The Interaction between Ca2+ and Molybdenite Edges and Its Effect on Molybdenum Flotation

He Wan,Yongjun Peng,Jianbo Yang,Lin Guo,Weicheng Cao,Wei Yang,Tingshu He,Yanying Liu

doi:10.3390/min7080141

He Wan, Yongjun Peng + Show 6 more

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https://doi.org/10.3390/min7080141

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Abstract

In this paper, the influence of Ca2+ on the flotation of a skarn type molybdenum ore and pure molybdenite mineral at pH 8 was studied using diesel as the collector. It was found that Ca2+ had little effect on molybdenum flotation at low concentrations. By further increasing Ca2+ concentration, the floatability of molybdenite—especially from the fine size fractions—was depressed even without the presence of fine gangue minerals. The mechanism responsible for the deleterious effect of Ca2+ on molybdenite flotation was studied by a range of techniques including zeta potential measurements, Scanning Electron Microscopy, and Energy Dispersive X-ray Spectrometer (SEM-EDS) analyses and molybdenum phase analyses. It was found that Ca2+ interacted with molybdenite edges producing CaMoO4 precipitates which were responsible for the depression of molybdenite flotation of Ca2+ by preventing the adsorption of diesel.

Highlights

Flotation exploits a difference in surface wettability on valuable and gangue minerals, and water quality has a significant impact on mineral flotation through the modification of surface wettability by ions in water [1,2,3,4]
It has been found that calcium ions can adsorb on molybdenite as a result of electrostatic interactions and increase the zeta potential of molybdenite or even reverse the zeta potential from negative to positive [11].Adsorbed calcium ions are attractive to negatively charged fine quartz or other gangue particles, deteriorating molybdenite flotation
This study indicates that the formation of CaMoO4 on molybdenum edges prevented the adsorption of diesel leading to the depression of molybdenum floatability

Summary

Introduction

Flotation exploits a difference in surface wettability on valuable and gangue minerals, and water quality has a significant impact on mineral flotation through the modification of surface wettability by ions in water [1,2,3,4]. Due to the scarcity of fresh water and increasingly stringent regulations on the quality of discharged water, groundwater or sea water with a high strength of ions and recycled water are used by most flotation plants. This practice has resulted in an increase in ion strength of process water as a result of evaporation and ongoing ion inputs from groundwater (or seawater), chemicals added in flotation and run off from spoil [5,6,7]. The negative impact of calcium ions has been attributed to the bridging role of calcium ions which promote the coating of fine gangue (e.g., quartz) particles on molybdenite.

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