Upload
others
View
8
Download
0
Embed Size (px)
Citation preview
Design of a Hydrometallurgical Treatment System for Aluminium Waste
Thomas J. Robshaw, Keith Bonser, Glyn Coxhill, Dr Robert Dawson & Dr Mark D. Ogden
1
The SNUCER Group
Dr Mark D. Ogden
2
SHEFFIELD
Ion-Exchange: What We Do
R A+ B+ R B+ A+Polymermatrix
R+X Y R+Y X
Cationexchange
Anionexchange
Gold refiningPharmaceutical
purification
Juice processing
Water softening
Metal separation
Sugar decolourisation3
HallHéroult electrolytic cellFor aluminium production
REDOX reactions:
2Al2O3 + 3C 4Al + 3CO2
Al2O3 + 3C 2Al + 3CO
Spent Potlining (SPL)
4
Al2O3, Na3AlF6,
AlF3
~50% carbon10% fluoride1% cyanide
1stcut
2ndcutGraphitebased
Cementbased
TOXIC EXPLOSIVE
ENORMOUS SAFE STORAGE CHALLENGE
Characteristics of SPL
5
Fluorspar (CaF2)Global reserves: 310 MT“CRITICAL MINERAL”
2ndcut
GraphiteGlobal reserves: 800 MT
Graphite and Fluorspar
6
050
100150200250300350400450
Eur
o to
nne
1
Hydrometallurgical SPL Treatment
Proposed new system for maximum fluoride recovery
7
Grinding and screening
Caustic leach
Solid/liquid separation Acid leach
Leachate mixing
Solid/liquid separation
Inert carbon/cement
product
Solid/liquid separation
Ionexchange circuit
NaOH
Mixedcut SPL
H2SO4
Input
Process
Output
Solid wastestream
Liquid wastestream
SPL Characterisation and Leaching
10 20 30 40 50 60 70 800
50100150200250300350PXRD
spectra
10 20 30 40 50 60 70 800
1000
2000
3000
4000
Inte
nsity
(a.u
.)
2 theta
Sample A Sample B
NaOH (1M) / H2O2 (3%), 3 hrsH2SO4 (0.5M), 2 hrsCombine leachates F NO3
Fe Al Ca Si0
500
1000
1500
2000
Con
cent
ratio
n in
leac
hate
(mg
L1)
0.5 M Na0.25 M SO4
2
pH ~310 30 50 70
0
500
1000
1500
2000
2500
10 30 50 700
5000
10000
15000
Sample A Sample B
Inte
nsity
(a.u
.)
2 theta
La-MTS9501 Resincitrate > sulfate > oxalate > iodide > nitrate > cromate
> bromide > thiocyanide > chloride > formate > acetate >
fluoride
FFM. Kanesato et al., Chem. Letters, 1988, 207. 9
Puromet MTS9501
Bead diameter = 300 µm
*Full coordinate spheres not shown for clarity
Change of recovery strategy (Na3AlF6) ?
Uptake Mechanisms
T.J. Robshaw et al., Chem. Eng. J., 2019, 367, 149.
F
FF
F
OFH
H
+F
OH
H
2+OH
HAl Al Al
CaF2
€370 per Tonne
Na3AlF6
€750 per Tonne
Proposed Ion-Exchange Circuit
SPL leachate streams Carousel
Lead column
Breakthrough column
Fluorideloaded column
Pump
NaOH(aq)
Fluoride-selective electrode
Pump
pH electrode
Pump
pH adjust
Na3AlF6(aq)
Defluoridated leachate
To precipitation
stage
Fluorideselective electrode
11T.J. Robshaw et al., J. Hazard. Mater., 2019, 361, 200.
LaMTS9501
LaMTS9501
LaMTS9501
100 150 200 250 300 350 400 450 5000
0,5
1
1,5
ExperimentalDoseResponse model
Effluent volume (mL)
Bre
akth
roug
h (a
.u.)
20 30 40 50 60 70 80 90 100 110 1200
0,20,40,60,8
11,2
Bre
akth
roug
h (a
.u.)
0 50 100 150 200 250 300 350 400 450 5000
50
100
150
200
250
300
350
400
450
500
Effluent volume (mL)
Fluo
ride
efflu
ent c
once
ntra
tion
(mg
L1)
q0 = 37 mg g1
SPL leachate
Pump
Fluorideselective electrode
12
Dynamic Resin Performance
Contaminants
Recovery
0 100 200 300 400 500 600 7000
200
400
600
800
1000
1200
1400
1600
1800
Fluoride AluminiummL eluent
Con
c. in
elu
ent (
mg
L1)
Elution with water 1M NaOH
€
€€
€
€
€
€€€
13
Conclusions
LaMTS9501 resin is highly suitable for purpose
Al in SPL leachate produces synergistic uptake mechanism
Recovery of synthetic cryolite may be possible
14
AcknowledgementsDr Mark Ogden & the SNUCER groupDr Robert Dawson & research groupPolymer Centre CDTEngineering & Physical Sciences Research CouncilBawtry Carbon InternationalTrimet AluminiumRoyal Society of Chemistry (Environment Sustainability & Energy Division)You for listening
15
See poster 123 for more fluoride [email protected]
Supporting Information
16
Al Metal Productio
n
Pyrometallurgical SPL Treatment
D.G. Brooks et al., Light Metals, 1992, 283-287.
✦ Produces 2.5 T waste per T SPL processed✦ In operation today
17
Proposed Leaching Treatment
Caustic leachate
To IX circuit
Solid/liquid separation
Na3AlF6 and Al2O3 solublised
Solid/liquid separation
CaF2 and NaAl4O17 solublised
Purifiedgraphite
Leachate mixing?
Slurry
Impellor
CN- destruction
H2O2
NaOH(aq)
Ground & screened
SPL
HNO3(aq)
Acidic leachate
18
Cryolite PrecipitationPXRD spectrum of cryolite precipitated from leachate before IX treatment
19
10 20 30 40 50 60 70 800
100
200
300
400
500
600
700
800
900
1000
10 20 30 40 50 60 70 800
100
200
300
400
500
600
700
2 theta
Inte
nsity
(a.u
.)
Literature spectrum for comparison
XPS Analysis of Resin Beads
La environmentsAl environments O environments
6567697173757779818385100
200
300
400
500
Binding energy (eV)
Cou
nts
(s1
)
5225275325375421000200030004000500060007000
Binding energy (eV)
Cou
nts
(s1
)
8208308408508608701800200022002400260028003000
Binding energy (eV)
Cou
nts
(s1
)
52252753253754215002000250030003500400045005000
Cou
nts
(s1
)
8208308408508608702000
2500
3000
3500
4000
4500
5000
Cou
nts
(s1
)(none)
NaF
sol
utio
nLe
acha
te
C. Stosiek et al., Chem. Mater., 2010, 22, 2347. S. Selvasekarapandian et al., Physica B., 2003, 337, 52.
Aluminium hydroxyfluoride
(AHF)
20
Resin Regeneration Study
Equilibrium fluoride uptake of LaMTS9501 over 5 adsorption/desorption cycles
21
0
10
20
30
40
50
60
70
qe (m
g g
1)