Research question about burning metals and their flashes and colors

[BenkeiDNA]

TL;DR Summary

metals, reactions, flashes, iron, magnesium, aluminium, molten, fire, colors.

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 let's 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, let's 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 let's 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?.

 

[BenkeiDNA]

Regarding flashes, 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 I am 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 don't 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.".

 

[anorlunda]

Are you asking about the physics of fireworks? If not, I can't imagine a municipal interest in those questions. I also find it hard to imagine how the answers to these questions could relate to a municipal ordinance or urban management.

A dominant factor in most fireworks is that the ingredients include oxidizers that provide oxygen independent of the oxygen in the air. Think of a bullet. Clearly there is no air inside the cartridge, so how can it burn? The answer is oxidizers in the ingredients.

 

[BenkeiDNA]

Are you asking about the physics of fireworks? If not, I can't imagine a municipal interest in those questions. I also find it hard to imagine how the answers to these questions could relate to a municipal ordinance or urban management.

A dominant factor in most fireworks is that the ingredients include oxidizers that provide oxygen independent of the oxygen in the air. Think of a bullet. Clearly there is no air inside the cartridge, so how can it burn? The answer is oxidizers in the ingredients.

I haven't said that there is any municipal interest in these questions. Its my private interest. I am not talking about fireworks as you know if you read the questions, its about the color and flash effect of metals, you can read that i am talking about alloys and stuff.

 

[berkeman]

I haven't said that there is any municipal interest in these questions. Its my private interest. I am not talking about fireworks as you know if you read the questions, its about the color and flash effect of metals, you can read that i am talking about alloys and stuff.

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.

Out of curiosity, who is this report targeted at? What type engineer are you working with on it? (EE, ME, ChemE, etc.?) What is your technical background? Knowing the answers will help us to try to get you better information. Thanks.

 

[BenkeiDNA]

It is a ChemE that will be doing the report. I don't have a background in chemistry or engineering myself. The report will try to show how and why certain things cannot flash and behave certain ways when burning, and show the limited, of limited, possibilities with some reactions and colors of molten metals etc, is the best way i can describe it, what it will be about.

 

[256bits]

1. What is this flash you are talking about? A sudden increase in brightness? Maybe investigate and explain. I do not comprehend why there should be a timetable to their occurrence, or duration down to the 0.87 seconds. Where is that coming from?
2. A flash in molten iron. Do iron and magnesium react with one another?
3. The integrity of the protective layer can be breached when the metal is molten.
4. Moving air brings in fresh oxidizer, which in this case would be oxygen.
5. Aluminium oxide is in granular form a white powder. Corundum, a crystal of the oxide, is transparent, but the color for ruby or sapphire us due to impurities. Depending in the oxide layer thickness over the metal one might see some color.

It was mentioned that a magnesium rod would not burn. ( For some reason three times ) It is difficult, that us true. A spot that does ignite, may self-extinguish once the flame is removed, owing to the fact of heat removal along the rod to the cooler end. and or radiation, thus cooling the flame. If the whole rod is brought to near ignition temperature, magnesium oxidation could be stimulated on a large enough area so that the flame front travels along the rod.

Steel wool easy to ignite and burn due to the large surface area available for combustion.

Do note that magnesium will also continue burning under water and in a carbon dioxide environment.

 

[BenkeiDNA]

I will write the most important questions in a better way for you.1. Can iron somehow in a fire below 1538C under any conditions without any powder/material mixtures added melt?, like for example in a hypothetical scenario if 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 by the fire touching the steel, this i don't know if it is true or not, but i would like for us to find out, 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, would they then have zero effect on the fire?. And the same question for aluminium in a fire below 1200C. I am told that temperature is a terrible way to think of heat transfer. That a 1500C fire means nothing to a chemist. That what matters is how much energy is being produced, how quickly its being transferred, where its being transferred to, and how quickly the object that is collecting that energy is dissipating that energy. That a chemist would try to figure out the heat capacity of the system (how much energy it takes to raise the temperature by one degree), then calculate how much energy is being produced. If it’s a closed system, this is easy. If it’s an open system then you need to factor in Newtonian cooling. Once this is all factored in, then you can hypothesize the temperature of the object you wish to study. Explanation of how if you had enough cotton balls and oxygen, you could make iron melt, this scenario i know is true. The rate of the combustion reaction is the determination of how much energy is produced (and thus temperature of the surroundings). Steel melts at a lower temperature (~1300C). And explanation of if much oxygen instead was pulled out of the air, for example, If within minutes the oxygen in a fire zone is 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, how it then would make the melting of iron extremely unlikely, and also write about if the same then is true for aluminium even at its lower melting point then iron. As i understand it a flame temp of 1000C will not produce a temp of 1000C in anything it contacts without very prolonged exposure. The greater the thermal conductivity of the object exposed to flame the longer it will take to heat it up. If fires for exampel dies out after 20 minutes in one place, then it would be hard for the fire to produce any molten metals i think.

2. 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. I can't think of how magnesium in a regular office fire could explain a very bright white flame like this. 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. Would it maybe require some exotic powder or material to create such a strong bright white flame?, at least we should be able to rule out a couple of metals that could be behind this, i don't think iron, magnesium or aluminium could be behind it, and maybe it would need some very high temperature?, and if there where white plumes of smoke coming from it, could that be explained by some kind of reaction?, or is the fact that white plumes of smoke only can be explained by paper and paint burning and nothing else?.

3. If we look at a scenario in where there is some kind of explosive impact that 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 i think as i am told by foundries that work with aluminium that ""Aluminum when taken past the melting point will have a very dull red glow to it but as you stated, it returns to silver very quickly. At no point does it resemble molten iron or steel, which is almost yellow in color and throws a considerable amount of sparks. Aluminum sparks which are small particles of aluminum burning should always be silver or white, no orange color." but would it still not make any flashes as regular Al won't do in a fire is the question, and what would happen if such a Al powder that was mixed with hydrocarbon got mixed with molten iron and started to fall down in the air?, would it flash or not. The flashes of powder aluminium or sparks occur when the small particles burn (or oxidize) in the air. Similar to sparklers used for special events. A sparkler consists of a gunpowder tye of material mixed with powdered metal and molded with wax or a similar material. As it burns, the burning metal sparks give the sparklet effect. But could such sparks occur from the mixture of it in the molten iron?. We can look at three scenarios here, regular aluminium alone beeing melted, the aluminium powder beeing created by an explosive impact and how it could behave in a fire alone and when falling in the air and then how the Al powder would react and behave and look when mixed with molten iron, even if molten iron should not be present in a office fire we still look at these scenarios with the iron in this way.

4. When you have flashes from metals that are burning/melting, how often should you see the flashes, and what will the duration of the flashes be?, can any regular metals not in powder form when molten flash 6 times in let's say 8 seconds?, with the longest duration of one flash beeing close to let's say one second 0.90s?, is there any general information regarding this that could tell us what one should expect regarding flashes?. The likelihood of certain metal powders making flashes under the right conditions, together with the unlikelihood of regular metals that are burning or melting making flashes i will have included in my report. I know that iron don't flash, and that magnesium can't mix with molten iron in a fire and flash from it, and that regular aluminum that is not in powder form don't flash.

 

[berkeman]

in a better way for you.

(wall-o-text is better?)...

 

[BenkeiDNA]

(wall-o-text is better?)...

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 let's say 20 min, it might be much more unlikely?.

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?.

 

[Rive]

It is a bit difficult to understand your question - maybe because you yourself does not really know yet what do you want to ask and how.

Let's just throw in something about flames and metals (ions).

There is an experiment called 'flame test'. This works at relative low temperature, and metals (or other materials) does not have to melt: yet it produces nice, easily recognizable colors.

Does this help to re-phrase your inquiry?

 

[256bits]

chimney effect

There are such things as forges that blacksmiths use to heat metal so that the metal becomes softer to form into a shape usually by pounding it. Heard of horse shoes, made of steel, for example.
Wood, charcoal, coal, or any combustible for that matter, have each a particular flame temperature which cannot be exceeded. The adiabatic flame temperature is that which would have no heat loss to the environment, which of course does not occur in actual practice - the flame temperature would be lower.
Blowing on the combustible increases the rate of oxidation. If the heat loss to the environment of an object subjected to the flame is less than the heat gain from the flame, the objects temperature will increase, which is what blowing on the combustible attempts to do.

Here is a discussion on adiabatic flame temperature.
In real life, which is what your questions are about, there is not a complete answer due to the fact that the environmental conditions are not known. A reply answer could be yes no, or maybe depending upon the actual facts of the scenario.
https://en.wikipedia.org/wiki/Adiabatic_flame_temperature

One answer to ,

an unusual flame visible within a office fire, a very bright white flame,

The adiabatic flame temp of magnesium is 1982 C in air.
Yet, some of the hydrocarbons come very close to that value, or exceed it if pure oxygen is supplied.
Conclusion is that the unusual office flame combustible is indeterminate. More facts would needed and accessed for investigators.

You still did not say anything about what a "flash" is.

 

[anorlunda]

I will write the most important questions in a better way for you.

174 people have read your question so far, and none of us understand what you're talking about.

Unless you can explain better what you are trying to do, helpful replies are not likely.