**1. Introduction**

The steelmaking industry plays an important role in economy and in a modern society development. As a provider of employment and essential materials, this sector is connected to a huge variety of industrial productive chains. However, a clearer related view on how to manage this key industry with greater sustainability could positively impact the economy and the environment globally. To provide a more sustainable productive chain, besides avoiding

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

generating residue, the solid residues may be managed through a more noble and environmentally correct destination.

**2. Steelmaking plant wastes as raw materials for clay brick** 

roofing tiles, blocks, and paving ceramic floors, among others.

**2.1. The ceramic industry as an active agent for the improvement of sustainable** 

The industrial segment of red clay-based ceramics, also known as structural ceramics, is part of the nonmetallic mineral sector of the mineral processing industry, sharing the entire production chain of civil construction. The following products make up this segment, bricks,

Recycling of Steelmaking Plant Wastes in Clay Bricks http://dx.doi.org/10.5772/intechopen.74431 27

Several researches have reported on the state of the art of using various wastes to red clay-based ceramic products, such as red mud of Bayer process [7], fluorescent lamp glass waste [8], granite waste [9], effluent sludge from paper industry [10], blast furnace sludge [11], and sugarcane bagasse ash [12], among others. This potential is based on basically two particularities of this industrial sector, the characteristics of the raw material and the high production volume [4].

Dondi, Marsigli, and Fabbri [6] elaborated a classification in order to organize different types of industrial solid wastes as to their main influence when incorporated to the clayey bodies for ceramic production. Through extensive bibliographical research, these authors categorized the residues into combustible residues, fly ash, flux residues, and plasticity-modifying residues. More recently, Vieira and Monteiro [13] presented a new classification for industrial solid waste aiming its application as raw material for ceramic production for civil construction. In this classification, the authors propose only three categories, being combustible residues, flux residues, and property-modifying residues. Thus, fly ash was excluded from the old classification and should now be classified as combustible waste, and the category of plasticitymodifying waste was renamed as property-modifying waste, since not only plasticity but also other properties could be altered by waste that did not fit the other categories of classification.

The steel industry generates a huge variety of wastes in the course of its process, mainly in the case of integrated mills. In relation to the solid wastes generated, the transformation of iron ore into steel can be classified into slags, sludges, and dusts, which together represent between 2 and 4 tons per ton of steel produced. The composition of these wastes varies according to the source of generation but usually contains iron, carbon, calcium, magnesium, silicon, manganese, zinc, and lead. Besides that, some slag and sludge contain a notable amount of heavy metals, and their improper deposition can negatively impact the environment [3, 14–19].

So, the disposals of these wastes in landfills are becoming less attractive which not only occupy plenty of land but also increase the costs. Therefore, it is desirable to identify productive cycles capable of using the steelmaking wastes as raw material. In this way, this will lead to a better evolution of sustainable development. The following will be analyzed as to how the

**2.2. Characteristics of steelmaking wastes and their influence on clay brick** 

**production**

**development**

**properties**

There are basically two main routes for steel production; they are the integrated route and the semi-integrated route. At the first route, the reduction of ore, including iron ore, coal or charcoal, and fluxing agents, occurs in the blast furnace to generate pig iron, in which it is then refined to produce steel, while in the second route the steel is directly produced in electric arc furnace [1].

During the steelmaking at both routes and also at the reefing step, the main residues generated can be divided into categories such as slag, sludge, and dust [2]. The mineralogical and chemical compositions of each of these wastes vary according to the raw materials employed in the process and to what they have as common elements, mostly composed of iron, carbon, calcium, magnesium, silicon, and manganese and still containing smaller proportions of aluminum, zinc, alkaline earth metals, and traces of other elements [3].

It is preferable that the valorization of the solid wastes is carried out on the steelmaking route itself; however, if this practice is not possible, it is necessary to look for other productive processes capable of incorporating this waste as raw material. In association with this practice, it is desired that these wastes, when hazardous or not inert, are inertized in order to reduce their toxicity. In this sense, it is verified that much of this waste is still disposed in landfills or sent for incineration; even if this constitutes an environmentally correct practice, it is considered the least noble practice according to solid waste management [2].

The ceramic industry for civil construction has gained prominence in recent years due to its potential for incorporation of solid waste generated in the most diverse industrial activities. This potential is based primarily on the characteristics of the raw material and the high production volume in this industrial sector [4].

The basic raw material for the bricks and roofing tiles manufacturing is clay, and due to the nature of its formation, it has natural variability in its chemical and mineralogical composition. This variation, coupled with the low technical performance required for its products, allows residues of different compositions to be incorporated into the ceramic clayey body. In addition to direct environmental benefit, technical improvements in processing or product quality may occur, and even energy savings can be generated when certain wastes are incorporated with combustibility characteristics. Another notorious benefit is the possibility of inertization, in the ceramic matrix, toxic metals contained in these residues [5]. Dondi, Marsigli, and Fabbri [6] still emphasize the function of improving sustainable development by providing the economy of clay, which is a natural nonrenewable resource.

The purpose of this book chapter was to provide a summary based on existing scientific references on the environmental, technical, and economic benefits of using the waste generated in the steelmaking process as a raw material for the ceramic industry, seeking, whenever possible, to correlate the characteristics of the residues and their influence on the properties and microstructure of the ceramics.
