Research question about burning metals and their flashes and colors

[BenkeiDNA]

I work for municipality with urban management and i have a interest for the environment, and have become fascinated with metals. Together with a engineer i will be making a report about metal reactions etc. So i would like to get you guys take on these questions that i have in mind for my report.

1. When you have flashes from metals that are burning, like from magnesium, aluminium or iron, how often should you see the flashes, and what will the duration of the flashes be?, can any of these 3 metals when molten flash 6 times in lets say 8 seconds?, with the longest duration of one flash beeing 0.87s?. And is it possible for any molten material falling in the air to give off these flashes because of rapid vaporization of the water in the air when the water vapor in the air is at normal levels of 68% RH and not 100% RH or is this extremely unlikely?.

2. If within minutes the oxygen in a fire zone is depleted, and you have some molten iron pouring, could metallic alloy magnesium get mixed somehow with the molten iron in a fire, and while the molten iron was pouring and flowing in the air with a orange color, could the alloy magnesium then from the falling and flowing molten iron in the air make a couple, lets say 6 flashes, in short time of 8 seconds, white flashes from inside of the molten iron?, like the burning specks of burning magnesium in a foundry with oxygen that flash white while they burn?, or is this not how alloy magnesium behave?. I am told that a magnesium rod, about 1 cm in diameter, will not ignite in a Bunsen burner flame, even with prolonged heating. Magnesium burns to produce magnesium oxide. That product is quite inert by normal conditions. It does not flash nor will it burn, i am told.

3. And my next question about magnesium is not about any flash effect, but about a flame effect. If you have an unusual flame visible within a office fire, a very bright white flame, as opposed to the typical yellow or orange surrounding regular flames, this would suggest that some type of metal is burning, i know aluminum will burn, but in normal fires it usually melts instead because the metal surface is protected by an oxide layer that must be breeched before ignition can take place. Aluminium oxide melts at 2072C that typical office fires will not reach. But do you think that the burning of alloy magnesium in a regular office fire could explain a very bright white flame?. I am told that metallic magnesium can be difficult to ignite depending on it thickness. That a magnesium rod, about 1 cm in diameter, will not ignite in a Bunsen burner flame, even with prolonged heating. Magnesium burns to produce magnesium oxide. That product is quite inert by normal conditions. It does not flash nor will it burn, i am told. So maybe it would haft to be some form of hot reaction that made the white flame, and not alloy magnesium by itself?.

4. If within minutes the oxygen in the fire zone depleted, and the pace of burning was regulated by the area available for venting the hot exhaust gases, and the area available for the entry of fresh air. And forces of impact and explosion could have broken some of the aluminum in the building into small granules and powder. Chemical reactions with hydrocarbon or water vapors might have occurred on the surfaces of freshly granulated hot aluminum. And lets add in this hypothetical scenario that there was strong 35 mph winds that through a large hole turned the building into a large blast furnace. Since iron can be made molten in a small furnace only 12 feet high, one that was several stories high with plenty of fuel and air would maybe have some effect on the fire so that some amounts of molten iron could be produced?, but i am not sure?, how powerful would the winds haft to be to have any effect on the fire on the steel in a scenario like this?, would 35 mph be enough?, and if the winds where much lower, maybe 10 mph, they would have zero effect on the fire?, please speak a little about this possible wind effect on a fire.

5. I also wonder what happens when aluminium is molten and flowing and falling down in the air, if the molten aluminium will have a orange or silver color as it falls down in the air and if it will remain orange during its whole descent or if it will have a silvery color the whole time. I once saw aluminium being heated in a container to 980c or 1800 F and you could see that it cools rapidly to a silvery colour, it didnt have any orange color. I also saw when they added organic materials to the molten aluminium and it floats on the liguid aluminium and burns up (oxidizes), it didnt change the silvery color of the aluminium. Rapid cooling of aluminum does produce a silvery looking "precipitate" for lack of a better word right now. As i understand it they would only stay molten for as long as they're above the melting temperature and flowing, once it stops flowing it begins to cool even faster than it already is. But while it's falling, could it have the molten orange color or not is the question, i know iron will have orange color when molten and falling in the air, but now i want to find out if the same is true for aluminium. I heard that aluminium only rapid cools when it's standing, because it's flowing, the silver is an oxidized layer, it can't form that layer if the surface it's constantly being broken up. I guess this also could depend on flow rate. Personally aluminum sparks which are small particles of aluminum burning i have only seen burn silver or white, no orange color. Even if we look at the scenario in question number 3, and some explosion impact had broken some of the aluminum in the building into small granules and powder and chemical reactions with hydrocarbon or water vapors might have occurred, this would still not change the silver color of any molten aluminum into a orange color while it was falling in the air, and would not make it flash either?, like the effect i described in my first question with 6 flashes in 8 seconds from a orange melted material falling in the air?.

Edited February 3, 2020 by BenkeiDNA

[Bufofrog]

7 minutes ago, BenkeiDNA said:

When you have flashes from metals that are burning, like from magnesium, aluminium or iron, how often should you see the flashes, and what will the duration of the flashes be?, can any of these 3 metals when molten flash 6 times in lets say 8 seconds?,

I am not sure what you mean by flashes, could you expound on this?

[BenkeiDNA]

2 minutes ago, Bufofrog said:

I am not sure what you mean by flashes, could you expound on this?

Yes, for example there is metallic flash powders, and nano poweders of aluminium that can flash in exotic reactions, but when we think of only metals that are burning or melting it is less likely that there are any flashes, and im trying to figure this all out, what would and would not flash, i am told that there is white flashes when magnesium burns with oxygen due to the extremely high temperature of the flame, making it look white. The burning specks of magnesium with oxygen flash white while they burn, leaving a white MgO-powder when all of the magnesium has reacted with oxygen. But i dont think regular magnesium alloys that are burning in like a office fire would make flashes or make a very bright white flame. As i said in the post above also "I am told that metallic magnesium can be difficult to ignite depending on it thickness. That a magnesium rod, about 1 cm in diameter, will not ignite in a Bunsen burner flame, even with prolonged heating. Magnesium burns to produce magnesium oxide. That product is quite inert by normal conditions. It does not flash nor will it burn, i am told.". 

[Bufofrog]

2 minutes ago, BenkeiDNA said:

i am told that there is white flashes when magnesium burns with oxygen due to the extremely high temperature of the flame, making it look white.

I have ignited a strip of magnesium foil and it didn't have any flashes as it burnt.  I looked at couple of you tube videos and I didn't see any flashes.  Powders will flash, which is probably due to the uneven amounts of powder the fire front encounters.

You talk about office fires, is this related to specific event of scenario?  If not it would be best to leave out the office part as it only confuses the situation IMO.

[BenkeiDNA]

13 minutes ago, Bufofrog said:

I have ignited a strip of magnesium foil and it didn't have any flashes as it burnt.  I looked at couple of you tube videos and I didn't see any flashes.  Powders will flash, which is probably due to the uneven amounts of powder the fire front encounters.

You talk about office fires, is this related to specific event of scenario?  If not it would be best to leave out the office part as it only confuses the situation IMO.

It was a foundry guy that told me this about that when magnesium burns with oxygen and extremely high temperatures, maybe its different somehow in their foundry due to the extreme heat, i don't know. He was talking about a magnesium wire.  

The scenario i am thinking about, and thats why i mention a fire in a office, is when the molten metal escapes the room and falls in the air through a open window. How would it react in those conditions, when falling in the air molten, and then after we think about the color and what is possible or not regarding flashes from the metal itself, we can add the rapid vaporization  effect of water in the air, but under normal conditions/leves like i said, i wonder if it still would be possible with any flashes then from the water. 

Edited February 3, 2020 by BenkeiDNA
forgot text

[Bufofrog]

11 minutes ago, BenkeiDNA said:

The scenario i am thinking about, and thats why i mention a fire in a office, is when the molten metal and materal escape the room and falls in the air through a open window. How would it react in those conditions, when falling in the air molten, and then after we think about the color and what is possible or not regarding flashes from the metal itself, we can add the evaporation effect of water in the air, but under normal conditions/leves like i said, i wonder if it still would be possible with any flashes then from the water.

I would not expect there to be large amounts of molten metal in an office fire, certainly not enough to pour out of a window.  Again the whole office fire thing is not important, I assume.  What is your question?  Is it something about how a stream of molten metal (a specific metal?) will react with the air or water or what exactly

[BenkeiDNA]

22 minutes ago, Bufofrog said:

I would not expect there to be large amounts of molten metal in an office fire, certainly not enough to pour out of a window.  Again the whole office fire thing is not important, I assume.  What is your question?  Is it something about how a stream of molten metal (a specific metal?) will react with the air or water or what exactly

I have the 5 detailed questions as above. But yes i wonder if it is very unlikely that molten metals will give off flashes as a result of the water effect in the air that i mentioned, with normal levels of water vapor in the air, 68% RH. And i want to know the effect of 10 mph winds compared to 35 mph on burning steel, if there would be any chance at all for the steel to become molten in a office fire with destroyed windows or a hole in the wall if the wind of 10 mph came into the burning office. These two questions of water vapor and winds are important for me.  

Edited February 3, 2020 by BenkeiDNA

[Strange]

41 minutes ago, Bufofrog said:

Powders will flash, which is probably due to the uneven amounts of powder the fire front encounters.

Also because they are finely divided and will bur very rapidly. Small amounts of flour or sawdust dispersed in the air with a flash (or an explosion, for larger amounts, so don't try this at home).

1 hour ago, BenkeiDNA said:

1. When you have flashes from metals that are burning, like from magnesium, aluminium or iron, how often should you see the flashes, and what will the duration of the flashes be?,

It depends on whether they are also being mechanically dispersed at the time. For example, burning a strip of magnesium will not cause any flashes. But if it were being torn apart or something, so that fragments got thrown off, then it could.

1 hour ago, BenkeiDNA said:

can any of these 3 metals when molten flash 6 times in lets say 8 seconds?, with the longest duration of one flash beeing 0.87s?.

It is impossible to answer something this general. It has almost nothing to do with the type of metal. I'm sure you could build a mechanical devices which knocked off chunks of burning metal about once per second (with those bits being small enough to burn in less than a second). Could that happen in a building fire? Possibly.

1 hour ago, BenkeiDNA said:

And is it possible for any molten material falling in the air to give off these flashes because of rapid vaporization of the water in the air when the water vapor in the air is at normal levels of 68% RH and not 100% RH or is this extremely unlikely?.

Water vapour in the air is already vapourised. 

And I'm not sure why water vapour would cause these flashes.

1 hour ago, BenkeiDNA said:

Together with a engineer i will be making a report about metal reactions etc.

Why are you writing a report you know nothing about? Why not employ an expert?

[BenkeiDNA]

5 minutes ago, Strange said:

Why are you writing a report you know nothing about? Why not employ an expert?

It is not me writing the report, its an educated engineer, but i am doing some research and asking around to get some better ideas of how i want things explained in the report.

When you say that water vapour in the air is already vapourised, i am told that the heat from the metal can have some effect on the water so there could be a quick speck of light rather than a continuous light emission. You'd need high speed camera zoned in to high res to see it.

Edited February 3, 2020 by BenkeiDNA

[Strange]

6 minutes ago, BenkeiDNA said:

When you say that water vapour in the air is already vapourised, i am told that the heat from the metal can have some effect on the water so there could be a quick speck of light rather than a continuous light emission.

Not an effect I am aware of. Nor can I imagine a mechanism where the level of water vapour would affect molten metal.

If there were a mist of water droplets in the air then I can imagine that coming into contact with a hot surface might have some small effect.

13 minutes ago, BenkeiDNA said:

I have the 5 detailed questions as above.

They are bizarre and oddly specific. What are they based on? 

1 hour ago, BenkeiDNA said:

4. If within minutes the oxygen in the fire zone depleted, and the pace of burning was regulated by the area available for venting the hot exhaust gases, and the area available for the entry of fresh air.

If the oxygen was depleted, then the burning would stop.

[Bufofrog]

2 minutes ago, BenkeiDNA said:

i am told that the heat from the metal can have some effect on the water so there could be a quick speck of light rather than a continuous light emission. You'd need high speed camera zoned in to high res to see it

Do you have a source for this or is this something you heard somewhere?  

it is difficult to answer questions about how the wind would effect burning steel in an office fire when a piece of steel doesn't burn.

You need to formulate a better question.

[studiot]

Just now, Bufofrog said:

You need to formulate a better question.

+1

Just now, Strange said:

They are bizarre and oddly specific. What are they based on? 

+1

 

Folks are trying to help you here but you definitely need to clarify your thinking.

Perhaps if you were to base your question(s) on conventional fire analysis that would help.

Are you aware of the concept of 'fire load' ?

https://www.google.co.uk/search?source=hp&ei=5Cc4XvKACceHjLsP66ShwAs&q=building+fire+load&oq=building+fire+load&gs_l=psy-ab.3..0i22i30l2.2066.5876..6192...0.0..0.1094.7148.0j2j3j3j2j0j4j1......0....1..gws-wiz.......0i131j0j0i3j0i13j0i13i5i30j0i8i13i30.c-32UuhPEzk&ved=0ahUKEwjygsT1xbXnAhXHA2MBHWtSCLgQ4dUDCAc&uact=5

[Strange]

1 hour ago, BenkeiDNA said:

5. I also wonder what happens when aluminium is molten and flowing and falling down in the air, if the molten aluminium will have a orange or silver color as it falls down in the air and if it will remain orange during its whole descent or if it will have a silvery color the whole time.

The colour of a hot material depends on the temperature. In the case of aluminium, the melting point is sufficiently low that it could be barely glowing and would appear silver, like the metal. But if it is hotter, it will appear red, orange and eventually white.

Iron has a much higher melting point so, when molten, it will always be reddish at least.

2 hours ago, BenkeiDNA said:

once it stops flowing it begins to cool even faster than it already is.

I would imagine that the static material would cool more slowly because when it is flowing it comes into contact with more cool surfaces and cool air, plus it is being "stirred" by the motion so that heat will be dissipated from inside the volume of liquid more quickly.

 

[BenkeiDNA]

On 2/3/2020 at 2:52 PM, Bufofrog said:

Do you have a source for this or is this something you heard somewhere?  

it is difficult to answer questions about how the wind would effect burning steel in an office fire when a piece of steel doesn't burn.

You need to formulate a better question.

In extreme cases, for example in the case of a well-ventilated fire with a chimney effect (or the 35 mph wind effect i said before), the fire temperature, which is normally 800-1000 degrees, may rise to a few hundred degrees more i was thinking, if the fire is directly on the steel, it might make some molten iron i was thinking?, but if the fire only last lets say 20 min, it might be much more unlikely?.

And If there were strong winds of 35 mph at high altitude, and a molten material and its sparks fell out of a window down through the air, then should not these 35 mph winds make this material and its sparks travel sharply to the left or right so that it was not possible for the material to fall straight down a straight line?.

Edited February 4, 2020 by BenkeiDNA

[Bufofrog]

2 hours ago, BenkeiDNA said:

In extreme cases, for example in the case of a well-ventilated fire with a chimney effect (or the 35 mph wind effect i said before), the fire temperature, which is normally 800-1000 degrees, may rise to a few hundred degrees more i was thinking, if the fire is directly on the steel, it might make some molten iron i was thinking?, but if the fire only last lets say 20 min, it might be much more unlikely?.

Steel is an alloy of iron, so subjecting steel to heat will not make molten iron, it will make molten steel.  Steel melts well above 1000 C so the steel would not melt.

 

2 hours ago, BenkeiDNA said:

And If there were strong winds of 35 mph at high altitude, and a molten material and its sparks fell out of a window down through the air, then should not these 35 mph winds make this material and its sparks travel sharply to the left or right so that it was not possible for the material to fall straight down a straight line?.

Yes, the wind would blow the Sparks through the air.  

[BenkeiDNA]

1 hour ago, Bufofrog said:

Steel is an alloy of iron, so subjecting steel to heat will not make molten iron, it will make molten steel.  Steel melts well above 1000 C so the steel would not melt.

 

Yes, the wind would blow the Sparks through the air.  

What could be found in a tall building that when molten could produce molten iron?. 

[StringJunky]

51 minutes ago, BenkeiDNA said:

What could be found in a tall building that when molten could produce molten iron?. 

Iron is a structurally weak metal compared to steel, so I could only see it being used for something like ornamental castings in/on the building.