Pyrite consumption of xanthate in hellyer base metal sulfide pulps

Xanthate requirements for the lead rougher flotation of Hellyer ore approximately halved as the pH increased from 10 to 12. At pH 12 or after an addition of 200 glt NaCN, size by size analysis showed an increased recovery for galena and sphalerite, while pyrite flotation remained at entrainment values. This suggested that xanthate may have adsorbed to a greater extent on galena and sphalerite as a result of decreased adsorption onto pyrite. Thermodynamic calculations and UV analysis of a pyrite pulp have shown that, in the pH range from 10 to 12, a transition occurs from a region of ferric-hydroxide xanthate stability to one of ferric hydroxide or ferri-cyano complex stability, resulting in a decreased adsorption of xanthate onto pyrite.