Refractory Solutions by Laboratory Tests and Fieldworks …
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in the bottom area of all investigated samples (0–25 mm). A yellow/greenish coating
was formed due to volatilization and precipitation of slag components at the upper
part of the samples. Based on SEM-analyses, this coating consists of sodium, sulfur,
tin, antimony, and lead.
Crucible Test
Another important laboratory test is the crucible test. Therefore, the same magnesiachromite brick brands tested in the HF-IF, with a dimension of 80 × 80 × 70 mm
and a drill hole with 45 mm depth and 40 mm diameter, were prepared and filled
with a defined amount of slag material. Afterwards, a cover consisting of the same
brick brand was fixed with mortar material on the crucible. The crucibles were placed
inside the furnace and heated up to the defined temperature (1500 °C under controlled
atmosphere). After the defined test duration of 480 min, the furnace cooled down
and the crucibles were cut through diagonally. The evaluation of the samples and
their corrosion behaviour is again done on a macro- and microscopical view (Fig. 3).
Macroscopically, there is no difference between the samples in corrosion resistance;
however, no remaining slag was found in the crucibles after the tests, probably due
to volatilization of several compounds due to low vapor pressure of slag components
and in combination with the high test temperature. Hence, just slight corrosion by the
slag was detected (Fig. 4). The magnesia component was corroded due to SiO 2 supply
of the slag under formation of forsterite (Mg 2 SiO 4 ) and monticellite (CaMgSiO 4 ).
Chromites are highly enriched with Sb and Sn oxides.
A difference can be seen in the infiltration—brick 1 shows a lower infiltration
depth of approx. 1.5 cm compared to approx. 3 cm for bricks 2 and 3.
Post-Mortem Study
Magnesia-Chromite Brick
Due to the results of the laboratory tests, brick 1 was chosen for practical test in a
lead reverberatory furnace.
In general, a post-mortem study starts with a macroscopical investigation of the
sample, followed by chemical analysis and microscopical investigation.
563
in the bottom area of all investigated samples (0–25 mm). A yellow/greenish coating
was formed due to volatilization and precipitation of slag components at the upper
part of the samples. Based on SEM-analyses, this coating consists of sodium, sulfur,
tin, antimony, and lead.
Crucible Test
Another important laboratory test is the crucible test. Therefore, the same magnesiachromite brick brands tested in the HF-IF, with a dimension of 80 × 80 × 70 mm
and a drill hole with 45 mm depth and 40 mm diameter, were prepared and filled
with a defined amount of slag material. Afterwards, a cover consisting of the same
brick brand was fixed with mortar material on the crucible. The crucibles were placed
inside the furnace and heated up to the defined temperature (1500 °C under controlled
atmosphere). After the defined test duration of 480 min, the furnace cooled down
and the crucibles were cut through diagonally. The evaluation of the samples and
their corrosion behaviour is again done on a macro- and microscopical view (Fig. 3).
Macroscopically, there is no difference between the samples in corrosion resistance;
however, no remaining slag was found in the crucibles after the tests, probably due
to volatilization of several compounds due to low vapor pressure of slag components
and in combination with the high test temperature. Hence, just slight corrosion by the
slag was detected (Fig. 4). The magnesia component was corroded due to SiO 2 supply
of the slag under formation of forsterite (Mg 2 SiO 4 ) and monticellite (CaMgSiO 4 ).
Chromites are highly enriched with Sb and Sn oxides.
A difference can be seen in the infiltration—brick 1 shows a lower infiltration
depth of approx. 1.5 cm compared to approx. 3 cm for bricks 2 and 3.
Post-Mortem Study
Magnesia-Chromite Brick
Due to the results of the laboratory tests, brick 1 was chosen for practical test in a
lead reverberatory furnace.
In general, a post-mortem study starts with a macroscopical investigation of the
sample, followed by chemical analysis and microscopical investigation.