Activation mechanism of lead ions in the flotation of sphalerite depressed with zinc sulfate

• Published in: Minerals engineering Vol. 146; p. 106132
• Main Authors: Wang, Han, Wen, Shuming, Han, Guang, Xu, Lei, Feng, Qicheng
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.01.2020
• Subjects: Lead activation; LEIS; ToF-SIMS; ZnSO4-depressed sphalerite; LEIS; ZnSO4-depressed sphalerite; ToF-SIMS; Lead activation
• ISSN: 0892-6875; 1872-9444
• DOI: 10.1016/j.mineng.2019.106132

[Display omitted] •Flotation recovery of ZnSO4-depressed sphalerite was significantly increased after treatment with lead ions.•A greater amount of xanthate species adsorbed on the lead-treated surface of ZnSO4-depressed sphalerite.•O atoms on the ZnSO4-depressed sphalerite surface were primary reactive sites for adsorption of lead species.•An adsorption layer of activated products on the ZnSO4-depressed sphalerite surface was observed by ToF-SIMS. Sphalerite is commonly associated with other metal-sulfide minerals, and is usually depressed with zinc sulfate (ZnSO4) prior to the preferential flotation of other sulfide minerals with excellent floatability. In subsequent processing, ZnSO4-depressed sphalerite activation is necessary for the maximum recovery of zinc resources. In this work, lead nitrate (Pb(NO3)2) was used to activate the depressed sphalerite surface by zinc sulfate (ZnSO4). The lead-ion activation mechanism was studied in the flotation of ZnSO4-depressed sphalerite through microflotation tests, zeta-potential experiments, local electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry. Floatability of ZnSO4-depressed sphalerite after treatment with Pb(NO3)2 improved significantly and the maximum recovery reached 96.4%. The zeta potential, local electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy outcome displayed lead species could adsorb on the Zn-depressed sphalerite surface as Pb2+ and Pb(OH)+ and form –Zn–O–Pb complexes, which enhanced the active sites at mineral surfaces significantly, promoted xanthate species attachment to the depressed minerals surface, and enhanced mineral-particle hydrophobicity. The adsorption layer of activated products on the ZnSO4-depressed samples surface was represented by ToF-SIMS, which illuminated its activation mechanism further.