**Acknowledgements**

**Figure 17.** SEM micrographs of ceramic with 20 wt.% of steel dust incorporated and sintered at 1050°C, including EDS

of a kaolinitic clay. In this case, the Si and al predominantly constitute the aluminosilicate

**Figure 17** shows two SEM micrographs of ceramic specimen with 20 wt.% of dust steel waste incorporated, sintered at 1050°C. In this figure selected punctual regions, marked in the micrographs, were analyzed by EDS. In both micrographs of **Figure 17**, defects associated

As already mentioned for the microstructure of ceramics with no dust waste addition (**Figure 16**), these defects are associated with the conformation step and further consolidation on sintering. It is important to notice in relation to **Figure 17** that the main microstructural distinction between the ceramics with residue addition and those with no waste (**Figure 16**) is the relatively larger particles apparently belonging to the waste. In fact, the EDS spectrum of the large particle in **Figure 17** (a) indicates the presence of Ca and Fe that are, as listed in **Table 4**, characteristics of the PMW. Moreover, the microcracks that surround the particles indicate

It is correct mentioning that, in spite of the defects observed, this waste acts as an inert material and assists on the plasticity control of the clayey body. Despite the inert character of the residue particles, the observed microcracks (**Figure 16(a)**) may be associated due their different expansion coefficient at sintering stage, more pronounced at 1050°C. The particle analyzed in **Figure 16(b)** is relatively small and by its EDS spectrum, with Si and O, corre-

At this sense, it is technically possible to recycle steel slag by incorporating into clayey ceramic. However, the incorporation of this waste into clayey ceramics must be done in amounts of up to 10 wt.%. An elevated amount of steel slag can increase the porosity of the fired ceramic and

decrease its mechanical strength due to its inert action and elevated weight loss.

spectra of selected points [18].

amorphous clayey matrix.

**3. Final considerations**

with microcracks and pores can be observed.

40 Current Topics in the Utilization of Clay in Industrial and Medical Applications

that this residue can lead to occasional defects in ceramics.

sponds to a quartz particle, which already exists in the natural clay.

The financial support provided by the Brazilian agencies, FAPERJ and CNPq, is gratefully acknowledged.
