just for undarstanding

1. Raw materials for Iron making
• Raw material required for iron making are:
– Iron ore, including sinter , pellet etc.
– Coking coal or coke
– Pulverized coal ( by tuyere)
– Limestone
– Air
Iron ore
• Iron constitutes about 4.6 % of earth crust.
• Most widely distributed and abundant element in nature
• It is not generally found in native state.

2. Classification of Iron Ores
• Iron ores are classified in terms of their appearance, nature of
gangue content associate with it and based on texture.
• In terms of appearance:
– Hematite Red ore
– Magnetite Black ore
– Limonite Brown ore
– Carbonate Grey or whitish ore
• In terms of gangue content associate with ore:
• Siliceous ore predominantly silica
• Aluminous Largely alumina
• calcarious predominantly lime
• Bituminoius large amount of coaly matter
• Titaniferous large amount of Ilmenite (FeO.TiO2)

3. Types of Iron Ores
• Magnetite Ores: These ores are broadly classified into
three categories- sedimentary metamorphic, contact
metamorphic and magmatic.
 Sedimentary metamorphic: usually fine-grained and
texture may be banded.
Ores of this generally contains iron carbonates and
silicates.
 Gangue is mostly quartz and S, P are generally low.
 Contact metasomatic: occurs in grains of different sizes
and the amount of sulphides of iron, cu and Zn can be
high.
 considerable amount of CaO is present with siliceous
gangue.
 Magmatic: differs widely in grain size and composition.
P content is also generally high.

4. • Hematite ores: These are usually of the sedimentary-
metamorphic type.
• Due to the differences in condition of formation of
the metamorphic processes the granulometry,
structure and the iron content of these ores very
considerably.
• The S and P contents of hematite ores are usually low.
• The gangue mainly contains SiO2 but Al2O3 can also
be appreciable.
• Siderites (Spathic ores): These are carbonate type of
ores
• Siderites are prone to oxidation and the ore often
contains hydroxides, these ores bodies are covered by
siderite-limonite-hematite cap.

5. • Titanomagnetitites: These are complex ores.
• The main ore mineral is magnetite with titanium
present as ilmenite.
• The composition varies considerably and may contain
60-70 % magnetite and 20-27 % ilmenite.
• Lateritites: contains 50-60 % iron in the form o f
hydroxides and a high proportion of Al2O3.
• Contains impurities like Cr, Ni, CO etc.
• These ores are difficult to process and hence still
largely remain unused.

6. Structure and texture of Iron ores
• The presence or distribution of mineral content in the
ore depends on geological (area), metamorphic
(transformation due to heat and pressure) and
geochemical ( chemical composition of the earth)
influences which the ore body has undergone.
• The pattern of the mineral content in the ore, will
have a bearing on the course which ore preparation
should follow and on the behavior of the ore in the
blast furnace.

7. Classification of ores based on texture
• Oolitic ores: contains (45 - 49 % Fe), Oolitic iron ores are a
distinctive subset of iron ore deposits, and are characterized by
their spherical grains composed of concentric layers containing
goethite, limonite and quartz and a minor amount of hematite
along with impurity elements such as Si and P.
BSE image of oolitic iron ores

8. • Lateritic ores: These are formed by surface action at the
expense of underlying rock rich in iron and consist of iron
hydroxides, alumina hydroxides and other minerals.
• Forms in hot and wet tropical areas
• Powdery ores:
• These can not be charged as such in the furnace. It must be
agglomerated before charging

9. • Banded ores: These are characterized by alternate bands
usually a few mm thick to several cms.
• In this some bands may have predominance of iron minerals
while other may have predominance of quartz and silicates.
• All banded ores are easy to beneficiate.
• These ores are exists in different types based on thickness of
banding, grain size, degree of liberation, constituent minerals.

10. • Hard massive ores:
• It consist mainly of hematite (> 80 %) with minor amounts of
goethite and limonite.
• The constituents are intergrown into a homogeneous mass showing
no preferential direction except occasionally very slight banding.
• It is a fine grained material and offers high resistance to crushing
and abrasion.
• These ores are difficult to reduce in the blast furnace.
• Soft ores:
• The ore minerals consist mainly of goethite and limonite together
with minor amount of hematite.
• These can be massive but the crystals are more loosely joined
together to somehow a banded structure.
• These are more porous and are liable to produce more fines during
handling.

11. Valuation of Iron ores
• Value of an iron ore deposits depends upon several
factors:
 Richness – Fe content
 Location- geographical & geological
 Composition of gangue- P, Al2O3, S, alkali content
 Treatment and preparation needed for smelting-
Dense ore (crushing or breaking) Fine ores
(agglomeration)
 End use ( Produce in the form of liquid or DRI)