis of the raw ore, the mineral composition was identified, including montmorillonite, cristobalite, and dolomite. The raw ore was subjected to systematic treatments such as wet purification, sodium modification, and filtration membrane separation. The results showed that the wet purification process increased the montmorillonite content from 49.5% in the raw ore to over 90%. Subsequent sodium modification further improved the montmorillonite content, although a small amount of cristobalite remained. Finally, nanofiltration membrane filtration was employed for refined purification, yielding a final product with 100% montmorillonite content and no detectable impurities such as quartz. Comprehensive pharmaceutical performance tests indicated that all evaluated parameters—including pH, cristobalite content, adsorption capacity, and active ingredient content—complied with the standards specified in the Chinese Pharmacopoeia (2020 edition). This study provides a reliable technical pathway and theoretical foundation for the industrial production of pharmaceutical grade montmorillonite.