Pilot-plant treatment of a Quebec talc ore

CIM Bulletin, Vol. 82, No. 932, 1989

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

Talc ore from Bakertalc, Highwater, Quebec analyzing about 60% talc, previously dry ground to about 95% minus 53 nm was beneficiated in an 11.4 kg/h pilot-plant flotation circuit. A concentrate of 95.9% talc (necessary for paper-grade) was obtained at a recovery at 75.3% by employing 53 g/t of Dowfroth 250 collector at pH 9.2; further cleaning increased the grade to 97.2% talc at a recovery of 57.5%. Flotation of fresh ground 60% minus 44 pm ore at a feed rate of 18.6 kg/h produced a grade of 96.4 % talc with a recovery of 78.2%, using Aerofroth 70 collector a six carbon-branch chain alcohol, at pH 9.2. The similarity in the concentrate grade and recovery between pre-ground and fresh-ground ore indicated that it was not necessary to grind to 95% minus 53/j.m to achieve comparable selectivity. A grind of 60% minus 44 \i.m corresponds to 100% minus 300 urn. Flotation retention times obtained with fresh ground ore indicate 33 min. for combined rougher/scavenger, and 15 min. each for the first and second cleaners. Talc-magnesite flotation separation is explained in terms of physico-chemical forces, with reference to surface charge and adsorption mechanisms.

Mots Clés: Talc ore, Grinding, Flotation, Multiple cleaning, Iron oxide reduction, Leaching, Pilot-plant, Retention times.