SPONGE IRON PLANTS IN DURGAPUR

SPONGE IRON PLANTS: A NECESSITY OR JUST ANOTHER                                             MODE  OF   POLLUTION.

In the years to come, India's expanding steel production will be largely driven by sponge iron. But its manufacturing process, based on coal, is highly polluting. The repercussions are already visible near sponge iron factories which have mushroomed in iron ore- and coal-rich areas. People are protesting loudly, and in some cases even violently, while the pollution control agencies look the other way.

Protests are happening because sponge iron is made through a process that is highly polluting and poorly regulated. The Central Pollution Control Board(CPCB) has classified sponge iron as red category industry which denotes its high potential to pollute. The classification means the industry needs strict pollution norms and guidelines and should be monitored and inspected regularly. On both these counts, the regulatory framework fails miserably.

History of sponge iron

Producing sponge iron and then working it was the earliest method used to obtain iron in the Middle East, Egypt, and Europe, where it remained in use until at least the 16th century. There is some evidence that the bloomery method was also used in China, but China had developed blast furnaces to obtain pig iron by 500 BC.

How is it produced?

Direct-reduced iron (DRI), also called sponge iron,is produced from direct reduction of iron ore (in the form of lumps, pellets or fines) by a reducing gas produced from natural gas or coal. The reducing gas is a mixture majority of hydrogen (H₂) and carbon monoxide (CO) which acts as reducing agent. This process of directly reducing the iron ore in solid form by reducing gases is called direct reduction.

The conventional route for making steel consists of sintering or pelletization plants, coke ovens, blast furnaces, and basic oxygen furnaces. Such plants require high capital expenses and raw materials of stringent specifications. Coking coal is needed to make a coke strong enough to support the burden in the blast furnace. Integrated steel plants of less than one million tons annual capacity are generally not economically viable. The coke ovens and sintering plants in an integrated steel plant are polluting and expensive units.

Use of sponge iron

Sponge iron is not useful by itself, but can be processed to create wrought iron. The sponge is removed from the furnace, called a bloomery, and repeatedly beaten with heavy hammers and folded over to remove the slag, oxidise any carbon or carbide and weld the iron together. This treatment usually creates wrought iron with about three percent slag and a fraction of a percent of other impurities. Further treatment may add controlled amounts of carbon, allowing various kinds of heat treatment (e.g. "steeling").

Today, sponge iron is created by reducing iron ore without melting it. This makes for an energy-efficient feedstock for specialty steelmanufacturers which used to rely upon scrap metal.

Problems faced in India due to Sponge Iron industries

The major problems with Indian sponge iron industry are that these are mostly coal-based units. Coal based sponge iron units are found to be extremely polluting. While globally gas based DRI is regarded as cleanest one, in Indian scenario majority of them are coal based. Sponge iron plants are categorized under “red categories3” industries which mean they have higher pollution potentials and cause serious health hazards. During operation it emits huge quantity of smoke containing oxides of sulphur and carbon, un-born carbon and silica particles. Similarly the processes also release extreme heat. The dust problem becomes aggravate when the electrostatic precipitator is not operated. Solid waste disposal is another major problem in sponge iron plants. Char, flue dust, GCP sludge and kiln accretions are the solid wastes generated from DRI plants. Char comprises unburnt carbon, oxides and gangue and is segregated from the product during magnetic separation. The materials deposited on the inner surface of kiln, comprising metallic oxides is called accretion. Flue dust is generated from air pollution control systems like DSC, ESP and Bag Filter. Sludge is generated from the GCP, if the plant is based on wet scrubber for dust treatment. The amount of char fines generated in the sponge iron plants are high because of the non- availability of good grade of coal in our country. The size of char varies in size of 0.5 mm to 3 mm and is thus difficult to handle. Apart from this, it takes a lot of area for disposal. A 100 TPD plants requires 10 acres of land annually for disposal of solid waste. In the absence of land, the industries sometimes are dumping this waste nearer to the crop filed, human settlement and in forest areas.Another problem is sponge iron plants are being established very close to the main city creating more severe impact on the health of human beings living near by it.

It has also been found that even if the sponge iron plants have the necessary pollution monitoring and control devices, there is lack of availability of competent manpower to run these systems. 

Effects on towns like Durgapur

During the years 2001-2007 Durgapur saw the setting up of 10 to 15 middle/ large scale industrial investment in iron and steel manufacturing sector including value added products like sponge iron . The prominent investors in these sectors thus favouring its growth.

Due to all this a clean and green place like Durgapur is getting engulfed in the hands of the deadly disaster called pollution.A place like Durgapur where skies were once blue have now turned black; a place where once trees were more than the number of people has been reduced to nothing more than a industrial and pollution hub.

Maybe in today’s  world we cannot function without industries like these but definitely we can do a lot to stop the pollution caused by them.