Characteristics of Solid waste – Residues Gardanne Coal Power Plant Geochemistry, Petrography , Mineralogy Naze - Nancy Masalehdani & Jean-Luc Potdevin [email protected]
Characteristics of Solid waste – Residues Gardanne Coal Power Plant
Geochemistry, Petrography , Mineralogy
Naze - Nancy Masalehdani & Jean-Luc Potdevin
• Exploit two Chimney-Units: T4 &T5
o T4: CFBC, 268 MWe, known to combust high Sulphur, low rank coal
o T5: 600 MWe, combust pulverized coal
• Total capacity: 868 MWe
• Situated in: Gardanne - Meyreuil
• Owned and operated: by SNET
• Types of Fuel:
o T4: Petroleum coke (Pet-coke) & Imported coal (e.g.S- Africa …)
o T5: Imported coal
• Sorbent (SB): Limeston to trap the acidic SO2 before the atmospheric
emission
• Temperature of combustion: T4 ≈ 850°C, T5 ≥1000°C
• Residues:
o Fly Ash (FA) resulting from dust filtration of the flue gas
o Bottom Ash (BA) extracting from the bottom of the boiler
Introduction
Provence-Gardanne Thermal Power Plant
• Dumping waste location: « Terril Bramefan »
Waste heap
Stockage of Ash
Area: ≈ 76ha
Source:www.asn.fr
• X-Ray Diffraction (XRD)
• Optical microscope (OM)
• Scanning Electron Microscope -energy-dispersive spectroscopy (SEM-EDS)
• Electron Probe Micro Analysis-wavelength dispersion spectrometry(EMPA-WDS)
• Raman spectroscopy (RS)
• Chemical analysis (ICP-FIMS-INAA)
Objectives Principal: Investigate characteristics of Solid waste - Residues
“Petrology, Mineralogy & Chemical compositions”
Divers: Chemical composition of Pet-Coke
Methodes
Results
Unit T4
Unit T5
Fly ash, fine material
transported from the
combustion chamber by
exhaust gases
(i.e. dust filtration of the
flue gas).
Bottom ash a coarse, granular,
incombustible by-product collected
from the bottom of boiler.
Combustion by-products from T4CFBC and T5
A B C D A: S-African Coal
B: Colombian Coal
C: Pet-Coke
D: Limestone
Imported Coal: S-African Coal (example)
Proximate analysis
Mineral Matter: South African coals have relatively high amount of clay
minerals (illite and kaolinite), quartz, sulphides , carbonates in the form of
dolomite and siderite as the minor minerals.
SEM-EDS
S: 19,33 % C: 80,67 %
• Is a solid by-product of heavy oil refining process
• Has high heat (carbon-fuel) & low ash content
• Contains relatively high sulphur ± trace metals
• Is cheaper than coal
• Should be co-fired with coal in coal-fired plants
SEM-SE
Components of Pet-Coke: Gardanne Thermal Power Plant
P
E
T
C
O
K
E
Chemical Composition: Pet-Coke, Gardanne Thermal Power Plant
SiO2 Al2O3 CaO Na2O K2O Fe2O3 MgO MnO P2O5 TiO2 N C S H LOI
1.57 0.98 0.24 0.02 0.14 0.44 0.07 0.018 0.05 0.059 1.27 73.93 5.50 3.46 96.00
Major elements (wt%)
As Ba Be Bi Cd Ce Co Cr Cs Cu Dy Er Eu Ga Gd
ID 40.30 ID ID ID 5.39 2.05 6.00 1.23 10.40 3.08 0.15 0.08 3.18 0.35
Trace elements (ppm)
Ge Hf Hg Ho In La Lu Mo Nb Nd Ni Pb Pr Rb Sb
ID 0.21 0.033 0.06 0.11 8.47 0.02 17.3 0.63 2.09 252 2.74 0.65 6.65 1.76
Se Sm Sn Sr Ta Tb Th Tm U V W Y Yb Zn Zr
0.20 0.46 0.57 11.1 0.05 0.05 1.09 0.02 0.36 1395 0.33 1.69 0.15 ID 7.54
Minerals
XRD RM OM SEM-EDS EPMA-WDS
FA4 BA4 FA5 BA5
Anhydrite CaSO4 Lime CaO
Calcite CaCO3 Dolomite
MgCa(CO3)2
√
√
√
√
√
√
√
√
√ √
√
√
√
√
√
√
√ √ √
√ √ √ √ √ √
√
Hematite Fe2O3 Maghemite Fe2O3
Magnetite Fe3O4
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√ √ √
√
√
Quartz SiO2 Tridymite SiO2 Mullite Al6Si2O13 Anorthite
CaAl2Si2O8
√
√
√
√
√ √ √
√
√
√
√ √ √ √ √
√
√
Barite BaSO4
Brookite TiO2 Anatase TiO2
√
√
√
√
√ √ √
√ √
Al-Si-Oxide
Ca-Al-Si-Oxide
√
√ √
√ √ √
√
Compounds
Al-P-Si-Ba-Ca
Si-Na-Ca-Mg
√
√
√
√
√ √ √
√
Glass √ √ √ √
Identified mineral phases in Fly and Bottom Ashes
Methods Samples & Units
Characteristics of Solid Residues:Sorbent «LM T4»
SiO2 Al2O3 CaO Na2O K2O Fe2O3 MgO MnO P2O5 TiO2 N C S H LOI
3.19 1.04 53.92 0.01 0.11 0.42 0.54 0.015 0.04 0.08 ND 11.35 ND 0.17 45.56
As Ba
Ce
Co Cr Cs Dy Er Eu Ga Gd Hf Hg Ho
1.29 33.8 3.85 1.23 6.1 0.63 0.291 0.144 0.072 1.74 0.28 0.31 0.008 0.05
La Lu Mo Nb Nd pb Pr Rb Se Sm Sr Ta Tb
2.08 0.02 1.37 0.91 1.27 1.65 0.44 6.02 0.09 0.34 340 0.09 0.05
Th Tm U V Y Yb Zr
0.64 0.23 1.73 7.5 1.63 0.144 11.0
Trace elements (ppm)
Major elements (wt%)
XRD Patterns
Calcite (CaCO3)
Quartz (SiO2)
OM-CPL
Characteristics of Solid Residues: Fly Ash « T4 »
H
L
AlSi-oxide
H
Q
Ba
L
AlSi-oxide
Q
Al- P-Si-Ba-Ca-compound
L An
Lime > Anhydrite
XRD Patterns: Anhydrite, Lime, Quartz, Hematite
Characteristics of Solid Residues: Bottom Ash«T4»
A
L
Q
L Al-Si-oxide
Bottom Ash from unit T4 has relatively homogenous mineralisation. Concentration of
Anhydrite is being higher than Lime. Mineral zoning occurs between Anhydrite & Lime
as observed in Fly ash. Amorphous AlSi-Oxide (? metakaolinite) occurs as small
isolated phase or within Anhydrite -Lime grains.
L
Si-Na-Ca-Mg
compound
Al-Ca-Si-Oxide
Anhydrite > Lime
Wt
% SiO2 Al2O3 CaO Na2O K2O Fe2O3 MgO MnO P2O5 TiO2 N C S H LOI
FA 26.70 14.40 30.37 0.12 0.54 2.62 1.30 0.035 0.75 0.74 0.10 7.13 4.59 0.28 12.89
BA 13.74 6.53 50.99 0.06
0.26 1.39 0.99 0.03 0.30 0.47
ND 3.14 6.46 0.46 5.56
ICPS-MS Analysis: Residues from « T4 »
ppm As Ba Be Bi Cd Ce Co Cr Cs Cu Dy Er Eu Ga
FA
7.18 836 5.45 1.65 0.38 113 19.6 94.1 4.30 40.9 7.44 4.20 1.69 29.0
BA 8.09 489 4.45 0.67 0.18 66.0 17.3 97.5 2.22 14.7 4.15 2.30 0.99 20.40
ppm Gd Ge Hf Hg Ho In La Lu Mo Nb Nd Ni Pb
FA 8.06 6.61 6.30 0.441 1.48 0.19 64.70 0.61 17.0 16.30 47.2 275 36.5
BA 4.28 6.32 3.40 0.0015
0.83 0.14 37.5 0.35 17.4 10.60 26.6 300 4.49
ppm
Pr Rb Sb Se Sm Sn Sr Ta Tb Th Tm U V W
FA
12.6 29.1 2.38 3.8 9.05 4.37 1214 1.51 1.23 20.2 0.63 7.70 960 3.60
BA 7.38 14.2 2.10 0.08 5.05 4.04 909 0.94 0.67 12.4 0.36 5.98 1240 2.30
ppm Y Yb Zn Zr
FA 46.7 4.15 29.3 243
BA 24.9 2.36 36.8 135
FA: Fly Ash
BA: Bottom Ash
Characteristics of Solid Residues: Fly Ash « T5 »
Spherical texture, Fly Ash from Unit T5 contains high temperature T≥ 1000°C
mineral phases, more Si-bearing minerals and Iron oxides compared to T4 Fly
Ash. Quartz and Tridymite (both SiO2) occur together. Mineral Mullite
Al6Si2O13 was also identified. Lesser amounts of Lime and Anhydrite were
observed.
Mh
Mh
AlSi-oxide
Q
L
Characteristics of Solid Residues: Bottom Ash « T5 » OM-CPL
SEM-BSE
SEM-EDS
Microphotographs showing hoste Magnetite
(Fe3O4) crystallised in glass matrix. Quenched
texture indicates rapid crystallisation from melt.
Glass composition is: Al-Si-Na-silicate.
ICPS-MS Analysis: Residues from T5
Wt
% SiO2 Al2O3 CaO Na2O K2O Fe2O3 MgO MnO P2O5 TiO2 N C S H LOI
FA 52.84 24.06 5.21 0.63 2.03 6.74 1.83 0.08 0.67 1.11
ND
3.81 0.43
0.10
5.53
BA 45.89 15.20 8.58 0.42 1.13 9.50 1.93 0.15 0.27 0.62 0,19 10.49 0.60 0.69 16.52
ppm As Ba Be Bi Cd Ce Co Cr Cs Cu Dy Er Eu Ga
FA 39.0 1305 8.84 1.95 1.53 143 34.6 205 11.5 81.6 9.92 5.59 2.54 48.0
BA 13.7 682 3.65 0.28 0.91 63.9 16.5 289 4.92 66.1 5.11 2.86 1.27 13.9
ppm Gd Ge Hf Hg Ho In La Lu Mo Nb Nd Ni Pb
FA 10.8 18.6 7.34 0.199 1.99 0.21 77.3 0.88 18.2 20.8 63.8 128 57.4
BA 5.43 5.30 4.41 0.582
1.02 ID 33.9 0.48 13.8 11.2 29.0 142 15.4
ppm
Pr Rb Sb Se Sm Sn Sr Ta Tb Th Tm U V W
FA 17.1 97.8 14.4 21 12.4 7.17 945 1.89 1.70 26.3 0.85 10.2 312 7.57
BA 7.73 49.4 3.65 2.2 5.99 2.49 480 0.98 0.87 11.9 0.46 4.79 429 2.23
ppm Y Yb Zn Zr
FA 62.5 5.77 163 284
BA 31.8 3.06 155 171
FA: Fly Ash
BA: Bottom Ash
(Kaolinite) Al2Si2O5(OH)4
39.50 % Al2O3
46.55 % SiO2
13.96 % H2O
100 – 200 °C
Loss of H2O
Al2Si2O5 + H2O 500 – 600 °C
Dehydroxylated
Endothermic process
Metakaolinite
39.50 % Al2O3
46.55 % SiO2
Process of mineral formation during Ashing
* AlSi-Oxide found in Flay Ash and Bottom Ash from Unit T4 is an amorphous phase i.e.
metakaolinite which was not decomposed into Al-Si-spinel because the combustion
temperature remained T≤ 850°C.
EPMA - Result: Al2O3 35.83%, SiO2 45.26%, with 1.34% K2O, 0.54% CaO, 3.19%TiO2
as impurities.
** Al-Ca-Si-Oxide found in Flay Ash and Bottom Ash from Unit T4 is an amorphous
phase. A reaction of decomposed clays with lime (CaO) and partly quartz (SiO2) to form
Al-Si-Oxide (? pre-formation of Gehlenite) at 820-850°C.
EPMA - Result: Al2O3 18.48%, SiO2 26.7%,CaO 28.86%, with 1.98% FeO and 0.93%
TiO2 as impurities.
*** Al-P-Si-Ba-Ca-Compound in Fly Ashes (T4 & T5) and Bottom Ash (T4) could be a
mixed amorphous phase (Apatite + Lime + Al-Silicate ± Barite)
T5 Fly Ash: Si > Al > Ca
T5 Bottom Ash: Si > Al > Ca
T4 Bottom Ash: Ca >Si >Al
T4 Fly Ash: Ca >Al >Si
Ternary diagram chemical composition (wt%):
Fly and Bottom Ashes
Fly & Bottom Ashes from T4: produced from burning bituminous coals
& Pet-Coke have Sulfo-Calcic
compositions, contain lime (CaO) and
Anhydrite (CaSO4)
Fly & Bottom Ashes from T5: produced from burning bituminous coals
have Silico-Aluminous compositions,
contain higher concentration of Al-si-
oxides
Wt
%
Residues
• Unit T4: Higher sulphur concentration in residues confirmes the presence
of Anhydrite (CaSO4) • Unit T5:
* Higher iron concentration in residues confirmes Magnetite (Fe3O4), Hematite and/or Maghemite (Fe2O3) as principal Fe-Oxides
* Higher concentration of Carbon in bottom ash is related to presence of
Calcite (CaCO3), and probably to ± char (i.e.unburnt carbon)
Concentration of Sulphur,Carbon & Iron in Residues
0
2
4
6
8
10
12
T4 FA T5 FA T4 BA T5 BA
S
C
Fe
Elements
pp
m
ICP-FIMS-INAA Analysis
Concentration of Trace elements in Residues p
pb
0
200
400
600
800
1000
1200
1400
1600
As Cu Cr Ni Sr V Zn Pb
T4 FAT5 FAT4 BAT5 BACP
0
50
100
150
200
250
300
350
400
450
500
T4 FA T5 FA T4 BA T5 BA CP LM
Hg
pp
m
0
5
10
15
20
25
T4FA T5FA T4BA T5BA CP LM
Se
The Pet-Coke-Coal residues (Ashes) produced by
Provence-Gardanne Thermal Power Plant are:
enriched in Vanadium and Nickel
• V & Ni compounds are not toxic as Hg, Cd, As, Pb
or other «heavy metals».
• Most health problems related to Nickel deal with skin
& respiratory exposure (Nielsen,1977, p.134).
• The most common health problems associated with
Vanadium (if present as V2O5) exposure result from
inhalation e.g. coughing, bronchitis, eyes, nose & throat
irritation (Waters, 1977, p.148, pp.160-161).
The ash chemical composition for both Fly ash and
Bottom ash from the particulate control device at
Provence-Gardanne Thermal Power Plant directly
arises from the fuel characteristics
& sorbent composition They result:
1. from the chemical composition of the inorganic fraction
of the fuel,
2. from the fuel sulphur content and the SO2 removal rate.
Thank you for your attention
Conclusions