Usage method
For 0-5 T furnace use:
While a small amount molten iron in the furnace
Or with some molten iron remained. add the carbon additive one-time
Then add the other material
Which can make carbon additive fully absorbed.

For greater than 5 T furnace
Mix proper carbon additive with charging material as suggested first,
And then along with the increase of furnace charge down into the furnace inside gradually.
That is, before the molten metal rising up to about 2/3 height of furnace
All carbon additive shall be added
It guarantees sufficient melting absorbing time before molten metal out, and improves the absorption of carbon.