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

1

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

Presented by: MS Mashao

Kumba Iron Ore


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)


3

OVERVIEW

• List of most popular tests performed:– Corex tests– REAS (Reduktion Erweichung und

Abschmelzung)– Drop tests


4

PHYSICAL PROPERTIES

• Important properties– Size distribution– Strength– Degradation


5

PHYSICAL PROPERTIES

Screening

Transport

Blast Furnace

Top

Middle Shaft 950 °C

Bosh 1100 °C

Bosh +1300 °C

Shaft 500 °C


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

METALLURGICAL PROPERTIES

• Important properties– Reduction Disintegration– Reducibility– Swelling– Sticking– Softening and melting


10


Screening

Transport

Blast Furnace

Top


Bosh 1100 °C

Bosh +1300 °C

Shaft 500 °C

RDI

RI &RR

REAS & RUL

REAS


11

REDUCTION DISINTEGRATION

• RDI for blast furnace• RDI for Midrex• RDI for Corex


12


Blast Furnace

Direct Reduction

% - 3.15 mm < 40

% - 0.5 mm < 5

Acceptable Preferred

% -3.36 5 Max. 2

% Metallization 91 Min 93


13


– 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

REDUCIBILITY

Screening

Transport

Blast Furnace

Top


Bosh 1100 °C

Bosh +1300 °C

Shaft 500 °C

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


Screening

Transport

Blast Furnace

Top


Bosh 1100 °C

Bosh +1300 °C

Shaft 500 °C

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

REAS TEST RESULTS F2040326 RMT2231B

0

200

400

600

800

1000

1200

1400

1600

1800

1 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475

Time (min)

Tem

per

atu

re (

°C);

dP

(m

mH

2);

Dri

p

mas

s (g

); C

-sta

rt (

g/m

in)

0

20

40

60

80

100

120

Com

pac

tion

(%

); R

edu

ctio

n (

%)

F-Temp S-Temp dP Mass C-start Compaction Total reduction


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

Pellet 20 mm ore

Size Range

9 x 16 mm 85 % - Min95% – Pref.

83.5 %

Fines 5 % Max< 3% Pref.

3.9 %

Tumble Strength

% + 6.3 mm 92 % 88

% - 0.5 mm 6 4.4

Hot Load

% Metallization 98 98

% Clustering 0 0

Linder

% Metallization 91 95

% < 3.36 5 2.4 (10)

Price $/tonne 240 205

Documents

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