Technical Paper
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Figure 8: Wear profile after 8 years. (Fos-sur-Mer - ArcelorMittal – blast furnace n°1)
(Figure 8). However, a slightly more pronounced corrosion could be noticed, located just below the tuyere area (level 11.15 m). The wear profile is also regular all along the blast furnace circumferential part, without any local “weak point” occurring during blast furnace operation.
For example, compared to the average data listed in Figure 7, maximum GRW erosion rates found are 17% both at tuyere (level 06) and pad/bottom intersection (level 03).
These observations and measures prove that Coranit Al lining is still present all along the hearth elevation and on the entire circumference with a regular wear profile. This conclusion is also fully validated by the user, considering that after at least 8 years, Coranit Al wall continues to protect actively the carbon lining, thus contributing to increase blast furnace lifetime.
BF n°2
For this blast furnace, the blow-in was performed on 19th September 2011. After 4.5 years, it is not surprising to find that Sialon bonded lining is still present inside BF hearth. If we consider the most corroded parts (level 03 to 06), the residual average Coranit Al brick thickness is measured around 257 mm.
GRW thickness (meter)
BF n°2 level
BF
elevation (meter)
01 02 03 04 05 06
5.35 5.95 7.15 8.40 9.80 11.15
Initial
1.83 1.83 1.73 1.73 1.73 1.58
Average in- situ measure
1.80 1.80 1.56 1.59 1.60 1.43
Average wear evolution (%)
CW GRW
1% 1%
10% 8% 7%
10%
Figure 9: Wear profile data measured 4.5 years after BF n°2 blow-in (ArcelorMittal – Fos-sur-Mer)
(Coranit Al)
5% 5%
41% 33% 31% 38%
For this blast furnace, same observations were made as for BF n°1 with a wear profile homogeneous all along the BF elevation (Figure 10) and a regular profile all along the BF circumferential part.
For example, for the highest corroded point measured in the elephant foot zone, the GRW residual thickness is measured around 1.43 m, corresponding to a wear rate of 17% (vs. 10% for the average).
Comparative study between BF n°1 and BF n°2
The comparison between the 2 blast furnaces within a same period of time of 4.5 years is given in Figure 11. Both wear profiles are similar even if it appears that a higher erosion rate is measured for BF n°2 in the elephant foot zone (Figure 11).
Indeed, for BF n°2, Coranit Al remaining thickness is measured around 59% in comparison to 87% found for BF n°1, making this elephant foot zone, an area to be controlled and checked regularly for BF n°2.
As additional information, the results from hearth monitoring seem consistent with in-situ stress measurements that we performed on BF n°2 steel shell during the blow-in stage in 2011. As theoretically expected [21], these in-situ measurements confirm that the elephant foot zone, which corresponds close to the pad/wall intersection [22], suffers the maximum stress after blow-in (Figure 12).
This critical area is still the most stressed zone even after the stress relaxation which starts after 2 months. Unfortunately the same study has never been performed on BF n°1 and the level of stress could consequently not be compared.
ThyssenKrupp Steel Europe – Duisburg Schwelgern blast furnace n°2 – (Campaign 1993-2014)
In 1993, Schwelgern II one of the largest blast furnaces in the world employed a hearth equipped with a Coranit brick wall of 400 mm (Figure 130 for the first time. Refractory concept including materials choice and design is a key criterion to extend blast furnace lifetime for ThyssenKrupp.
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ENGINEER THE REFRACTORIES
July 2017 Issue
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