This afternoon I tested my Frosty T burner for melting cast iron. It appeared that it heated more slowly despite using the same propane pressure (30 psi), so after 20 minutes (indoors the furnace it was 1370 C) I swapped burners to an air forced burner which I used previously. Other nice test as I attached quick couplings / shortcuts to both burners and the propane tank. That makes even hot swapping (when the furnace is hot) easy, within a minute. Then the temperature rose to 1450 C but when I decreased gas pressure to 22 psi the temperature rose further to 1530 C. Inside the crucible it is somewhat cooler (1400 C). Flame too rich ? Anyway, the iron was ready within a few minutes and it showed a lustrous mirror below the slag. So I poured and the result was nice. It was the same 2mm thick round lid of 75mm (3") diameter with an edge. Earlier attempts failed even without risers and a central entry point. On both bronze or cast iron. Now I made four risers (actually made as air vents) which all filled. So the way to go is a central sprue and four vents which act as risers. https://www.metallab.net/jwplayer/video.php?f=/forums/ironcast-20211023.mp4
