Understanding Copper Activation and Xanthate Adsorption on Sphalerite by Time-of-Flight Secondary Ion Mass Spectrometry, X-ray Photoelectron Spectroscopy, and in Situ Scanning Electrochemical Microscopy

Abstract

In situ scanning electrochemical microscopy (SECM) was applied for the first time to study the copper activation and subsequent xanthate adsorption on sphalerite. The corresponding surface compositions were analyzed by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). The probe approach curve (PAC) using SECM shows that unactivated and activated sphalerite surfaces have negative current feedback and partially positive current feedback, respectively, suggesting that Cu x S is formed on the sphalerite after copper activation. The copper activation of sphalerite strongly depends on the surface heterogeneity (e.g., presence of polishing defects, chemical composition), impacting the subsequent xanthate adsorption process. The SECM, ToF-SIMS, and XPS analyses show that during the copper activation the polishing defects, which have high excess surface energy, tend to consume more copper ions, resulting in Cu-rich regions by forming CuS-like species, while Fe oxide/hydroxide forms at Fe-rich regions. The XPS spectra further confirm that the CuS-like species involve Cu(I) and S(−I). The SECM imaging shows that after xanthate adsorption the current response at the Cu-rich regions decreases because of the formation of cuprous xanthate (CuX) and dixanthogen (X2) while increases at the Fe-rich regions mainly due to the chemisorption of xanthate on Fe oxide/hydroxide. Our results shed light on the fundamental understanding of the electrochemical processes on sphalerite surface associated with its copper activation and subsequent xanthate adsorption in flotation.

Effects of salinity on xanthate adsorption on sphalerite and bubble–sphalerite interactions

“…Sphalerite minerals were freshly crushed, polished by using SiC paper from 60 to 1200 grit, rinsed with Milli-Q water, and then dried by N 2 (Wang et al, 2013). Then the minerals were treated in a desired conditioning solution for 10 min.…”

Anisotropic Polymer Adsorption on Molybdenite Basal and Edge Surfaces and Interaction Mechanism With Air Bubbles

“…After curing overnight, the epoxy samples were polished by hand with wet silicon carbide paper of 60 grit to expose the edge plane. The smooth edge surface was obtained by polishing with wet silicon carbide paper of 60, 240, 320, 400, 600, 800, and 1200 grit, and then polishing with 5, 1, and 0.3 μm alumina powder suspension, respectively (Wang et al, 2013 ). The freshly polished edge samples were ultrasonically washed in Milli-Q water, ethanol and Milli-Q water for 5 min, respectively.…”

“…In this work, the thin edge plane of MoS 2 with relatively large surface area (15 × 5 mm 2 ) and low root-mean-square (rms) roughness (~1.6 nm) was prepared by carefully polishing the edge sample (see Materials and Methods) (Wang et al, 2013 ), which could be used for AFM imaging and force measurements in a fluid cell. The effect of adsorbed polymer (i.e., CMC) on the wettability and morphology of MoS 2 basal and edge surfaces was compared using contact angle measurement and in-situ AFM imaging.…”

Novel Insights into the Hydroxylation Behaviors of α-Quartz (101) Surface and its Effects on the Adsorption of Sodium Oleate

“…In most cases, before the addition of sodium oleate, metal ion activators should be previously added to the pulp and adsorbed onto the quartz's surface as active sites. Actually, the activation mechanisms of metal ions on mineral surfaces have been research hotspots in the field of flotation [15,16]. Divalent ions, such as Cu 2+ , Pb 2+ , Ca 2+ , etc., are widely used to activate specific mineral surfaces [15,[17][18][19].…”