Application of Semi—rebonded Magnesite—Chrome Bricks of LRF at RH Lower Vessl of NKK Keihin Wroks

The application results of semi-rebonded magnesite-chrome bricks at RH lowe vessel of NKK Corporation Keihin Works have been analysed,The results indicate that the main reasons that cause the damage of the refactory brcks include:chemical attack of slage to the semi-rebonded magnesite-chrome bricks;pene-tration of molten stel,slag into the bricks;and therma spalling due to temperature fluctua-tion during steel making operation.The results of multiple effection of these factors lead to alternative action of erosion(chemical attack and penetration)and spalling(thermal spalling and structure peeling) resulting in the damage of the brik ,In order to improve the performance of the bricks ,it is necessary to promote the resistance to erosion and thermal shock resistance as well as to keep the accurate dimensions of the brick,The measures of improvement of resistance to erosion of magne-site-chrome bricks taken by the researches mainly include:lowering the contents of impu-rities in the bricks(mainly including SiO2,CaO,and next Fe2O3 and Al2O3);promoting the extent of direct bond of the brick;forming a large amount of magnesia-chrome composite spinel well-distributed in the bricks through adding a large amount of synthesized materi-als;enhancing the resistance to erosion by adding a little amount of high-effective additives,Improvement of thermal shock resistance of the bricks is mainly through introducing some additive to make a certain amount of mi-cro-cracks occur in the brick so as to obtain an effect of increasing toughnes or through for-mation of second high temperature solid phase in the brick by adopting additive,In addition,it is needed to improve the quality of the brick appearance and ensure accurate dimensions of the brick,The purpose of this paper is to further iprove the service life of the refractory bricks by making use of the improvement mea-sures taken on the basis of the analysis results of the used bricks.     

Development and Application of High Quality Magnesite—Chrome Bricks for VOD Refining Furnaces

The paper describes the process of producing high quality magnesite-chrome bricks for VOD re-fining furnace,The service life reaches 14 heats,average life 12 heats.The studies show that the wear of the magnesity-chrome bricks is mainly due to chemical corrosion,thermal spalling induced by thermal shock and the corrosion aroused from accumulation of molten materials in transition zone.     

Development of High Quality Magnesite—Chrome Bricks for Secondary Steelmaking Furnaces

This paper describes developments of high quality magnesite-chrome bricks used for secondary steelmaking furnaces,mainly including direct-bond-ed magnesite-chrome brick,fully synthesized(co-clinker) magnesite-chrome brick,semi-rebonded magnesite-chrome brick and fused grain rebonded magnesite-chroe brick,Investigations have also been conducted on the effects of various chromites on the properties of the direct bonded magnesite-chrome brick,effects of different sesquioxides (CrO3,Al3O3,Fe2O3) on the properties of the fully synthe-sized(co-clinker) magnesite-hrome brick and ef-fects of ZrO2,Cr-Fe alloy,ultra-fine powders on the properties of the fused grain rebonded brick and the semi-rebonded magnesite-chrome brick ,Applica-tions of the bricks in various secondary steelmaking furnaces have been briefly introduced as well.     

Development and Application of High Quality Magnesite—Chrome Bricks fro VOD Refining Furnace

The paper describe the process of producing high quality magnesite-chrome bricks for VOD refining furnace,The Service life reaches 14 heasts,average life 12 heats.The studies show that the wear of the magnesite-chrome bricks is mainly due to chemical corrosion,thermal spalling induced by thermal shock and the corro-sion aroused from accumulation of molten mate-rials in transitional zone.     

Study on Mechanism of Reaction Between AOD Slag and Rebonded Magnesite—Chrome Brick

The influence of the composition of AOD slag on the corrosion of rebonded magnesite-chrome brick has been studied by analyzing the residual bricks at the tuyere zone of AOD .It indicates that the corrosion degree increased with the increase of the basicity of slag and decreased with the increase of the content of MgO ,Cr2O3 and Al2O3 in slag.And the addition of refractories to slag up to satura-tion could decrease the corrosion abiliy of sag.It is important to make a resonable slagmaking rule and ensure the percentage of MgO in slag more than 11wt% for pro-longing the service life of lining.     

Development and Application of High-Performance Magnesia-Chrome Bricks for RH Degasser

The paper analyses the wear mechanism of magnesiachrome bricks for snorkel of RH degasser.High-performance magnesia-chrome bricks with good resistance to molten slag and infiltration resistance have been manufactured by means of reasonable fabricating technology.The application results of the developed magnesia-chrome bricks at 300t RH degasser of Baosteel indicate that the lining life has been increased up to 150 heats.     

Change Mechanism in Property and Microstruture of Magnesite—chrome Brick for Use in Super H—T Tunnel Kiln

On the basis of determination of property and microstructure of two kinds of primary MgO-Cr2O3 bricks and residual magnesite-chrome bricks for super H-T tunnel kiln,combining with the both residul bricks‘s application result,the paper expounds the change mechanism of the two kinds of magnesite-chrome bricks during the operation period,especially stresses the advantages of low Cr2O3 MgO-Cr2O3 bricks.