Activating anions in the cassiterite-dodecylamine hydrochloride system

CIM Bulletin, Vol. 84, No. 954, 1991

P.R.A. Andrews, Industrial Minerals Section, Mineral Processing Laboratory, CANMET-EMR

Areas of bubble contact were delineated for cassiterite in the presence of chloride, fluoride, sulphate, phosphate, oxalate and citrate ions using dodecylamine hydrochloride collector. The limits ofpH, and the minimum collector concentration were established using the bubble pick-up technique. Bubble contact did not occur below the p.z.c. (point of zero charge), estimated to be 4.7, in the presence of chloride ion, and fluoride ion showed only a weak response in the same pH range. These anions are considered to act as indifferent electrolytes. Activation at pH values below the p.z.c. was obtained with sulphate, phosphate, oxalate and citrate ions; the greatest response was by oxalate and phosphate ions extending pick-up to between pH 2.0 and 2.5. Activation appeared to be strongest when anionic protonated species were in maximum concentration. Strong activation also corresponded to the formation of very stable metal ion species, thought to be formed on the surface of cassiterite, between exposed stannic ions and modifying anions; dodecylammonium ions being absorbed on the surface so modified.

Keywords: Cassiterite, Dodecylamine hydrochloride, Chloride, Fluoride, Phosphate, Sulphate, Oxalate, Citrate, Bubble pick-up, Mineral processing, Industrial minerals.