2025 Volume 47 Issue 3 Pages 107-115
To properly address scaling issues and understand the chemical and physical properties of scale, it is important to accurately determine phase ratios through quantitative analysis. Although simple and easy to use, the conventionally used Quartz Index (QI) method has the disadvantage of underestimating clay mineral and amorphous phases with low crystallinity. In this study, we propose the PONKCS (Partial Or No Known Crystal Structures)/Rietveld approach, which is widely used to quantify amorphous materials in cement research. To evaluate the applicability of the PONKCS/Rietveld approach, mixtures of artificially synthesized stevensite and silica gel samples, as well as an actual scale sample, were prepared. Quantification results using the PONKCS/Rietveld approach showed that the difference between the adjusted and quantified values for the mixed samples was 1.7% on average. In addition, the quantified value of the actual scale showed some agreement with that obtained from the methylene blue adsorption experiment. This study showed that the PONKCS/Rietveld approach has a high potential for accurately quantifying clay minerals and amorphous in scale.
