Pollution in Coal Based
Summer Internship Project, 2012
DRI, or directly reduced iron is a
method of producing solid iron from
Iron from iron ore can be
• In solid form
In solid form, iron ore can
1. DRI produced in coal
2. HBI produced in gas
3. DRI does not need
coking coal at all.
• Or in molten form
In molten form iron can
be produced in the
1. Blast Furnace, needs
2. Corex , can use
significant quantities of
non coking coal but
cannot do away with it
DRI is preferred in India because of
1. Small scale of production.
2. Access to iron ore.
3. Paucity of coking coal in India.
Between 2004-05 and 2009-10, the DRI
production in India has increased by 24% as
compared to only 8% for steel. For steel
produced through the coking coal route, the
production growth is only 5.5%.
• Source: JPC ,2011.
In India, 27% of all steel is produced
through coal DRI
And 7% of all steel is produced through Gas DRI
And 20% is through the scrap route.
54% OF INDIAN STEEL IS THROUGH THE
NON BLAST FURNACE ROUTE.
SOURCE: JPC, 2012.
This means that the DRI segment is a vital constituency of the steel
India is the world’s largest producer
India produced 28 million tonnes of DRI in 2010
as against 57 million tonnes of global
Source: World Steel Association, 2012.
locally; being unstable
in composition, DRI
cannot be exported
out or transported
over long distances.
Factories are located
close to raw material
No wonder then most DRI
plants are located in Odisha,
West Bengal and Karnataka
Since they are rich
in iron ore and
Source: CSE, 2012.
the rotary kiln
Rotary kiln= 2.5% Slopeand 0.47 rpm speed
where coal is
Solid iron and
and hot air is
Paths of Iron and Gas
1. Raw material yard
2. Crusher, screener
3. Rotary kiln
5. Cooler discharge
6. Product separator
7. Stock house
8. Loading points
Reactant Gas route
1. Rotary kiln discharge or
2. Gas Conditioning tower
3. After Burn Chamber
4. Gas cleaning plant
5. Dust settling chamber
6. Waste Heat Recovery
Input Output In DRI Plants
per tonne of DRI
Matter Input Output
Solids Iron Ore 6-20 mm : 1500 kg
Coal 0-3 mm : 300 kg
Coal 3-15 mm: 700 kg
Limestone: 0-3 mm: 75 kg
Sponge Iron +3 mm: 790 kg
Sponge Iron 1-3 mm: 210 kgs
Sponge Iron -1 mm: 50 kg
Char +3mm :30 kg
Char 1-3mm: 75 kg
Char -1mm:195 kg
Air 6000 Nm3 5000 Nm3
Energy in Gcal
= 10 (9)
Coal = 6 Char = 1.15
Sponge Iron =1.7
Waste Heat Recovered = 2.25
Unaccounted radioactive = 0.6
Source: http://www.newagepublishers.com/samplechapter/001741.pdf 13
DRI is a polluting
Air, water, solid
mainly PM, SO2, NOX
and CO abound the
Garbage Factor for a tonne of sponge
INPUT (in Tonnes) OUTPUT (in Tonnes)
1.6-1.75 Iron Ore 1.8-2 Carbon Dioxide
1.2-1.5 Coal 0.25 Dust
0.035-0. 5 Dolomite 0.29 Coal Char
1.5-2 Water 0.02 Kiln accretions
0.2 Sulfur Dioxide with water vapour
Source: Down to Earth, September 16,2006.
Sources of Air Pollution
1. Combustion of coal in the
preheating zone, kiln
2. Oxidation of iron ore in the
process zone, kiln
3. Flue gas from the kiln
through the upper end.
4. Dust of char, unburnt lime,
sulphur, alumina and others
through the discharge end.
5. Flue gas through the cap of
the After Burn Chamber.
6. Particulate matter from ESP
1. Raw material handling and
2. Recuperator (in lieu of
3. Discharge end and cooler
4. Product separator.
5. Work area of plant.
Dust Collection Centers
Source: CSE 2008
Raw material storage yard Stock house
Coal is crushed for charging as powder Coal Crusher
Iron ore is crushed to fit 5 to 16 mm size Iron crusher
Raw materials sent to plants Transfer points
Sponge iron is cooled by spraying water Cooler discharge
Sponge iron rests before screening and separation Intermediate bin
Sponge iron is separated from char Product separation
Product is stocked Product house
Norms of Air Pollution
Source: CPCB, 2010.
• 100 mg/Nm3 for CPCB.
• Lower at 86 mg/Nm3 for
Karnataka, 69mg/Nm3 for
• 2 mg/Nm3
Sources of water consumption and
1. Rotary kiln cooler.
2. Cooler discharge.
3. Gas Cooling
Water is circulating water
in the sense the water
which is used to cool the
kilns is again used to cool
the coolers of solid
discharge and flue gas.
Make up water is kept in
1. Cooler discharge contains
solid waste particle.
2. Gas coolers also contain solid
3. Some sulphides are mixed
irretrievably into water.
4. Water is sprayed on dust
while disposing it off in
5. Water in gas scrubbing may
contain PAH compounds.
Water Requirement in m3/tonne DRI
Purpose Water in m3/tonne DRI Nature of water
Cooling 1.32 Circulating and non contact
ABC 0.48 Direct and contact
Dust suppression 0.30 Direct and contact
Wet Scrubber 0.78 Direct and contact
Total Contact 1.54 To be recycled
Total Circulating 1.32 To be made up
Source: CSE, 2008
707 kgs/ tonne of DRI is solid waste.
from DRI is wet
dust in the
form of sludge
And is mostly
allowed to drain
out into rivers,
Solid waste in DRI Plants
Source CSE, June 2012
Dust Due to Source Percentage
of Total Dust
Char Dust Incomplete combustion.
Gangue and stony elements.
Rotary kiln, Recuperator 42%
ESP Dust Ash in coal, incomplete waste
recovery and gas cleaning.
Stack connected to ESP 24%
Impurities in raw materials,
incomplete combustion of
coal, poor oxidation of ore.
Stack connected to Gas Cleaning
Plant, sometimes the Waste
Heat Recovery Boiler.
Due to physical fall of
Ambient spillage, bag filter 15%
ABC Dust Poor waste heat recovery ABC Cap 5%
Kiln accretions Poor quality coal, non
preheated material, over
oxidation of iron ore due to
presence of sulphur.
Stack connected to kiln 11%
Standard Norms for discharged effluents.
Source: CPCB, 2008.
PARAMETER PERMISSIBLE LIMIT
pH 6.5 ~ 8.5
COD (mg/L) 250
BOD (mg/L) 30
O & G (mg/L) 10
Flouride (mg/L) 5
Iron (mg/L) 3
Total Chromium (mg/L) 2
TSS (mg/L) 100
Cyanide (mg/L) 0.2
Phenolic Compounds (mg/L) 1
Sulphide (mg/L) 2 24
Pollution from the sponge iron
industries is the core reason why
communities rise in arms against this
Various CSE Reports of 2008 inform us
1. In Odisha, women from the Bonai Vana Suraksha Committee
marched up to the District Collector with samples of soil,
water and grain to protest against sponge iron plants.
2. Similar protests in Keonjhar and Sundargarh.
3. In Chhattisgarh, popular protests led to closure of offending
units and discovery of illegal operators.
4. Public protests in Chhatisgarh were around a sudden
increase in respiratory diseases and skin allergies.
5. In Andhra Pradesh people filed cases in courts and obtained
compensation for lost kharif crops.
6. In Karnataka, there is an ongoing protest in Bellary against
sponge iron industries.
Blast Furnace vs. DRI
BF must be taken together with
Coke Ovens and Sinter Plants
• Raw material consumption
in tonnes per tonne of iron
• Thermal Energy
Consumption = 0.4 ( C0)
+0.5 (Sinter/Pellet) + 4.5
(BF) = 5.4 Gcal/ tonne of
• Pollution Norms = 50 ( CO) +
100 (Sinter/Pellet) + 150
(BF) = 300 mg/Nm3
Coal based DRI
• Raw material consumption
in tonnes per tonne of iron
• Thermal Energy
Consumption = 7.5Gcal/
• Pollution Norms = 100
Blast furnaces have higher stack
heights due to larger volume
DRI have lower stack due to smaller
volumes and hence pollution impact
Interestingly, Coal DRI is one third as much polluting as
the Blast Furnace
Raising the stack height might actually help.
Features of sample
1. Nearly 95% of sponge iron units in West Bengal have
2. All plants are declared as red hot.
3. Plants occur in clusters like Durgapur, Jamuria and
others in Burdwan; in Bankura, Purulia, Haldia in East
Midnapore and in West Midnapore.
4. All plants had run for 720 hours from the last
5. All plants are coal based DRI, using SL/RN Process.
6. Sampling was done for 25 to 30 minutes.
1. Size is not related to flouting of norms. Lower stack heights are not
related to pollution.
2. Commonest source of pollution is the kiln area due to combustion and
carbonization faults. This is due to poor quality of raw materials.
3. Due to poor combustion, thermal efficiency is low and heat exchange is
4. The existence of pollution control equipment does not guarantee clean
operations. Poor raw material quality may not permit the proper
running of facilities.
5. Sulphides lead to higher temperature of flue gas.
6. High CO2 interferes in nitrogen cycle leading to high Nox in emissions.
7. Sludge is not controlled because of poor commercial reuse value.
8. Char is generated due to low quality of coal.
CSE Study, West Bengal Sponge Iron
Industry Clusters November 2011
1. WBPCB fails to control pollution. Irregular monitoring. No
2. Factories are repeat and habitual offenders.
3. 92% of inspection reports show abnormally high emissions from
4. 52% fail to meet emission standards.
5. Solid waste management is pathetic.
6. Open storage of raw materials a major issue.
7. Sponge Iron units do not use the pollution control equipment.
West Midnapore, CSE Report
• People’s movement very strong against the
sponge iron industry especially Rashmi Cement/
Ispat in 2009, in West Midnapore.
• Maoist politics emerged solely due to pollution
from sponge iron plants in West Midnapore.
• Pollution Control Board found gross violation on
water, air and solid waste disposal.
• Nagarik Mancha led campaign against Rashmi
• Poor water quality.
• Cattle has stopped grazing.
• Fish inedible.
• Units release pollutants at night from the ABC
cap to avoid inspection.
• Due to water shortage in Jamuria, water is not
used as dust suppressant.
West Bengal Pollution Control Board
• Romita Dutta in Live mint reports that WBPCB
has issued closure notice to 50-60 units out of
the 250 units in West Bengal.
• More than 40% of the units in West Bengal
violate the environment.
• WBPCB claims that night inspection in West
Midnapore was stalled because of Maoists.
• According to WBPCB, air pollution has been
the main problem.
• Kilns with capacity less than 300 tpd should be
• Only integrated plants should be allowed in
• Mandatory standards for material handling,
storage and transportation must be enacted.
• New cluster based standards should be
• Stricter enforcement.
Pollution Control Mechanisms (CSE &
1. Concrete floor in the work area as well as in the material
2. Use of covered trucks and enclosed hoppers to transport
dust and ash.
3. To put a WHRB after the ABC so that the GCC is avoided.
4. Use of ESP instead of the DSC attached to ABC and GCC.
5. Use of magnetic separator at the discharge end.
6. Use of suction hood, bag filter and ESP to cooler
7. Use of raw material i.e. coal preheating to reduce energy
consumption and char.
8. Use of pellets.
Our recommendations for waste
Utilization in DRI
• Char is used as fuel in thermal power plants, industries
and domestic purposes. Coal fines can be mixed with
char fines for fuel.
• Dust and fly ash can be made into bricks.
• Kiln accretions and slag can be used as landfills and road
• Product circuit dust can be used as activated carbon in
edible oil refineries.
• Dolchar and char can be used in cement making.
• Waste Heat is recovered in captive power plants.
• Waste water recycled as make-up water.
Our Recommendations ( Technical)
1. We can set up air quality monitoring stations to track certain specified air
pollutants and toxins. Delhi for example has set up several real time air quality
monitoring stations. The system uses Lidar (light detection and ranging)
technology, which releases and captures a laser beam and measures the before-
after difference to gauge the concentrations of various pollutants in the air.
2. Construction of screen grit chambers to trap the sludge from the effluent
through the introduction of de-salting tables to minimize the quantity of salt in
3. Use of Sonic Horns, a pneumatically actuated device which produces high
pressure acoustic energy or sound waves that are capable of fluidizing powder
that adheres to surfaces in the bag filter. This low frequency vibration provides
an effective means of cleaning the filter. The FES sonic horn helps in the removal
of powder from walls, ceilings, curtain, and filter bags in the dust collector. (
4. Use of Heat pipe Exchangers instead of WHRB, which can transfer up to 100
times more thermal energy than copper, the best known conductor. Heat pipe is
a thermal energy absorbing and transferring system and have no moving parts
and hence require minimum maintenance.
Heat Pipe Exchanger (HPHE) Sonic Horn
Our Recommendations (Legal)
• reduction of green house gas by
implementation of clean development
mechanism (listed by UNDP/GEF) is found to
be depend upon the sincerity and integrity of
the plant owner.
• Granting land on lease basis with ultimate
owner as the community.
• Granting license on term basis to the plant
Our recommendations (Institutional)
1. Sponge iron industries may come under a cooperative
organization for management of waste.
2. Assured quality of raw materials must be provided. Raw
material quality must be declared.
3. Pooled resources to set up common facilities towards
pelletization, or ore beneficiation, transportation and
4. Electronic alarms in the Air monitoring systems (that use
LIDAR technology) might be set up on facilities connected to
a central computer which shuts operations whenever limits
of emission are crossed. This has been CPCB’s
recommendation for a long time.