Hesham Saad Al-Sherbiny: Sustainability and across-industry cooperation

The transition from a linear economic model to a circular economy requires a joint effort from actors at all levels: governments, businesses, and civil society.

While companies are among the drivers of circular transformation, they find it difficult to achieve a circular economy on their own.

Hence, collaboration across industries is one of the necessities of expanding the circular economy.

In this article, the steel industry and the cement industry will be taken…

In the steel industry iron slag is produced … Granulated melting furnace slag … During the process of preparing solid iron by melting cast iron in the blast furnace, which is a phosphorous fertilizer, where the phosphorous impurities in the iron combine with the lining in the conversion furnace, and due to the fact that the slag is less dense than iron, it floats on the surface of the magma and is separated in the form of a porous body with a dark color.

Slag is also used as a fertilizer for acidic or neutral agricultural soil because of its alkaline nature, in addition to its use in the manufacture of building materials (cement), slag is called “Thomas phosphate” in relation to one of the innovative scientists of the conversion furnace liner

In the cement industry, clinker is used, which is a dark gray material with a diameter of 3 to 25 mm and is produced by heating clay and limestone at a temperature of 1400 ° C to 1500 ° C.

They can be kept in stores for a long time without any change in their quality. Cement manufacturers buy clinker for the production of cement in areas where there are not enough raw materials.

The steel industry is currently undergoing structural change as steel production is transitioned through a combination of direct reduced iron by means of natural gas today and future green hydrogen, and electric arc melting furnaces, which significantly reduces carbon dioxide emissions as classical blast furnace processes (the traditional and most common path) reach the end of the road, Granulated blast furnace slag will become less available as an alternative to clinker needed for cement.

Granulated blast furnace slag is used as a complementary cement material because of its ability to reduce clinker and thus the possibility of reducing carbon dioxide for the production of cement and concrete…

According to industry sources, crude steel production worldwide reached 1,884 million tons in 2022 while the capacity was 2,460 million tons.

On average, 72% was produced by blast furnace track/oxygen converters and 28% by electric arc furnace track mainly using scrap.

Iron ore production was 1301 million tons while direct reduced iron production was only 125 million tons. With 1018 million tons, China is the largest steel producer by far.

The shares of blast furnace methods/oxygen transformers and arc furnaces vary from country to country (Germany: 70% and 30%, EU 56% and 44%, Turkey: 30% and 71%, USA: 31% and 69%, China: 91% and 9%).

Thus, blast furnace outputs and steel slag sizes vary from region to region. In total, it can be estimated that in 2022 worldwide about 312 million tons of granulated blast furnace slag, 104 million tons of air-cooled blast furnace slag, 143 million tons of oxygen transformer furnace slag, and 68 million tons of electric arc furnace slag were produced.

For 2021, other studies show that the production of granulated melting furnace slag is 377 metric tons or 331 metric tons.

For the production of iron with arc furnaces or induction furnaces, it can be assumed that about 14 million tons of slag were produced.

Global steel production is expected to reach a maximum of 2.8 billion tonnes in 2070. The total slag volume produced will peak at about 1 billion tonnes per year.

Provided that 1 ton of granulated melting furnace slag replaces 1 ton of Portland cement clinker and considering the average specific carbon dioxide emissions (122 kg/t for granulated melting furnace slag including metal process allocation, 900 kg/ton of clinker), it can be calculated that for cement production for 2022, about 243 million tons of carbon dioxide emissions were avoided and that about 480 million tons of natural raw materials for burning clinker.

Therefore, among other activities, the further reduction of clinker content in cement by adding complementary cement materials is an integral part of the various dioxide emission reduction roadmaps for the cement and concrete industry.

Thus, it is necessary not only to investigate materials such as calcined clay, recycled concrete fines, etc. but also alternatives to granulated melting furnace slag.