The steel industry is one of the most important industries in India. The main environmental issues faced by Steel Industry are: Air emissions Wastewater Solid Waste

2. “
“Water and air,the two essential fluids on
which all life depends,have become global
garbage cans”.
-Jacques-Yves-Cousteau
2

3. AIM
INDUSTRIAL WASTE
TREATMENT AND DISPOSAL
IN STEEL MANUFACTURING
INDUSTRY

4. INTRODUCTION
The steel industry is one of the most
important industries in India. Mainly
there are two major processes for
making steel, one being basic oxygen
steelmaking and electric arc furnace.
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5. 5

6. 1.
The production
process of steel
Let’s understand the basic
processes involved.

7. Major sources
for steel
production
IRON ORE COAL
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8. 8
Integrated Steel Production Processes

9. 9

10. STEEL INDUSTRY PROCESS FLOWCHART
IRON ORE COAL LIMESTONE
COKE OVEN
PLANT
CASTING
IRON
REFINING
BASIC OXYGEN
FURNACE
BLAST
FURNACE

11. Main
environmental
issues faced by
Steel Industry
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12. 12

13. 13
•The operation comprises the following steps: coal charging, heating
/ firing of the chambers, coking, coke pushing, and coke quenching.
•The carbonization process starts immediately after coal charging. Volatile
organic compounds (VOC) are eliminated from the coal, and forms a coke
oven gas.The solid carbon which remains in the oven is the coke.
•Depending on oven width and heating conditions the coking process lasts for
approximately 14 to 24 hours. The coke is pushed out of the oven into a
container by the ram of a pusher machine.The container transports
the hot coke to a quenching tower, where it is cooled by dry quenching which
consists of circulating an inert gas (nitrogen).
COKE OVEN PLANT

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15. 15

16. “BLAST FURNANCE
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•A blast furnace (BF) is an enclosed system into which the raw materials enter
while the products (molten iron and slag) are tapped from the bottom (the hearth).
•The blast furnace is periodically tapped to remove
the molten pig iron and slag from the hearth.

17. 17
BASIC OXYGEN FURNANCE
•The Basic Oxygen Furnace (BOF) comprise the commonly used methods to
convert pig iron produced by BF into steel. Oxygen injection
•oxidizes undesirable impurities contained in the metallic feedstock.The
main elements converted into oxides are carbon, silicon, manganese,
phosphorus, and sulfur.
•The operation of a basic oxygen furnace (BOF) is a batch operation. A
complete cycle consists of the following phases: charging scrap and
molten pig iron; oxygen blowing;
•sampling and temperature recording; and tapping

18. 18
Casting, Rolling, and Finishing
•Further steel processing includes casting, hot rolling, forming, pickling,
cold rolling, wire drawing, and coating. The continuous casting process
bypasses several steps of the conventional ingot process by casting steel
directly into slabs or billets and typically achieves 10 – 12 percent higher
yield.
•Hot steel is transformed in size and shape through a
•series of hot rolling and forming steps to manufacture semi finished and
finished products.

19. WASTE
GENERATED
AIR EMISSIONS
○ PARTICULATE
MATTER (arsenic,
cadmium,
mercury,lead, nickel,
chromium,
zinc,Manganese)
○ NITROGEN OXIDES
○ FUGITIVE
EMISSIONS(COAL
DUST)
○ SULFUR DIOXIDES
○ CARBON
MONOXIDE
○ CHLORIDES
FLUORIDES
○ DIOXINS AND
FURANS
WATER POLLUTANTS
EFFLUENT FROM
VARIOUS
PROCESSES
WHICH CONTAIN
○ SUSPENDED
SOLIDS
○ INCLUDING
HEAVY METALS,
○ PAHS,
○ SULFUR
COMPOUNDS,
○ AND FLUORIDES /
CHLORIDES
○ AMMONIA
○ CYANIDES
○ PHENOLS
SOLID WASTES
GENERATED
○DUST
○METALLIC WASTE
○FURNACE SLAG
○REFRACTORY
WASTE
○COAL DUST
○TAR SLUDGE
○ACIDS
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20. 2.TREATMENT
OF WASTES
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21. WASTE WATER
TREATMENT

22. •Water usage
in steel
industry
•22•Steel plants use a large amount of water for a variety of
usage which includes cooling, dust suppression,
cleaning, temperature control (heat treatment),
transport of waste materials (ash, sludge, and scale
etc.), and other usages.
•Use of large amount of water also generate huge
quantity of waste water which may contain suspended
solids and many dissolved substances and chemicals.
The quality of waste water depends on the process where
the water is used and for the purpose for which it is used.
•The large volumes of process water that come into direct contact with the
raw materials, products, and off gases is required to be treated for reuse of
water, for recycle of the water, or for the removal of pollutants to the levels
fixed by the regulatory authorities prior to its discharge.

23. Major environmental
effects of the untreated
waste waters of the
steel
○ (I) Toxicity To Aquatic Life
○ (Ii) Reduction Of Dissolved Oxygen
○ (Iii) Silting Due To Suspended Solids
○ (Iv) Taste And Odour Problems
○ (V) Temperature Rise Affecting The
Dissolved Oxygen
○ (Vi) Effect On The Aquatic Life
○ (Vii) Formation Of Oil Slicks Due To The
Floating Oil Etc.
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24. Major Wastes
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Suspended solids
 Oil and grease
Phenol
Cyanide
Ammonia
Heavy metals such as
oLead
o Zinc
oChromium,
oNickel.
In addition, there are several organic
compounds

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26. 26

27. 27
Control of suspended solids
Removal of suspended solids from the waste water is
practically necessary for all of the production shops in the steel
plant from coke making to the finishing mills. Solid particulates
become suspended in process water streams during cleaning
and cooling of flue and off-gases, slag granulation, descaling,
roll and product cooling, flume flushing in rolling mills, and
during product rinsing in finishing operations etc
.
The methods which are generally employed for removing
suspended solids are (i) sedimentation, (ii) centrifugal
separation, and (iii) filtration.

28. •28
•Centrifugal separation is a technology which is being used to
remove suspended materials from the water column utilizing
centrifugal forces.
•Multi-media or single media filtration, by either pressure or gravity,
are other methods for the removal of fine suspended particulates
and these are generally applied to the waste waters of the steel
plant. The waste water is passed through a filter media contained in
a container.
•The collected particulate is to be removed periodically from the
filter media by back washing

29. 29
Control of oil and grease
Oil and grease are usually found in waste waters from
continuous casting machines, hot and cold rolling mills,
pickling, electroplating, and coating operations. The oils
originate from equipments, product lubricants and coolants,
hydraulic systems, and preservative coatings applied on the
product during certain processes. Oil and grease are usually
removed from the waste waters by employing several methods
which include skimming, gravity separation, air flotation,
filtration and ultra-filtration. If the oils are insoluble in water,
they are removed from waste water by gravity separation and
skimming.

30. •30
•Skimming can be used on any waste water which contains
ingredients that float to the surface and is normally used to
remove free oil, grease, and soaps. Skimming is often used
with air flotation or clarification to improve removal of both
settling and floating materials.
•Air flotation process is generally used to separate floatable
materials having a density which is close to the density of water
and hence cannot be effectively separated by gravity alone
•Ultra filtration process includes the use of pressure and semi-
permeable polymeric or ceramic membranes to separate
emulsified or colloidal materials suspended in a liquid phase

31. 31
Control of heavy metals
Regulatory authorities normally limits the discharge of heavy
metals from the steel plant process waters from blast furnace
shop, steel melting shop, as well as from pickling, cold rolling,
electroplating, and hot coating operations. The normal method
used for removal of these trace metals is chemical precipitation
followed by clarification or filtration.
Chemical precipitation as a mechanism for removing metals
from waste water is a complex process generally consisting of
two steps namely (i) precipitation of the unwanted metals, and
(ii) removal of the precipitate.

32. 32
Biological treatment
Biological oxidation is the normally used technology for the
treatment of coke oven and by product plant waste waters.
These waste waters contain substantial quantities of phenol,
cyanide, thiocyanate, and ammonia, plus lesser concentrations
of other organic compounds, mainly because of the
condensation from the raw coke-oven gas which contains
these substances.
Biological treatment is a conventional method used for the
treatment of the waste water from the of coke oven and by
product plant before its disposal.

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Sewage treatment
There are two methods to treat waste water in sewage treatment plant.
These are given below.
1. Conventional sewage treatment
2. Ozonation
The conventional sewage treatment involves three stages, which are
called primary, secondary and tertiary treatments.
The primary treatment consists of temporarily holding the sewage in a
still tank where heavy solids can settle to the bottom while oil, grease
and lighter solids float to the surface. The settled and floating materials
are removed and the remaining liquid is discharged or subjected to
secondary treatment. The secondary treatment removes dissolved and
suspended biological matter. Secondary treatment is typically performed
by indigenous, water-borne micro-organisms in a managed habitat

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oSecondary treatment may require a separation process to
remove the micro-organisms from the treated water prior to
discharge or tertiary treatment.
o The tertiary treatment is often defined as anything more than
primary and secondary treatment.
oTreated water is sometimes disinfected chemically or
physically (for example, by lagoons and microfiltration) prior to
discharge or it can be used for the gardening purpose.

35. COVENTIONAL
SEWAGE
TREATMENT
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36. PRELIMINARY
TREATMENTS
○SCREENING
○GRIT CHAMBER
○SKIMMING PROCESS
PRIMARY
TREATMENTS
○SEDIMENTATION
○REMOVAL OF
SUSPENDED SOLIDS
AND ORGANIC WASTE
IF ANY.
SECONDARY
TREATMENTS
○ASP
○TRICKILING FILTER
Methodology
TERITIARY
TREATMENTS
○DE-CHLORINATION
○ION EXCHANGE
○REVERSE OSMOSIS
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37. 37
•In the second method which is the ozonation method, the incoming
raw sewage pass through a bar screen chamber to remove coarse
suspended solids, fibres, plastics etc. and is collected into a septic tank
/ holding tank.
• A sewage transfer pump transfers the raw effluent into a manual self-
cleaning filter, pressure sand filter, and then onward to an ozonator.
Ozone is injected into the raw sewage and mixed in to a contact
chamber / holding tank.
• The ozone oxidizes the organics present in the sewage, thereby
reducing the BOD (biological oxygen demand) / COD (chemical oxygen
demand) levels of the sewage to acceptable limits.
• The ozonated effluent is filtered through a pressure sand filter to
remove trace suspended solids / turbidity, etc. The outlet water can be
reused suitably for gardening, etc.
OZONATION METHOD

38. 38
Terminal treatment
•A common practice in the waste water treatment
within the steel plant is to combine waste waters from
several different types of operations for treatment in a
so-called terminal treatment plant.
•This practice has been particularly successful in the
handling of waste waters from the various finishing
operations.
•These waste waters may typically contain suspended
solids, free and emulsified oils from cold rolling, acids
from pickling rinse waters, and heavy metals from
pickling and coating processes

39. 39
Breakpoint chlorination
•Chlorination is one of the technologies for the treatment of
ammonia, phenols, and free cyanide.
• Chlorine has long been utilized as a biocide in the drinking
water treatment facilities and is known for its strong oxidation
potential.
• When chlorine is added to water, hydrolysis of the chlorine
molecule occurs, creating hypochlorous acid and hypochlorite
ions which together comprise the free available chlorine.
• Alkaline chlorination (at pH greater than 9.5 in the presence
of excess chlorine) is needed for the destruction of free
cyanide.

40. AIR EMISSION
CONTROL

41. AIR EMISSION
CONTROL
41
AIR
POLLUTION
STANDARDS
AIR
POLLUTION
NORMS
AIR
POLLUTION
CONTROL

42. 42
Air Purification techniques
The function of air quality management is checking of emissions. The
control - technology or control measurements describes the apparatus,
processes which reduces air pollution. The emission reduction depends
on the technology or process.
In general the technologies or processes which the reduces the pollution
the best are placed in areas with the largest pollution. The choice of the
control technology depends on the environment, technique, economic
factors and the type of pollutant.
There are 2 types of emissions, i.e. particulate emissions and gaseous
emissions. For these 2 types of emissions there are also 2 types of
emission-reduction techniques, i.e. particulate-purification techniques
and gas purification techniques

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Particulate-Purification techniques
Particulate purification techniques concentrates at catching the
particles which are transmitted by a pollution source. There are
several factors that play a role at selecting a purification
technique.
The characteristics of the particles in the exhaust flow influence
the choice of purification technique.
These characteristics are the particle size, flow of the exhaust
flow, the temperature, the humidity, and several chemical
properties such as explosion limits, acidity, alkality, and
combustibility.
:

44. 44
Sedimentation chamber (Gravity
separator)
 Cyclone separator
 Rotating scrubber
 Venturi scrubber
 Spray chamber
Dry electro filter
 Wet electro filter
 Cloth filter
 Ceramic filter
Absolute filter
Following techniques are applied at purifying particles from a
polluted air flow

45. 45
Gas- Purification techniques
The methods for controlling gaseous pollutants is the use of techniques to
recover or destroy polluting substances. There are 4 commonly used
technologies for gaseous pollutants: absorption, adsorption, condensation,
and combustion (flare). The choice of technology depends on the pollutants
that must be removed, purification efficiency, the characteristics of the
polluted gas flow, and specific characteristics of the place. Absorption,
adsorption, and condensation are recovery techniques whereas combustion
implies the destruction of the pollutant.

46. 46
Condensation
 Cryocondensation
Regenerative adsorption (active carbon, zeolite,
polymere adsorption)
 Dry and semi-dry lime absorption
Gas scrubbing (acid, alkaline scrubber, wet lime
scrubbing, basic oxidating scrubbing, biofilter,
biotricklingfilter and water scrubber)
 Thermic combustion (Recuperative, regenerative
thermic oxidation)
Catalytic combustion (Recuperative, regenerative
catalytic oxidation)
 Flaring
 Foto-oxidation
Ionization Selective non catalytic reduction (SNCR)
Selective catalytic reduction (SCR)
Following techniques apply at purifying pollutants from the
air flow:

47. SOLID WASTE
MANAGEMENT

48. SOLID WASTE
MANAGEMENT
48Steel industry in general, produces large amounts
of solid wastes while processing materials through
its various processes. These solid wastes have
many valuable products, which can be reused if
recovered economically.
One of the major concerns of world steel industry is the
disposal of wastes generated at various stages of
processing. Because of natural drive to be cost-effective,
there is a growing trend of adopting such waste recovery
technologies which convert wastes into wealth, thereby
treating wastes as by-products. This has led to aiming at
development of zero-waste technologies.

49. Various
processes which
generate solid
waste

50. 50Coke making
The main solid wastes generated in the production of metallurgical
coke are coal dust, coke dust, tar sludge and acid sludge. Coal dust is
recycled back through the coal blend. Coal dust can also be recycled
along with coke dust by adding them in the sinter charge mix. Tar
sludge is added to the coal blend to improve its density. Acid sludge
need to be neutralized before its disposal.
Sinter making
Solid wastes generated in the sinter making are dusts and sludges.
Dusts are generated at sinter machine building floors, cyclones and
ESP (Electrostatic precipitator). Sludge is generated at the clarifier of
the water treatment plant. These dusts and sludges are rich in iron
(Fe) and contain good amount of lime (CaO), magnesia (MgO) and
carbon (C). These materials are very good materials for recycling
back in sinter making. These materials are either blended with iron
ore fines or briquetted for recycling

51. 51
Pellet plant
The major solid wastes generated in pellet plant are
dusts and undersized green pellets. Both of these are
recycled back in the pellet feed material.
Blast furnace iron making
Solid wastes generated during the blast furnace (BF)
iron making process are dusts, burden screenings at
the stock house, cast house runner jam, cast house
muck, blast furnace slag, flue dust, GCP dust or
sludge, refractory waste, and hot metal (HM) ladle
skull

52. 52
Continuous casting
Major waste materials generated in the continuous casting
process is continuous casting scale, refractory waste, scrap,
slag and muck. Here also waste materials are generated in
the mixed condition and sorting is needed as the first step for
separating different types of wastes.
Rolling mills
Major solid waste materials generated in rolling mills are mill
scale, refractory waste from reheating furnace, and scrap.
Lime calcining
Solid wastes generated at the calcining plant are limestone
and dolomite screenings, lime dust and lime fines. Lime dust
and lime fines are briquetted and recycled either in sinter
plant or steel melting shop. Limestone and dolomite
screenings are recycled in the sinter plant.

53. 53Solid waste management
Waste management of solid wastes consists of generation,
prevention, characterization, monitoring, treatment, handling,
reuse and residual disposition. It requires a new attitude of the
employees and management. Traditional thinking places all
the responsibility on a few experts who are in charge for it.
The ultimate goal of the management must be the zero
solid waste from the plant. For this follow-up and
continuous improvements are crucial.

54. Thanks!
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