Iron wreck temperature 30 oC fed into the electric furnace , 20 minutes later the temperature to 150 ° C . when the casting temperature 1200 o C , how long the iron melting process in an electric furnace in the air at the time when tempelatur 270C .

you want to try that again in complete sentences? The fragment

when the casting temperature 1200 o C

is bogus

If this is a linear heat increase, no calculus is needed. If not, what model are you using?