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By-products and residues

Gerdau seeks intelligent and sustainable alternatives for the use of by-products generated during the steel production. This is done through several initiatives such as identifying recycling opportunities in the production process of steel itself, developing research partnerships with universities, research institutions, and industries, as well as making internal improvements in the processing of by-products to facilitate recycling.
 
In 2011, Gerdau increased the level of reuse of its byproducts, contributing to the conservation of natural resources. The reuse rate of these materials, which considers the volume of waste reused by different segments of economy and the steel industry itself, reached 78.3%. During the year, one of the highlights was the beginning of recycling 100% of the dust collected by the dust removal systems of the electric melt shops of the mills located in São Paulo and Rio de Janeiro. During the process, all of the zinc contained in the dust is reused and the rest is transformed into products for construction. In 2012, feasibility studies were initiated to extend this project to other industrial mills located in Brazil. Moreover, Gerdau’s mills in the United States, Canada and Spain also have initiatives for the reuse of melt shop dust. The entire process of transportation, storage, and selling of by-products meets legal requirements and of the Gerdau’s Environmental Management System.

Learn about some of Gerdau´s by-products:
Scale

This material is created by oxidation of the steel’s surface when it comes into contact with the oxygen. It is generated during the casting, forging, and the hot and cold rolling processes. It is predominantly constituted of metal oxides present in the steel’s composition, with the majority of this being iron oxide.


Main applications:

Used as a raw material in sintering, in the cement industry, for the production of concrete, and in iron alloys. Some parts of the scale are used to enrich the metallic charge in pig iron and steel furnaces.
Steelmaking Slag

This is a by-product formed by the production of steel at melt shop. It plays an important role in process control and steel quality. It is composed mainly the following oxides: calcium, iron, silicon, magnesium, manganese, aluminum, phosphorus and sulfur.


Main applications:

After processing, it is used as aggregate for paving, drainage, rip rap construction, gabions, for the production of concrete tiles and asphaltic mixtures, and as recycled material at the furnace.
Blast Furnace Slag

This is a by-product formed by the production of pig iron in blast furnaces. It is formed by ore gangue, reducing agent ash and fluxes. It is composed mainly the following oxides: calcium, silicon, aluminum, magnesium.


Main applications:

The material is granulated and used in the production of cement.
Ore Fines

It is a material that results from the handling or screening of iron ore. It appears in the form of fine iron oxide particles.


Main applications:

As a raw material for sintering and in the cement production.
Coal and coke fines

These are materials resulting from the handling or screening of coal or coke. This material has a very small grain size.


Main applications:

As fuel for re-use in steelworks or other industries.
RECYCLING
  • Gerdau transforms scrap into new steel products.