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76                                             New Trends in Coal Conversion



         Table 3.3 Trace element concentrations in coal and biomass
          Fuel        <1 ppm            1e10 ppm      10e100 ppm  >100 ppm
          Polish coal  Cd, Hg,Mo, Tl    As, Be, Co, Sb,  Cr, Cu, Ni,  Ba, Mn
                                          Se           Pb, Sr, V,
                                                       Zn
          Colombian   Be, Cd, Hg, Sb, Tl  As, Co, Cu, Ni,  Ba, Cr, Mn,
            coal                          Mo, Pb, Se   Sr, V, Zn
          Wood bark   As, Be, Cd, Co, Hg,  Ni, Mo, Pb, V  Cr, Cu, Sr  Ba, Mn, Zn
                        Se, Sb, Tl
          Straw       As, Be, Cd, Co, Hg,  Cr, Cu, Pb  Ba, Mn, Zn
                        Ni, Mo, Sb, Tl, V
          Paper sludge  As, Be, Cd, Co, Hg,  Ni, Mo, Sb, V  Cr, Cu, Mn,  Ba, Zn
                        Se, Tl                         Pb, Sr
          Sewage      Be, Hg, Tl        As, Cd, Co, Sb  Ni, Mo, Pb, V  Ba, Cr, Cu,
            sludge                                                  Mn, Sr,
                                                                    Zn
          Agricultural  As, Be, Cd, Co, Hg,  Cr, Mo, V  Ba, Ni, Sr, Cu  Mn, Zn
            wastes      Pb, Sb, Se, Tl
          Pulp sludge  As, Be, Co, Hg, Mo,  Cd, Pb, V  Ba, Cr, Cu,  Mn, Zn
                        Sb, Se, Tl                     Ni, Sr
          Plastic     As, Be, Hg, Se, Tl  Cd, Co, Ni,  Cr, Cu, Mn,  Ba, Zn
            wastes                        Mo, Sb, V    Pb, Sr


         Data from Miller, B.B., Kandiyoti, R., Dugwell, D.R., 2002. Trace element emissions from Co-combustion of secondary
         fuels with coal: a comparison of bench-scale experimental data with predictions of a thermodynamic equilibrium model.
         Energy and Fuels 2002 (16), 956e963.
         with the organic fraction of the coal (L  opez-Ant  on et al., 2006). The amount of
         mercury removed by coal washing varies considerably from coal to coal from virtually
         no mercury removal up to 64% (in unique cases). The average mercury removal with
         standard coal washing is around 20%e30% (Sloss, 2012).
            Existing technologies for particulates, SO 2 and NO x , such as ESPs, baghouses (FF),
         FGD, and SCR, can often help reduce TE emissions as a cobenefit. Taking advantage
         of cobenefit effects could be a cost-effective way of reducing mercury emissions in
         developing countries.


         3.5.1  Particle control devices
         Efficient particulate control devices capture the majority of TEs in the fly ash. Accord-
         ing to (Zevenhoven and Kilpinen, 2001), ESP and FF removal efficiencies are of the
         order of 99%e99.9% for most TEs, especially group 1. For some group 2 elements,
         the removal efficiency is somewhat lower at around 95%e99% and even less for group
         3 TEs. Fine particles tend to carry more of the semivolatile TEs due to their larger
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