Is Iron Powder Flammable?

This article will answer the following question: “Is Iron Powder Flammable?”. We will also discuss important matters regarding iron ores, iron hazards, and some Safety Data Sheets.

Is Iron Powder Flammable?

Yes, iron powder is flammable. Although we can’t really see flames from iron powder, the reaction between iron powder and the air liberates heat, so we can say that iron powder is flammable and potentially dangerous.

What is Iron?

Iron is a metal, it’s solid and can be found in nature in the form of ores. Synthetically, it can be used to compose alloys. Pure forms of iron can be obtained industrially by chemical reactions.

It can’t melt until reaches at least 1500ºC/ 2738ºF.

Iron is tough, brittle, and fairly fusible. It is used to produce other alloys, especially steel. Minted iron contains only a few percent of carbon, but it enhances its durability, fracture resistance, and strength.

Pure forms of iron can’t really be found naturally, not originally. Although iron is common in meteorites, so we can find pure forms of iron that “naturally” came from extraterrestrial sources.

Iron has the ability to form many kinds of ores. Its chemistry is wide.

Steel is an alloy made with the addition of other minor compounds like manganese, nickel, sulfur, titanium, phosphorous, tungsten, cobalt, and niobium.

Stainless steel, although, is typically made by adding 11% chromium, making the material oxidation-resistant.

Iron is known since prehistoric times, at least 5 thousand years ago. It is the cheaper and most abundant of all metals.

Iron Chemistry

Iron is a kind of metallic atom that can suffer oxidation. By chance, this chemical reaction liberates energy, and that’s why iron can be considered an uncommon but possible source of fuel.

Iron has many special properties. It’s present in a wide variety of mixes, such as: in our red blood cells, in many kinds of plants, in the soil, and in any piece of steel. 

Iron powder, although, is considered in this article as a pure kind of iron, in a powder form.

Iron can form several alloys. These materials are what we often encounter commercially. The iron constituent in these products is what generates rust.

What is rust?

Rust happens when iron oxides, form a reddish-brown compound. The reaction is much more possible in the presence of liquid water, or air moisture.

Rust is composed of many kinds of iron oxides, especially ferric oxide. It is a result of the iron alloys’ oxidation. 

It’s important to say that every rust is a result of oxidation, but not all oxidations result in rust. The rust is just a byproduct of a chemical reaction.

Whenever a reaction produces rust, it also liberates energy. Although, we wouldn’t feel rust becoming warm to the touch because it takes a long time to happen.

But if we light a fire on iron powder we wouldn’t definitely feel it getting warmer, and even burning our skin. This is because an oxidation reaction took place in a short time.

Iron properties

Here are a few iron properties:

  • Phase at STP: solid
  • Melting point: 1538 °C, ​2800 °F
  • Boiling point: 2862 °C, ​5182 °F
  • Density: 7.874 g/cm3
  • when liquid: 6.98 g/cm3
  • Heat of fusion: 13.81 kJ/mol
  • Heat of vaporization: 340 kJ/mol
  • Thermal conductivity 80.4 W/(m⋅K)
  • Molar heat capacity: 25.10 J/(mol·K)
  • Oxidation states : −4, −2, −1, 0, +1, +2, +3, +4, +5,+6, +7

One of the most important iron properties is its high thermal conductivity. This is the main reason why our pans are made with iron materials.

This is the very same reason why iron is not a good fire insulation material. Even though metal bars and sheets are not flammable themselves, they can conduct heat that lead to a fire, if there’s another source of fuel nearby.

How flammable iron powder is?

The iron powder does liberate energy upon burning. Let’s analyze how big this energy liberation is.

We can only assess how flammable something is if we note how much energy it liberates, and compare it. Anything that’s considered flammable would liberate a good amount of energy in a short time.

Scientifically speaking, iron powder liberates around 4800J of energy for each gram of the compound. We can write it as 4800J/g, or 4.8kJg-1

Now we’re going to compare it with other fuels, imagining the same amount (1g) of them is burning. For example:

  • Carbon monoxide: 10103J (10.103kJ)
  • Wood: 21700J (21.700kJ)
  • Coal: 32500J (32.5kJ)
  • Alcohol (ethanol): 30000J (30kJ)
  • Diesel: 44800J (4.8kJ)
  • Gasoline: ~45000J (45kJ)

By simple comparison, we can say that iron powder produces half the energy carbon monoxide produces.

Wood is almost 5 times more combustible than iron powder. Coal and alcohol, almost 7 times. Gasoline, although, liberates 9 times more energy than iron powder.

We can assume then that iron powder is not flammable as other sources of fuel, but this doesn’t mean that it’s not a problem. 

For example, even though diesel unleashes much more energy than iron powder, diesel won’t catch fire spontaneously if we light a match and toss it on. Iron Powder would.

There are many ways to understand how flammable a substance is, but it’s not so easy to deduce its hazards. At least, note this: iron powder can be a fire hazard.

Is iron a fire hazard?

Well, it depends. As we saw, iron is flammable when in powder form. But the kind of fire that arises from it is not like other sources of fuel.

If you burn iron powder, it would happen quickly. There wouldn’t even be much time to extinguish the reaction. 

For comparison, a glass of gasoline burn as much as 1.35 kilograms (around 3 pounds) of iron powder.

It can become a fire hazard if direct flames are applied to it, or if you possess a big amount of iron wool to be burned, for example.

Also, iron powder burning depends on the size of the particles. Bigger particles would be less flammable. 

Since the reaction is quick, the powder can be ejected all around if there’s a big enough iron pile. This means that iron powder can fly around and ignite other things, and that’s the biggest hazard.

Eventually, an iron particle is too big to become flammable, and the flammability hazard extinguishes. No iron bar is considered flammable.

At the same time, iron must before be ignited itself so it can ignite other things, so it’s a small fire hazard.

Examples of ignition sources

An ignition source is anything that generates flames, heat, or sparks. We note:

  • Open flames;
  • Cutting and welding;
  • Hot surfaces;
  • Heat;
  • Lightning;
  • Smoking;
  • Spontaneous ignition;
  • Friction;
  • Static electricity;
  • Electrical Sparks;
  • Stray Currents;
  • Ovens, furnaces, and any heating equipment;
  • Pyrotechnical materials.

Safety Data Sheets

In this section, we will explore a few specific Safety Data Sheets (SDS) from iron powder products.

SDS are documents that exploit the hazards substances have. They’re normally made by the manufacturer.

This material, although is stainless, can still catch fire. It can also form explosive dust in the air, so it must be kept away from any sources of ignition.

This product is meant to be used as decoration or a chemical agent. The weight percentage of the material is around 97% iron.

Although, the material presents no flammability and can’t suffer from auto-ignition, according to the manufacturer.

The manufacturer claims that the product is combustible, but it will not ignite readily. Auto-ignition can happen in temperatures around 350ºC/ 662ºF.

The material is considered flammable in the presence of heat. The manufacturer also states that the product might be explosive in the presence of open flames, sparks, and/or heat.

Although, it is only flammable in powder form.

Conclusion

Iron powder is flammable. It can ignite easily if a source of heat, flames, or sparks are directly provided to it. It can also rust more easily, especially if in contact with water as well.

Frequently Asked Questions (FAQS): Is Iron Powder Flammable?

Is iron powder toxic?

The iron powder doesn’t possess big toxicity, but it does unleash toxic fumes during thermal decomposition (when it burns). It’s more dangerous when the exposure is chronic.

Also, eating too much iron nutrient will result in acute toxicity for the body. The is much more common among children, who end up accidentally ingesting too many tabs of the vitamin.

Is iron powder magnetic?

Yes. Iron powder is normally used by teachers to demonstrate how the magnetic field of a magnet material would look visually. You can see an example in the picture below.

The experiment is only possible because the iron powder is magnetic.

Is iron powder explosive?

In contact with a source of ignition, iron powder is easily oxidized. This chemical reaction liberates a good amount of heat in a short time, which may be considered an explosion.

Although, a lot of the material would be required to do so. Such an explosion wouldn’t generate a shock wave, which is common in bombings. It would look much more like a flare or a burst of light.

Citations

https://en.wikipedia.org/wiki/Carbon_monoxide
https://en.wikipedia.org/wiki/Heat_of_combustion
https://en.wikipedia.org/wiki/Rust
https://en.wikipedia.org/wiki/Thermal_conductivity
https://en.wikipedia.org/wiki/Ethanol
https://en.wikipedia.org/wiki/Carbon_monoxide
https://en.wikipedia.org/wiki/Combustion
https://en.wikipedia.org/wiki/Wood_fuel
https://pubchem.ncbi.nlm.nih.gov/element/Iron
https://www.freepik.com/premium-photo/red-blue-bar-magnet-with-iron-powder-magnetic-field-white-background_2435308.htm

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