Considering the Ionic Strength and pH of Process Water on - - PowerPoint PPT Presentation

Lisa October

• K. Corin, M. Manono, N. Schreithofer,
• J. Wiese

Considering the Ionic Strength and pH of Process Water on Bubble-Particle Attachment of Sulfide Minerals: Implications for Froth Flotation in Saline Water

IMWA 2019 Perm, Russia 15-19 July 2019

Background

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Wills and Finch (2015)

 Creating the hydrophobic mineral surface  The formation of bubbles with a fixed size and distribution  The collision between the mineral and bubble and potential attachment  Transport of the bubble-particle aggregate through the pulp phase  Transfer of the bubble-particle aggregate to the froth phase  Collection of the bubble-particle aggregate from the froth phase

Background

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Pulp Phase = 80 – 85 % Water (Muzenda, 2010) NEED TO RECYCLE & RECIRCULATE WATER WITHIN MINING OPERATIONS

Wills and Finch (2015)

Ca2+

CO3

• Mg2+

SO4

2-

Na+

SO4

2-

Ca2+

Mg2+

Na+

Cl-

Bubble-Particle Attachment

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From Albijanic et al. (2010)

Thinning of wetting film to critical thickness.

Wetting film becomes unstable and ruptures leading formation of 3 phase contact line and the attachment of particle to bubble.

The bubble-particle contact line spreading across surface = stable wetting perimeter.

2 1 3

Factors Affecting B-P Attachment

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Particle Characteristics

• Particle Size
• Particle Shape
• Surface Liberation
• f Value

Bubble Characteristics

• Bubble Size
• Gas Type

Pulp Chemistry

• Temperature
• pH
• Electrolytes/Ions
• Reagents

Fundamental Bubble-Particle Attachment

Measuring this Parameter

History of Attachment Timers

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Sven- Nilsson (1934)

Glembotsky (1953)

Eigeles and Volova (1960)

Yoon and Yordan (1991) Gu et al. (2003) Albijanic et al. (2015)

A New Attachment Timer

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Needles Shovel Collection Bin Pool with Particle Bed and Water Camera

Effect of Electrolytes on B-P Attachment

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From Yoon and Yordan (1991), Gu et al. (2003)

KCl-Quartz Bitumen

What happens in a complex water system?

Effect of IS and pH

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50 100 150 200 250 0 100 500 0 100 500 0 100 500 0 100 500 0 100 500 0 100 500 g/t g/t g/t g/t g/t g/t 1SPW 5SPW 10 SPW 1SPW 5SPW 10 SPW pH 9 pH 11 Solids recovery, g Solids Recovered (g)

From Tadie et al. (2016), Manono et al. (2017) Recovery ↑ with ↑ IS, ↓Recovery with ↑ pH At pH 11: Recovery ↑ with ↑ IS Recovery ↑ with ↑ IS, ↓Recovery with ↑ pH

Key Question

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But How Does an Increase in both Ionic Strength and pH of Process Water Affect the Fundamental Bubble- Particle Attachment Process?

?

Experimental Programme

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10 SPW 5 SPW 1 SPW Synthetic Plant Waters

Galena (PbS) Chalcopyrite (Cu2S)

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Water type Ca2+ ppm Mg2+ ppm Na+ ppm Cl- ppm SO4

2-

ppm NO3

• ppm

CO3

2-

ppm TDS mg/L Ionic Strength mol/L 1SPW 80 70 153 287 240 176 17 1023 0.0213 5 SPW 400 350 765 1435 1200 880 85 5115 0.0977 10 SPW 800 700 1530 2870 2400 1760 170 10230 0.1860

pH Modifiers: NaOH/HCl Collector: SIBX

Attachment Probability: Galena

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1 SPW 5 SPW 10 SPW Natural pH 45.7 44.4 41.0 pH 11 9.09 3.54 5.05 5 10 15 20 25 30 35 40 45 50 Attachment Probabilty (%) 1 SPW 5 SPW 10 SPW Natural pH 0.85 4.2 9.95 pH 11 0.85 1.25 2.5 2 4 6 8 10 12 Mass Recovered (mg)

↑ pH = ↓ Attachment Probability ↑ pH = ↓ Mass Recovered; ↑ IS = ↑ Mass Recovered

Fundamental B-P Attachment Vs Classical Microflotation

14 Nyabeze and McFadzean, 2016

Fundamental B-P Attachment Vs Classical Microflotation

15 Nyabeze and McFadzean, 2016

Microflotation: Galena

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10 20 30 40 50 60 70 80 90 100 5 10 15 20 25 Galena Recovery (%) Time (mins) 1 SPW_pH11 5 SPW_pH11 10 SPW_pH11 1 SPW 5 SPW 10 SPW

Attachment Probability: Chalcopyrite

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1 SPW 5 SPW 10 SPW Natural pH 69.6 85.2 90.4 pH 11 2.02 4.67 11.87 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 Attachment Probability (%)

1 SPW 5 SPW 10 SPW Natural pH 2.35 2.7 6.5 pH 11 0.45 1.9 2.75 1 2 3 4 5 6 7 8 Mass Recovered (mg)

↑ pH = ↓ Attachment Probability ↑ IS = ↑ Attachment Probability ↑ pH = ↓ Mass Recovered ↑ IS = ↑Mass Recovered

Microflotation: Chalcopyrite

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10 20 30 40 50 60 70 80 90 100 5 10 15 20 25 CHALCOPYRITE RECOVERY (%) TIME (MINS) 1 SPW 5 SPW 10 SPW 1 SPW_pH11 5 SPW_pH11 10 SPW_pH11

Zeta Potential

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Potential difference across phase boundaries between solids & liquids. Measure of electric charge on particles suspended in liquid.

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• 30
• 25
• 20
• 15
• 10
• 5

5 10 15 2 4 6 8 10 12 14

Zeta Potential (mV) pH

1 SPW 5 SPW 10 SPW Ultra-Purified Water

• 40
• 30
• 20
• 10

10 20 2 4 6 8 10 12 14

Zeta Potential (mV) pH

1 SPW 5 SPW 10 SPW Ultra-Purified Water

↑ IS = ↑ Zeta Potential

• f Chalcopyrite

pH 11 : ↑ Zeta Potential ↑ IS = ↑ Zeta Potential

• f Galena

pH 11 : ↑ Zeta Potential

Value of this Work

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↑ Ions In Process Water ↑ Hydroxo complexes In Process Water Simultaneous Effect - Various Hydroxo Complexes

Recycle/Recirculate Process Water Combination of Varying Water Streams = pH Change

↑B-P Attachment: Compression of EDL ↓B-P Attachment: Hydroxo Complexes Deposited on Mineral Surface At Elevated pH: ↑ IS Not Detrimental to Sulfide B-P Attachment

Acknowledgements

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This Project has received funding from the European Union H2020 programme under grant agreement No 730480

Measuring Attachment Probability

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Before Attachment After Attachment