Sponge Iron Consumption against Metallic Steel Scrap

Transcription

1 ISC UDYOG LTD Sponge Iron Consumption against Metallic Steel Scrap In Secondary Steel Making. Presented by Mr. Jitendra Singh, Patron of All India Induction Furnace Association, Mumbai, India

2 I. Introduction We are all aware that, steel sector in India is on a fast track growth with demand for steel growing at nearly 10% rate per year. India s per capita consumption of steel is around 0.07tonnes as compared to 0.14tonnes for the global average. This indicates that there is a lot of potential for increasing the steel consumption in India. In addition to integrated primary steel producers, India is a Unique Country in the world where almost 50% steel is produced from the secondary steel sector which includes Electric Arc Furnace (EAF), Electric Induction Furnace (EIF). Even though Electric Arc Furnaces are not very large in operation, say around 50, whereas there are more than 1300 Induction Furnaces and more than 1800 re-rolling mills in operation. Also, 50% of total crude steel production is contributed by this sector. Therefore, the secondary steel producers are equally important in Indian scenario. The prospect for steel industry in India is very bright. World steel production has already crossed a billion tonnes per annum. In the last one decade, it was China due to which the world steel production increased rapidly and China accounted for 40-45% of the steel production. Now it is the turn of India to increase its steel production to a level of a least 200 Mt/yr in the next decade. Increase in the production of coal based Sponge Iron (DRI) and its conversion to steel accounting is 25-30% of steel production. It is expected that sponge iron production continues to play a leading role in the growth of Indian steel industry. However, due to rising production worldwide, the demand for iron ore is also going to increase both in India and World over. Calibrated lump ore which is already scarce is going to be a weak link in the supply chain for increased production of steel. In the near future, only low grade iron ore fines are going to be available aplenty. With the growth in Steel Making by EIF, today India occupies a unique place of Steel Making by EIF in the World. In the past, India had faced acute shortage of domestic availability of adequate metallic melting scrap. Large quantities of Steel Scrap were being imported individually by each consumer to meet their requirements. With the wide fluctuation of International scrap prices and Currency fluctuations, sometimes import of steel scrap becomes uneconomical. Then came another revolution of domestic production of Sponge Iron as the raw material input to the EIF industry. II. Steel Production by Secondary Steel Sector The last boom in the steel sector has evolved a tremendous growth in the steel making through induction furnace route. Thanks to the high capital cost and a higher gestation period in setting up an Arc furnace route steel complex, the induction furnace population has surpassed the previous decade s installations. It has almost mushroomed in all parts of the country. In fact many benefits the Induction Furnace has had over the Arc furnace, like low capital cost, easy operation, ecofriendly, less skilled manpower requirement and last but not the least the minimum time required to set up such a plant has made it more popular in the mini steel complexes. Today thousands of induction furnace based steel plants are operating in India producing Ingots and Billets for the domestic as well international requirements of long products.

3 III. Sponge Iron (DRI) Production In India: To combat the scrap shortage for EIF industry, Direct Reduced Iron (DRI) started being produced with low capacity kilns of 30 T per Day in the mid-nineties and today there are many DRI plants of 100 T to 500 T per day Capacity in operation. It is no mean achievement, as at present India is one of the World s largest producer of DRI which is entirely consumed by the EIF industry in the country and nothing is exported. The DRI is produced by using natural gas or low grade coal as a fuel or reducing agent to convert iron ore into commonly known Sponge Iron (DRI). Consumption of DRI by EIF Industry ranges from 60 to 80%as an input along with the metallic scrap thus easing the demand of steel scrap. India produces 22 Mil T annually of DRI. With the rising domestic steel demand for the ongoing Infrastructure Projects in India, shortage in availability of steel is envisaged, new production capacities are being added by EIF Industry which is better placed to bridge the shortfall of Constructional Grade Steel. No wonder with the present production of 35 (42%) Mil T of finished Steel by EIF Industry out of 84 Mil T Approx. of total Steel production in India, the present Capacity utilisation of EIF industry is only 85 %. Future growth of Steel Making is un-stoppable and annual Steel production figures are rising in India in spite of global slowdown and financial crunch being faced by most of the developed Countries. India has been highly successful in substituting steel scrap with sponge iron for steel making. Freedom from dependence on coking coal. Availability of non-coking coal and natural gas. Short supply and high price of scrap. Shorter gestation period and lower capital cost of DRI units as compared to Blast Furnace. Eco Friendly Advantage of using waste gas for generation of power Economical integration with downstream facilities for steel making, continuous casting and rolling of finished products. Affordable investment requirement for such mini steel plants, with forward integration of EIF and Rolling Mill. Increasing demand for construction steel can be profitably produced from such mini steel plants. There are two main categories of sponge iron plants, gas based and coal based. At present, the share of coal based sponge iron units in the production of sponge iron is 65%-70% and the balance is by gas based units. This share is likely to increase further because of the restricted availability of gaseous reluctant in India. Basically Sponge Iron manufacturing in India is predominately through coal based Sponge Iron Plants. Setting up such units with less investment, a plant can be set up in just about 8 to 10 months unlike the time taken for a gas based sponge iron plant. The availability of gas is limited to certain areas however coal availability is not a big bottleneck as of now. Although coal based sponge iron has fewer yields as compared to gas based sponge iron its availability is the main reason for such extensive use in steel making. Today it is the main feed material for induction furnace and going to be there for times to come.

4 Process Flow Diagram for Pelletisation + DRI Plant

5 INDIAN DRI PRODUCTION - FINANCIAL YEAR ('1000 Tons) Gas Based ('1000 Tons) Coal Based ('1000 Tons) nd Qtr 2nd Qtr 3nd Qtr 4nd Qtr SPONGE IRON MANUFACTURERS ASSOCIATION INDIAN DRI PRODUCTION - FINANCIAL YEAR ('1000 Tons) 1nd Qtr 2nd Qtr 3nd Qtr 4nd Qtr Total (April- June) (July - Sept) (Oct - Dec) (Jan - Mar) (April - March) Gas Based ('1000 Tons) Coal Based ('1000 Tons) TOTAL A+B Source: SIMA India SEGMENT WISE PRODUCTION AND CAPACITY UTILIZATION VS % Growth A. Gas Based Units - Production ('1000 Tons) Annual Installed Capacity (Lakh Tons) (-) Capacity Utilization (%) B. Coal Based Units - Production ('1000 Tons) Installed Capacity ('1000 Tons) (+) Capacity Utilization (%) Grand Total (A+B) (-) 3.01 Total Capacity (Lakh Tons) Overall Capacity Utilization Source: SIMA India

6 SEGMENT WISE PRODUCTION AND CAPACITY UTILIZATION VS Gas Based Gas Based Units - Production ('1000 Tons) Annual Installed Capacity (Lakh Tons) (Gas Based) Capacity Utilisation (%) (Gas Based)

7 Coal Based Coal Based Units - Production ('1000 Tons) Installed Capacity ('1000 Tons) (Coal Based) Capacity Utilization (%) (Coal Based)

8 IV. Advantages of Sponge Iron: Grain Size of Sponge Iron: Induction furnaces users always prefer to use fines of sponge iron (Coal Based sponge iron in sizes from 2mm to 5mm) than lumps as fines give better yield and hence less power consumption. So good sponge iron manufactures always try to use iron ore in the size of 5mm to 12 mm, which gives better quality sponge iron. Carbon Percentage: The carbon present in the sponge iron has the capacity to reduce the FeO content to Fe. So it is always advisable to keep a watch on the C percentage. Non Magnetic Material: A better magnetic separator will reduce the amount of non magnetic material in the sponge iron which will help in the induction furnace to give better productivity, less power consumption and better lining life. Uniform Chemical Composition V. Disadvantages of Sponge Iron: Yield of Sponge Iron: Yield of sponge iron depends on the metallization percentage. It is nothing but the percentage of the molten metal you get from the sponge iron you have charged in the furnace. Better yield will give lesser power consumption and better productivity. As the slag content in sponge iron plays a vital role. And the power consumption increases drastically with each percentage increase in slag content. As it is not a proportional increase. For example a 2% increase in slag content will increase the power consumption by about 5%, because slag consumes almost 2.5 times more power than metal. It also decreases the lining life of the furnaces. Highly Hygroscopic: DRI absorbs atmospheric moisture which lowers the quality of it. Highly Exothermic: Absorption of moisture generates heat which increases the temperature of DRI during storage, leading to fire and total damage of DRI. Low self life: Storage and transportation is hazardous which leads DRI to have low shelf life between DRI Production and Consumption of DRI. VI. Some of major issues faced by Induction Furnace plants using Sponge Iron: Government of India BIS Quality Control Order: The Secondary Steel sector using DRI as a raw material for the production of structural steel in Induction Furnace are encountering problem in maintaining composition, especially in terms of the phosphorous content. Since Induction Furnace is a melting unit and refining reactions are not generally possible here in order to reduce/control the percentage of Carbon, Phosphorus and Sulphur content which in turn directly affect the quality of steel while making through this route. Moreover, it may be noted that, Marking clause in the BIS Standard for Sponge Iron is missing and hence it is not covered under the Quality Control order which should be incorporated so as to produce quality steel as per BIS.

9 VII. Quality Steel manufactured by EIF: Most of the large Capacity EIF Steel Plants have lately installed process equipments indigenously manufactured like Low cost Dephos, Desulph, Ladle Refining (LRF),Vacuum Degassing (VD), VOD, for making Alloy Steels. The advantages of EIF over Ultra High Power (UHP) Electric Arc Furnaces are its Low Capital cost, Low Operation Cost, Low cost of conversion and it does not require Highly Skilled Man Power. The greatest advantage is a very short start to commissioning time and of course, the return on investment (ROI) is the fastest among all the steel manufacturing processes. VIII. Cost Comparison of Consumption between Sponge Iron and Metallic Scrap Category Cost Comparison of Sponge Iron & Metallic Scrap Rate Delivered at Steel Plants (Rs.) (West Region) Yield (%) Rate Delivered at Steel Plants (Rs.) (West Region) Yield (%) Metallic Scrap HMS I Sponge Iron LUMPS IX. Present and Future prospects of Iron ore supply: Jan 2015 (a) Iron ore is the major raw material for steel industry: It constitutes 4 to 5 percent of the earth s crust, but is not evenly distributed. Iron ore reserves are largely distributed in Australia, Brazil, China and India. India ranks 5 th in terms of iron ore reserves and contributes about 7.6% to world iron ore production. Major deposits of iron ore are located in the states of Jharkhand, Orrisa, Madhya Pradesh, Chhattisgarh, Karnataka and Goa. The Indian Deposits of hematite grade belong to the pre-cambrian iron ore series and are with the banded iron ore formations occurring as massive, laminated, friable and also powdery forms. According to report of Indian Bureau of Mines, most important magnetic deposits are found in Bababudan, Kudremukh, Bellary and Bangarkal areas of Karnatak, Ongole and Guntur districts of Andhra Pradesh and Salem and Tiruvanamalai in North Arcot districts of Tamil Nadu. All the well established iron making processes need iron ore in lumpy form, naturally occurring or agglomerated. However, the mining operation generates large amount of iron ore fines. These are agglomerated into sinter or pellets. While sinter is used exclusively in blast furnaces, pellets and iron ore lumps can be used in all the iron making processes. Thus, the entire quantity of iron ore mined is used for producing iron which is subsequently converted into steel. Though high iron and low gangue content is the desirable characteristics of iron ore, the Blast Furnace (BF) route to steel making accepts iron ores with 60% Fe also. However, the sponge iron manufactures stipulate that iron ore should have Fe 65% minimum and silica and alumina together 3.5% maximum. This specification is made sometimes made more stringent, keeping in mind the economics of steel making, where sponge iron is used to substitute steel scrap.

10 (b) Beneficiation of low grade iron ore: India has been endowed with rich iron ore which could be directly used for steel making without any enrichment. India has been sharing this wealth liberally with other countries too. This resulted in higher and faster depletion of better grades of iron ore. The beneficiation of low grade (about 34% iron) hematite-magnetite mix from Kudremukh deposits to a concentrate having iron content above 65% on a large scale is the success story of Kudremukh Iron Ore Company Limited for last three decades. Use of Pellets to manufacture sponge iron: Almost all the coal based sponge iron plants use iron ore lumps. The requirement is generally 1.8 t/t of sponge iron. This high requirement is mainly due to the fines generated in handling the purchased ore from the source to the plant. Use of high ash indigenous coal not only raises the coal requirement to 1.4 t/t, but leads to kiln accretions. This reduces the kiln campaign length and increases ore fines lost. The pellet consumption would be about 1.45 t/t. requirement of low ash imported coal will be about 0.8 t/t. further, the production from the kiln is expected to increase by 25% to 30%. Lump ore and Indigenous coal Lump Ore Indigenous Coal 1.8 t/t 1.4 t/t It is noteworthy that many iron ore mine owners are operating sponge iron plants too. For them, the profit margin will still be higher, while using pellets, if they have a captive pe4lletising plant. X. Upcoming Technological Developments In Steel Making By EIF Better furnace feeding system Better Scrap Management High Speed Caster to cast at speeds of 4 to 4.5 M/min/strand Automatic Mould Level Controller for high casting speeds Electromagnetic stirrer to achieve uniform temperature and chemical composition Better man management system Automation in Billet Cutting system High speed Rolling Mills with PLC based Automation XI. Conclusion: In order to meet the rising demand of iron ore for the production of sponge iron in India, it is suggested that low grade iron ore be beneficiated and agglomerated into pellets in mini pellet plants. The comparison of cost implication of pellet usage for the production of sponge iron is made to current practice of using calibrated iron ore. The World at present is passing through considerable technological reforms in regard to up grading Economic Steel manufacturing process, with depleting natural resources like Iron Ore, Coal, Lime Stone and fossil fuels. The National GDP of a country is largely dependent with a co relation on the per Capita Steel Consumption and the domestic Steel prices have a great impact on the Inflation rate of the country.

11 Thank You!!