1

Steve Chesters

Genesys International

Keeping Mine-Water Membranes

Clean

2

Wife Gill and dog Jen

Please

Wave

3

•What is a Reverse Osmosis Membrane plant?

•What are they used for in mining?

•Who uses them? Where are they?

•What are the problems?

•New products to keep membranes clean

First reference – 1970 Written by Rex Chainbelt Inc. for US Dept. of the

Interior.

Concluded good quality water could be obtained but

problems of membrane fouling, iron &

gypsum(calcium sulphate)

Agenda

4

Osmosis

100mg/l TDS = 1 psi pressure

Reverse OsmosisApplied Pressure

Flow Flow

MembraneConcentrated

SolutionDilute Solution

What is reverse osmosis?

5

Thin Film Composite Polyamide Membrane

0.2 µm

40 µm

120µm

Polyamide

Polysulfone

UltrathinBarrier Layer

MicroporousPolysulfoneSubstrate

ReinforcingFabric

6

Polyamide Membrane Surface

7

Feed Spacer

8

Spiral Wound Element

Source: Courtesy of DOW Filmtec

Brine (Concentrate) Channel Spacer

Product (Permeate)Water Tube

MembranesPermeate

Channel Spacer

Water Flow

Feed

Concentrate

Permeate

U-cup Seal

Concentrate

9

Membrane Leaves

10

Proven technology

+2.5M membrane elements

+15,000 plants

Producing 130M m³/day

Supply 300m people

RO Membrane Elements

Source; Global water intelligence 2014

11

RO Membrane System

75% Recovery 4 cycles of concentration

High Pressure

pump

Reject/Concentrate Stream

Product/Permeate

StreamCartridge Filter

Feed Water

100m³/hr75m³/hr

25m³/hr

12

Reverse Osmosis Installation

HP PumpCartridge Filter

PressureVessels

Fouling

@ Front

Scaling

@ Back

13

Membrane use in Mines

Source: http://www.waterworld.com/articles/wwi/print/volume-27/issue-1/regulars/creative-finance/thirsty-world-of-mining.html

Mining- 4th largest water consumer

Gold- 1,155,000 litres/kg

Copper- 18,000 litres/kg

Aluminium – 8,000 litres/kg

Coal – 6,000 litres/kg

>90% minewater reusable by applying

RO & MF (Szyplinska, 2012)

14

RO/NF Membrane use in Mining

WA

STE

Acid Mine Drainwater

Acid Rock Drainwater

Tailings Storage Reduction

Environmental Discharge

Waste Metal RemovalP

RO

CES

S

Pregnant Solution Concentration

Barren Solution Concentration

Acid Reclamation

Cyanide Recovery

Copper Gold Fractionation

Lithium Recovery

Process Make up Water

Boiler Feed

DOMESTIC

Drinking Water

Domestic Water

Environmental DischargeMetals ConcentrationLeaching solution recoveryProcess water make upDomestic water

15

3,500-4,100m asl in Andes

Mountains

30miles north of Cajamarca city

Enhanced Metal Recovery

Yanacocha Gold Mine Peru

16

Lime blended, heap leached

Free cyanide 30-50 mg/L

Drip & spray Irrigation

Excess rainwater dilutes the leachate

Enhanced Metal Recovery

Yanacocha Gold Mine Peru

17

• Dewater pregnant liquor for Merrill Crowe

extraction process

• Remove excess cyanide for reuse

• Remove excess metals

• Problems of calcium sulfate scale on

membranes

• Autopsies and antiscalant supply from

2013

Enhanced Metal RecoveryYanacocha Gold Mine Peru

Source: MDS Membrane Separations & System Technologies and Case Studies

18

Barren pond storage prior to treatment and

disposal

Clean barren liquor

Treated for discharge to environment

Additional gold recovered via carbon column

Concentrate returned to heap leach pond

Enhanced Metal Recovery

Yanacocha Gold Mine Peru

Source: MDS Membrane Separations & System Technologies and Case Studies

19

Barren Liquor treatment

Heap Leach

Cyanide Solution

MiningGold

Extraction

Merrill-Crowe

Gold Recovery

Carbon Column

117.5 ppm CN WAD

Returned to Extraction

1750 m3/hr after

Chlorine Treatment

Discharged into Environment

2200 m3/hr

RO

Source: MDS Membrane Separations & System Technologies and Case Studies

20

2

Membrane application

Markus Kyburz

20

21

Markus Kyburz

21

22

Genesys Mining Research

UK Government Research grant for $700k £500k

- Calcium sulphate scale research

- Threshold testing

- Develop new antiscalants & cleaners

- Application testing on different minewaters

- Minewater scaling prediction software

- Install pilot plants

23

2.5” Pilot Plant

24

8” Pilot Plant

25

8” RO membrane Pilot Plant

26

Database identifying + 800 mines

389 operational mine based membrane plants.

47 Sea water desalination plants

Main Adopters

Glencore

Barrick

Anglo American

Rio Tinto

Newmont

Research Project

27

Identified RO/NF plants

28

RO/NF Membrane applications

29

Africa 93 plants, 15 countries

Mine name Company Location Commodity Date Application m3/d

Trekkopje- ErongoChina GNPG

Swakop UraniumNamibia Uranium 2016

SWRO mine

process55,000

eMalahleni Anglo AmericanSouth

AfricaCoal 2007

AMD

Drinking Water50,000

Tweefontein GlencoreSouth

AfricaCoal 2018

AMD

Drinking Water26,000

Ahafo Newmont Ghana Gold 2016Cyanide recovery

Env Discharge24,000

New Vaal Anglo AmericanSouth

AfricaCoal 2010

AMD

Cooling tower 20,000

Bogoso/PresteaGolden Star

ResourcesGhana Gold 2013

Cyanide recovery

Env Discharge16,000

Optimum CollieryOptimum Coal

Glencore

South

AfricaCoal 2010 AMD Water reuse 15,000

30

Latin America 87 plants 12 countries

Mine name Company Location: Commodity Date Application m3/d

Lagunas Norte Barrick Peru Gold 2014 Metal recovery 12,000

Antapaccay Glencore Peru Copper Gold 2017 Metal recovery 14,440

Yauliyacu Glencore Peru Copper Gold 2014 Env Discharge 20,304

CopiapoMinera del

Pacifico Chile Iron 2014

SWRO Mine and

community supply54,000

Yanacocha Newmont Peru Gold 2003 Metal recovery 66,000

Pampa Larga Newmont Peru Gold 2006 Metal recovery 24,000

La Quinua Newmont Peru Gold 2007 Metal recovery 18,000

Cerro de Maimon Perilya Dominican

RepublicCopper Gold 2012 Wastewater reuse 22,800

Escondida Rio Tinto Chile SWRO 2017SWRO Mine and

community supply216,000

31

Australasia 75 plants

Mine name Company Location Commodity Date ApplicationOn Line m3/d

Sino Iron Cape Preston

Citic Pacific WA Iron 2010SWRO Mine supply

140,000

Roy HillHancock Marubeni

WA Iron 2017BWRO Mine supply

15,000

Ulan GlencoreMudgee NSW

Coal 2014Waste Water reuse

21,300

RangerRio Tinto-ERA

NT Uranium 2011Waste Water reuse

11,000

Murrin MurrinGlencore Minara

WA Nickel 1998Process & Domestic

8,000

Bellbird Austar Coal NSW Coal 2014 Process 7,500

32

North America – 67 plants

Mine name Company: Location: Production Date ApplicationOn Line

m3/d

Monongalia Murray EnergyWest

VirginiaCoal 2012 AMD treatment 55,200

McClean Lake Areva Denison Canada Uranium 2008 Env Discharge 25,000

Goldstrike Barrick Nevada Gold 2015Leachate

recovery24,000

Key Lake (Mill)Cameco

CorporationCanada Uranium 2008 Env Discharge 23,000

MorgantownMorgantown Utility

Board

West

VirginiaCoal 2015 Env Discharge 19,000

Bingham

CanyonRio Tinto (Au, Uk) Utah Gold 2010 AMD treatment 17,500

Fort Knox Kinross Alaska Gold 2015 Env Discharge 13,000

Smoky

Canyon Simplot Idaho Phosphate 2017 AMD treatment 11,000

Ochoa IC Potash Corp New

MexicoPotash 2014 Env Discharge 9,000

Chino &

Tyrone Freeport McMoRan

New

MexicoCopper 2008 Env Discharge 9,000

33

RO/NF plants by commodity

398

9

9

11

16

17

21

48

64

85

118

0 50 100 150 200 250 300 350 400 450

TOTAL

DIAMONDS

LITHIUM

NI

ZN

URANIUM

IRON

COAL

OTHERS

COPPER

GOLD

34

RO/NF plants by Mining Company

5

6

7

9

12

12

13

20

0 5 10 15 20 25

ARCELLOR

BHP BILITON

CODELCO

NEWMONT

BARRICK

ANGLO AMERICAN

RIO TINTO

GLENCORE

35

SCALING

FOULING

PHYSICAL DAMAGE

CHEMICAL DAMAGE

What can go wrong?

36

Membrane scaling & inhibition

37

Antiscalants

38

3 Major forms of calcium sulphate

Hemihydrate CaSO4. 0.5H2O

Dihydrate CaSO4.2H2O

Anhydrite CaSO4

3 differing solubility isotherms

Dihydrate form is gypsum

Membrane scaling & inhibition

Calcium Sulphate Chemistry

39

Saturation Point

2,600mg/l of CaSO4

@ pH 7 25°C

Calcium sulphate solubility

40

Calcium sulphate (Gypsum) scale

Crystal platelets form in low flow cross over points of feed spacer

Clearly displayed when spacer removed during autopsy

Damaging to membrane

Scale formation initially needle platelets & rosettes resulting in blades

Chemical removal difficult

Membrane scaling & inhibitionCalcium Sulphate Chemistry

41

Performance of conventional antiscalants

tested at varying pH and in presence of metals

New formulations that can operate in acidic

mine water conditions tested

Threshold Tests

42

Blank 2 mg/l 4 mg/l 6 mg/l

Threshold Testing - Methodology

Antiscalants tested: A, B & C

pH 1 to 7, Temp: Ambient, 24hrs static jar test

Ca = 2000ppm, SO4 = 20,000ppm (Saturation Index CaSO4 ~7.5)

43

Conventional calcium sulphate antiscalant

0

20

40

60

80

100

120

0 2 4 6 8

% In

hib

itio

n

ppm Product A/S A A/S B

pH 7 pH 1

0

20

40

60

80

100

120

0 20 40 60 80 100 120

% In

hib

itio

n

ppm Product A/S A A/S C

44

Ca SO4 % inhibition Antiscalant C pH 2 Varying ferrous levels

0

20

40

60

80

100

120

0 20 40 60 80 100 120

% In

hib

itio

n

No Fe

10ppm Fe²⁺

50ppm Fe²⁺

100ppm Fe²⁺

200ppm Fe²⁺

300ppm Fe²⁺30ppm

100% inhibition

ppm of antiscalant C

45

0

20

40

60

80

100

120

0 20 40 60 80 100 120 140 160

% In

hib

itio

n

No Al

10ppm Al

50ppm Al

100ppm Al

200ppm Al

300ppm Al

ppm Antiscalant C

Ca SO4 % inhibition Antiscalant C pH 2 Varying aluminium levels

46

0

20

40

60

80

100

120

0 10 20 30 40 50 60

% In

hib

itio

n

No Cu

300ppm Cu

400ppm Cu

500ppm Cu

ppm antiscalant C

Ca SO4 % inhibition Antiscalant C pH 2 Varying copper levels

47

0

20

40

60

80

100

120

0 20 40 60 80 100 120 140 160

% In

hib

itio

n

No Zn

10ppm Zn

300ppm Zn

ppm antiscalant C

Ca SO4 % inhibition Antiscalant C pH 2 Varying zinc levels

48

Ca SO4 % inhibition Antiscalant C pH 2 Varying Manganese levels

0

20

40

60

80

100

120

0 20 40 60 80 100 120 140 160

% In

hib

itio

n

No Mn

10ppm Mn

300ppm Mn

49

CaSO4 inhibition Antiscalant C dose in presence of 300 ppm Iron

50ppm A/S C 150ppm A/S C 300ppm A/S C

50

Flat Sheet Test MethodologyTest conditions – recirculating system

Antiscalant C, pH 2 Temp: Ambient, 4 hrs circulation

Ca = 2000ppm, SO4 = 5000ppm (SI CaSO4 ~3) Metals: Fe (0 to 300ppm)

Standard Filmtec BW30 membrane operated at 15 bar

51

Flat sheet results – pH 4 and 100 ppm Fe²⁺

Calcium and sulphate NO Antiscalant Calcium and sulphate 175 ppm Antiscalant C

0

1000

2000

3000

4000

5000

0 0.5 1 1.5 2 2.5

Time - Hrs Ca ppm SO4 ppm

0

1000

2000

3000

4000

5000

0 0.5 1 1.5 2 2.5

Time - Hrs Ca ppm SO4 ppm

52

0

5

10

15

20

25

30

35

0 1 2 3 4

Flu

x (L

MH

)

Time - Hrs LMH 25C

0

5

10

15

20

25

30

0 0.5 1 1.5 2 2.5

Flu

x (L

MH

)

Time - Hrs LMH 25C

Flat sheet results – pH 4 and 100 ppm Fe²⁺

Complete flux loss no Antiscalant Result with Antiscalant C

53

2.6

3.2

0.8

2

0

0.5

1

1.5

2

2.5

3

3.5

1 2 3

Mem weight g Spacer weight g

2.42.6

0.8 0.8

0

0.5

1

1.5

2

2.5

3

0 1 2

Mem weight g Spacer weight g

Flat sheet results – pH 4 and 100 ppm Fe²⁺

54

Flat sheet results – pH 4 and 100 ppm Fe²⁺

Clean feed spacer No Antiscalant Antiscalant C

X40 Magnification

55

Flat sheet results – pH 4 and 100 ppm Fe²⁺

No Antiscalant Antiscalant C

56

Flat sheet results – pH 4 and 100 ppm Fe²⁺

Membrane surface No Antiscalant With Antiscalant C

X10 Magnification

57

Scale Prediction Software

58

• Antiscalant A & B can control CaSO4 scale at 8 times normal

saturation point at neutral and alkaline pH

• Antiscalant A & B are ineffective at controlling CaSO4 scale at

pH below 4

• Antiscalant C was very effective at preventing CaSO4

precipitation and scale in acidic conditions

• Antiscalant C works in presence of soluble metals

• Higher proportional dose rates are required with levels of iron

and aluminium

Conclusions

59

Cleaning CaSO4 Scale Methodology

• 15cm x 15m 0.225m² sample of scaled membrane

• 5% Cleaning solution recirculated for 30 minutes, soak 15

minutes and repeated for a 2 and 3 hour period

• New formulated cleaners A, B & C were tested alongside

traditional cleaner D

• Weight of feed spacer measured before and after

• Before and after pictures used for comparison

• Flux and salt passage measured before and after

60

Membrane sample

61

Cleaning CaSO4 Scale

5 % Cleaner A pH=11.9 for 3 hours @ 20-25°C

5 % Cleaner B at pH=7.0 for 3 hours @ 20-25°C

5 % Cleaner C at pH=11.3 for 3 hours @ 20-25°C

5 % Cleaner D at pH=11.8 for 2 hours @ 20-25°C

62

Cleaning CaSO4 Scale

Cleaner C

2 H

ou

rs3

Ho

urs

Cleaner DCleaner BCleaner AStarting

Condition

63

Cleaning CaSO4 Scale – weight of spacer

32.7

8.2

2.5

31.3

12.3

3.4

31.6

31.6

29.4

15.7

BEFORE CLNR A 2HR

CLNR B 3HR

BEFORE CLNR B 2HR

CLNR B 3HR

BEFORE CLNR C 2HR

CLNR C 3HR

BEFORE CLNR D 3HR

We

igh

t o

f Sp

ace

r (g

)

64

This element weighed 32 Kg!

Cleaned using our Pilot Plant

65

Cleaning Calcium Sulphate

66

Results: Cleaning Heavily Scaled Element

32 LMH

0

12.39.7

22.5

34.9

DP=1

18.7

5.9

4 1.71

17 Kg

32.9 kg

26 25.4

19.617

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

Fiu

xLM

H 2

5C

de

lta

P (

bar

) an

d W

eig

ht

kgFlux dP Weight (kg)

67

New Antiscalants modelled in the software

68

New Membrane cleaners

69

Conclusions

• Membrane plants already in use in 390 mines

• Double benefit - enhanced metal recovery + waste water clean up

• Calcium sulfate is a limiting factor

• New antiscalants– can inhibit CaSO4 at 8-10 times saturation

– Effective in acidic conditions

– Work in presence of soluble metals

– Prevent metal fouling of membranes

– No need for capex on metal removal and neutralisation of feed water

• New cleaners can remove CaSO4 scale

• Security of operation will lead to more widespread use.

70

Thank You

Questions?