Recycling of steel slag

The steel sector is booming, increasing the generation of slag. Steel slag is a by-product generated during the production of steel, and may come from different processes, such as those generated in Linz-Donawitz (LD) converter furnaces or electric arc (FEA). World crude steel production in 2008 reached 1.3 billion tons, setting a new production record. Considering that for each ton of steel produced, around 150 kg of steel slag is generated, that is, 15% of the total produced, in 2008 alone, approximately 200 million tons of this waste were produced.

The steel slag application projects were developed in order to use this residue in construction materials, such as concrete, mortar and asphalt base. However, studies have shown that this use has restrictions regarding the hydration capacity of the steel slag after its use, causing the manufactured materials to have their physical integrity compromised. Approximately 30% of Brazilian production and 20% of world production of steel slag are not reused, destined for extensive areas of industrial parks and causing disposal costs.

Therefore, the reuse of steel slag represents a technical, economic and ecological solution for steelmakers. This line of research has the objective of inserting the electric steel slag as a partial raw material for the production of glass fibers. With this practice, it is possible to reduce the impact caused by the exposure of this waste to the environment, provide a profitable destination for the slag and reduce the extraction of non-renewable resources that are currently used in the production of glass fibers.

Glass fibers are composed of glass filaments wrapped in a binder polymer, these fibers have characteristics such as high chemical and mechanical resistance, durability and lightness. The composition of the glass fiber varies according to the application of the final product. In this work, the fibers used for thermo-acoustic insulation, which are called mineral wool, were adopted as the basis. In the group of synthetic mineral wools, glass wool (made using molten glass of sodium carbonate and lime) and rock wool (made using basaltic rocks) stand out, both of which have raw materials from non-natural resources. renewable. These wools have a glassy structure and melting test of steel slag (1500ºC) as such they support quantities of different elements in solution and are therefore ideal for assimilating complex residues in their composition. Due to their thermo-acoustic characteristics, glass and rock wool have a wide consumer market, serving the sectors of civil construction, industrial, automotive, among others.