A member of the Anglo American plc group 1 EVALUATION OF IRON ORE SINTERS AND PELLETS FOR BF AND DR USE Presented by: MS Mashao Kumba Iron Ore

A member of the Anglo American plc group 2 OVERVIEW 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)

A member of the Anglo American plc group 3 OVERVIEW List of most popular tests performed: –Corex tests –REAS (Reduktion Erweichung und Abschmelzung) –Drop tests

A member of the Anglo American plc group 4 PHYSICAL PROPERTIES Important properties –Size distribution –Strength –Degradation

A member of the Anglo American plc group 5 PHYSICAL PROPERTIES Screening Transport Blast Furnace Top Middle Shaft 950 °C Bosh 1100 °C Bosh °C Shaft 500 °C

A member of the Anglo American plc group 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

A member of the Anglo American plc group 7 PHYSICAL PROPERTIES Compression Strength –Criterion of acceptance:  250 kg/pellet

A member of the Anglo American plc group 8 PHYSICAL PROPERTIES Characterize material susceptibility to: –Breakage –Degradation

A member of the Anglo American plc group 9 METALLURGICAL PROPERTIES Important properties –Reduction Disintegration –Reducibility –Swelling –Sticking –Softening and melting

A member of the Anglo American plc group 10 METALLURGICAL PROPERTIES Screening Transport Blast Furnace Top Middle Shaft 950 °C Bosh 1100 °C Bosh °C Shaft 500 °C RDI RI &RR REAS & RUL REAS

A member of the Anglo American plc group 11 REDUCTION DISINTEGRATION RDI for blast furnace RDI for Midrex RDI for Corex

A member of the Anglo American plc group 12 REDUCTION DISINTEGRATION Blast Furnace Direct Reduction % mm < 40 % mm < 5 AcceptablePreferred % Max.2 % Metallization91 Min93

A member of the Anglo American plc group 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 ( )°C

A member of the Anglo American plc group 14 REDUCIBILITY Screening Transport Blast Furnace Top Middle Shaft 950 °C Bosh 1100 °C Bosh °C Shaft 500 °C RI & RR

A member of the Anglo American plc group 15 REDUCIBILITY Reducibility Index Relative Reducibility

A member of the Anglo American plc group 16 REDUCIBILITY Reducibility for sinters generally higher –Typical values for sinters ( )%/min –Typical values for pellets ( )%/min Final degree of reduction: –Typical value for sinters (60-70)% –Typical value for pellets (50-60)%

A member of the Anglo American plc group 17 REDUCIBILITY Productivity requires reducible feedstock Reducibility depends on: –Porosity –Surface area –Gas-solid contact

A member of the Anglo American plc group 18 FREE SWELLING INDEX General criterion for acceptance: – Swelling not be higher than (25-30)% –Noted that alkalis promote excessive swelling

A member of the Anglo American plc group 19 FREE SWELLING INDEX Increase in volume which in turn decreases voids in charge –Impedes gas flow –Pressure drop

A member of the Anglo American plc group 20 STICKING INDEX Impact on maximum bustle gas temperature Bustle temperature determines overall productivity

A member of the Anglo American plc group 21 METALLURGICAL PROPERTIES Screening Transport Blast Furnace Top Middle Shaft 950 °C Bosh 1100 °C Bosh °C Shaft 500 °C REAS

A member of the Anglo American plc group 22 REAS Ideal BF conditions Temperature profile increases from ambient to 1600°C in 8hrs Sample subjected to a fixed load

A member of the Anglo American plc group 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

A member of the Anglo American plc group 24 REAS

A member of the Anglo American plc group 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)

A member of the Anglo American plc group 26 PELLET vs. SISHEN 20mm Pellet 20 mm ore Size Range 9 x 16 mm85 % - Min 95% – Pref % Fines5 % Max < 3% Pref. 3.9 % Tumble Strength % mm92 %88 % mm64.4 Hot Load % Metallization98 % Clustering00 Linder % Metallization9195 % < (10) Price $/tonne240205