Clay content refers to the proportion of clay minerals present in an ore body, overburden, waste material, or process stream, and is a critical parameter affecting mining, processing, and environmental management across bauxite, gold, iron ore, and diamond mining operations. Clays are fine-grained aluminosilicate minerals with particle sizes typically less than 2 micrometres, including kaolinite, smectite, illite, and montmorillonite. In bauxite mining, high clay content in the ore is a major processing challenge because reactive silica in clay minerals consumes sodium hydroxide (caustic soda) in the Bayer Process digestion circuit, reducing alumina yield and increasing operating costs — a phenomenon known as the reactive silica problem. In gold mining, high clay content in ore causes viscous slurries that are difficult to pump and screen, reducing grinding circuit efficiency, clogging carbon in CIP/CIL systems, and slowing gold leach kinetics. In iron ore mining, clay minerals affect the quality of the final concentrate, increase water consumption in wet processing, and cause difficulties in pelletizing and sintering. In diamond mining, clay-rich kimberlite requires intensive scrubbing to liberate diamonds and prevent clay overcoating of diamonds in recovery equipment. Clay content is typically measured using X-ray diffraction (XRD), laser particle sizing, and Atterberg limit testing.
