Implementation of industrial waste ferrochrome slag in conventional and low cement castables: Effect of calcined alumina

Effect of reclaimed bauxite on andalusite-based refractory castables for tundish applications

“…For example, S1 and S3, with comparatively higher mullite contents (see Table VIII), achieved the highest HMOR values of 2.12 MPa and 2.68 MPa, respectively. Congruent with findings from other studies, the formation of mullite significantly increases the hot strength properties of refractory castables (Myhre, 1994;Parr et al, 1997;Zawrah and Khalil, 2001;Rebouillat and Rigaud, 2002;Kumar, Kumar-Singh, and Strivastava, 2013;Kumar et al, 2014;Frulli, 2016). In fact, the higher HMORs for S1 and S3 can be attributed to both the higher mullite content and lower amount of amorphous phases, as indicated in Table VIII.…”

“…The effect of the amount of grog is clearly observed in samples S3 and S4 fired at 1000ºC and 1200ºC. Since these castables had higher water requirements (see Table IV) than the reference castable, the higher porosity can be attributed to disappearance of water of crystallization and hydration, which created porosity in the castable body structure without any meaningful bonding taking place (Kumar et al, 2014). At fixed firing temperature of 1000ºC, it can be inferred that the pore volume remained almost unchanged from VS to S3, but increased in S4 due to the apparent effect of grog addition (Zawrah and Khalil, 2001).…”

“…Based on the principle of downward position, Hanagiri et al (2008) developed a methodology to recycle processed refractory waste wherein the reprocessed materials are used to produce materials of lower quality than the original materials. In other studies, Kumar et al (2014) developed a new class of conventional and lowcement castables using 40 wt.% ferrochrome slag and 45 wt.% calcined alumina. The findings from these studies have proved the suitability of the products made from the recycled materials.…”

“…Furthermore, it can be inferred that the slagcastable interaction occurred via the slag penetrating through the available pathways (open pores, cracks, phase boundaries, etc. ), with the degree of penetration being controlled by the bulk density and apparent porosity of the castables (Pivinskii, 1998;Zawrah and Khalil, 2001;Poirier et al, 2008;Braulio et al, 2011;Sako, Braulio, and Pandolfelli, 2012;Parr, Fryda, and Wöhrmeyer, 2013;Kumar et al, 2014;Sadik, El-Amraniand, and Albizane, 2014;Tomba-Martinez et al, 2017). Thus, the corrosion behaviour indicates the need to further optimize the bulk density and open porosity properties of the formulated castables.…”

“…Mullite, in particular, provides chemical stability to resist corrosion attack, and as such, the better corrosion resistance of S1, S2, and S3 can be attributed to the increased amounts of these phases in the castables (Zawrah and Khalil, 2001;Rebouillat and Rigaud, 2002;Garbers-Craig, 2008;Abou-Sekkina et al, 2011;Frulli, 2016;Tomba-Martinez et al, 2017). Although S4 was expected to have higher resistance to slag attack due to the greater amounts of mullite and corundum phases, the integrity of the formulation was negated by synergistic effects of poor physicochemical properties such as bulk density and open porosity (Kumar et al, 2014).…”