Elimination of adverse effects of seawater on molybdenite flotation using sodium silicate. (15th January 2020)

• Record Type: Journal Article
• Authors: Peng, Ying; Li, Yubiao; Li, Wanqing; Fang, Xin; Liu, Cheng; Fan, Rong
• Is Part Of: Minerals engineering. Volume 146(2020)
• Publication Date: 2020-01-15
• Subjects: Molybdenite -- Flotation -- Seawater -- Sodium silicate; Mines and mineral resources -- Periodicals; Ressources minérales -- Périodiques; Mines and mineral resources; Periodicals; Electronic journals; 622
• DOI: 10.1016/j.mineng.2019.106108
• Languages: English
• ISSNs: 0892-6875

Abstract

Graphical abstract: Highlights: XRD verified the formation of Mg(OH)2 and CaCO3 during seawater flotation. MoS2 was mainly depressed by Mg(OH)2 rather than CaCO3 . Lower frothability of CaCl2 and MgCl2 was not responsible for lower MoS2 recovery. SS prevents adsorption of Mg(OH)2 colloids onto MoS2 surface. SS reverses attractive force to repulsive force between MoS2 and Mg(OH)2 . Abstract: Seawater has been increasingly applied in mineral flotation process due to the scarcity of freshwater. However, seawater plays an adverse effect on molybdenite (MoS2 ) flotation under alkaline condition, but the influencing mechanisms were still unclear, limiting its application in flotation plants. In this study, seawater, and the ions with the most influence of Ca 2+ and Mg 2+ were applied in MoS2 flotation, with the addition of sodium silicate (SS). As compared to that in freshwater, MoS2 flotation recovery was signifiantly decreased in seawater. In addition, MoS2 recovery in 0.05 M MgCl2 solution was significantly lower than that in the 0.01 M CaCl2 solution (these concentrations being consistent with seawater), indicating that Mg 2+ plays a more detrimental role than that of CaCl2 . The addition of SS increased MoS2 recovery to different contents, with the most apparent being for that in 0.05 M MgCl2 solution. Various measurements including contact angle, zeta potential, species calculation, and XPS analysis indicate that the decreased flotation recovery is primary due to the adsorption of Ca and Mg complexes and precipitates onto MoS2 surface. Moreover, the DLVO theory calculation suggests that SS prevents the adsorption of positively charged Mg precipitates onto negatively charged MoS2 surface by reversing the interaction force betwen MoS2 particles and Mg(OH)2 colloids from attraction to repulsion. This study therefore provides a new insight into utilizing seawater for MoS2 flotation.