JAES Learning

Electric Furnace - Direct Reduced iron (HBI) - the future of steel

Index:
Introduction on scrap, from what it is obtained, in which sector.
Electric furnace technology utilising scrap.
Electric furnace benefits for the environment.
Future scrap shortage, scrap data sorted by country.
Scrap, what it is, how it is produced, advantages.

Have you ever thought about the destiny of vehicle wreck? For example, what’s the destiny of dismissed military tanks or your cars?

The majority of these vehicles components are composed of steel, resistant and abiding irony material, capable of resisting crashes and corrosion.

In our previous video we showed you steel’s history and its features, the various type of steel existing nowadays and how to produce it. But with this new video we want to show you its most important feature, which is recyclability.

Let’s take our tank as an example, an armoured, blast-resistant vehicle composed mostly of alloy steel plates, as we can see here. From this technical division, we notice that there are many parts made of steel, and the same goes for cars, in which the chassis with its uprights are all made of ultra-high-strength steel.

All these components in different types of steel, once they fall into disuse can easily become material for the production of new steel; that’s when steel scrap comes into play. Scrap steel is nothing more than steel scraps that are used by steel plants using electric furnaces to produce clean steel.

Now let’s talk about the whole steel production chain to better understand the use of steel scrap.

Basically, there are two big categories: steel plants using blast furnaces and steel plants using electricfurnaces.

For the first category of steel plants, blast furnaces use guarantees a wide production of steel thanks to the furnace’s capacity. In fact, this is a complex process which implies raw materials like iron minerals and limestone to be united with coke to obtain cast iron, subsequently becoming steel by using a converter. Moreover, this process creates big amounts of polluting substances, especially CO2, throughout its different stages. The process is very polluting since the beginning: for example, coke plants need to burn high quantities of fossil carbon in order to produce the coke needed. Doing that, they emit enormous quantities of CO2. For this process, steel scrap is only used during the last stage, when it is added to cast iron in the converter in order to increase the steel purity.

For steel plants that use electric furnaces, the process is very different; the material used by these plants is limited to just one, the scrap steel indeed. With graphite electrodes, in presence of an electric arc furnace, they melt the scrap at a temperature of 2000 °C or 3.600 °F with small additions of coal or cast iron to provide with the carbon needed to produce the steel.

This process is much more simpler than the integrated cycle described before, and it also produces fewer pollutants by not using fuel to feed the blast furnace and the converter, and it doesn’t even need coke, which is highly pollutant. The advantages of electric furnaces, in addition to lower emissions, are multiple: lower investment costs, flexibility, for it can employ either large or small furnaces, reduction of the melting process, use of steel scrap, and lastly, the possibility of shutting down the plant if necessary, which is impossible with blast furnaces of the integrated cycle.

Moreover, if the energy used to power the electric furnaces came from renewable sources, such as wind power, the production cycle would be in line with COP21, the climate change convention signed by 177 countries committing to decarbonising the planet.

Unfortunately, steel industry contributes to 24% of industrial CO2 emissions, amounting in 2.8 Gt in 2017. By using steel scrap and replacing old plants with electric arc plants, emissions would be limited: an electric arc plant produces 400 kgCO2/t of steel as opposed to 1700,1800 kgCO2/t produced by blast furnace. Using scrap, combined with electric furnace technology, results in reducing 64% of CO2 in the environment, facilitating not only the production process but also Earth’s health.

Currently, the country that imports most steel scrap is Turkey, with almost 22 million tonnes, but we also find South Korea, India, and even Italy, who imports 5 to 6 million tonnes of scrap per year, used in its 17 electric furnace plants.

If the entire global steel production were to convert to electric furnace technology, a huge amount of steel scrap would be needed, which according to predictions the scrap market would not be able to satisfy. This is precisely where the Direct Reduced iron/ Pre-shredders comes into play!

Direct Reduced iron/ Pre-shredders Iron is a spongy iron, consisting of 85% iron ore, obtained by reducing iron oxide pellets with CO and H2 produced by methane reforming. Direct Reduced iron/ Pre-shredders has a chemical composition similar to cast iron. Generally, this product can replace scrap steel and it guarantees clean steel without tin and copper contamination.

Pre-shredding seems to be the solution to a future scrap famine, but let’s not forget that to produce it, a large amount of natural gas is required to compress and reduce iron pellets. On the other hand, this product allows steel plant to abandon carbon coke as a raw material, and consequently to dismiss coal deposits in plants mineral parks.

We have now come to the end of our overview about steel scrap, a product that will influence the future of global steel industry, helping to sustain our planet ecologically.