Elsevier

Minerals Engineering

Volume 81, 1 October 2015, Pages 161-166
Minerals Engineering

Study of froth behaviour in a controlled plant environment – Part 2: Effect of collector and frother concentration

https://doi.org/10.1016/j.mineng.2015.06.014Get rights and content

Highlights

  • A device is developed to determine the recovery of collection and froth zones in a controlled plant environment.

  • Increasing the collector concentration results in a significant increase in coarse particle recovery in the collection zone.

  • Froth is destabilised at high collector concentrations, resulting in decreases in froth recovery.

  • Increasing frother concentration leads to a substantial improvement in froth recovery.

  • Dropback particles mainly consist of composite or middling fractions.

Abstract

An investigation into froth zone recovery in a controlled plant environment is presented. The effect of operating conditions on the froth performance is given in our previous work (Rahman et al., 2015). This paper is primarily concerned with the influence of chemical properties such as frother and collector concentration on the froth behaviour. The results suggested that increasing the collector concentration gave expected results in the collection (pulp) zone, with a significant increase in coarse particle recovery. However, at high collector concentrations, it was observed that there was an increase in bubble coalescence and froth instability as well as a slight decrease in froth recovery. Increasing frother concentration gave a significant improvement in froth recovery and a slight increase in the collection zone recovery was also found. This was attributed to the formation of finer, more stable, bubbles and a corresponding increase in froth stability. Size and grade analysis of the samples suggested that the dropback particles were mainly composite or middling fractions. It appeared that particles whose grade was higher than the feed may be collected into the froth zone, but some particles with grades lower than the concentrate may detach from the froth.

Introduction

An investigation into froth zone recovery using a unique device is presented. The device has ability to collect the froth dropback particles and allow independent measurement of both froth and pulp phase recoveries. The effect of operating conditions (froth depth and air flow rate) on the froth performance was recently reported by the authors (Rahman et al., 2015). The work was carried out at the Northparkes concentrator (NSW, Australia) using a feed taken directly from the head of the cleaner scavenger bank.

This paper presents the results of a parallel investigation into the effect of the chemical parameters on the froth behaviour where the influence of collector and frother concentration on froth recovery was studied.

Section snippets

Experiments

The design of the froth dropback (FDB) device, a schematic diagram of the rig and the experimental procedure are given in Rahman et al. (2015). Feed to the cell was taken from the head of the cleaner–scavenger of Module 1 of Northparkes copper concentrator. The procedure followed for the treatment of raw data may also be found in the previous paper.

In Module 1 reagents were added at different stages of the flotation circuit. The cleaner–scavenger feed contained approximately PAX – 5 g/ton and

Effect of collector concentration: overall recovery

Two consecutive runs, donated as Runs 5 and 6, were completed at four different collector concentrations of 5 g/ton, 10 g/ton, 15 g/ton and 22 g/ton. The superficial air velocity (Jg) and froth depth were maintained at 1 cm/s and 240 mm, respectively. Collector (PAX) was added to the feed sump.

The average froth recovery Rf, collection zone recovery Rc and overall recovery R, at different collector concentrations are presented in Table 1. The table shows that the collector concentration has a distinct

Comparison with previous froth recovery results

The results from our previous work (Rahman et al., 2015) which forms the first part of the study and the present study show that froth recoveries can be very high, and it is of interest to compare the results obtained here with those found previously. The results can be summarised as follows, for each of the key variables.

  • Air flow rate: The froth recovery varied from 71% to 91%.

  • Particle size: The froth recovery is lowest for coarse 150 μm particles (35%) at low air rates, and highest for fine 10 

Conclusions

  • The collector concentration had a significant effect on the flotation of the Northparkes ore. Increasing the collector concentration significantly improved the capture of particles in the collection zone. However, at higher collector concentrations, the froth recovery decreased, presumably because of froth instability. A decrease in the grades of concentrate and dropback was found with increasing collector concentration, suggesting that higher collector additions are more likely to improve the

Acknowledgments

Financial support from the sponsors of the AMIRA (Australian Mineral Industry Research Association) Project P90 is greatly acknowledged. The authors wish to thank Kitty Tang, Cagri Emer and Ghislain Bournival for their contribution to the test work. The authors would also like to acknowledge the support from the Northparkes concentrator personnel during the testwork, especially Jaclyn McMaster, Tom Rivett and Heather Gault.

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