Biological beneficiation of kaolin: A review on iron removal

• The generation of different forms of iron impurities in clays was described.
• Fundamentals of kaolin bio-beneficiation approaches were concisely explained.
• Literatures on the kaolin bioleaching by fungi and bacteria were reviewed.
• Kaolin bioflocculation and bioflotation studies were reviewed.

Application of mineral bio-beneficiation to remove iron oxyhydroxides from kaolinite clays has been the center of interest in recent decades, and many research works over the world have been dedicated to study the potential of this approach for upgrading the clay whiteness and refractoriness while preserving the inherent specifications and therefore improving the commercial value of kaolin. Microbial purification methods are preferred since they are environmentally benign (neither use nor release hazardous chemicals), not energy intensive, low in initial and operational costs, and they preserve the crystal structure of the clay. The present review offers the general concepts and fundamentals of the process along with an outline and critical assessment of the latest studies carried out on the biological dissolution of iron from kaolinite clays.