Pellet and its use in blast furnace

Pellets
akmistrymistry@gmail,com,8895500177,9968605977
Need of
pellet
Effect in
blast
furnace
Benefits of
Pellet Usage

Total ore requirement will be 550 to meet Vision 2030 of MOS(300MnT PA)
Present ore requirement equals 380MnT
Pellet 85 100
Sponge iron 48 80
Steel 110 200
Iron ore production has to keep pace with capacity
increase every year
If supply side is adequate, price in auto correction
mode
Presently, supply o f iron ore is throttled due to
various reasons
Pelletisation with Beneficiation will increase the feeding to Steel Plants
by 15 years to achieve production of 300MnT Steel(500MnT of Iron ore)
Type Proved Probable Remaining
resources
Grand total
Hematite 5982042 2111504 9788551 17882098
Magnetita 15973 5783 10622305 10644061
Total 5998015 2117287 20410856 28526158
Out of total 28.5 billion tonnes of iron ore;around 20% are of high grade,30% of medium
grade & 50% of low grade.
Around 25 to 30 % of low grade fines of grade 45 to 60% Fe being generated every year. These
are continuously lying in dumps in the mining lease hold areas.
[Source: Indian Mineral Year book 2010,Indian Bureau of Mines]
akmistrymistry@gmail.com,8895500177,9968605977

PELLETS IN IRON & STEEL MAKING-how Pellets contribute to
reduction in CO2emmission
• Considering 100 Million Tonnes of Steel production & 85 Million Tonnes of Pellet
production per year, following CO2 emissions can be reduced per year.
• 1)Mining–As perFIMI,around100 million tonnes of iron ore fines stocks are available in
our country.Existing Iron ore Beneficiation units shall use these fines’dumps,which
inturn reduce further mining & reduction in CO2 emission by
0.09Mil.Tonnes(0.9KgCO2/tX100Mil.Tonnes)
• 2)Pipeline–Around 40MTPA Iron ore slurry is being transported through underground
pipe line from various Beneficiation Plants to respective Pellet Plants.It reduces CO2
emission by 1.14Mil.Tonnes((32.2-3.8)KgCO /tX40Mil.Tonnes)per annum comparing to
2
emission by 1.14Mil.Tonnes((32.2-3.8)KgCO2/tX40Mil.Tonnes)per annum comparing to
road transport.
• 3)Agglomeration–85MTPAIron ore pellet production will reduce CO2 emission by
16.2Mil.Tonnes((220-30)KgCO2/tX85Mil.Tonnes)per annum comparing to sintering
process.
• 4)Iron & SteelMaking–By use of 85MTPA Iron ore pellets for iron & steel making will
reduce CO2 emission by 26.7Mil.Tonnes((1255- 941)KgCO2/tX85Mil.Tonnes)per annum
comparing to the use of sinters.
• In total; around 44 Million Tonnes of CO2 emission per year can be reduced by use of
pellets.
[Source: United States Environmental Protection Agency (US EPA),
Analysis Report, Department of Energy & Climate Change (DECC), Government of UK]

Enviroment and Pellets in Iron & Steel making
• Lower emission rate
• Emissions in sintering process are much higher than compared to
pelletizing process. Decreases the emission rate CO2 by 85%,SOX by
90%,NOx by 20% compared to sinters.
Process SOx(gm/t) NOx(gm/t) CO(Kg/t) CO2(Kg/t) Particulate
matter(gm/t)
sintering 1670 640 38 220 260
sintering 1670 640 38 220 260
Pelletising
hematite
200 500 1 30 80-85
Pelletising
magnetite
100 200 <1 25 125
[Source:ResearchPapers,US Environment Protection Agency & BTGP actual

Non-availability
of calibrated
ore and rising
prices of Iron
ore fines
Most optimum
route for
agglomeration
Utilisationof
low grade
ores/fines/
slimes/ tailings
Superior feed
material
compare to
calibrated lump
ore (CLO)
Pelletisation Plants –Need of the Hour

Facts to know about pellets
Why
pellets
Affordable, high quality
raw materials for iron
making are steadily
decreasing on a global
scale
Fine and Ultra fine iron
ores will command an
ever larger share of iron
ore sales in future
Growing number of iron
and steel producers
increasing proportion of
pellets in burden
Fluctuating prices of iron
ore fines and pellets in
world market can
seriously affect cost
efficient iron making
Pellets preferred over
sinter and lump ore due
to their shape, size,
strength and excellent
metallurgical properties
Pellets are ground
iron ore fines
converted to
spherical shaped
balls Have good
physical properties
for mechanical
transportation over
long distances
Have excellent
Technology uses
the powder that is
• Pellets are small and hard iron ore balls. Their diameter
is usually 10–16 mm. They are hot-bonded in order to
have sufficient mechanical strength.
• Some additives are often used in order to meet blast
furnace specific requirements. Iron ore pellets are
usually bonded with bentonite, which is a clay mineral
Pellets??
Have excellent
metallurgical
properties(similar
or better than lump
iron ore-CLO)
Vital raw material
for all types of
ironmaking
the powder that is
generated during
ore extraction
process,once
considered waste,
usually bonded with bentonite, which is a clay mineral
containing some silica.
• The most common pellet types for iron making purposes
are: acid pellets (B2 < 0.5), basic or fluxed pellets (0.9 <
B2 < 1.3) using limestone or dolomite as an additive, and
olivine pellets using olivine as the fluxing additive.
• In order to produce high quality pellets with good
reducibility and superior softening and melting
properties, certain additives are necessary. The most
common fluxing materials for iron ore pellet production
are limestone (CaCO3), dolomite (Ca,Mg(CO3)2) and
olivine (Mg2SiO4), but sometimes magnesite (MgCO3) is
also used.
• Additives are used not only to enhance slag formation,
but also to improve softening and melting properties and
to enhance the gaseous reduction of the burden

Existing pelletising technology and advantages in iron making

By increasing the pellets from 0 to 28% following effects are observed in the Blast Furnace
The increase in pellet per cent has promoted the uniform distribution of burden
materials and has led to effective utilization of BF gas which has resulted in
improving the gas utilization by 4%.
The cohesive zone where ferrous burden softens and melts is lowered by increasing
the pellet proportion in the burden mixture. The above burden probe temperatures
have sinked at the centre of the BF with high pellet operation, which represents the
lowering of the cohesive zone root.
Under high pellet operation, the position of cohesive zone has greatly affected the
gas flow pattern and has resulted in the improvement in gas utilization. Moreover, it
has enabled the reduction in coke rate by 10 kg/ thm with the increase in the pellet
proportion in the burden mixture.
The improved gas utilization has also eliminated the operational nuances of high
top gas temperature. It is observed that the top gas temperature is reduced by 30 C
when pellet per cent in the burden mixture is increased up to 28%.
The CWI is maintained between 2.2 and 2.4, to ensure improved furnace
performance under high pellet operation. The gas permeability is increased, and it
means the permeability resistance has decreased with the increase in the pellet per
cent in the burden mixture.

Effect of increasing pellet quantity in blast furnace

Changes made on blowing parameters with increasing pellet quantity
and trend of changes made in blast humidity and coal injection rate
with increasing pellet quantity on blowing parameters

Physical and economic attributes of Pellets
shows the average reduction-swelling indices of
the whole eight-pellet
sample consisting of three grades of magnetically
classified olivine pellets and the acid1 pellets as a
function of the average reduction degree under
different reducing conditions.
The figure indicates that sulphur in the reducing
gas results in the smaller volume of the pellets
after reduction, and large amounts of potassium
lead to a larger volume of the pellets after
reduction when compared to the reference
test without additional gases. The largest pellet
swelling was noticed in the “High- K” test, the RSI
value being 10.5 vol-%.

However, normal swelling can be considered advantageous for the reduction process due to the increased porosity of the pellets (Singh & Björkman 2004).
Under certain conditions, for example in the presence of alkalis, the swelling can become excessive. This coincides with the low compression strength of this
structure, with the possibility of generating fines (Geerdes et al. 2015).
Abnormal swelling occurs during the transformation of wüstite to metallic iron in the latter stages of reduction and is generally believed to be caused by the
growth of iron whiskers during reduction of wüstite to metallic iron.
Swelling can be categorized into normal swelling, up to 20% in volume, and abnormal, i.e. catastrophic swelling, which may exceed 400% in volume at worst.
Normal swelling of up to 20 vol-% occurs during the transformation of the pellets from hematite to magnetite in the initial stages of reduction.
Pellets, in contrast to sinter and lump ores, can have the tendency to swell during reduction. Generally a volume increase of over 20%, measured according to
ISO 4698, is seen as critical.
However, normal swelling can be considered advantageous for the reduction process due to the increased porosity of the pellets (Singh & Björkman 2004).
The effect of pellet B4 basicity on swelling. The maximum tolerated amount of swelling is marked with a horizontal dashed line

low temperature degradation and swelling

ADVANTAGES OF USING PELLETS AS A BLAST FURNACE FEED
1) Minimum closure of pores by fusion or slagging, pellets show very good reducibility due to high micro porosity.
2) Spherical (Egg) shaped and small uniform size (10-20 mm) gives ver/ good bed permeability.
3) More accessible surface per unit weight and more iron per unit of furnace volume because of high bulk density 3-3.5 tonnes/m3 larger surface and
increased time of residence per unit weight of iron give better and longer gas/ solid contact and improved heat exchange.
4) High iron content and more uniform chemical composition because of fine grinding. Hence lower flux and fuel requirement in the furnace, which lowers
the slag volume.
5) High softening temperature, 1200° to 13 50°C with narrow range; Dolomitized pellets have a softening temperature about 80°C higher than the
corresponding limy pellets.
6) Heat consumption is much less than that for sintering.
7) High strength-average compression strength is about 150-250 Kg or more for acid pellets.
8) Easy handling, e.g. by pneumatic method.
9) Ideal for direct reduction processes.
10) Acid pellets are stronger than fluxed sinter. Reducibility of fluxed pellets is higher than that of fluxed sinter or acid pellets.
11) Fluxed pellets are more economical than fluxed sinters.
12) Alkali attack on fluxed pellets is less than that on acid pellets.

Benefits in Iron and Steel making Emission control

Revision of the pellet -Facts to optimise fuel in blast furnace
The early softening of the
acid pellet is due to melting
of fayalite at 1205 °C
This could be avoided
by adding MgO or an
appropriate amount of
CaO in relation to the
proportion of SiO2 to
the pelletizing blend.
Another potential
means to prevent
liquid formation would
be to decrease the
SiO2 content in the
iron burden materials

Typical acid and flux pellet properties

• Thanks for your valuable time

Pellet and its use in blast furnace

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