Title

BLAST FURNACE HEARTH CAMPAIGN EXTENSION THROUGH MONOLITHIC REPAIR

BLAST FURNACE HEARTH CAMPAIGN EXTENSION THROUGH MONOLITHIC REPAIR

Authorship

Costa, Allan Alipio

DOI

10.5151/2594-357X-39686

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Abstract

Presently in blast furnaces (BF), the refractory campaign may well surpass 20 years’ operation, which is mainly achieved due to effective charging patterns, the use of rutilite sands and eventually a TiO2 source in order to form TiCN to create the coating layer of the hearth. In many cases this is enough to extent the campaign of the hearth and control the progressive wear in the hearth. However, in other cases the wear in the hearth have reached a dangerous level, which will lead to higher thermal loss, unpredictable operation condition and risk for a higher wear and collapse in the hearth. In this sense, the re-profiling by monolithic can be recommended. While the monolithic repair by shotcrete in the shaft (bosh, belly, stack and throat armor) is known and relatively normal, still to this day the monolithic lining in the hearth represents a challenge, due to the higher thicknesses and the pre-existing sol-gel technologies poor green properties combined with a safe heating up/drying out procedures. This contribution aims to show the development of Hybrid technology material intended for all areas of blast furnace shaft and the hearth. The work begins with a review of the common refractory linings for BF’s and the current repair practices, secondly the results of a small-scale laboratory assessment for Hybrid are provided. In the third part, a large-scale laboratory assessment. The results and laboratory evidence an outstanding green properties behavior even against the steam pressure provide by extremely abrupt heating procedures. Industrial experiences in hearth repairs results seem to corroborate that Hybrid technology is extremely suitable shaft repairs and also hearth repairs.

 

Presently in blast furnaces (BF), the refractory campaign may well surpass 20 years’ operation, which is mainly achieved due to effective charging patterns, the use of rutilite sands and eventually a TiO2 source in order to form TiCN to create the coating layer of the hearth. In many cases this is enough to extent the campaign of the hearth and control the progressive wear in the hearth. However, in other cases the wear in the hearth have reached a dangerous level, which will lead to higher thermal loss, unpredictable operation condition and risk for a higher wear and collapse in the hearth. In this sense, the re-profiling by monolithic can be recommended. While the monolithic repair by shotcrete in the shaft (bosh, belly, stack and throat armor) is known and relatively normal, still to this day the monolithic lining in the hearth represents a challenge, due to the higher thicknesses and the pre-existing sol-gel technologies poor green properties combined with a safe heating up/drying out procedures. This contribution aims to show the development of Hybrid technology material intended for all areas of blast furnace shaft and the hearth. The work begins with a review of the common refractory linings for BF’s and the current repair practices, secondly the results of a small-scale laboratory assessment for Hybrid are provided. In the third part, a large-scale laboratory assessment. The results and laboratory evidence an outstanding green properties behavior even against the steam pressure provide by extremely abrupt heating procedures. Industrial experiences in hearth repairs results seem to corroborate that Hybrid technology is extremely suitable shaft repairs and also hearth repairs.

Keywords

Refractory, Blast Furnace, Shotcrete, Shaft, Hearth, monolithic, Concrete, Castable, Hybrid

Refractory, Blast Furnace, Shotcrete, Shaft, Hearth, monolithic, Concrete, Castable, Hybrid