Post on 15-Jul-2015
ARAVIND GOLI
The removal phosphrous should be done after the removal silicon only
The one most important removal material during the processes of steel making otherwise it forms a iron phosphide its brittle in nature.
In Ellingham diagrame Fe and p are clos to each other.These lines widely can separated by adding storng basic flux i.e LIME
For effctive removal p ,we have to employ “high basicity”.Basicity incresed by adding lime
Soda ash is 100 times superior to lime but in practise we don’t prefer bcoz of its high corrosive action
Phosphorous oxidation is Highly exothermic reaction
The low temparatures are best suitable for removal phosphorous bcoz at higher temparatures the Reversion of phosporoustakes place.
Dephosphorising index(DP):it’s the ratio of phophorous content in the slag to phophorous content in the metal.
Its higher for high basicity slag and higher for oxidising of slag.
Dp propotional to basicity & Iron oxide(Feo) and inversely propotional to the TEMPARATURE
De phophosrization done under oxidising conditions only
If silicon is less den sulphur content high vice versa in pig iron
If less temp in the blast f/c the silicon reduction decresed,it leads to more viscous slag
Cac2,Cao,Na2o…etc,these are elements mix in pig iron to remove the sulphur
The maximum level of sulphur is 0.020%
Sulphur we have to maintain as low as possible 10ppm(0.001%)
If the temparature of the blast furnace is high,leads to high silicon content in the pig iron since at high temparature silica reduction is incresed
De-siliconized by
Laddle de-siliconizing by oxygen lancingin a transffer laddle
In active mixer by maintaing a suitable basic salg
In acid bessmer proccesse by partial blowing
We can remove the silicon by adding flux
Now a days removal of silicon takes place by “Tarpedo laddle”
Hot metal is taken in tarpedo laddle,scarpadded to it the reactions takes place during the processes and forms slag its skimmed off….