Long term stabilization of Sb in MSWI bottom ash Bram Verbinnen Jo - - PowerPoint PPT Presentation

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Long term stabilization of Sb in MSWI bottom ash Bram Verbinnen Jo - - PowerPoint PPT Presentation

Jun 21, 2023 111 likes •274 views

Long term stabilization of Sb in MSWI bottom ash Bram Verbinnen Jo Van Caneghem, Pieter Billen, Carlo Vandecasteele KU Leuven, Belgium Cyprus 2016 conference, 23/06/2016 MSWI Bottom Ash 2 MSWI Bottom Ash Each application: specific

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Long term stabilization of Sb in MSWI bottom ash

Bram Verbinnen

Jo Van Caneghem, Pieter Billen, Carlo Vandecasteele

KU Leuven, Belgium Cyprus 2016 conference, 23/06/2016

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SLIDE 2

MSWI Bottom Ash

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MSWI Bottom Ash

  • Each application: specific chemical barrier
  • Most barriers can be overcome!
  • Some problems remain, or more strict legislation
  • Netherlands: Green Deal
  • By 2017: 50% of BA in applications without protective measures
  • By 2020: No more use in applications with protective measures
  • Enhanced recovery of NF metals
  • Most problematic: leaching of Sb

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Sb leaching

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  • Sb leaching known to be governed by:
  • Formation of calcium antimonates (romeites)1
  • Adsorption to iron (hydr)oxides
  • Formation of iron antimonate (tripuhyite, FeSbO4)2
  • (Incorporation in ettringite)
  • All pH dependent!

1: Cornelis et al..: Antimony leaching from MSWI bottom ash: Modelling of the effect of pH and carbonation. Waste Management 32, 278-286 (2012) 2: Okkenhaug et al..: Treatment of air pollution control residues with iron rich waste sulfuric acid: Does it work for antimony (Sb)? Journal of Hazardous Materials 248, 159-166 (2013)

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Reduce Sb leaching

  • Based on these mechanisms: addition of
  • Fe- and Ca- salts
  • Industrial waste streams containing Fe- and Ca-salts
  • Experimental
  • Short term leaching behavior
  • Lab batch tests
  • Middle-long term leaching behavior
  • Outdoor field tests
  • Long term leaching behavior
  • Lab carbonation tests

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Short term leaching behavior

  • pH dependent leaching behavior
  • Addition of:

Fe- and Ca-containing compounds Fe- and Ca-containing industrial residues (10%)

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Short term leaching behavior

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  • Additives:
  • Ca-compounds
  • CaO, CaCl2: formation and precipitation of romeites
  • CaCO3: less soluble, no precipitation
  • Fe-compounds
  • Formation of tripuhyite
  • Industrial residues
  • Formation of Ca-antimonates (A2, A3: soluble Ca-compounds)
  • No adsorption on iron oxides (A1: no soluble Ca-compounds,

iron oxides)

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Middle-long term leaching behavior

  • Outdoor field tests
  • Sb concentrations initially decreased
  • Lower than untreated BA & regulatory limit value
  • Increase slightly over time as pH decreases
  • Romeites become more soluble at lower pH values

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Long term leaching behavior

  • Carbonation
  • BA: decreasing
  • Fe2(SO4)3: initially lower, increasing

0,2 0,4 0,6 0,8 1 1,2 1,4 1,6 1,8 4,0 6,0 8,0 10,0 12,0 14,0

Sb Leaching concentration (mgkgDM

  • 1)

Leachate pH pH sweep BA 2.5% Fe2(SO4)3 Dutch limit value

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Long term leaching behavior

  • Carbonation
  • A2: initially lower, increasing, below limit value
  • A3: initially lower, increasing, around limit value

0,2 0,4 0,6 0,8 1 1,2 1,4 1,6 1,8 4,0 6,0 8,0 10,0 12,0 14,0

Sb Leaching concentration (mgkgDM

  • 1)

Leachate pH pH sweep BA 10% A2 10% A3 Dutch limit value

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Long term leaching behavior

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  • Sb leaching from treated BA increasing after carbonation
  • Romeites more soluble at lower pH1
  • Sb leaching from untreated BA decreases after carbonation
  • Can not be explained by 4 mechanisms

1: Cornelis et al..: Antimony leaching from MSWI bottom ash: Modelling of the effect of pH and carbonation. Waste Management 32, 278-286 (2012)

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Additional tests

  • Explain Sb leaching from untreated BA after carbonation
  • Leaching behavior similar to Cu leaching
  • Sb leaching also influenced by organic acids?
  • Sb known to form complexes with organic acids3
  • Heat treatment (400°C, 30 min)
  • Addition of activated carbon

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pH

4 6 8 10 12 14

Cu leached (mg/kg)

1 10 pH dependent leaching After carbonation

pH

4 6 8 10 12 14

Sb leached (mg/kg)

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 pH dependent leaching After carbonation

Sb Cu

3: Steely et al.: An investigation of inorganic antimony species and antimony associated with soil humic acid molar mass fractions in contaminated soils. Environmental Pollution 148, 590-598 (2007)

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Leaching behavior after heat treatment and AC addition

  • Behavior similar to Cu
  • AC addition: adsorption of complexes on AC
  • Heat treatment: decarboxylation of organic acids
  • Carbonation: adsorption of organo-metallic complexes4?

pH

4 6 8 10 12 14

Cu leached (mg/kg)

0.01 0.1 1 10 pH dependent leaching After carbonation Activated carbon Heating pH 4 6 8 10 12 14 Sb leached (mg/kg) 0.0 0.2 0.4 0.6 0.8 1.0 1.2

pH dependent Carbonation Activated carbon Heating

Additional tests

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Sb Cu

4: Arickx et al..: Effect of carbonation on the leaching of organic carbon and of copper from MSWI bottom ash. Waste Management 30, 1296-1302 (2010)

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Conclusions

  • Sb leaching from MSWI BA can be reduced by addition of

chemical compounds and Ca- and Fe-containing industrial residues

  • Effect of addition endures in middle-long and long term

leaching experiments

  • More insight is gained in mechanisms governing Sb

leaching from MSWI BA:

  • Plausible that organic matter plays a role
  • Influence needs to be further investigated

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Thank you!

Bram.verbinnen@kuleuven.be