[eric2011 (OP)]

Hi

I have a question regarding Iron oxide/aluminum thermite. After I ignite the thermite reaction and after a minute when molten lava is remained in the flower pot, how can I retain that yellow lava state for a long time say ciuple days without cooling at all?. Like putting something on a thermos and it can stay hot for a long time

What material can I use to conduct this experiment which can insulate and keep it hot for a long tume? Any ideas are welcomed

[chiralSPO]

Keeping "lava" molten for long periods will require either amazing insulation, or a lot of energy.

As I understand it, the "lava" you are asking about is liquid iron. Because it is a metal, it is both excellent at emitting radiation, and conducting heat. You would need a very good thermos to prevent it from cooling quickly (and it would need to be stable at high temperatures). Also, you would not be able to see it glowing, because allowing that energy to escape as light would be the main way that it cools if you were able to sufficiently reduce cooling through conduction and convection.

Which brings me to the second option: store it in a furnace like this one:

furnace.jpg (31.73 kB . 500x350 - viewed 3171 times)

You wouldn't even need to do the thermite... just put iron in there, turn up the heat, and voila!

The last option (not recommended), is just to scale up dramatically. If you set off a couple hundred tons of thermite, it would probably glow for days!

[syhprum]

I have seen pictures of industrial plant where they store molten Iron in special insulated containers and transport it to a different part of the plant by rail.
I recall an accident when water got into one of the containers causing an explosion killing several workers

[Bored chemist]

Because it is a metal, it is both excellent at emitting radiation,

Erm, actually, no. Shiny things are poor at radiating heat.

I have seen pictures of industrial plant where they store molten Iron in special insulated containers and transport it to a different part of the plant by rail.

The biggest factor in their favour is that they do it on a big scale.
That way, most of the metal is "far" from the surface and can't cool so quickly (you can look up the stuff on surface are to volume ratios to get the maths if you like)

That's entirely consistent with the first reply here.

Keeping "lava" molten for long periods will require either amazing insulation, or a lot of energy.

[chiralSPO]

Quote from: chiralSPO on Yesterday at 19:18:31
Because it is a metal, it is both excellent at emitting radiation,
Erm, actually, no. Shiny things are poor at radiating heat.

Oops! You're right! I knew that...

But I stand by the rest of my post. (and as metals go, iron is pretty emissive... https://www.engineeringtoolbox.com/emissivity-coefficients-d_447.html)

[evan_au]

Yesterday I started reading a book "How to..." by Randall Monroe (better known as the author of the xkcd cartoons)*.

He addresses the closely-related question of "How to surround your home with a lava moat".
He calculates that to have a nicely glowing lava at 900C, it will radiate about 100kW of power for every square meter of surface area, or about $10/hour in electricity per square meter.

*Highly recommended for science nerds

[Bored chemist]

Yesterday I started reading a book "How to..." by Randall Monroe (better known as the author of the xkcd cartoons)*.

He addresses the closely-related question of "How to surround your home with a lava moat".
He calculates that to have a nicely glowing lava at 900C, it will radiate about 100kW of power for every square meter of surface area, or about $10/hour in electricity per square meter.

*Highly recommended for science nerds

Suitable glazing might be able to keep the power consumption down a bit.
https://en.wikipedia.org/wiki/Insulated_glazing

[Petrochemicals]

Quote from: chiralSPO on Yesterday at 19:18:31
Because it is a metal, it is both excellent at emitting radiation,
Erm, actually, no. Shiny things are poor at radiating heat.

Oops! You're right! I knew that...

But I stand by the rest of my post. (and as metals go, iron is pretty emissive... https://www.engineeringtoolbox.com/emissivity-coefficients-d_447.html)

I must say that metal looses heat faster than other subsoances, what ever colour. Cars often have frost on them, where as wheelie bins do not. No difference in convection currents, nor ground heating, nor content insulation.

I doubt also it is latent heat in condensation either. I suspect in convection metal sheds heat far easier, and it would have to too as its thermal mass is far denser. Perhaps something to do with electronic conduction of nmetals ?

[Bored chemist]

A car made from steel as thick as the plastic lid of a wheelie bin would be rather heavy.

It remains the case that shiny things have low emissivity
If they didn't, it would let you build a perpetual energy machine.

The more formal formulation of the statement can be found here
https://en.wikipedia.org/wiki/Kirchhoff%27s_law_of_thermal_radiation

[evan_au]

As I understand it, the lava pool from thermite consists of iron metal, and aluminium oxide.

Does the aluminium oxide affect the thermal radiation significantly?

[evan_au]

how can I retain that yellow lava state for a long time say ciuple days without cooling at all?

I can understand the average arch-villain wanting a lava moat around their lair - but why do you want this?

[chiralSPO]

Given the member's previous posting history, my guess is that they are trying to grow gemstones...

[Bored chemist]

Does the aluminium oxide affect the thermal radiation significantly?

Yes, and not in a good way.

Given the member's previous posting history, my guess is that they are trying to grow gemstones...

Given the presence of iron and air, this is about as good as it gets.

https://en.wikipedia.org/wiki/Emery_(rock)

Edit: repaired a link.