Alkali and sulfur balances in the blast furnace

1
Alkali and sulfur balances in the blast furnace

• Mikko Helle
• Åbo Akademi

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Alkali IN and OUT flows (BF1)

• Inputs sinter (incl. pellets), coke, scrap
  (BF1), other
• Outputs slag, dust
• Alkali analysis, daily values, interpolated if
  missing

3
Alkali IN and OUT flows (BF2)

• Inputs sinter (incl. pellets), coke, other
• Outputs slag, dust

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Alkali balance

• Cumulative balances
• Contain errors
• Inaccurate massflows and analysis ? Similar
  trends can be seen

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Alkali input and output

• Filtered sums of in- and outflows
• Explains the drifting in cumulative balances

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Alkali input and output

• Same inputs ? Similar total balances
• Sinter and slag can explain some overall changes

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Removing drift

• Original balance curve (blue) is filtered (red)
• Corrected balance blue-red

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Corrected balances

• Similar behavior can be seen between BF1 BF2
• Errors in analysis of input materials?
• Note the scale, 15t

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Influence of filtering on correction

• Differences can be seen better when using less
  filtering, but real changes should not be
  eliminated

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Sulfur IN and OUT flows (BF1)

• Inputs coke, oil, sinter (incl. pellets), scrap,
  other
• Outputs slag, iron, dust, (gas 40 ppm)

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Sulfur IN and OUT flows (BF2)

• Inputs coke, oil, sinter (incl. pellets), other
  (very little)
• Outputs slag, iron, dust, (gas 100 ppm)

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Sulfur balances

• Cumulative balances
• Drifting can be decreased by playing with the gas
  sulfur content
• Hard to estimate sulfur content in gas
• Correcting with filtering gives same
  information

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Corrected balances

• Drift removed with filtering
• Similarities can be seen between BF1 BF2

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Explaining errors

• Outflow decreases before inflow and in both
  BFs?!?
• Inaccurate sulfur content of oil?

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Oil sulfur content

• Calculating the correct sulfur content of oil
• If every other flow is correct, what should the S
  in oil to be for INOUT
• Filtered values compared with the used one

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Hearth volume and sulfur

• S-rich skull melts in the hearth
• Outflow of S increases and returns to original
  level when skull melting stops

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Future

• Information from balances will be used in efforts
  to explain BF behavior together with information
  on coke properties