The colloid chemistry of acid rock drainage solution from an abandoned Zn–Pb–Ag mine

Abstract Acid rock drainage (ARD) solution from an abandoned ore mine (pH 2.7, SO 2− 4 concentration 411 mmol/l, Fe concentration 93.5 mmol/l) was investigated by photon correlation spectroscopy, centrifugation, filtration, ultrafiltration, scanning electron microscopy, ICP–MS, AAS, ion chromatography, TOC analysis, and extended X-ray absorption fine structure (EXAFS) spectroscopy. A colloid concentration of ⩾1 g/l was found. The prevailing particle size was