Do you mean that you wish to melt pure iron with 3% Si,with very low carbon? It should be brittle I suppose, You can use knock off risers/feeders. Hence no need to flame cut the gates and risers.
Interesting application,what is it used for and will there be any machining? I plan to process a small quantity out of curiosity perhaps tomorrow.
I shall then share a few more experiences. As the metal is low in carbon,most of the silicon addition might be consumed as a degasser. You may need to compensate for this loss.
Hope this helps.