Abstract:

 According to the mass balance principle, the mineral contents of the bentonites from Yangxian of Shaanxi Province, Queshan of Henan Province, and Chifeng of the Inner Mongolia Autonomous Region were estimated by solving the phase mixing equation constructed from the data of Xray diffraction, microprobe analysis of montmorillonite grains, and wet chemical analysis of the bentonites. The crystal formulas of montmorillonite in the bentonites were calculated by using the anion hydrogen equivalent method. The cell lattice constants of the principal minerals in the bentonites were calculated with a FORTRAN90 program CELLSR. Compared with both methods of the methylene blue absorption and XRD Rietveld multiphase analysis, the phase mixing equation was confirmed to be the most accurate modal analysis method for determining the content of montmorillonite in bentonites with several minerals coexisted.

Key words:  bentonite, montmorillonite, modal analysis, phase mixing equation