Investigating the potential impact of efflorescent mineral crusts on water quality: complementing analytical techniques with geochemical modelling

Efflorescent crusts are a common feature forming on the surface of gold mining sites and tailings storage facilities during the dry season. Their dissolution at the start of the wet sea- son releases an acidic pulse of water rich in metal pollutants. The composition of the crusts is indicative of the water from which they precipitated. This study aimed at assessing the crust formation and dissolution processes that result in episodic changes in receiving water quality. The approach involved characterising the composition of the crusts by analytical techniques (powder X-ray di2raction (PXRD)) and establishing compositional discrepancies by modelling the formation and dissolution processes.