1) Rich MnO slags can lead to Mn-rich metallic particles and solid solution with Mg (and, indeed, carbon oxydation) at the interface between slag and lining.
Anyway, this is seldom the first cause of erosion: it generally occurs after the lining has been weared for some other reason (i.e. slags unsaturated in MgO or rich in FeO).
2) Mn presence in converter causes erosion faster, as it behaves acidic, makes the liquid less viscous, penetrates the pores and joints and reacts with MgO at the contact point. For Mn steel, different of configuration of MgC brick is used.
3) it is observed that after a low grade ore(high impurity i.e Mn,Si) converter life is almost reduced and high erosion profile is being observed.
as my observation high Mn slag is very fluid and do not cover the converter lining after slag splashing. reducing use of iron ore as coolant may help.
MnO + SiO2 = very low melting and corrosive liquid.
I suppose primary wear area limiiting converter life will be the trunnions. Trunnions can be zoned with higher quality MgO containing bricks - MgO purity should be 97.5 minimum and of largest MgO crystal size available. Graphite should be 10-20% and have coarse flaked quality -- exact amount of graphite is function of sracp charge; hot metal chemistry; gunning practice; slag viscosity etc. A good start would be 15% C. Metal additions should be aluminum and silicon metal which will form carbides for added strength and corrosion resistance.
Turkish fused MgO is superior to Chinese fused MgO especially for corrision resistance - crystal size is larger and grain chemistry is more homogeneous.
Some other thoughts:
The operator should be adding enough lime/limestone/dolomitic lime to maintain slag basciity at a > 3:1 lime:silca ratio and some MgO is helpful to reduce slag liquidity and reactability.
Reblows will be especialy harmful as added FeO can result and FeO+MnO+SiO2 is a refractory solvent that is very aggressive. So effort should be taken to control reblowing to minimum.
Overblowing such that temperature is overheated should be controlled.
Corriosive slag should be slagged off shortly after tap.
A high purity MgO gun mix and laser readings to identify low spots for added gunning maintenance will extend service life.
Do practice slag splashing; a special lance is used to inject nitrogen after tap - the slag is made more refractory prior to the nitrogen splasing by addition of dolomitic lime.
A good strategy would be to plan for Continuous Improvement over several linings rather than thinking that one design change can be a silver bullet. Key is to study the wear profile, identify the wear mechanism and develop new lining design that addresses the wear area and wear meachanism; this should be repeated in several iterations over several linings as in "chaisng the hole". As one area is upgraded the weak link might move to another area of the vessel. EX: An upgrade of trunnions might shift the limiting zone to the cone or the slagline or the charge pad or the tap pad...
Anyway, this is seldom the first cause of erosion: it generally occurs after the lining has been weared for some other reason (i.e. slags unsaturated in MgO or rich in FeO).
2) Mn presence in converter causes erosion faster, as it behaves acidic, makes the liquid less viscous, penetrates the pores and joints and reacts with MgO at the contact point. For Mn steel, different of configuration of MgC brick is used.
3) it is observed that after a low grade ore(high impurity i.e Mn,Si) converter life is almost reduced and high erosion profile is being observed.
as my observation high Mn slag is very fluid and do not cover the converter lining after slag splashing. reducing use of iron ore as coolant may help.
MnO + SiO2 = very low melting and corrosive liquid.
I suppose primary wear area limiiting converter life will be the trunnions. Trunnions can be zoned with higher quality MgO containing bricks - MgO purity should be 97.5 minimum and of largest MgO crystal size available. Graphite should be 10-20% and have coarse flaked quality -- exact amount of graphite is function of sracp charge; hot metal chemistry; gunning practice; slag viscosity etc. A good start would be 15% C. Metal additions should be aluminum and silicon metal which will form carbides for added strength and corrosion resistance.
Turkish fused MgO is superior to Chinese fused MgO especially for corrision resistance - crystal size is larger and grain chemistry is more homogeneous.
Some other thoughts:
The operator should be adding enough lime/limestone/dolomitic lime to maintain slag basciity at a > 3:1 lime:silca ratio and some MgO is helpful to reduce slag liquidity and reactability.
Reblows will be especialy harmful as added FeO can result and FeO+MnO+SiO2 is a refractory solvent that is very aggressive. So effort should be taken to control reblowing to minimum.
Overblowing such that temperature is overheated should be controlled.
Corriosive slag should be slagged off shortly after tap.
A high purity MgO gun mix and laser readings to identify low spots for added gunning maintenance will extend service life.
Do practice slag splashing; a special lance is used to inject nitrogen after tap - the slag is made more refractory prior to the nitrogen splasing by addition of dolomitic lime.
A good strategy would be to plan for Continuous Improvement over several linings rather than thinking that one design change can be a silver bullet. Key is to study the wear profile, identify the wear mechanism and develop new lining design that addresses the wear area and wear meachanism; this should be repeated in several iterations over several linings as in "chaisng the hole". As one area is upgraded the weak link might move to another area of the vessel. EX: An upgrade of trunnions might shift the limiting zone to the cone or the slagline or the charge pad or the tap pad...
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