This paper compares three types of kaolin clay: raw kaolin clay, refined kaolin clay, and commercial kaolin clay. The idea is to know their composition as well as to know which of the samples is best suited to be used in industries. Kaolin clay is a significant raw material in various industries such as ceramics, paper, paints, rubber, cosmetics and pharmaceutical industries. Due to this, the purity and quality of it are of great significance. In order to measure the samples, we adopted spectrophotometric, complexometric and gravimetric method. These were used to measure the quantities of calcium oxide (CaO), silica (SiO32-), iron oxide (Fe2O3), titanium oxide (TiO2), and magnesium hardness. The results indicated that raw kaolin contained the most amount of calcium oxide (2.10%), and refined kaolin contained the least (1.11%), indicating that it was purer. There was 1.54% calcium oxide in commercial kaolin. Silica, too, varied in a similar manner, with raw kaolin having a silica content of 1.30%. The refined kaolin contained 0.71% and commercial kaolin contained 0.91%. Iron oxide concentration was varied with spectrophotometric analysis showing the following results: 0.79% in raw kaolin, 0.39% in refined kaolin and 1.73% in commercial kaolin. The gravimetric method gives lower values implying that it could be more precise. Commercial kaolin (1016.4 ppm), followed by refined kaolin (966 ppm), and raw kaolin (932.4 ppm) had the highest levels of magnesium hardness. The levels of titanium oxide were acceptable in all samples, with a range between 0.89% and 1.87%. In general, refined kaolin was found to be the best quality sample. It contained less impurities and exhibited more suitability in industrial uses. This paper has highlighted the issue of good testing and quality management in the processing of kaolin.
Kashyap et al. (2026) studied this question.