modeling of hydrometallurgical process solutions with oli · activity coefficient models regression...

Vladimiros G. Papangelakis

Department of Chemical Engineering and Applied ChemistryUniversity of Toronto, Canada

Modeling of Hydrometallurgical Process Solutions with OLI

Reagents

Discharge

VentFeed

OLI 23rd User Conference October 5 -6, 2005

1

• Chemical Modeling Approach• The OLI Software• Applications in

Hydrometallurgical Solutions

Outline

2

• Use of aqueous solutions to selectively extract and produce metals from natural resources: minerals and ores.

• It employs aqueous processing systems (leaching, precipitation, SX/IX, electrolysis) under ambient and/or elevated pressures and temperatures (up to 270°C).

• Aqueous solutions are highly concentrated near, at, or over saturation.

• Can be one-, two-, or, three-phase systems

What is Hydrometallurgy?

3

• To understand and explain the process extremes - limits

• To be more predictive outside the range of available experimental data

• Speciation reactions in aqueous phase are much faster than Aqueous-Solid reactions (leaching or precipitation): aqueous solution is at equilibrium

Why Thermodynamics in Hydrometallurgy?

4

Solid - Aqueous Equilibria

Solid

Leac

hing

)nz(n

z MLnLM −−+ ⇔+

Precipitation

Aqueous

REDOX Reactions

5

• Inadequate theory to account for the physics of ionic interactions and structures

• Inconsistent and incomplete thermodynamic databases

• Weak mathematical framework, when it based on the “infinite dilution” – “ideal solution” standard state

Simulating Concentrated Electrolyte Solutions: Challenges

Success is measured by how well models can predict(as opposed to fit) experimental measurements

6

• Debye-Hückel, Debye and Hückel 1923

• Extended Debye-Hückel Davies Equation, Davies 1962B-dot Equation, Helgeson 1969

• Bromley, Bromley 1973; 1986

• Pitzer, Pitzer 1973; 1991

• Meissner, Meissner et al.,1972

• Chen, Chen 1982; 1986

• Mixed-solvent electrolyte, Anderko et al. 2002; Wang et al. 2002

Activity Coefficient Models

Regression on experimental data to obtain model parameters

7

Mixed Solvent Electrolyte (MSE) Model

• FeaturesElectrolytes in organic or water or mixed organic + water solvents from infinite dilution to pure electrolytesUnit scale: mole fraction xReference state: Symmetrical

• The activity coefficient expressionSRi

MRi

LRii γγγγ lnlnlnln ++=

LR: Long Range electrostatic interactions between ions, Pitzer-Debye-Hückel expression is used

MR: Middle Range interactions involving charged ions, Ion-Ion, Ion-Molecule

SR: Short Range interactions between all species, Ion-Ion, Ion-Molecule, Molecule-Molecule, UNIQUAC equation is used

C A

M

C A

C A

M2M1

8

MSE Middle Range Interaction Term

∑ ∑∑∑

∑∑

−∂

∂⎟⎠

⎞⎜⎝

⎛−

=γ

i ixiki

j k

xijji

ii

i jxijji

MRi

IBxn

IBxxn

IBxx

)(2)(

)(ln

)01.0exp( +−⋅+= xijijij IcbBcij= CMD0+CMD1×T+CMD2/T

bij= BMD0+BMD1×T+BMD2/T

Bij : Middle range parameters, ionic strength dependentBii= Bjj=0, Bij= Bji

9

Software ⎯ OLI Systems®

An extensive databank of over 3,000 species

Advanced thermodynamic framework to calculate thermodynamic properties like free energy, entropy, enthalpy, heat capacity, pH, ionic strength, density, conductivity, osmotic pressure etc.Built-in data regression capabilities to obtain thermodynamic model parameters based on experimental dataWide applicability for the aqueous phase:

-50<T<300 °C, 0<P<1500 Bar, 0 < I < 30 molal

10

• Pressure acid leaching process of laterites

• Oxygen solubility in ZnSO4-H2SO4-H2O

• Gypsum solubility

• Lead and nickel chemistry in mixed H2SO4+HCl solutions

Case Studies in Hydromet Processes


11

Pressure Acid Leaching of laterites

H2SO4

OreCCD

AUTOCLAVE

CaCO3(s)

Gypsum(Fe, Al)

CaO(s)

Gypsum(Mg, Trace metals)

Ni, Co + Solvents

S2

S3E1S1

Waste Water

H2SO4 + Organic Solvent

12

• Feed: FeOOH + Mg3Si2O5(OH)4 + Al(OH)3

• Ni at 1-2 wt% as: Fe(Ni)OOH + Ni3Si2O5(OH)4

• Conceptual main reactions:

H2SO4 dissolves Ni, Mg and part of Al(as well as various impurities)

FeOOH → Fe2O3(s)

Pressure Acid Leach of Laterites

13

• Model: OLI-Aqueous Electrolyte

• Regression of experimental data in simple systems at 200-300°C :

H2SO4-H2OAl2(SO4)3-H2SO4-H2OMgSO4-H2SO4-H2ONiSO4-H2SO4-H2OFe2(SO4)3-H2SO4-H2O

• Simulation of real laterite leach solutionsPrediction of solubilities of Al, Mg, Ni, FeTrue acidity (pH) at high temperature

Pressure Acid Leach of Laterites

14

Solubility of Metals in H2SO4-H2O

Al Experimental data from Baghalha et al. 1998, Zhu 2002; Mg from Marshall et al. 1965; Ni from Marshall et al. 1962; Fe from Liu et al. 2003

0

0.2

0.4

0.6

0.8

0 0.2 0.4 0.6 0.8H2SO4, molal

Al 2(

SO4) 3

, mol

al

Exp, 230 CExp, 250 C

Exp, 270 CModel

0.0

0.3

0.6

0.9

1.2

1.5

1.8

0.0 0.4 0.8 1.2 1.6H2SO4, molal

MgS

O4,

mol

al

Exp, 200 CExp, 235 CExp, 270 CExp, 300 C Model

0.0

0.3

0.6

0.9

1.2

1.5

0 0.4 0.8 1.2 1.6

H2SO4, molal

NiS

O4,

mol

al

Exp, 200 CExp, 225 CExp, 250 CExp, 275 CExp, 300 CModel

0.000

0.002

0.004

0.006

0.008

0.010

0 0.2 0.4 0.6 0.8

H2SO4, molal

Fe2(

SO4)

3, m

olal

Exp, 230 CExp, 250 CExp, 270 CModel

15

Speciation in Saturated Metal Sulfate Solutions at 250°C

0

20

40

60

80

100

0 0.2 0.4 0.6 0.8H2SO4, molal

Al S

peci

es, %

Al2(SO4)30

AlSO4+

Al(SO4)2-

0

20

40

60

80

100

0 0.2 0.4 0.6 0.8 1

H2SO4 , molal

Mg

Spec

ies,

%

MgHSO4+

Mg2+

MgSO40

0.01

0.1

1

10

100

0 0.2 0.4 0.6 0.8

H2SO4, molal

Fe(II

I) Sp

ecie

s, %

Fe(OH)2SO4-

FeHSO42+FeSO4

+

Fe3+

Fe(SO4)2-

Fe2(SO4)30

0

20

40

60

80

100

0 0.2 0.4 0.6 0.8 1H2SO4, molal

Ni S

peci

es, %

NiHSO4+

Ni2+

NiSO40

16

Calculated and measuredmeasured pH at 250°C

0

0.5

1

1.5

2

2.5

0 0.3 0.6 0.9 1.2H2SO4, molal

pH

No Ni 0.05 0.1

NiSO4molal

0.10.05

0.00.5

Sat. Ni

0.0

1.0

2.0

3.0

4.0

0 0.2 0.4 0.6 0.8 1

H2SO4, molal

pH

Na2SO4 , molal

0.0

0.25 0.5

0.0

0.5

1.0

1.5

2.0

2.5

0.0 0.3 0.6 0.9 1.2H2SO4, molal

pH

no Mg 0.05 0.1 0.15

MgSO4 molal

Sat. Mg

0.0 0.5 0.75

0.05

0.10.15

17

pH in Saturated Al2(SO4)3 Solutions, 250°C

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0.0 20.0 40.0 60.0 80.0 100.0

H2SO4, g/L

pH

Exp, No Mg Exp, 1.22 g/L Mg Exp, 2.43 g/L Mg Exp, 3.65 g/L Mg Model

Sat. Mg & Al

Limonite

0.0

1.22

2.43 3.65

12.218.23 g/L Mg

..... Sat. Al

8.63

Mg

Limonite+Saprolite

18

pH in 250°C-Saturated Al2(SO4)3 Solutions, Measured at 25°C

0.0

0.5

1.0

1.5

2.0

2.5

0.0 0.2 0.4 0.6 0.8 1.0 1.2

H2SO4, m

pH

Pure H2SO4

Saturated Mg & Al

Sat. Al

19

Industrial Process Development

• Elemental composition (%wt) of laterite feeds

• Operating conditionsTemperature: 250, 270°C Slurry density: 30%

• Required acid addition vs. feed composition (Krause et al. 1997)

wt% H2SO4=4 + 6(wt%Mg) + 2.4(wt%Al - 0.8) +3(wt%Ni+Co+Mn) + 4(wt%CO2)

Feed Ni Co Fe Al Mg

Lim/Lim+Sap 1.36-2.23 0.07-0.16 41.7-49.8 1.93-3.08 0.25-3.78

20

Predicted pH for Goro Piloting

L⎯ limonite; S ⎯ saprolite

0

0.2

0.4

0.6

0.8

1

1.2

0 10 20 30 40 50

H2SO4 , %

pH

250 C, L

270 C, L

250 C, L+S

270 C, L+S

Average

250 C, PureH2SO4

270 C, pureH2SO4

21

Acid Calculation at pHT=1

0

5

10

15

20

25

30

35

40

0 0.5 1 1.5 2 2.5 3 3.5

Mg, wt%

Req

uire

d ac

id, w

t%

Limonite, this work Limonite, by Eqn. (12) Limonite+Saprolite, this work Limonite+Saprolite, by Eqn. (12)

0

5

10

15

20

25

30

35

40

0 1 2 3 4 5

Al, wt%R

equi

red

acid

, wt%

Limonite, this work Limonite, by Eqn. (12) Limonite+Saprolite, this work Limonite+Saprolite, by Eqn. (12)

wt% H2SO4 = 4+6(wt%Mg) +2.4(wt%Al-0.8)+3(wt%Ni+Co+Mn)+4(wt%CO2)

INCO equation for ~30% solids of Goro laterite in fresh water, 240 to 270°C

22





Case Studies

23

Pressure Oxidative Leaching of ZnS

Sphalerite ZnS

Acid Oxidative Pressure LeachingT: 140-1500C, PO2: 5-10 atm

Solution Purification

S/L Separation Leach Residue

Fe, Cu etc.

Electrolysis

Metal

O2, H2SO4

Process chemistry:ZnS+0.5O2+2H2SO4 =

ZnSO4+S+H2O

24

Solubility of O2 in Pure Water

0

1

2

3

4

5

0 50 100 150 200 250 300

Temperature, 0C

O2(

aq)x

103 , m

olal

Battino 1981

Calculated by OLI

Smoothed Line by Groisman and Khomutov 1990

P(O2)=1 atm

0.00

0.03

0.06

0.09

0.12

0.15

0.18

10 30 50 70P(O2), atm

O2(

aq),

mol

al

100 C, Stephan et al163 C, Stephan et al260 C, Stephan et al

25

Solution Chemistry in ZnSO4-H2SO4-H2O System

Solubility of ZnSO4 in H2O

0

1

2

3

4

5

0 50 100 150 200 250 300

Temperature, 0C

ZnSO

4, m

olal

Linke & Seidell

Rodulph et al. Model

ZnSO4.6H2O

ZnSO4.7H2O

ZnSO4.H2O

0

1

2

3

4

5

0 0.5 1 1.5 2 2.5 3

H2SO4, molal

ZnS

O 4, m

olal

6 C 15 C 25 C 35 C 45 C

Solubility of ZnSO4 in H2SO4, exp from Linke & Seidell

26

Solubility of O2 in H2SO4 and ZnSO4

0.0

0.3

0.6

0.9

1.2

1.5

1.8

0 0.5 1 1.5 2 2.5 3 3.5

ZnSO4, molalO

2(aq

)x10

3 , mol

al

25 C

Model

Solubility of O2 in H2SO4, data from Battino 1981

Solubility of O2 in ZnSO4, data from Narita et al.1983

0.6

0.8

1.0

1.2

1.4

1.6

0 0.5 1 1.5 2 2.5 3H2SO4, molal

O2(

aq) x

103 , m

olal

15 C

25 C

27

Solubility of O2 in H2SO4-H2O

Experimental data from Battino 1981

0.0

0.5

1.0

1.5

2.0

2.5

0 50 100 150 200 250

Temperature, 0C

O2(

aq)x

103 , m

olal

0.5 M 1.0 M 1.5 M Model

Pure water

PO2 = 1 bar

28

Prediction of O2 Solubility inZn POX

Experimental data fromHayduk 1991

0

0.3

0.6

0.9

1.2

1.5

1.8

0 50 100 150 200 250

Temperature, 0C

O2(

aq)x

103 , m

olal

120 g/L H2SO4 + 30 g/L ZnSO4

60 g/L H2SO4 + 75 g/L ZnSO4

5 g/L H2SO4 + 110 g/L ZnSO4

Pure water

120 g/L H2SO4 + 30 g/L Zn2+

60 g/L H2SO4 + 75 g/L Zn2+

120 g/L H2SO4 + 110 g/L Zn2+

Model

29

Solubility of O2 in H2SO4 ⎯ Overmeasurement by Hayduk

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0 50 100 150 200 250

Temperature, 0C

O2(

aq)x

103 , m

olal

Pure water, Model

1.0 mol/L, Model

Experimental data from Hayduk 1991

0.051 mol/L, Hayduk 1.225 mol/L, Hayduk

30





Case Studies

31

Where Does Gypsum Scale Occur

H2SO4

OreCCD

AUTOCLAVE

CaCO3(s)

Gypsum(Fe, Al)

CaO(s)

Gypsum(Mg, Trace metals)

Ni, Co + Solvents

S2

S3E1S1

Waste Water

H2SO4 + Organic Solvent

CaCO3+H2SO4 = CaSO4·2H2O+H2O+CO2↑

CaO+H2SO4 = CaSO4·2H2O+H2O

32

Gypsum Solubility in H2O

0

0.004

0.008

0.012

0.016

0.02

20 40 60 80 100

Temperature (°C)

CaS

O4,

mol

al

Marshall & SlusherModel

33

OLI-Fitted Gypsum Solubility vs. H2SO4AE Model

Data points for gypsum in zinc sulphate from: Dutrizac, J., “Calcium Sulphate Solubilities in Simulated Zinc Processing Solutions”, Hydrometallurgy, 65, no. 2-3, (2002) 109-135

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0 0.25 0.5 0.75 1 1.25 1.5 1.75 2

Sulphuric Acid Concentration (m)

Cal

cium

Con

cent

ratio

n (m

)90 °C

60 °C

75 °C

45 °C

25 °C

34

Fitting of Gypsum Solubility in Sulfate Solutions

0

0.02

0.04

0.06

0.08

0.1

0 0.5 1 1.5 2H2SO4, molal

CaS

O4,

mol

al

90 C 75 C 60 C 25 C

0

0.01

0.02

0.03

0.04

0 1 2 3 4

Na2SO4, molal

CaS

O4,

mol

al

25 C

75 C

CaSO4.2H2O

CaSO4.Na2SO4

CaSO4-H2SO4-H2O, exp data from Dutrizac 2002

CaSO4-Na2SO4-H2O, exp data from Hill & Wills 1938

35

OLI-Fitted Gypsum Solubility vs. NiSO4

Data points for gypsum in nickel sulphate above 0.5 m from: Campbell, A. and N. Yanick, “The System NiSO4-CaSO4-H2O”, Trans. Farad. Soc., 28, (1932) 657-66. Data below 0.5 m from UofT.

0

0.005

0.01

0.015

0.02

0.025

0.03

0 0.5 1 1.5 2

Nickel Sulphate Concentration (m)

Cal

cium

Con

cent

ratio

n (m

)

45°C

75°C

90°C

36

0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80 100Zinc Concentration (g/L)

Cal

cium

Con

cent

ratio

n (g

/L)

50 °C75 °C

20 °C

OLI-Predicted gypsum solubility vs. ZnSO4in 10 g/L H2SO4

Data points for gypsum in zinc sulphate from: Dutrizac, J., “Calcium Sulphate Solubilities in Simulated Zinc Processing Solutions”, Hydrometallurgy, 65, no. 2-3, (2002) 109-135

37

OLI-Predicted Gypsum Solubility

0

0.2

0.4

0.6

0.8

0 20 40 60 80 100Temperature (°C)

Cal

cium

Con

cent

ratio

n (g

/L)

12.5 g/L Mg

Pure Water

2.5 g/L Mg

38

Conclusions

• OLI Systems offer the best available software for chemical modelling of both low and high temperature Hydrometallurgical processes

• Reagent requirements, impurity levels, solution speciation, scaling tendencies are all understood in terms of solution chemistry and are computed in terms of ore composition and temperature → $$ Savings in Piloting

• UofT-OLI collaborative project: International consortium to develop verified databases for the Hydrometallurgical industry

39





Case Studies

40

Pb(II) Solubility in H2O

0

0.2

0.4

0.6

0.8

0 50 100 150 200 250 300Temperature, 0C

PbC

l 2, m

olal

Bartels 1980

Model

0

0.5

1

1.5

2

2.5

0 20 40 60 80

Temperature, 0C

PbSO

4, x1

04 m

olal

Linke & Seidell

Model

41

PbCl2–HCl–H2O

0

5

10

15

20

25

30

0 50 100 150 200 250 300 350

HCl, g/L

Pb2+

, g/L

Linke et al., 1958 Tan et al., 1987 Model

50 0C

0

10

20

30

40

0 50 100 150 200 250 300 350HCl, g/L

Pb2+

, g/L

Linke et al., 1958 Tan et al., 1987 Model

80 0C0

5

10

15

20

25

30

35

0 50 100 150 200 250 300 350

HCl, g/L

Pb2+

, g/L

Linke et al., 1958 Tan et al., 1987 Mgaidi et al., 1991 Pred with default database Pred with fitted PbCl2-H2O Model

25 0C

42

Speciation in PbCl2-HCl-H2O at 25 °C

0

20

40

60

80

0 1 2 3 4 5 6

HCl, molal

Pb-C

l spe

cies

, %

PbCl42-

Pb2+

PbCl20PbCl+

PbCl3-

43

Prediction of PbSO4 Solubility in H2SO4

0

5

10

15

20

0.01 0.1 1 10 100 1000H2SO4, g/L

Pb2+

, mg/

L

Crockford et al. 1934, 0 C Craig et al. 1939, 0 C Crockford et al. 1934, 50 C Praige et al. 1991, 60 C Predition

60 0C

500C

00C

0

5

10

15

20

0.01 0.1 1 10 100 1000

H2SO4, g/L

Pb2+

, mg/

L

Crockford et al., 1934 Craig et al., 1939 Kryukova et al., 1939 Kolthoff et al., 1942 Prediction

25 0C

44

Prediction of PbSO4 Solubility in HCl

0

0.3

0.6

0.9

1.2

1.5

1.8

0 10 20 30 40 50 60

HCl, g/L

Pb2+

, g/L

Beck et al. 1910,18 C

Beck et al., 25 C

Beck et al., 37 C

Huybrechts etal.1928, 18 C

Huybrechts et al.,30 C

PbSO4

PbCl2

180C

250C

300C

370C

45

Prediction in PbSO4–H2SO4–HCl– H2O

1

10

100

1000

0.1 1 10 100

H2SO4, g/L

Pb2+

, mg/

L

PbCl2

PbSO4

4.89

10

25.150.1

HCl, g/L180C

Exp data from Linke et al. 1958

46

Solubility of NiSO4 in H2O

0

1

2

3

4

5

6

0 50 100 150 200 250

Temperature, 0C

NiS

O4 ,

mol

al

Exp, Linke 1958 Exp, Linke 1958 Exp, Bruhn et al. 1965 Model

NiSO4.7H2O

NiSO4.6H2O

NiSO4.H2O

47

Heat Capacity of NiSO4-H2O System

0.65

0.7

0.75

0.8

0.85

0.9

0.95

1

0 0.5 1 1.5 2 2.5 3

NiSO4, molal

Cp,

cal

/g/K

Aseyev 1996, 25 C Aseyev 1996, 100 C Model

48

Vapor Pressure of NiCl2 Solutions

0.01

0.015

0.02

0.025

0.03

0.035

0 1 2 3 4 5

NiCl2, molal

Pre

ssur

e, a

tm

Aseyev 1999, 25 C Model

0.4

0.6

0.8

1

1.2

0 2 4 6

NiCl2, molal

Pres

sure

, atm

Aseyev 1999, 100 C

Model

49

Solubility of NiCl2 in HCl

0

1

2

3

4

5

6

7

0 2 4 6 8 10 12HCl, molal

NiC

l 2, m

olal

Foote 1923, 0 C Babav et al., 1935, 20 C Babav et al., 1935, 80 C Model

NiCl2.6H2O

NiCl2.2H2O

00C200C

800C

50

Prediction in NiCl2–NaCl–H2O

0

1

2

3

4

5

6

0 1 2 3 4 5 6 7

NaCl, molal

NiC

l 2, m

olal

Filippov et al., 1986 Model

NiCl2

NaCl 250C

modeling of hydrometallurgical process solutions with oli · activity coefficient models regression...

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