I am melting ferro alloys with mild steel to form a specific composition But the final product has high sulphur content leading to detrimental inclusions.
Is any way or industrial practice to reduce sulphur content of ferro alloys eg. Fe-Si (S>0.05%) ?
Hi,
Either you can modify the inclusion size and shape to avoid detrimental effects or you can maintain a adequate desulfurization environment during melting (Flux=CaO).
/Me/ + / S/ = (MeS)
(CaO) + /S/ = (CaS) + /O/
Your options are here,
1. Choose perfect raw materials such that your initial sulphur is well below the allowable limit.
2. Remove the sulphur by slag metal reaction. Add few gram of lime or dolomite and keep the liquid metal at high temperature preferably 1873 K for 15-20 mins and remove the slag before casting.
3. Even then you are not satisfied, go for inclusion modification by adding reactive elements like Ca, La, Ce etc...such that detrimental effect could be eliminated.
Ashok Nice suggestion but holding the melt for 15-20 mins will affect the chemistry of melt as the deoxidising alloying elements will reduce
Dear Kritika,
The best way is by adding desulphurization reagents creating a slag which can easily be removed by tilting the ladle and rake the slag off with the help of a slag raking.
The most commonly used desulphurizing reagents are lime (CaO), calcium carbide (CaC2) or magnesium (Mg).
Please find enclosed a website describing the process.
http://ispatguru.com/desulphurization-of-hot-metal/
Hi Kritika,
Assuming that you are using submerged arc furnace and tapping the molten metal in a ladle, I suggest the following trial.
You may put CaC2 lump in the ladle just before tapping and tap the molten metal over it. You have to take care of the violent reaction during tapping; one way is to continuous throw small amount till the ladle is half full.
I would be interested to know your trial results.
Definitely it will reduce the alloying elements. but the primary condition for desulphurization is you have to maintain the reducing atmosphere. therefore, deoxidation of steel is must and at the 15 min you may check the composition bt taking lollypop sample and go for trimming alloy additions.
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