Improving metallurgical performance in an industrial flotation bank by upgrading the first cell design

P. Vallejos1, J. Yianatos1, R. Grau2, A. Yáñez2, A. López3 and D. Davoise3

1. Department of Chemical and Environmental Engineering, CASIM, UTFSM, Chile.2. Metso Outotec, Finland.3. Proyecto Riotinto, Atalaya Mining, Spain.

INTRODUCTION

Sharp decrease in feed

mineral grade over time

More complex mineralogy of feed

minerals

Significant increase in cell size

(up to cell of 600 m3)

New Challenges:

• Control strategies

•Operating conditions

• Froth management

• Prediction of results due to changes in mineralogy and/or cell design.

Improvement of metallurgical performance in industrial circuits

METHODOLOGY

Metallurgical performance of a rougher flotation bank by sampling (initial condition).

Metallurgical performance prediction after installing new launders in the first cell (simulation)

Installation of new launders in the first cell.

Metallurgical performance of the bank by sampling, after new launders (simulation validation).

Effect of the new launders on variables that are not commonly obtained from plant surveys (simulation analysis).

METHODOLOGY: Metallurgical sampling Atalaya Mining, Proyecto Riotinto copper concentrator (Spain).

Metallurgical performance characterization of the first cell and the full bank from sampling (shift composites forthree months before and after the launder upgrade, 2018 and 2019).

Sampling before (simulator calibration) and after (simulation validation) the installation of the new launders.

Feed flowrate= 1196 t/h

Cu grade = 0.42 - 0.49%

Solid content of 40 - 41%

Particle size (P80) = 180 - 200 µm.

Atalaya Mining Concentrator

First Cleaner:HG Cells (with wash

water) 2 TC100

3 TC100s (Rougher)

TC300 (beforeupgrade)

TC3

00

tai

ls

METHODOLOGY: Launder design in the first cell

Internal Peripherical Launder

New Launders design

BEFORE AFTER

A new adjustable crowder and center launders were installed to complement the original design to improve bank recovery.

Reduction in the froth surface area and increase in the overflow perimeter, improving the froth recovery.

The gas flowrate had to be reduced after launder upgrade (from 37 to 22.6 m3/h).

METHODOLOGY: Launder design in the first cell

The launder upgrade was carried out during a shut down at the end of July 2018.

Before the launder upgrade After the launder upgrade

TankCell e300:

METHODOLOGY: Industrial flotation simulator

Metallurgical behaviour of

each cell along banks

Operating conditions

Flotation cell design

Feed mineral characteristics

Calculation of each single cell in series: two-zone model

FROTH ZONECOLLECTION ZONE

• Mixing model based on actual RTD

• Feed: Particles, Dij

Size-by-liberation

• Single rate constant kij and Rmax,i,j

• SB as a function of JG (effect on kij)

• 𝑅𝐹 = 𝑓(𝑆𝐹 , 𝜉𝐹 , 𝜏𝐹)

Function of:

Cell design Froth stability Residence time

• Model validation:

Using industrialdata based onfroth recovery

RESULTS: Validation of the simulator prediction

0

10

20

30

40

50

60

30

40

50

60

70

80

90

100

1° cell Final

Co

nce

ntr

ate

gra

de

Cu

, %

Cu

Rec

ov

ery

, %

Measured recoveryPredicted recoveryMeasured gradePredicted grade

Good prediction of the recovery and concentrategrade.

Differences attributed to the measurement error andchemical and mineralogical analysis for simulation.

The simulator allowed for representing the changesin recovery and concentrate grade by modifying thelaunders design in industrial circuits.

RESULTS: Effect of launder upgrade on Cu recovery

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5

Cu

rec

ove

ry (

%)

Cell number

Cum. recovery (before)Cum. Recovery (after)Recovery (before)Recovery (after)

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5C

u r

eco

very

(%

)Cell number

Froth (before)Froth (after)Collection (before)Collection (after)

0,0

0,5

1,0

1,5

2,0

2,5

3,0

0 1 2 3 4 5

Fro

th S

tab

ility

Fac

tor

Cell number

After

Before

Increase in the first cell recovery, but a decrease in the recovery of the next three cells.

However, the final recovery of the bank improved after upgrading the launder design.

Froth recovery increases in the first cell, but decreases in the next cells, mainly because of the decrease in froth stability.

OVERALL EFFECT:

RESULTS: Effect of launder upgrade on Cu recovery

Increase in froth recovery for all particle size classes in the first cell, but mainly for coarse (+150 µm) and intermediateparticles (45-150 µm).

Significant improvement of the final recovery of coarse particles, as well as of middling and locked particles.

0102030405060708090

100

0 1 2 3 4 5

Fro

th r

eco

very

(%

)

Cell number

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5C

u r

eco

very

(%

)Cell number

Coarse (before)Coarse (after)Medium (before)Medium (after)Fine (before)Fine (after)

0102030405060708090

100

0 1 2 3 4 5

Cu

rec

ove

ry (

%)

Cell numberOcclud (before) Occlud (after) Midd (before)

Midd (after) Lib (before) Lib (after)

EFFECT BY SIZE CLASS:

RESULTS: Effect of launder upgrade on conc. grade

0

4

8

12

16

20

24

0 1 2 3 4 5

Co

nce

ntr

ate

grad

e (%

)

Cell number

Coarse (before) Coarse (after)Medium (before) Medium (after)Fine (before) Fine (after)

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

4,5

0 1 2 3 4 5

Entr

ain

men

t fl

ow

rate

(tp

h)

Cell number

Before

After

Cu grade decreased in the first cell, for the three size classes, but more strongly for coarse particles.

The Cu grade in the next three cells also decreases because of the decrease in the mineral grade fed to these cells.

The concentrate grade of fine particles decreases in the first cell, due to the gangue entrainment.

CONCLUSIONS

• The industrial simulator suitably predicted the metallurgical performance of the rougher flotation bank at ProyectoRiotinto, after modifying the launders design in the first cell.

• The simulation study showed that the launders upgrade in the first cell allowed for a significant increase in the Curecovery, mainly for coarse particles, due to the improvement in froth recovery.

• A significant increase in the final bank recovery was observed, despite the slight negative effect on the Cu recovery inthe next three cells (lower collection and froth recoveries).

• The launder upgrade in the first cell caused a minor decrease in the concentrate grade because of the increase inmineral recovery and in the gangue entrainment. However, the final concentrate grade after launders upgrade wassuitable, considering a rougher stage.

• These results show the important effect that the first cell operation has on the other cells in flotation banks. Thisbecomes relevant when changes are required, focused on optimizing the metallurgical performance.

ACKNOWLEDGEMENTS

Atalaya Mining

Agencia Nacional de Investigación y Desarrollo (ANID), FONDECYT Project Nº 1201335.

Federico Santa Maria Technical University.

Improving metallurgical performance in an industrial flotation bank by upgrading the first cell design

P. Vallejos1, J. Yianatos1, R. Grau2, A. Yáñez2, A. López3 and D. Davoise3

1. Department of Chemical and Environmental Engineering, CASIM, UTFSM, Chile.2. Metso Outotec, Finland.3. Proyecto Riotinto, Atalaya Mining, Spain.