Abstract
An atomic force microscope (AFM) was applied to study of the adsorption of xanthate on bornite surfaces in situ in aqueous solutions. AFM images showed that xanthate, i.e., potassium ethyl xanthate (KEX) and potassium amyl xanthate (PAX), adsorbed strongly on bornite, and the adsorbate bound strongly with the mineral surface without being removed by flushing with ethanol alcohol. The AFM images also showed that the adsorption increased with the increased collector concentration and contact time. Xanthate adsorbed on bornite in a similar manner when the solution pH changed to pH 10. The AFM force measurement results showed that the probe–substrate adhesion increased due to the adsorption of xanthate on bornite. The sharp “jump-in” and “jump-off” points on force curve suggest that the adsorbate is not “soft” in nature, ruling out the existence of dixanthogen, an oily substance. Finally, the ATR-FTIR (attenuated total reflection-Fourier-transform infrared) result confirms that the adsorbate on bornite in xanthate solutions is mainly in the form of insoluble cuprous xanthate (CuX) instead of dixanthogen. This xanthate/bornite adsorption mechanism is very similar to what is obtained with the xanthate/chalcocite system, while it is different from the xanthate/chalcopyrite system, for which oily dixanthogen is the main adsorption product on the chalcopyrite surface. The present study helps clarify the flotation mechanism of bornite in industry practice using xanthate as a collector.
Highlights
Flotation has been widely studied as the most efficient separation technique in the copper extraction industry
Buckley et al [9] investigated the surface oxidation of bornite by linear potential sweep voltammetry and X-ray Photoelectron Spectroscopy, and proposed the adsorption products on bornite depended on the solution potential
The change of the morphology of the bornite surface cannot be attributed to the reaction of the mineral surface with water, because the atomic force microscope (AFM) images obtained with the addition of xanthate solutions are completely different from those shown in Figure 2, which were captured within same timeframe
Summary
Flotation has been widely studied as the most efficient separation technique in the copper extraction industry. The adsorption of the collector on the mineral surface is vital for a successful flotation process to achieve a recovery. Compared to other copper minerals, such as chalcopyrite and chalcocite, the adsorption of collector on bornite has been rarely studied. Allison et al [3] studied the reaction products of various sulfide minerals with xanthate solutions. The authors reported that the measured rest potential of bornite in 6.25 × 10−4 M KEX solution at pH 7 was +60 mV, and the reaction product of PAX on bornite was cuprous alkyl xanthate. Mielczarski and Suoninen [7,8] applied XPS and studied the adsorption of potassium ethyl xanthate on cuprous sulfide. Buckley et al [9] investigated the surface oxidation of bornite by linear potential sweep voltammetry and X-ray Photoelectron Spectroscopy, and proposed the adsorption products on bornite depended on the solution potential
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