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EVALUATION OF IRON ORE SINTERS AND PELLETS FOR BF AND DR USE

EVALUATION OF IRON ORE SINTERS AND PELLETS FOR BF AND DR USE. Presented by: MS Mashao Kumba Iron Ore. List of most popular tests performed: Tumble Strength (ISO 3271) Crushing Strength (ISO 4700) Swelling Index (ISO 4698) Size range Reducibility (ISO 4695)

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EVALUATION OF IRON ORE SINTERS AND PELLETS FOR BF AND DR USE

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  1. EVALUATION OF IRON ORE SINTERS AND PELLETS FOR BF AND DR USE Presented by: MS Mashao Kumba Iron Ore

  2. List of most popular tests performed: Tumble Strength (ISO 3271) Crushing Strength (ISO 4700) Swelling Index (ISO 4698) Size range Reducibility (ISO 4695) Relative Reducibility (ISO 7215) Reduction Disintegration (ISO 4695) Reduction Disintegration and metallization for DR feedstock (ISO 11257) OVERVIEW

  3. List of most popular tests performed: Corex tests REAS (Reduktion Erweichung und Abschmelzung) Drop tests OVERVIEW

  4. Important properties Size distribution Strength Degradation PHYSICAL PROPERTIES

  5. Transport Screening Blast Furnace Top Shaft 500 °C Middle Shaft 950 °C Bosh 1100 °C Bosh +1300 °C PHYSICAL PROPERTIES

  6. PHYSICAL PROPERTIES • Tumble Strength • Percentage of + 6.3mm fraction gives TI • Percentage of – 0.5mm fraction in gives AI • Criterion of acceptance: • 70% for TI • Less than 5% for AI

  7. PHYSICAL PROPERTIES • Compression Strength • Criterion of acceptance: • 250 kg/pellet

  8. PHYSICAL PROPERTIES • Characterize material susceptibility to: • Breakage • Degradation

  9. Important properties Reduction Disintegration Reducibility Swelling Sticking Softening and melting METALLURGICAL PROPERTIES

  10. Transport Screening Blast Furnace Top Shaft 500 °C Middle Shaft 950 °C Bosh 1100 °C Bosh +1300 °C METALLURGICAL PROPERTIES RDI RI &RR REAS & RUL REAS

  11. REDUCTION DISINTEGRATION • RDI for blast furnace • RDI for Midrex • RDI for Corex

  12. REDUCTION DISINTEGRATION

  13. REDUCTION DISINTEGRATION • Decrease in burden permeability • Poor gas distribution • Scaffolding • Increases fuel consumption • Lower productivity • Increased dust load in off gas • Material more susceptible between (400-600)°C

  14. Transport Screening Blast Furnace Top Shaft 500 °C Middle Shaft 950 °C Bosh 1100 °C Bosh +1300 °C REDUCIBILITY RI & RR

  15. REDUCIBILITY • Reducibility Index • Relative Reducibility

  16. REDUCIBILITY • Reducibility for sinters generally higher • Typical values for sinters (1.1 -1.4)%/min • Typical values for pellets (0.8 -1.4)%/min • Final degree of reduction: • Typical value for sinters (60-70)% • Typical value for pellets (50-60)%

  17. REDUCIBILITY • Productivity requires reducible feedstock • Reducibility depends on: • Porosity • Surface area • Gas-solid contact

  18. FREE SWELLING INDEX • General criterion for acceptance: • Swelling not be higher than (25-30)% • Noted that alkalis promote excessive swelling

  19. FREE SWELLING INDEX • Increase in volume which in turn decreases voids in charge • Impedes gas flow • Pressure drop

  20. STICKING INDEX • Impact on maximum bustle gas temperature • Bustle temperature determines overall productivity

  21. Transport Screening Blast Furnace Top Shaft 500 °C Middle Shaft 950 °C Bosh 1100 °C Bosh +1300 °C METALLURGICAL PROPERTIES REAS REAS

  22. REAS • Ideal BF conditions • Temperature profile increases from ambient to 1600°C in 8hrs • Sample subjected to a fixed load

  23. REAS • Softening temperature • Melting temperature • Dripping temperature • Differential pressure (dP) • Degree of reduction at time and temperature • Compaction at time and temperature • Mass of dripping melt at time

  24. REAS

  25. REAS • General criterion for acceptance: • Cohesive zone should be small but at high temperatures • Relative drip mass at least 70 per cent • Shape of dP curve • Width • Height • Position of peak(s)

  26. PELLET vs. SISHEN 20mm

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