Addressing the Phosphorus Menace

India produces around one third of its total steel through induction furnace route. The steel producers having Induction Furnaces for melting invariably use high percentage of sponge iron as their major raw material. Sponge iron, which uses iron ore and coal, has high percentage of phosphorus and sulphur, and therefore it has always been a challenge for such steel producers to maintain phosphorus and sulphur within the acceptable norms at competitive operating costs. Probably, due to absence of a suitable equipment and process for reducing phosphorous and sulphur through the induction route, the Bureau of Indian Standards (BIS) had several times postponed implementation of its new norms related with chemical composition of steel, before finally making it mandatory for all steel producers with effect from March 18, 2016.

While we heartily welcome the decision, as it would ensure improved quality of construction for roads, bridges, flyovers, buildings etc, there is a mixed reaction within the steel making fraternity. Nevertheless, no one can deny the fact that good quality steel is always a prerequisite for any civil construction.
As a company providing equipment and services to secondary steel industry for over three decades, Electrotherm has always endeavoured to provide innovative products and processes which can help the steel makers improve the quality of their end products and still remain profitable. Therefore, soon after identifying this gap, we began in- house research, design and development of a suitable equipment and process to meet requirements of these steel producers, which led to the development of revolutionary ERF (Electrotherm Refining Furnace) with ELdFOS® process (Electrotherm Ladle Furnace for Dephosphorization and Desulphurization). As a leading manufacturer of all process machinery for secondary steel making plants and a prominent steel producer, we can say with authority that steel produced through Induction Furnace – Electrotherm Refining Furnace with ELdFOS® process is inferior to none in terms of quality, be it chemical composition or metallurgical parameters or mechanical properties.

Both phosphorus and sulphur are reduced in the ERF under typically opposite conditions. Phosphorus is reduced under basic oxidising atmosphere at temperature closer to liquidus temperature, while sulphur removal happens under basic reducing atmosphere at higher temperature. ERF is capable of reducing both phosphorus and sulphur by up to 70 points (0.07%) each.

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With this development, Induction Furnaces of 8 ton and above capacities can comfortably fall in the league of BIS compliant steel producers as they can install ERF for reducing phosphorus and sulphur by using well established ELdFOS® process. As a matter of fact, a plant through Induction Furnace – ERF route with ELdFOS® process using liquid Pig iron from mini blast furnace and sponge iron can be categorised among ‘Primary’ steel producers, provided it uses no steel scrap in the process, like our steel plant. Obviously, the quality of steel produced through this route, using 100% virgin material, is at par with steel produced through any other route.

ERF with ELdFOS process will enable Induction Furnace users to:

1. Reduce phosphorus and sulphur contents from steel melted in induction furnaces with a minimal additional capital investment and process cost,

2. Meet the newly imposed stringent chemical composition norms by the BIS for long products (TMT rebars / structural section),

3. Migrate from production of FE415 grade in TMT bars towards production of high quality and higher tensile strengths grades like 500D / 550D and thereby relieving primary producers to concentrate on production of flat products, and

4. Produce low alloy / alloy steel grades requiring stringent phosphorus, sulphur and inclusion levels for automotive and forging applications.

Fe 500D grade of steel usually commands a premium of INR 1,200 over and above the price of conventionally available Fe 415 grade (please refer to table). And Fe 550 grade is priced INR 2,500–3,000 over and above the price of Fe 415. With Fe 500D grade gaining more popularity on account of its metallurgical and mechanical properties, it becomes prudent to produce more Fe 500D grade and be the front runner in the market place. On generating awareness and demand of Fe 500D grade of steel, support and assistance is sought from the government and civil engineers & architects’ association that can bring about a change in the entire scenario.

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We firmly believe that Electrotherm Refining Furnace with ELdFOS ® process has the potential not only to change the way steel is produced through induction furnace route but also to change the perception about the quality of steel produced through this route.

Source: Steel 360 Magazine (April 16 Issue)