Snap Flasks would be the way to go. Just mold up the sand and then unlatch the flask and take it off. That way you can make up several molds with only one flask. Maybe XL can post another picture of his, they are pretty simple to make. You would need several molds ready, once the Iron starts flowing.
Looking at the pictures, you may need more air into the tuyere. Or a larger pipe from your blower. Scrap cast should be easier to melt than ore since the cast has Carbon and Silicon in it and has a lower melting point. Runs like water once it melts.
Keep us informed of your progress.
someday Ill be melting iron, hopefully anyway.
