Improved flotation of arsenopyrite associated with gold

Arsenopyrite is often associated with gold in refractory gold ore. The flotation process is one of the most prospective processes to be widely applied to this type of gold ore. The natural floatability of arsenopyrite is poor and the key factor for the successful flotation of auriferous gold ore is to activate the arsenopyrite flotation. Unfortunately, the past study on the arsenopyrite flotation has been paid little attention and the activation of arsenopyrite flotation has been hardly conducted.; The present study was undertaken in order to investigate the mechanism of arsenopyrite flotation and the new techniques to activate the arsenopyrite flotation.; The collectorless micro-flotation tests showed that pure arsenopyrite displayed poor floatability. The cupric ions, sodium sulfate, and EDTA did not improve its floatability. The ultrasonic pretreatment was found to improve the floatability of arsenopyrite significantly and a series of bench flotation tests on auriferous gold ores confirmed that the ultrasonic pretreatment is an effective technique to activate the flotation of arsenic and gold minerals in auriferous gold ore.; The thermodynamics studies of the Fe-S-As-H₂O system, Zeta potential measurements and the tests of the effect of iron species on the collectorless flotation of arsenopyrite indicated that the hydrophilic ferric oxide layer causes the poor floatability of arsenopyrite. The ferric oxide layer results from the oxidation of arsenopyrite surface. Ultrasonic energy removes the ferric oxide film to restore the hydrophobic property of arsenopyrite before the flotation.; The F-TIR analysis clearly demonstrated that Amyl Xanthate is oxidized into Diamyl Dixanthegon on the surface of arsenopyrite. The solution Eh in the presence of arsenopyrite determines the oxidation of xanthate. If the Eh in the solution in the presence of arsenopyrite is above the oxidation potential of xanthate, dixanthogen forms on the surface of arsenopyrite. Otherwise, the precipitation of metal xanthate salt forms.; Diphenyl Guanidine was found to have almost same strong collecting ability in strong acidic medium as xanthates in weak acidic or alkali medium. A series of bench flotation experiments on auriferous gold ore also demonstrated encouraging results and conformed that biphenyl Guanidine is a selective collector in the flotation of auriferous gold ores.; The theoretic analysis and contact angle measurements indicated that biphenyl Guanidine reacts on the surface of arsenopyrite through static electric charge attraction and chemical absorption.