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Table 3 Inorganic chemical analysis of condensates from different stages of gasification

From: Characterisation of the Contaminants Generated from a Large-Scale Ex-Situ Underground Coal Gasification Study Using High-Rank Coal from the South Wales Coalfield

   Atmosphere 30 bar
Stage name   S1 S2 S3 to S6   30S1 30S2 30S3 to 30S6  
Sample ID Unit Oxygen stage 1 condensate Oxygen + water stage 2 OEA + water stage 3 to 6 C1 (mix of S1 to S6) Oxygen stage 1 condensate Oxygen + water stage 2 OEA + water stage 3 to 6 C2 (mix of 30S1 to 30S6)
Electrical conductivity μS/cm 3630 ± 182 8030 ± 402 8900 ± 445 1506 1020 ± 51 1160 ± 58 2760 ± 140 396.3
pH   7.2 ± 0.2 7.0 ± 0.2 6.8 ± 0.2 7.3 4.6 ± 0.2 7.4 ± 0.2 8.3 ± 0.2 5.69
COD (Cr) mg/l 398 ± 60 1370 ± 206 1380 ± 207 – 208 ± 31 192 ± 29 521 ± 78 –
NH3(aq) mg/l (as N) 496 ± 50 1170 ± 117 1260 ± 126 997.5 68.5 ± 6.9 132 ± 13 387 ± 39 202.5
NO3− mg/l 0.92 ± 0.14 < 0.5 0.72 ± 0.11 0.71 0.88 ± 0.13 <0.5 0.58 ± 0.09 0.63
F− mg/l 0.35 ± 0.05 20 ± 3 34 ± 5 19.36 0.52 ± 0.08 0.50 ± 0.08 2.0 ± 0.3 1.02
Cl− mg/l 180 ± 18 784 ± 78 500 ± 50 488.8 11.6 ± 1.2 34.2 ± 3.4 117 ± 12 56.57
CN− mg/l 9.0 ± 0.9 8.2 ± 0.80 5.8 ± 0.6 7.52 0.02 ± 0.002 0.16 ± 0.02 0.53 ± 0.05 0.25
SO4−− mg/l 74 ± 7.4 375 ± 38 588 ± 59 364.6 394 ± 39 76.1 ± 7.6 121 ± 12 178.2
Fe mg/l 0.18 ± 0.02 2.73 ± 0.3 0.069 ± 0.007 0.92 4.04 ± 0.4 3.55 ± 0.36 1.66 ± 0.17 3.0
Al+++ mg/l 2.02 ± 0.50 0.50 ± 0.13 0.28 ± 0.07 0.88 0.12 ± 0.03 0.050 ± 0.013 0.055 ± 0.014 0.07
Mn++ mg/l 0.062 ± 0.009 0.075 ± 0.011 0.0031 ± 0.0005 0.043 0.12 ± 0.02 0.049 ± 0.012 0.042 ± 0.011 0.07
As mg/l 0.14 ± 0.035 1.13 ± 0.283 1.23 ± 0.308 1.6 as H2AsO4− 0.088 ± 0.022 0.017 ± 0.004 0.13 ± 0.03 0.14 as H2AsO4−
B mg/l 0.15 ± 0.04 0.96 ± 0.24 0.55 ± 0.14 3.2 as B(OH)3(aq) 0.12 ± 0.03 0.22 ± 0.04 0.35 ± 0.07 1.36 as B(OH)3(aq)
Cd++ mg/l < 0.001 < 0.001 < 0.001 – < 0.0005 <0.0005 <0.001 –
Co++ mg/l < 0.003 < 0.005 < 0.003 – 0.0066 ± 0.0017 <0.005 <0.005 –
Cr mg/l 0.078 ± 0.02 0.19 ± 0.04 0.11 ± 0.02 0.12 0.10 ± 0.02 0.47 ± 0.09 0.13 ± 0.03 0.252
Cu++ mg/l < 0.005 <0.005 < 0.005 0.006 < 0.005 <0.005 <0.01 0.006
Mo mg/l 0.0091 ± 0.0015 0.012 ± 0.002 0.0080 ± 0.001 0.016 as MoO4−− < 0.005 <0.005 0.015 ± 0.004 0.01 as MoO4−−
Ni++ mg/l 2.80 ± 0.7 0.23 ± 0.06 0.11 ± 0.03 0.97 1.95 ± 0.2 0.25 ± 0.05 0.17 ± 0.04 0.69
Pb++ mg/l < 0.01 < 0.005 0.0066 0.007 0.022 ± 0.006 0.026 ± 0.007 0.13 ± 0.03 0.06
Hg mg/l < 0.0005 < 0.0005 < 0.0005 – < 0.0005 <0.0005 0.002 ± 0.0004 –
Sb mg/l 0.39 ± 0.098 0.26 ± 0.063 0.12 ± 0.03 0.35 as Sb(OH)3(aq) 0.054 ± 0.014 <0.01 0.34 ± 0.09 0.19 Sb(OH)3(aq)
Se mg/l 0.049 ± 0.013 0.16 ± 0.04 0.39 ± 0.1 0.2148 < 0.005 <0.01 0.057 ± 0.014 0.025
Ti mg/l < 0.005 0.020 ± 0.005 0.016 ± 0.004 0.033 as Ti(OH)4(aq) < 0.003 <0.003 <0.003 0.01 as Ti(OH)4(aq)
Zn++ mg/l 0.18 ± 0.020 0.044 ± 0.004 0.093 ± 0.009 0.10 72.5 ± 7.3 0.040 ± 0.010 0.21 ± 0.04 19.85
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