THE ROLE OF METALLIC CATIONS ON THE COLLOIDAL STABILITY OF TIN TAILINGS SLURRIES

Tin tailings slurries from two ex-mining ponds were coagulated by mono -, di- and trivalent metallic cations. The optimum concentration for c oagulation and the aggregate size of these slurries were monitored for each cation. Both the constituent clay mineral and the pore fluid com positions of the slurry have a strong influence on its coagulation beh aviour. The interaction of these with various ionic species, formed by ion exchange processes of the clay minerals and the hydrolysis reacti on of the metallic cations in solution, enhanced this behaviour furthe r. This observation was supported by electrophoretic mobility data of the clay slurry in the presence of these cations measured as a functio n of dispersion pH and cation concentration. (C) 1998 Elsevier Science B.V.