Temperature of Molten Metal Bath

[ChrisTech]

In a 3000 lb. bath of molten iron what kind of thermal gradients would you expect to see (if any) from the surface to the bottom? The top of the vessel is exposed to ambient air and the bottom and 4 sides are steel lined with alumina refractory. I am taking temperatures from the top of the bath using an immersion thermocouple and am getting around 2550 F. The metal stream pours from the bottom of the vessel. Will this stream temperature be hotter than the surface temperature?

 

[Maui]

Is it simply iron or is it an iron alloy? How are you melting it? Do you perform processing with an electric arc furnace, or some other type of equipment? Is there a slag on the surface of the bath? Is there any ability to perform mixing in the bath such gas injection to promote stirring and therefore improve temperature uniformity? These types of questions need to be addressed in order for us to provide you with a meaningful answer.


Maui

 

[ChrisTech]

Iron Alloy -- Class 30 Gray Iron (~4.20 CE)
Melting -- Coreless induction furnace
Vessel is non-heated
Slag is removed after filling the vessel
No mechanical stirring action
New iron is added every 8 minutes

 

[IRstuff]

How thick is the alumina?

TTFN

 

[Maui]

I will assume that you are transferring the iron to a ladle from your coreless induction furnace, and that this ladle is the vessel that you referred to in your thread. The temperature of the alumina refractory will be approximately the same as that of the liquid iron. Since the iron is exposed to the atmosphere at the surface of the vessel with no slag to insulate it, there should be a transition zone where a temperature gradient does exist at this surface. This gradient would become larger the longer the liquid sits in the bath. If the vessel is re-filled every eight minutes, then I will also assume that you are teaming the contents of the ladle into a pattern or mold. Since you state that your temperature readings are taken by actually immersing a thermocouple into the bath, it is unlikely that there will be a significant temperature difference between the bottom of the vessel and the point near the surface where you take your readings. And by significant, I mean less than 50 degrees F. So yes, the stream temperature may be slightly hotter than the surface temperature, but the difference is not likely to be significant unless the bath temperature is very close to the solidus temperature.


Maui