Molybdenite Flotation in the Presence of a Polyacrylamide of Low Anionicity Subjected to Different Conditions of Mechanical Shearing

Darwin Estrada,Leopoldo Gutierrez,Andres Ramirez,Luver Echeverry

doi:10.3390/min10100895

Abstract

Polyacrylamides (PAM) are used as flocculants in the copper-molybdenum mining industry to improve the settling rate of flotation tailings. These types of reagents are recirculated to flotation in the water that is recovered from the thickeners, and as a result of this practice they can cause depression of flotation of some important minerals such as molybdenite. The objective of this work was to study the effect of a PAM of 11.9% of degree of anionicity on the flotation of molybdenite. The effect of the anionic PAM on molybdenite flotation was studied under different levels (three) of flocculant mechanical shearing. The flotation data was discussed along with intrinsic viscosity, adsorption, induction time, and electrophoretic mobility measurements. It was found that the non-sheared PAM (NS–PAM) had the strongest depressing effect on molybdenite flotation, followed by the moderately sheared PAM (MS–PAM). The depressing effect of the strongly sheared PAM (SS–PAM) was negligible. The flotation data correlated with the induction time measurements that showed that molybdenite became more hydrophilic in the presence of the NS–PAM. The SS–PAM has no effect on the induction times. Further work is ongoing to understand the effect of PAM on molybdenite flotation in the presence of clay minerals and different aqueous media.

Highlights

A significant fraction of the process water used in Cu–Mo flotation plants corresponds to water recovered from thickeners and tailings dams
Purified molybdenite was contacted with mili-Q water at different pH (6–11 adjusted with NaOH), and the liquid extracts were analyzed for Total Organic Carbon (TOC) to verify the absence of residual organic flotation reagents [2]
The results show that the highest values of induction times are obtained in the presence of the non-sheared PAM (NS–PAM) followed by the results obtained with the moderately sheared PAM (MS–PAM)

Summary

Introduction

A significant fraction of the process water used in Cu–Mo flotation plants corresponds to water recovered from thickeners and tailings dams. As a result of this operational practice, an important part of residual reagents dissolved in water are recirculated to flotation, causing flotation depression of some important minerals such as molybdenite [1]. Recycled water may contain slimes such as clay minerals, which can strongly affect the flotation of molybdenite as previously reported [2]. Polyacrylamides (PAM) are widely used flocculants in the mining industry [3], and Figure 1 shows the chemical structures of anionic (carboxylated and sulfonated), and cationic polyacrylamides. The main functional group in PAM is the amide group (Figure 1d), which form the polymer through a polyaddition process [4]. The ionic character and molecular weight of PAM can be achieved through copolymerization reactions to give them anionic or cationic character

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Conclusion