Effectiveness evaluation for X-ray diffraction and differential scanning calorimetry methods in the study of clay minerals

The aim of the study is to evaluate the effectiveness of X-ray diffraction analysis (XRD) and differential scanning calorimetry (DSC) used in the study of clay minerals. Due to the small particle size of clay minerals, XRD and DSC are considered most effective research methods. As a qualitative analysis for some kaolinite minerals is still a challenge, the authors present the results of a mineral composition analysis for three types of clays, i.e. VN 01 (Vietnam), Laos 02 (Laos) and NZ 03 (New Zealand) in order to evaluate the effectiveness of the two above-mentioned methods. The results show that the XRD method appears to be relatively effective in a qualitative analysis as well in distinguishing kaolinite and dickite from halloysite. As the diffraction peaks of kaolinite and dickite are quite close, it is difficult to differentiate between the two minerals, while kaolinite-dickite or dickite-halloysite pairs are easily distinguished by DSC due to their different endothermic effects. Kaolinite and halloysite have identical endothermic effects ranging from 530°C to 590°C which makes it difficult to differentiate between them using DSC. XRD method is effective in a qualitative analysis of clay minerals in general, and of kaolinite minerals in particular. It is also effective when distinguishing between kaolinite and halloysite, which is impossible when using DSC; though it is of a limited effectiveness when differentiating dickite and kaolinite. To improve the effectiveness of clay analysis for other research objects and to evaluate the quality of kaolin or other high-disperse minerals, combination of XRD and DSC methods is suggested.

X-ray diffraction analysis, differential scanning calorimetry method, clay minerals, exothermic effect, endothermic effect

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