Is steel good for the environment?


Watching my grandchildren playing in the woods is always a source of joy. As true Swedes, nature is a part of who we are. But at the same time watching my offspring building tree huts, also wakes the philosopher in me.


What will the future bring for them? As the chairman of a company where steel consumption is crucial to make our wire mesh products, I start wondering is it good for the environment? It raises the question, how can we as a company and myself as an entrepreneur contribute to a more sustainable future?

Is steel sustainable?

Steel production, like all other human activities, affects the environment in a negative way. It is a simple as that. But looking at the entire life cycle of steel products shows that it also possesses many positive qualities. Steel is not consumed just once and then disposed of, it is used over and over again without compromising its quality or strength. Unlike most materials, steel can be "recovered", i.e. its quality and strength can be increased through recycling. For this reason, it is a truly durable material.

Steel is part of the modern environmental and recycling society. It is 100 percent recyclable and always contains recycled materials in its production. If the final steel is not reused, the material can be recycled by remelting. From the period of the 1950s up to the year 2010, the recycling of waste containing steel has increased sharply from 50 to 92 percent. I was unable to find any numbers for the year 2020, but let’s assume the percentage has not decreased.

Steel demand

In the middle of the 19th century, the global annual steel production was about 10,000 tons. Since then, growth has picked up and production has massively increased. Jernkontoret, the Swedish iron and steel producers' association, points out that steel is today the most widely used metallic construction material in the world.


During the pandemic year of 2020, when demand for steel fell sharply in almost the entire world, demand in China still increased further by 10 percent. In 2021, the development was reversed, with demand falling by 1 percent in China while the rest of the world witnessed a strong upward rebound.


Overall, the development in 2021 meant that global demand increased by 4.5 percent and landed at a total of 1,855 Mton, according to the World Steel Associations' (WSA) calculations. Steel consumption increases with each passing year and by 2050, total consumption is estimated at 2,800 million tonnes per year.

The production of steel

In order to produce steel, raw iron materials in the form of iron ore or scrap metal are required together with alloying elements so that the material acquires the desired properties. In other words, steel can be manufactured via two main production routes: ore-based or scrap-based production. In figure 1 below you can see a schematic picture of these production routes:

 Figure 1: Schema of ore and crap based steel productions (Source: Jernkontoret)
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Ore-based production

About 4 percent of the earth's crust consists of the element iron. An insignificant part exists in the form of pure iron. On the other hand, there is plenty of iron which is chemically bonded, in association with other elements such as oxygen and sulphur.


The most abundant elements in the earth’s crust are oxygen, silicon, aluminium and iron. The compound that the iron forms with oxygen is called an oxide and the most abundant oxide formed is called magnetite or hematite, depending on the type of oxide.


For the extraction of metallic iron, the most important ore minerals are magnetite and hematite. Magnetite can be identified by its black streaks, while hematite contains streaks of red. A part of the iron, which is chemically bonded with oxygen, exists in the form of pure iron. On the other hand, there is a large amount of iron which is chemically bonded with oxygen and sulfur. The most abundant elements in the earth’s crust are: oxygen, silicon, aluminium and iron.

 

A rock that contains enough iron for it to be profitable to extract is called iron ore. The ore needs to be enriched because it often consists of more than 40 percent of waste rock. The enrichment takes place directly in the mine by sorting out non-ferrous pieces. After enrichment, a fine-grained product is obtained, so-called sludge. The sludge is transformed by heating to 1250°C creating larger pieces, so-called sinter, or pellets. Sinter / pellets and coke are then loaded into a blast furnace and melted together to form pig iron which has a carbon content of about 4 percent. Coke acts as a fuel for the blast furnace and as a reducing agent, it reduces the oxygen from iron oxides.


After the blast furnace, the pig iron is converted together with about 20 percent scrap to produce steel in a converter. The process is called refreshment and means that, among other things, the carbon content is reduced and that contaminants such as sulfur and phosphorus are removed.


In the final refining process, so-called ladle metallurgy, alloying elements are added and the steel is further purified before it can be cast. Casting means that the liquid steel is poured into molds and then solidifies into ingots. Strand casting means continuous casting into thin strands or strips. The cast steel blanks can then be rolled and processed into various products.

Scrap-based steel production and its share in the total production

In scrap-based steel production, scrap is melted down in an arc furnace. The arc furnace is heated by supplying electrical energy to graphite electrodes located in arcs. The crude steel is then refined in the same way as in ore-based production before it is finally cast and processed.

About 30 percent of steel consumption globally can be met with recycled scrap. To meet the demand, the remaining amount of steel is produced from iron ore. Jernkotoret forecasts that the world's steel needs will not be met entirely via scrap-based production until 2090.

In 2020, steel scrap consumption decreased in all seven key countries with the exception of China and Turkey. Overall, the COVID-19 pandemic led to a reduction in metal demand, which impacted the steel scrap market.

Environmental impact

Swedish industry makes up a quarter of Sweden's total emissions. In 2014, the iron and steel industry accounted for emissions of 3.866 million tonnes of carbon dioxide equivalents, which corresponds to 26% of the Swedish industries' greenhouse gas emissions.

Den skrotbaserade tillverkningsprocessen använder en femtedel av den energi som används i malmbaserad stålproduktion. För att producera 1 kg göt och ämnen, används 4,6 kWh i den malmbaserade tillverkningsprocessen och 0,9 kWh i den skrotbaserade tillverkningsprocessen. Beroende på vilken produkt som ska tillverkas är den totala energianvändningen efter gjutning 1,1–1,7 kWh/kg.

The scrap-based manufacturing process uses just one-fifth of the energy used in ore-based steel production. To produce 1 kg of ingots and substances, 4.6 kWh is used in the ore-based manufacturing process and 0.9 kWh in the scrap-based manufacturing process. Depending on which product is to be manufactured, the total energy use after casting is between 1.1-1.7 kWh / kg.

The main emissions released into the atmosphere from steel production are: carbon dioxide, nitrogen oxides, hydrocarbon compounds and dust containing complex metal oxides. Carbon dioxide emissions are largely caused by the use of coal to reduce iron ore in ore-based steel production. Oil and gas are used in the production, which also contributes to carbon dioxide emissions. The ore-based production is theoretically considered to be as efficient as possible with regard to carbon dioxide

emissions.

Sweden as steel producer

Steel is one of the world's most common construction materials. But there is a big difference between the various types of steel. The Swedish steel industry has for decades focused on higher value special steels to remain globally competitive. The result is a material development that allows us to do more with less resources. A stronger steel allows us to use smaller amounts. This gives the products less weight and thus reduces the consumption of raw materials and reduces carbon dioxide emissions when they are used. The environmental benefits are clearest on vehicles where high-strength steels can significantly reduce weight and thus fuel consumption. A vehicle with a 10 percent lower weight consumes 5 percent less fuel. When Ikea chose high-strength steel for kitchen chairs, 720 tonnes of carbon dioxide were saved because the 1.2 million chairs weigh less and can therefore be transported with lower emissions.

The environmental benefits of high-strength steel have been scientifically investigated and can radically reduce our emissions. It is in society's interest to build sustainably for the future, and here high-strength steel as the world's most widely used construction material can play a major role. Knowledge of the materials' environmental impact needs to increase if we are to achieve the sustainable society we strive for.

Circular economy

As a company we have the obligation to review how we can incorporate these circular models into our business. It is time to look at our scrap!

Lastly and before I forget, much of my blog is based on articles taken from Jernkontoret, I happily refer you their website https://www.jernkontoret.se should you wish to learn more.

 

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