Liquidus projection in the Al2O3-CaO-FeO-PbO-SiO2 quinary system. the isotherms are plotted for the regions

within the operational temperature range

Introduction

0

1

2

3

4

5

6

7

1970 1976 1982 1988 1994 2000 2006 2012

Am

ou

nt

of

Pb

, m

illi

on

to

nn

es

Year

Primary production

Secondary production

Primary (ore extraction) and secondary (recycling)

lead production ratesReference: www.ilzsg.org

55.0%26.0%

3.5%10.5%

5.0% Paste

Grids, poles

Plastic residue

Acid

Polypropylene

The main components of acid batteries

Reference: G. Martin, “Recycling of used lead-acid batteries and

recovery of the polypropylene content,” World Metall. – Erzmet.,

vol. 61, pp. 243-247, 2008

Reference: www.ilzsg.org

The fields of lead application

80.0%

1.0%6.0%

3.0%

2.0%

5.0%

3.0%

Batteries

Cable Sheathing

Rolled and Extruded

ProductsShot/Ammunition

Alloys

Pigments and other

CompoundsMiscellaneous

The share of recycled lead in its total production increases with

time because of its economic and environmental benefits

The main source of secondary lead is spent acid batteries which

contain lead in amounts, sufficient for effective recycling

Nowadays, spent acid batteries are recycled almost completely.

Both metallic (grids and electrode plates) and paste (PbSO4 +

some amount of PbOx) are used for lead extraction

Sulfate paste is transformed into lead carbonate (cerussite)

which undergoes reduction with carbon in a furnace

Reference: www.recobat.comReference: www.recobat.comReference: www.recobat.com

Obtained results

Objectives and calculation tools

Fact Optimal module of FactSage software is

a perspective and powerful tool of process

optimization, which allows to perform a

minimization procedure in multicomponent

systems using various constraints on the

system and components properties

At a given SiO2 content, the optimal liquidus

temperature was searched with the constraint

PbO(slag)≤40 wt%;

At each obtained temperature and

composition the slag viscosity was calculated

using Viscosity module

The operational temperature must not exceed ≈ 1100°C (the lower limit is ≈ 500°C)

Slag viscosity should be as low as possible

Lead losses with off-gases should be minimized as well

Although it is possible to minimize two properties simultaneously in Fact Optimal, the

current version does not allow to perform viscosity optimizations directly; it is assumed

that SiO2 makes the major contribution to the slag viscosity

Pb losses with off-gas can be assumed proportional to Amountoff-gas*PPb species. Both

factors grow with T, therefore the minimization of Pb losses is equivalent to the

minimization of the operational temperature0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0.10.20.30.40.50.60.70.80.9

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

SiO2

PbO CaOmole fraction

Liq

Liq + C2S

Liq + C2S + Mono

Liq + Mono

Liq + CS

Liq + C2S + CS

C2S +

CS

C2S + C3S2

C2S

+ C

S +

C3S

2

Liq

+ C

S +

S

Liq + S

log(visc) = 3

log(visc) = 2

log(visc) = 1log(visc) = 0

log(visc) = -1log(visc) = -2log(v

isc) =

-3

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0.10.20.30.40.50.60.70.80.9

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

SiO2

PbO FeOmole fraction

Liq

Liq

+ F

aya

lite

Liq +SiO2

Liq + Mono

log(visc) = -3

log(visc) = -2

log(visc) = -1

log(visc) = 0

log(visc) = 1log(visc) = 2

log(visc) = 3

-10

-5

0

5

10

15

20

25

30

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

lg(η

, P

ois

e)

molar SiO2/(SiO2+MOx)

CaO-SiO₂ MELTS viscosity database

PbO-SiO₂ MELTS viscosity database

FeO-SiO₂ MELTS viscosity database

FeO₁˳₅-SiO₂MELTS viscosity database

AlO₁˳₅-SiO₂MELTS viscosity database

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0.10.20.30.40.50.60.70.80.9

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

SiO2

PbO Al2O3mole fraction

Liq

Liq + PA6

Liq + Mull

Liq + S(s4)

Liq + Mull + S(s4)

Liq + A + PA6

Liq + Mull + A

Liq + A

log(visc

) = 3

log(visc

) = 2

log(visc

) = 1

log(v

isc

) = 0

log(v

isc

) = -1

log

(vis

c) =

-2

log(v

isc

) = -3

SiO2 - PbO - Al2O3

1200oC, 1 atm

T = 1200°C

Isoviscosity lines in the ternary systems including both silica and PbO

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

1020 1040 1060 1080 1100 1120 1140

Vis

cosi

ty,

Pois

e

Process temperature, C

min + 10 C

min + 20 C

min + 30 C

T(liq) + 10 C

T(liq) + 20 C

T(liq) + 30 C

Pareto front in the system CaO-FeO-Fe2O3-PbO-SiO2

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

24.0% 26.0% 28.0% 30.0% 32.0% 34.0% 36.0%

rela

tiv

e le

ad

loss

, %

wt% SiO2

T(liq) + 10 C

T(liq) + 20 C

T(liq) + 30 C

Lead losses in the system CaO-FeO-Fe2O3-PbO-SiO2

The optimization results in the system Al2O3-CaO-FeO-Fe2O3-PbO-SiO2 have shown that Al2O3

addition strongly increases slag viscosity and overall results are not substantially superior to

those without Al2O3

86.0

88.0

90.0

92.0

94.0

96.0

98.0

100.0

1020 1040 1060 1080 1100 1120 1140

carb

on

co

nsu

mp

rio

n,

kg

/to

nn

e o

f P

b

Process temperature, C

Carbon consumption per ton of lead produced

Results window of Fact Optimal module

Application of Fact Optimal module of FactSage to the optimization of

the lead recycling processEvgenii Nekhoroshev1, Sergei Decterov1

1Center for Research in Computational Thermochemistry (CRCT), Dép. de Génie Chimique, Ecole Polytechnique de Montréal, Montreal, QC, Canada