Coal Based Sponge Iron

Coal based Sponge Iron

Coal-Based Process:

·         This process utilizes non-coking coal as reducing agent along with lumpy rich grade iron ore.

·         The reduction is carried out in an inclined horizontal rotary kiln, which rotates at a predetermined speed. A temperature profile ranging from 800-1050 degree centigrade is maintained along the length of the kiln at different zones and as the material flows down due to gravity the ore is reduced.

·         The hot reduced sponge iron along with semi-burnt coal, discharged from kiln is cooled in water-cooled cylindrical rotary cooler to a temperature of 100–200 degree centigrade.

·         The discharge from cooler consisting of sponge iron, char other contaminations are passed on through magnetic separators so that sponge iron can be separated from other impurities.

·         Later the sponge iron is screened into two size fractions i.e. –3 mm & +3 mm. +3 mm fraction directly goes for usage, -3 mm fraction can be either used directly where ever it is possible or is to be briquetted by using molasses and hydrated lime as binders.


CHEMICAL COMPOSITION:

Constituent

%

Chemical Composition

 

Total iron

65 - 67 %

Sio2 + al2 o3

2 - 3 %

Cao + mgo

0.5 - 1 %

Sulphur

0.02 % max.

Phosphorous

0.04 % max.

Physical Composition

 

Size

5 - 20 mm

Shatter Index

+ 95 %

Tumbler Index

+ 88 %

Abrasion Index

+ 5 % max

Reducibility Index

+ 94 %

Thermal Degradation Index

5 %

»  Chemical and Physical Composition of Iron Ore


»  Typical Chemical Analysis of Coal

Constituent

%

Moisture

8 % max

Total Iron

27 - 30 %

Ash

23 -25 %

Fixed Carbon

+ 40 %

Size

0 - 20 %

Ash Softening Point

1250 deg cent

Calorific Value

5200 k . Cals / mole

Reactivity

2.2 co / gm . Deg c


»  Typical Chemical Analysis

Cao

40 - 45 %

L.O.I

40 - 45 %

Insolubles

5 - 7 %

Size

0.5 - 4 mm


»  Typical Analysis of Sponge Iron Produced in Coal Based Process

Total Iron

91 - 93 %

Metallic Iron

80 - 84 %

Metallisation

90 - 92 %

Gangue

3 - 4 %

Carbon

0.25 %

Sulphur

0.02 - 0.03 %

Phosphorous

0.035 - 0.05 %