How Steel industries are moving towards zero-waste production



On average, the production of one tonne of steel results in 200 kg ( in a Electric Arc Furnace) to 400 kg (Blast Furnace / Basic Oxygen Furnace) of by-products. These include slags, dusts, sludges and other materials. Over the last 2 decades, Steel Industries have concentrated on the recovery rate of the by-products in the manufacturing processes. The innovative technologies and developments to tackle this along with the assistance and collaboration of other industries have brought the aim of zero-waste closer each day.
The recycling and use of Steel by-products has contributed to a high degree of raw-material efficiency, increasing productivity, and also minimizing waste. These on-going efforts have raised the efficiency rate worldwide to 97. 6%, and the goal is to achieve 100 percent efficiency with zero-waste.

Here are the main by-products of Steel manufacturing and possible reuses:

Solid Waste: Slag
More than 400 million tonnes of iron and steel slag is produced each year. Slags are a mixture of silica, calcium oxide, magnesium oxide, and aluminium and iron oxides. The separation of slag from the production cycle is easy, due to its light-weight.
These slags are used as replacement for clinker for the manufacturing of composite cement and also to produce eco-friendly, green cement produced to reduce carbon footprint and are available at a cheaper price. Slag has become a very important raw-material for the Cement and Concrete industry.
Lime separated from the slag through various technologies available can be used as a fertilizer, for water treatment, and coastal areas to encourage coral growth.

By-product Gases
Once cleaned, by-product gases produced during Steel production processes serve as an attractive energy source option for efficient power supply. Depending on the production process followed, three main gases formed as by-products are, Coke Gas (Hydrogen & Methane), Blast Furnace Gas (Hydrogen & Carbon monoxide), and Converter Gas (Carbon monoxide). 
These by-product gases are mainly used internally, in the manufacturing setups as an alternate source of power to run various processes. The usage of these available product gases on-site reduces the dependence on the natural resources, minimizing fuel prices, and carbon emissions. These gases serve for both the power requirements at a steel making engine, steam and electricity needs.
Gases can be fully reused within the steel production site, and can provide up to 60% of the plant’s power. They can also be sold for power generation to earn additional revenue.

At Agni Steels, we ensure we follow the appropriate norms and facilities for minimal waste and recycling and using by-products as and when possible, without compromising the quality of our processes and final products.

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