**2. Experimental methods**

Synthetic CaO-SiO2-FeO slags were studied. FeO was produced using a mix of iron (purity of 99.99%, fineness <10 μm) and Fe2O3 (purity of 99.95%, fineness <5 μm) in a stoichiometric ratio corresponding to the reaction Fe2O3 + Fe = 3FeO. Quartz tube with the mix was closed with an iron wire sponge ball to prevent oxidation and purged with an Ar gas, then heated to 1050°C, held for 5 hours and quenched in water. "Pure for analysis" grade SiO2 and CaO powders were used to prepare ternary CaO-SiO2-FeO mixtures by weighing, mixing and grinding in a mortar.

Slag compositions (shown in **Table 1**) with relatively low liquidus temperature were chosen from different crystallization fields of a ternary CaO-SiO2-FeO system (**Figure 2**) representing Wollastonite, Olivine and Wüstite. Noteworthy, in 3D phase diagrams of a quaternary slag systems (with MgO or Al2O3 as the fourth slag component), liquidus surfaces in these crystallization fields are plateau-like, in contrast to surrounding steep surfaces of Tridymite and Dicalcium Silicate crystallization fields. Composition of low-melting slags from Wollastonite, Olivine and Wüstite crystallization fields is most relevant to the primary slags, formed in partly reduced iron ore materials.

Wettability of solid iron was studied using a sessile drop method. Experimental setup is demonstrated in **Figure 3**. Slag cone (1) with 5 mm diameter and 5 mm height and average mass of approximately 200 mg was placed on the ARMCO® pure iron


#### **Table 1.**

*Composition and properties of the studied slags.*

*Wetting of Solid Iron by Molten FeO-Containing Slag DOI: http://dx.doi.org/10.5772/intechopen.110701*

#### **Figure 2.**

*Ternary phase diagram for the CaO-SiO2-FeO system [14]. Points denote slag compositions for the experiments listed in* **Table 1***.*

#### **Figure 3.**

*Experimental setup: 1—slag sample, 2—iron substrate, 3—thermocouples, 4—gas outlet, 5—photo camera, 6—quartz tube, 7—SiC heating elements, 8—gas inlet, and 9—quartz glass.*

(99.98% Fe) substrate (2) established on the chamotte plate in the quartz glass tube (6) of the horizontal furnace with SiC heating elements (7). Two Pt-Pt/Rh type B thermocouples (9) were used: The first one, used for data recording, was placed near the studied sample and the second one-just under the quartz tube-to control isothermality of the reaction zone.

Technically pure Ar (99.99% Ar, Linde Gas) was constantly supplied to the reactor. Gas was exiting the reactor through the line (4) down to the water lock. Heating rate of 10° C per minute was applied. A digital photo camera was used to record the processes of melting and wetting. Obtained images were digitally processed using ImageJ [15] freeware. When the temperature of complete melting for a given slag was reached (i.e., when the entire sample formed a hemisphere), the temperature in the furnace was allowed to rise by another 20°C and stabilize within 5 minutes, and then, the contact angle was measured.

To ensure that the results are representative, three slag mix samples were studied. Two results with the smallest and the highest contact angle values were excluded, while the remaining result was retained for the analysis.
