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"Perfection"-an ant rolling a water droplet on a rough surface, an example of ideal nonwetting conditions. Photographer: Unknown. Student's Prayer-Umberto Maturana (Chilean biologist & philosopher) 

"Perfection"-an ant rolling a water droplet on a rough surface, an example of ideal nonwetting conditions. Photographer: Unknown. Student's Prayer-Umberto Maturana (Chilean biologist & philosopher) 

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The aim of the study presented here was to investigate the potential for chemical wear of carbon-based refractory materials in a silicomanganese furnace tap-hole. In the study, three research questions were addressed: 1. Is chemical reaction between refractory and slag or refractory and metal a potential wear mechanism? 2. Is the choice in carbon-...

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... is defined as the elevation or depression of a liquid in a narrow solid tube where capillary stems from the tubes being 'hairlike' [50] -see Figure 13. During capillary action in elevation, a liquid surface rises in a solid tube without an external differential pressure applied. ...
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... Contact angles (θ) formed at the solid-liquid-gas interface ( Figure 13). ii. ...
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... melting temperature for the slag was calculated in FACTSage 6.4 as 1217°C - Figure 30 -using the method described in paragraph 3.2 and the chemical composition in Table 26. For control purposes the target temperature was selected at 100°C above the melting temperature of the slag. ...
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... temperature was controlled by manually changing the power input to the furnace. After melting, the slag was poured into a graphite slag pot and allowed to solidify and cool - Figure 31. Once cooled, the slag was manually broken out of the slag pot using a hammer and chisel. ...
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... Bulk chemical composition was determined by wet chemical methods at an in-house laboratory at a South African producer of SiMn with ISO 9001:2000 accreditation: A schematic of the experimental setup for reaction of the slag is indicated in Figure 32 and of the crucible design in Figure 33. The design, procurement, installation and commissioning of the experimental setup (including the high frequency induction power supply) formed part of the scope of the study. ...
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... bulk chemical composition of the slag is given in Table 27. The predicted phase distribution is shown in Figure 34a and an SEM BSE image of the synthetic slag in Figure 34b. The average and standard deviation of 10 SEM EDS analyses of the amorphous slag phase is given in Table 28. ...
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... bulk chemical composition of the slag is given in Table 27. The predicted phase distribution is shown in Figure 34a and an SEM BSE image of the synthetic slag in Figure 34b. The average and standard deviation of 10 SEM EDS analyses of the amorphous slag phase is given in Table 28. ...
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... expected, the EDS analyses are similar to the bulk slag composition. The XRD results confirmed the fact that only amorphous (glass) phase was present in the synthetic slag - Figure 35. Table 29 respectively. ...
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... standard deviations of both silicon and manganese are high and a larger sample size will improve the results, but the analysis as is was considered suitable for the study. Figure 37, Figure 38 and Table 30 respectively. The modelled and measured EDS spectra for the SiC phase (found in the reacted sample) are presented in Figure 39. ...
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... standard deviations of both silicon and manganese are high and a larger sample size will improve the results, but the analysis as is was considered suitable for the study. Figure 37, Figure 38 and Table 30 respectively. The modelled and measured EDS spectra for the SiC phase (found in the reacted sample) are presented in Figure 39. ...
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... 37, Figure 38 and Table 30 respectively. The modelled and measured EDS spectra for the SiC phase (found in the reacted sample) are presented in Figure 39. ...
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... modelled and measured EDS spectra for the SiC phase present in the as-received industrial slag as identified in Figure 42 are presented in Figure 45; the measured EDS spectra correspond to that expected for pure SiC. The normalised composition of the amorphous slag and secondary slag phase - Figure 43 -as determined by SEM EDS is presented in Table 35 and simplified to a five component system in Table 36. The normalised composition of the metal phase -identified in Figure 42 and Figure 46 -as determined by SEM EDS is presented in Table 37. ...
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... considered but which did not match were corundum, moissanite 3C, TiC, ferrite and Al 4 C 3 . The XRD pattern of the carbon block is presented in Figure 52 and Figure 53. Markers indicate the significant peaks for phases considered based on SEM BSE microscopy and EDS analysis and confirmed by matching their predicted diffraction pattern in terms of positions and peak intensities [109]. ...
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... considered but which did not match were silicon, moissanite 6H and quartz. In Table 40 the crystallite size and inter planar distance of the refractory materials derived from the XRD results in Figure 51 and Figure 53 are presented. The data produced by XRT was manipulated to calculate the total porosity -presented in Table 41 - and cumulative porosity as a function of equivalent pore size is presented in Figure 54 to Figure 56 together with examples of the micrographs generated by XRT. ...
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... secondary, apparently crystalline slag phase was identified by SEM BSE in some of the slag particles ( Figure 43) and EDS (Table 35). The chemical composition of the secondary slag phase (taken from Table 36 but simplified to 20%Al 2 O 3 -10%MgO -45%SiO 2 -25%CaO) was projected onto the quaternary oxide phase diagram for the 20%Al 2 O 3 -CaO -MgO -SiO 2 slag system in Figure 58. ...
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... results are reported in Figure 63. At the melting point, the pyrometer reading had a -14°C offset and the type C thermocouple a +47°C offset. ...
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... line with the proposed role of reaction, SEM investigation of the sample revealed SiC formation (reduction according to Equation 28) -see Figure 73 and Figure 74 -but not of metal formation. ...
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... volume fluctuations are attributed to gas (CO) evolution from the occurrence of one or both of the chemical reaction(s) identified in Chapter 3 and Chapter 4: The reduction of SiO 2 in the slag to form SiC and the formation of metal through the reduction of SiO 2 and MnO in the slag. Evidence of SiC formation was found -see Figure 73 and Figure 74 -but not of metal. ...
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... Figure 83 possible relationships between maximum infiltration depth and the following variables are tested: (a) percentage total porosity (Table 41) ...
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... the cup tests, wetting of both carbon block and ramming paste refractories was observed at 1600°C but not at 1400°C or 1500°C (compare the slag / refractory / gas interface for each experiment in Table 52 to the definitions of wettability in Figure 13a or Figure 14c). Equilibrium calculations (refer Figure 21 and Figure 61) indicate that 1600°C is just above the minimum temperature required for chemical reaction between slag and carbon. ...
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... backscattered images of both ramming paste ( Figure 93) and carbon block (Figure 94) indicate that the binder phase reacted extensively with the slag rather than the carbon aggregate. This is in agreement with observations made in blast furnace ironmaking where alkali and zinc attack the binder phase first [72] and molten iron preferentially dissolves the (coal tar pitch-based) binder phase [78]. ...
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... steel shell temperatures (above 300°C and below 480°C) measured at the tap-hole area using thermal imaging techniques ( Figure 103) were the major factor leading to the switch-out of the furnace for a total reline. A typical tap size was 22 t of alloy and 17.6 t of slag. ...
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... the temperature increases, the solubility of the SiC in the metal increases to the point (above 1625°C) where the metal becomes unsaturated in SiC. This is in agreement with the C solubility diagram for Si-Mn-Fe alloys presented in Figure 113 and constructed from thermodynamic calculations conducted in FACTSage 6.4 [117]. Once the temperature has increased to such an extent that the metal is unsaturated in SiC, the metal will dissolve any SiC it comes into contact with, except for limitations posed by reaction kinetics [120]. ...
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... is expected, as slag reactions involve both chemical reaction and dissolution as discussed above, whereas metal reaction involves only dissolution. Dissolution of SiC into metal (Figure 116b) occurs only once the metal becomes unsaturated in SiC (Figure 112a and Figure 113), whereas the metal is already unsaturated in C (Figure 113), with carbon potentially dissolving in metal throughout the temperature range ( Figure 116a). ...
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... is expected, as slag reactions involve both chemical reaction and dissolution as discussed above, whereas metal reaction involves only dissolution. Dissolution of SiC into metal (Figure 116b) occurs only once the metal becomes unsaturated in SiC (Figure 112a and Figure 113), whereas the metal is already unsaturated in C (Figure 113), with carbon potentially dissolving in metal throughout the temperature range ( Figure 116a). ...

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