Carty (Adobe) (Killerin Reolojisi)2

8/8/2019 Carty (Adobe) (Killerin Reolojisi)2

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Rheology of Aqueous Clay

Suspensions

William M. Carty, Ph.D.New York State College of Ceramics

at Alfred University

Oil Sands Extraction Fundamentals and Process Water Workshop

Canadian Oil Sands Network for Research and Development

May 8, 2001

Whiteware Researc h Center


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5 Factors Controlling

Suspension Rheology

vParticle-Particle InteractionsColloidal Behavior

v Particle Concentration (Water Content)

v Particle Size and Distribution

v Particle Morphology

v Rheology of the Suspension Medium


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Outline Colloidal Nature of Kaolinite

Dispersants with Kaolinite

-Potential Measurements

Behavior of 2:1 Sheet Silicates

Ionic Strength Affects


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The Colloidal Nature ofKaolinite

1:1 Sheet silicate

Primary component of commercial clays

(Ball clays, kaolins, china clays)

Formed from the decomposition of feldspar

Variable degree of crystallization


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Historical View of a Kaolinite Particle

the famous gold particle experiments

it seems rather obviousthat the preferred edge

attachment of the goldparticles is the result of

mutual flocculation of the

negative gold particlesand the positive kaolinite

edges.H. van Olphen

P. A. Thiessen, "Wechselseitige Adsorption von Kolloiden,"

Ztachr. Elektrochem, 48 [12], 675-81 (1942).


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Prevailing Perspective

Basal planes are similarly charged;

Edges are oppositely charged.

Na+ is a dispersant(folklore particle surface is negative)

Not consistent with mineralogy anddispersant demand.


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Mineralogy ofthe common

sheet silicates


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2

5 10 15 20 25 30 35 40 45 50

RelativeIntensity

English Kaolin

Kaolin

Ball Clay

Montm

orillonite

Mica

Kaolinite

Qu

artz

Quartz

XRD results

confirmmineralogy

D. M. Moore & R. C.Reynolds, X-Ray

Diffraction and theIdentification andAnalysis of ClayMinerals, 2nd Ed.,Oxford UniversityPress.


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Morphology & Charge Distribution

Isoelectric Points (IEP)

8Alumina: 8.5-10.4

8Silica: 2.0-3.5

8Kaolinite: 3.0-5.0

- - - - - - - - - - - - -

+ + + + + + + + + + + + +

-+-

+-+

"Silica-like" surface

"Alumina-like" surface

Edge(neutral?)

Silica-likebasal plane

Alumina-likebasal plane

Edge

h

2L


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Well-Crystallized Georgia Kaolin

h=0.10(2L)

h

2L


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Surface Area of a Hexagonal Platelet

( )+=+= 2basaledgetot L2

332hL6A2AA

33x12

x12

A

Af

tot

edge

edge +==

L2

hx =

Fraction of edge to basal plane surface area

Total area

For fedge= 0.5 h = 0.866L

Where:


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Edge Surface Area Ratio

Aspect Ratio (h/2L)

10-2 10-1 100Edge

Area:TotalSurfaceArea

0.0

0.2

0.4

0.6

0.8


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Particle Dimensions:50% Edge & 50%

Basal Surfaces

h=0.433(2L)

h=0.10(2L)

h

2L


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Basal-Plane Surface Area Ratios

Aspect Ratio (h/2L)

10-2 10-1 100OneBasalPlaneSur

faceArea/

TotalSurfaceA

rea

0.0

0.1

0.2

0.3

0.4

0.5

0.6


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Thickness, h 103 nm (30nm)

Width, 2L 1.1 m (430nm)

Aspect ratio 0.095

fbasal 41%

Results of SEM Measurements


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Viscosity of Na-PAA on Kaolin and Alumina(Corrected for SSA & pH)

Dispersant Level (mg/m2)

0.0 0.2 0.4 0.6 0.8 1.0

Appa

rentViscosity

(1.0s-1;Pas)

10-1

100

101

Kaolin

Alumina

pH=8.5


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Adsorption of Na-PAA

PAA adsorbed (mg/m2)

0.0 0.2 0.4 0.6 0.8

N

a-PAAadded(mg/m2)

0.0

0.1

0.2

0.3

0.4pH=9.0

100% Adsorption

Al2O

3

Kaolin

SiO2


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Adsorption of Na-PAA

PAA adsorbed (mg/m2)

0.0 0.2 0.4 0.6 0.8 1.0 1.2

N

a-PAAadded(mg/m2)

0.0

0.2

0.4

0.6

0.8pH=6.0

100% Adsorption

Al2O3

Kaolin

SiO2


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The surface area ratios

Aspect ratio: 0.095 (roughly 1:10)

Basal plane surface area = 82%(41% for each surface)

Edge surface area = 18%

0.4180.411Ratio

0.400 (0.042)0.161 (0.014)Al2O3

0.167 (0.017)0.066 (0.014)Kaolin

pH=6.0pH=9.0


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Summary

Kaolin adsorbs approximately 41% of

the amount of dispersantcompared to alumina.

For an aspect ratio 1:10, the amountof dispersant corresponds to thecoating of one basal plane.

There are two different basal plane

surfaces on Kaolinite.


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Dispersants with Kaolinite

1:1as noted aboveNa-Silicate:Na-Ash Blend (1:1)

Na-ashNa2CO310H2ONa-Ash

Na-silicatexNa2O(1-x)SiO2Na-Silicate (x=0.22)

Na-HMP(NaPO3)6Na-Hexametaphosphate

Na-PMAAH-(NaC4O2H5)n-HNa-Poly Methacrylic Acid

Na-PAAH-(NaC3O2H3)n-HNa-Poly Acrylic Acid

AbbreviationChemical FormulaDispersant


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Experimental Specifics Stock suspension diluted to appropriate

level with dispersant + water additions.

pH measured but not adjusted.

Viscosity measured in Stress-Controlledrheometer (SR-200, Rheometrics Scientific).

Measured from high rate to low rate.


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Behavior of Commercial Dispersants

Concentration of Dispersant (mg/m2)

0.0 0.1 0.2 0.3 0.4 0.5 0.6

ApparentViscosity

(1.0s-1,Pas)

10-2

10-1

100

101

10240 vol.% Porcelain Batch

Na2CO3

PMAA

PAA

Na-HMPNa2SiO3


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-Potential Measurements Acoustophoretic Mobility on kaolin

suspensions (not the porcelain batch).

5 v/o suspensions

pH not adjusted, only measured as afunction of dispersant addition.


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pH

5 6 7 8 9 10

ZetaPotential(mV)

-70

-60

-50

-40

-30

-20

-10

0

Na-PAA

Na-Silicate

Na-Ash

-potential

versus pH


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Dispersant Concentration (mg/m2)

0.0 0.2 0.4 0.6 0.8 1.0

ZetaPotential(mV)

-70

-60

-50

-40

-30

-20

-10

0B.

-potentialversus

[dispersant]

Na-Silicate

Na-Ash

Na-PAA


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1:1 versus 2:1 Sheet Silicates

Seven commercial claysVeegum T (90.26 m2/g) 3.0 v/oVanGel (49.33 m2/g) 4.5 v/oWyoming Bentonite (31.74 m2/g) 4.5 v/oBentolite L (95.85 m2/g) 25 v/o

101 Ball Clay (15.61 m2/g) 26 v/o401 Ball Clay (14.68 m2/g) 26 v/oMarshall (24.01 m2/g) 26 v/o

Effect of clay concentration

Target Viscosity at 1.0 s-1: 100 Pas

Effect of dispersantsNa-PAA and Na-HMP


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VeeGum T (Mg-Montmorillonite?)

Dispersant Level (mg/m2)

0.0 0.2 0.4 0.6 0.8 1.0

Norm

alizedApparen

tViscosity

10-4

10

-3

10-2

10-1

100

101

Na+- PAA

Na-HMP

Specific Surface Area: 90.26 m2/g

Solids Loading: ~ 3 vol.%


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Montmorillonite and Bentonite

Na+- Poly Acrylic Acid (mg/m2)

0.0 0.2 0.4 0.6 0.8 1.0

NormalizedAppa

rentViscosity

10-4

10-3

10-2

10-1

100

10

1

Veegum T

Van Gel B

Wyoming Bentonite


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Bentonite (Bentolite L)

Dispersant (mg/m2)

0.0 0.2 0.4 0.6 0.8 1.0

Norm

alizedApparentViscosity

10-1

100

101

102

103

Na+- PAA

Na-HMP

Specific Surface Area: 95.85 m2/g

Solids Loading: ~ 25 vol.%


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Kaolin-Illite Mixtures (Indiana ball clays)

Na+- Poly Acrylic Acid (mg/m2)

0.0 0.2 0.4 0.6 0.8 1.0Norm

alizedAppar

entViscosity

10-4

10-3

10-2

10-1

100

101

101 Clay

401 Clay

Marshall


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Kaolin-Illite Mixtures (Indiana ball clays)

Sodium Hexametaphosphate (mg/m2)

0.0 0.2 0.4 0.6 0.8 1.0

Norm

alizedAppare

ntViscosity

10-4

10-3

10-2

10-1

100

101

101 Clay

401 Clay

Marshall


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Effects of Ionic Strength Six salts were evaluated:

NaCl, CaCl2, MgCl2,

Na2SO4, CaSO4, MgSO4 Salts were always added as

saturated solutions

Porcelain Batch; 3 Dispersant levels


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CATION CONCENTRATION (mMol/L)

10-2 10-1 100 101 102 103

APPARENTVISCOS

ITY(1.0s-1,mPa

s)

101

102

103

104

105

0.00 mg/m2

0.02 mg/m2

0.05 mg/m2

Suspension: 30 vol% (distilled water)Salt: CaCl2

Kaolin: 29.0 wt.%Ball Clay: 7.0 wt.%Quartz: 29.5 wt.%

Alumina: 12.5 wt.%Neph. Syen.: 22.0 wt.%

CaCl2


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10-2 10-1 100 101 102 103

AP

PARENTVISCOSITY(1.0s-1,mPas

)

101

102

103

104

105

CaCl2

CaSO4

Suspension: 30 vol% (distilled water)Dispersion Level: 0.05 mg/m2

Kaolin: 29.0 wt.%Ball Clay: 7.0 wt.%

Quartz: 29.5 wt.%Alumina: 12.5 wt.%

Neph. Syen.: 22.0 wt.%

Cation

affectsonly

CaCl2CaSO4


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10-2 10-1 100 101 102 103

AP

PARENTVISCOSIT

Y(1.0s-1,mPas)

101

102

103

104

105

NaCl

MgCl2

CaCl2

Suspension: 30 vol% (distilled water)

Dispersion Level: 0.02 mg/m2

Kaolin: 29.0 wt.%Ball Clay: 7.0 wt.%

Quartz: 29.5 wt.%Alumina: 12.5 wt.%

Neph. Syen.: 22.0 wt.%

Divalent

8xMonovalent


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Coagulation occurs at a specificdouble-layer thickness

(no significant specific adsorption of cations)

(via Debye-Hckel)

Viscosity

versusDouble-Layer

Thickness

Double-Layer Thickness (nm)

10-1 100 101 102

Appare

ntViscosity(1.0

s-1,Pas)

10-2

10-1

100

101

102

NaClMgSO

4

CaSO4


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Summary and Conclusions

Kaolinite has oppositely charged basal

planes + neutral/positive edges.

Kaolin/Typical Porcelain SuspensionAnion species responsible for dispersion.

Na+, Ca+2, & Mg+2 cause coagulation.

-potential does not always correlatewith dispersion. (Needs further study.)


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Acknowledgements

Hyojin Lee, Chris Caughel,

Mike Brumbach, Katherine Rossington,

Brian Sundlof, Pete Kupinski

Michele Hluchy

Whiteware Research Center

Carty (Adobe) (Killerin Reolojisi)2

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