Transcript A Lead Monoxide Precursor of High Surface-Area for Lead-Acid Battery Paste

A Lead Monoxide Precursor
of High Surface-Area for
Lead-Acid Battery Paste
R Vasant Kumar
Department of Materials Science
University of Cambridge, UK
Acknowledgements
 Seref Sonmez, Vega Kotzeva, Jiakuan Yang,
Lilia Sanchez, Richard Darby, Yingjun Liu,
David Zou, of Department of Materials
Science
 Lei Wang, Nigel Williams of the Business
School
 Maggie Wilkinson & Zlatka Stoeva of
Cambridge Enterprise
A Schematic Cut-Away of Lead Battery
Table 1 Range of Compositions
from a dry lead battery paste
Material
Wt %
Lead sulphate
55-65
Lead dioxide
15-40
Lead monoxide
5-25
Metallic lead
1-5
Carbon black, plastics, fibres, other
sulphates
1-4
Current Method - Pyrometallurgy
*Independent Consultants
*For 10,000
tpy plant
Capital: $45M
Energy:
14,000MWH
Battery Manufacture
 Lead is then chemically oxidised to PbO
for the battery industry
 PbO is electrochemically reduced to Pb
and oxidised to PbO2 to make anode and
cathode
A new process for recycling lead
battery waste Special Leaching/Crystallization Process
Waste
Battery
Paste
→
→
New
Lead Battery
↓
↑
Manufacturing Lead Battery
New Paste
Patent: PCT/GB2007/
004222; WO2008/056125
RV Kumar, S Sonmez and V
Kotzeva
Lead containing
Organic
Crystalline
Compounds
PbO
Precursor
Combustion/
Calcination
Process
A new process for recycling lead
battery waste
Waste
Battery
Paste
→
Pb Grid
New lead
Battery
New Grid
Kettle
Heat Energy from
paste
recycling
New Paste directly from paste recycling
Green PB Recycling Process
Wast
e
Batte
ry
Used
Paste
Leaching
Spent
Lead grid
Crystalline
Compound
s
New
Battery
CombustionCalcination
New
Paste
PBO
Precurs
or
Patent: PCT/GB2007/
004222; WO2008/056125
RV Kumar, S Sonmez, V
Kotzeva
Metallic
Lead
Leaching of battery paste PbO and PbO2
6
1.5 : 1
1.25 : 1
Temperature Rise / °C
5
Ratio of
1:1
Paste/
reagent
4
3
2
1
0
0
10
20
30
Time / mins
40
50
60
Temperature(℃ )
50
Lead (II) oxide
40
30
Lead (IV) dioxide
Lead sulfate
20
10
0 5 10 15 20 25 30 35 40 45 50 55 60 65
Reaction time(min)
pH vs time for varying paste/reagent ratio
4.5
4
3.5
pH
3
2.5
2
1.5
1.5 : 1
1.25 : 1
1:1
1
0
10
20
30
Time / mins
40
50
60
Intensity(a.u.)
A
B
C
D
5
15
25
35
45
55
65
2 θ(degree)
XRD Pattern of A: Standard Lead citrate; B: from PbO; C: from
PbO2 and D: from PbSO4
Lead organic crystallites of
Lead citrate (A) from PbO and PbO2
SEM images of Lead Citrate (B) from PbSO4
Precursors
Ideal
weight
loss
weight loss
Ideal weight
loss
weight loss
weight loss
(TGA)
For
after
exother
mic peak
of TGA
calcined
350℃
1h
decompo
sition to
PbO
From
dehydrating
Precursor I
[Pb(C6H6O7)]·H2O
Precursor II
[Pb(C6H6O7)]·H2O
Precursor III
[Pb3(C6H6O7)2]·3H2
O
4.3%
4.20%
46.3%
49.8%
48.2%
4.3%
4.20%
46.3%
49.8%
49.0%
5.1%
5.50%
36.6%
38.3%
37.5%
Combustion-Calcination of Lead citrates in Air
at
for
Sample: 20070423PbO-air
Size: 7.8140 mg
Method: Ramp
DSC-TGA
File: C:...\yj231\20070423\20070423PbO-air.002
Operator: yj231
Run Date: 23-Apr-2007 14:50
Instrument: SDT Q600 V8.2 Build 100
120
25
334.01°C
100
20
80
15
60
10
40
Heat Flow (W/g)
Weight (%)
2000J/g
5
285.09°C
151.79°C
238.7J/g
20
0
167.76°C
0
40
Exo Up
80
120
160
200
240
Temperature (°C)
280
320
360
-5
400
Universal V4.3A TA Instruments
Wt loss and heat produced on decomposing Pb citrate (A)
Sample: 20070411PbSO4air
Size: 15.9840 mg
Method: Ramp
DSC-TGA
File: C:...\DSC\20070411-PbSO4air-analysis.001
Operator: rs489
Run Date: 11-Apr-2007 14:27
Instrument: SDT Q600 V8.2 Build 100
120
25
357.91°C
2427J/g
100
20
80
15
60
10
284.16°C
40
Heat Flow (W/g)
Weight (%)
9.869%
5
20
0
117.77°C
0
40
Exo Up
80
120
160
200
240
Temperature (°C)
280
320
360
-5
400
Universal V4.3A TA Instruments
Wt loss and heat produced from lead citrate (B)
Pb
PbO
Intensity(a.u.)
450℃
400℃
350℃
300℃
10
20
30
40
50
60
70
80
90
2 θ(degree)
Mixture of α and β PbO and metallic Pb – can be controlled
to varying ratios
Heat Produced
 Combustion-calcination of lead citrates can
generate thermal energy of 2 kJ/ g of lead
battery paste
 The Raceway Adiabatic Flame Temperature
is over 1500K!
 This energy is equivalent to 550 kWh/kg of
paste!
PbO morphology after combustion-calcination
TEM
SEM
Spongy PbO
Agglomerated PbO
Skeletal PbO
Additives during leaching to control PbO morphology
Lead citrate
PbO
Addition of C-fibre to PbO precursor
FEGSEM – Each fibre is coated
with PbO
Physical Properties of PbO
 Free Pb: 0 to 20 %
 Crystal structure: α/β ratio: 0.05 to 1
 Crystal size: 20 – 100 nm
 Particle average size: 1 – 5 μm
 Specific surface area (BET) m2/g: 2.4 to 5.5
 Acid absorption (mg H2SO4/ g oxide): 270 –
530
Preliminary Electrochemical Testing
 First discharge capacity
0.10
C
0.05
I (Amps/cm2)
in the 130 – 160 mAh/g
of PbO
 Increase in discharge
capacity with no of
cycles up to 8-10
cycles and then
remained constant to 50
cycles
 Further work is ongoing
B
0
-0.05
-0.10
-5.0
D
E
A
-2.5
0
2.5
E (Volts)
A: PbO /PbSO4 reduction to Pb
B: Pb oxidation to PbSO4
C: PbSO4 oxidation to PbO2
D: PbO2 reduction to PbSO4
E: PbSO4 reduction to Pb
The Green PB Process
For 10,000 tpy plant
Capital: $1-1.5 M
Energy: 1750 MWH
5000 MWh
Energy
available
Conclusions
 New method for directly recovering PbO from
spent battery paste
 Many control variables available to vary
physical properties of PbO product
 Promising preliminary results
 Thank You