Optimized Sponge Iron Making Process [PDF]

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ISO 9001:2000

OPTIMISED SPONGE IRON MAKING PROCESS A.C. Verma – Jt. M.D., SPONGYTECH

The use of high-grade iron ore as well as non-coking coal for manufacture of DRI (Sponge Iron) as an alternative to steel scrap finally received due attention. The first DRI unit in India was commissioned in ’80 by Sponge Iron India Ltd. (SIIL) based on SL/RN process of LURGI with a capacity of 30,000 TPA. TILL Year 1995 DRI was used by electric arc and induction furnaces to the extent of 20-25 per cent, the balance being steel scrap. The sharp increase in the international price of steel scrap and the change in Dollar-Rupee parity have made import of steel scrap an expensive proposition. Therefore, import of scrap was in a declining trend and production of DRI increased steadily. In such a situation, the consumers of DRI have found indigenous ways to enhance the usage of DRI with appropriate feeding system to the furnace. While the induction furnace units are presently using up-to 70 % DRI, the EAF units have been using DRI to the extent of 75-80%. In other words, overall DRI has now become the major ingredient with steel scrap in steel making in India especially with the secondary producers

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ISO 9001:2000

Production of sponge iron in India has increased mainly because of expansion of coal based units. The present installed capacities of coal based sponge iron plants in India and segment wise production trend has been tabulated below for the better compression:(A)

INSTALLED CAPACITY Range of installed capacity in tonnes per annum

No. of units

0 – 30,000 30,000 – 60,000 60,000 – 1,00,000 1,00,000 – 2,50,000 more than 2,50,000 (B)

90 47 35 40 15

PRODUCTION TREND The Segment wise Iron & Steel production trend Segment

2001-02

02-03

03-04

04-05

05-06

06-07

Pig Iron

4.07

5.28

3.76

3.23

4.69

4.96

Sponge Iron Coal Based: 64.06% Gas Based: 35.94%

5.44

6.91

8.08

10.30

12.65

15.34

The Segment wise (Non Alloy) production trend ITEM

95-96

2000-01

03-04

04-05

05-06

NON-FLATS

10.99

12.48

15.14

15.88

17.78

FLATS

10.41

16.79

21.82

24.18

26.76

FINISHED STEEL

21.19

29.27

36.96

40.05

44.54

The paradigm shift in the segment wise production can be observed in the table above. India’s Integration with the External Markets:Because of the high level of protectionism, until recently, the volume of foreign trade relative to the size and diversity of the Indian economy has been low. In addition, there has been a persistent trade deficit, caused by imports of oil, Raw Materials, Consumer goods,

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ISO 9001:2000

Jewels, Chemicals and fertilizers. Exports of Iron & Steel products became almost as an excess or residue of domestic demand. But the situation has now been changed Indian steel is integrating with the external market and has become globally competitive. The facts are represented vividly in the following table:Table - 1 INDIA’S INTEGRATION TO EXTERNAL MARKETS: ALLOYS + Non-Alloy (1) YEAR

PRODUCTION

EXPORTS

EX% PRODUCTION

2001-02

31625

2829.2

8.9

03-04

39243

5891

15.0

04-05

42326

4966

11.7

05-06

46822

5189.1

11.1

06-07

49350

4750

9.6

Table - 2 INDIA’S INTEGRATION TO EXTERNAL MARKETS: Pig Iron

YEAR

PRODUCTION

EXPORTS

EX% PRODUCTION

2001-02

4071

312

7.7

02-03

5285

629

11.9

03-04

3764

518

13.8

04-05

3228

393

12.2

05-06

4695

440

9.4

Source: Ministry of Steel Government of India.

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ISO 9001:2000

DEMAND The growth of sponge iron sector has been phenomenal during the last 16 years in terms of both capacity and production. Installed capacity has increased from approx. 1.5 MTPA in 1990-91 to a current level of approx. 18.05 MTPA, while the production has grown from 0.9 MT 1990-91 to approx. 15.34 MT in 2006-07. However, the non-availability of natural gas in requisite amounts and the nonavailability of non-coking coal of required quantity and quality continue to be a problem for the gas-based plants.

QTY IN MILLION TONS

APPARENT STEEL CONSUMPTION IN INDIA 50 40 30 20 10 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 INDIA

22.6

23.5

25

26.5

27.4

28.9

31.2

33.3

36.7

40

Year

QTY IN MILLION TONS

PRODUCTION OF PIG IRON & CRUDE STEEL IN INDIA 50 40 30 20 10 PIG IRON CRUDE STEEL

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

21.1

20.2

20.1

21.3

21.9

24.3

26.6

25.1

27.1

28.3

24.4

23.5

24.3

26.9

27.3

28.8

31.8

32.6

40.9

44.0

Year

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ISO 9001:2000

DRI (Sponge Iron) is mainly consumed by the electric furnace units along with steel scrap as raw materials. Indian Steel Industry - Strengths:-

 A large Population Base…..over 1 billion heads  A booming middle Class over 100 million heads  Paradigm shift in consumer spending  Booming Housing sector  Strong and organised money market/Banking system  Skilled Labour and large pool of technical and managerial work force

 Large infrastructure projects(Highways / Expressways, Bridges, Airports / Ports / Railways)

 Low cost and efficient Labour force  Enhanced Energy Sector—by 2007-12 67,000 MW of Power  Strongly globalised and emerging global competitive industry  Strong DRI base, Highest Producer of Sponge Iron / DRI  Regional dispersal of merchant rolling mills The production of finished steel during 2006-07 has been 49.35 million tonnes for which 27 million tonnes of steel scrap/DRI/HBI was consumed. Considering the present charge mix, trend of export, the demand of DRI during 2007-08, Steel industry has a derived demand. It derives its strength for growth and development largely from the growth and development of the sectors having higher intensity of steel consumption. India has made significant investment in such sectors during the last two five year plan periods. The current five year plan (11th Plan: 2007-08 to 2011-12) also envisages higher investment.

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ISO 9001:2000

Investment pattern in Steel sectors, the back seat driver Vibrant Economy-expenditure Pattern during last two – V, year plans (Us $ Bn.)

Area

IX Plan

X Plan Growth (%)

Airports

0.6

0.9

56.7

Irrigation

7.6

19.3

152.9

Ports

0.5

1.1

98.6

Power

7.8

11.7

49.3

Railways

4.3

5.6

30.6

Roads

12.1

19

57.4

Telecom

1.8

1.9

8.6

Tourism

0.1

0.35

392.4

Urban Infrastr.

7.8

18.5

135.4

Total

42.6

78.5

83.6

 Steel being a capital intensive sector, public sector played a dominant role in pre liberalized era Situation has now been changed. Private sector has taken the lead in the Development and growth of this sector.  Distribution of share of public & private sector Production: 2006-07 (49.6 mlt)

RINL 7%

SAIL 25% Private Sector 68%

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ISO 9001:2000

Some weaknesses of the Indian Steel sector:1.

There is no denying the fact that new technologies can lead to higher productivity but the annual accounts of the steel companies reveal a very low level of expenditure on R&D aspect.

2.

The problem of poor labor productivity has to be tackled to bring the fruits of low labor cost.

3.

The bottleneck is regard to infrastructure, inadequate transport facilities have to be removed with improvement in the logistic network.

4.

Shortages of coking coal, another bottleneck has to be sorted out with long term negotiations with the supplying countries.

5.

High energy cost is another area that needs to be addressed on priority.

6.

The heat generated from the gas is being used to generate steam. This steam generated, is used for captive power generation with the result that the unit has become a considerable net exporter of electricity, with consequent economic benefits to the overall steel making facility.

The spiraling price of fuel, increasing demand of sponge iron and present market recession has forced the engineers to find out some alternative to reduce the production cost and make the sponge iron producing process cheaper and cheaper besides saving the global warming.  There has been continuous research and development in the field of various types of furnaces in the sector of STEEL, in terms of productivity, efficiencies, quality and environment.

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ISO 9001:2000

 To meet the high rate of production from plant, SPONGY TECH has come out with unique sponge iron making process.  In this process a fuel economizer named ―AAG‖ is suggested to install parallel to ABC on top of the feed chute of sponge iron kiln as shown in Schematic Diagram. The iron ore passes through the fuel economizer and enters into the kiln at temperature of around 7000C, where as the mixture of Coal and Dolomite follows the conventional route. The hot gases, induced from ABC, blown in to iron ore chamber, resulting the exchange of heat from the hot gases while passing through the fuel economizer and rise in temperature of the Iron Ore before entering into the kiln. It is known that heat transfer is directly proportional to the area in contact.  This fuel economizer, iron ore is continuously fed through in-built mechanism and traveling through multi deck platforms cum conveyor and in process, progress towards metallization due to surface area exposed to hot gases, the excellent heat transfer to the extent of 85% efficiency is achieved.  The Iron Oxide Reacts with carbon between 7270C and 11270C – C + O2  CO2 C + CO2  2CO C + H2O  CO + H2 CH4 + CO2  2H2 + 2CO First two reactions tack place in reactor when carbon is oxidized by oxygen of air. The second reaction is known as ―BOUDOUARD RECTION‖. The third reaction tacks place between carbon and water vapor, from the combustion of air or moisture from the raw Materials in the reactor. From the above reaction it is obvious that BOUDOUARD RECTION takes place only when the coal is present hence to avoid this reaction coal is not added in the fuel economizer.

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ISO 9001:2000

 The reduction of iron ore takes place beyond 7270C it is thus heating of iron ore is restricted to 7000C. The preheated iron ore goes into main reduction kiln at about 700 0C and reduction of this preheated Iron Ore literally starts from second zone of main reduction kiln instead of fourth zone, as in case of conventional kiln. Hence retention time of kiln feed is decreased as a result the output rate increases. This results the higher production of sponge iron. The preheating of iron ore in the Fuel economizer with the help of the HOT WASTE GAS coming out from ABC / DRI kiln results not only the saving of coal consumption but also reduction in the global atmospheric temperature rise i.e. the equipment is helping the humanity and thus liable to achieve international carbon credit without loosing the economic advantage. This technology will increase the use of CHEMICAL ENERGY in order to reduce ELECTRICAL ENERGY requirement. Hot gas temperature coming out of ABC

– 10000C

Approx heat available in this hot gas

– 360 Kcal / M3

Approx Heat required to raise the temp. of Iron Ore from ambient to 7000C

– 150 Kcal / Kg

Quantity of hot gas, at 10000C, required to raise the temperature of Iron Ore from ambient to 7000C, considering all losses

– 0.6 M3/Kg of I.O.

This confirms the availability of sufficient heat and quantity of gas for the purpose. Approx resultant temp. of hot gasses from ABC and the fuel economizer

– 9500C

This confirms that along with this fuel economizer WHRB also can be operated to produce power.

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ISO 9001:2000

SPECIAL FEATURE OF SPONGE IRON KILN WITH ―AAG‖ FUEL ECONOMIZER USE OF THIS UNIQUE EQUIPMENT – *

Increases the output of existing kiln to the extent of 20% minimum.

*

Reduces the coal consumption to extent of 4.5% minimum.

*

The retention time in Fuel Economizer can be adjusted to achieve the required temperature.

*

In this mechanism the material is pushed gently and not allowed to tumble.

*

Generation of – 3 mm fines in product is less as the slow heating has been avoided.

*

Requires no additional space to be installed.

*

This equipment can even be added in the existing plant with certain modifications. It requires minimum stoppage of plant to be hooked with existing plant.

*

The system can be adopted without disturbing the power generation system.

*

Pay back period is much less to compensate the investment.

This unique approach has been made to compensate the market shock and improve the environment along with saving the reserve of exhausting non-cooking coal.

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