Iron Burning

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Iron Burning

This topic has 10 replies, 9 voices, and was last updated 6 July 2011 at 07:43 by Clive Hartland.

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4 July 2011 at 20:44 #71329
Sub Mandrel
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@submandrel
I know that iron can burn. In my mis-spent youth a 9v battery and a bit of wire wool was a good way of making an igniter. I also know that oxygen down an iron pipe can be used to make a thermic lance, the most powerful cutter this side of Thunderbirds.

But I’ve just seen iron filings burn, without any aluminium or accelerant. I’ve been uding a rotary hand tool to trim the broken end off a used alternator. At one point I was sure I saw a red front burn quickly across a line of fine iron filings magneticaly stuck to one of the sharp edges of the work. It happened three more times, once lasting about a second and a half as the red-hot fronts wove across a patch of loosely packed filings about a quarter of an inch square. Ive never seen this before, but the filings were much more finely divided than normal grinding dust, it was a high-carbon steel (from the leafy, branching sparks) and the magnetism was keeping them in an open structure that air could penetrate easily. I imagine the metal they were stuck too was fairly hot as well, say over 100 degrees.

Not something I’ve seen before, quite striking and a remider how finely divided metal dust can be a major fire hazard.

Neil
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4 July 2011 at 20:44 #29439
Sub Mandrel
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@submandrel
4 July 2011 at 20:51 #71330
John Stevenson 1
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@johnstevenson1
Probably because it’s been a hot day today ?

Earlier I saw two lamp posts fighting over a dog.

John S.
4 July 2011 at 22:25 #71334
Anonymous
An interesting experience!

If iron is hot enough it will burn just with oxygen. When using a oxy-acetylene cutter, once the process is going the flame can be turned off and the process will continue just with a stream of oxygen, since it is strongly exothermic.

Many finely divided powders will burn or explode, not just metal powders. Flour mills are reknowned for explosions. Some years ago I worked on a coal mill used to crush coal to a fine powder for use in cement making. The fine powder was blown into the furnace using a fan driven by a 3MW DC electric motor (that’s not a typing error – the motor was bigger than a family car). We were trying to cancel out some of the noise created by the fan. Apparently there are two ways to make a coal mill explosion proof. One, do everything in an inert atmosphere, or two, build it like a brick built **** house, so when it goes bang it survives. The coal mill we worked on was designed for option two. Sadly, when it did go bang, the design proved to be wanting, and it cost a lot of money to put right. Didn’t do our noise cancelling loudspeakers much good either!

Regards,

Andrew
4 July 2011 at 23:30 #71337
Nicholas Farr
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@nicholasfarr14254
Hi Andrew, you talk about finely divided powders exploding, well I remember watching a programme on TV back in the late 70’s about exploding custard powder. In the programme they said that a surprising amount of everyday things that can produce large amounts of dust inside buildings ect. are potentially explosive. I knew a guy who was killed when he was blown of a grain silo when welding on it. due to an explosion, by the dust floating around inside it.

Regards Nick.
5 July 2011 at 09:40 #71339
Gordon W
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@gordonw
Don’t forget steel wool, many a loft fire started with that stuff, when an inattentive plumber caught it with his torch. Yes I have. One of the worst industrial fires started in an icing sugar plant, by a flash thru’ the building.
5 July 2011 at 18:40 #71359
Sub Mandrel
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@submandrel
As a boy I did a school visit to Rank’s Mill, Barry Dock. the chap showing us around was proud of two ‘facts’. 1 – the flour mill was the biggest explosion hazard in the town (not the nearby DOW chemical plant) and 2 – if it blew up it would rupture their chlorine tanks (for bleaching the flour) and gas the entire town.

Worryingly I don’t think he was joking!

Neil
5 July 2011 at 20:40 #71365
Speedy Builder5
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@speedybuilder5
Have you ever seen fireworks – lots of different metal powders used for specific colours. iron included.
5 July 2011 at 22:30 #71371
Steve Withnell
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@stevewithnell34426
finely divided aluminium and iron oxide mixed is a fun compound. Silly buggers thought it was a neat trick to paint the Hindenburg with it as a conductive paint to ensure electrostatic discharges could be safely conducted away.

Others know it as Thermite, which once it gets started, the local fire brigade couldn’t put it out…which is what they discovered with the Hindenburg. It generates it’s own heat and oxygen so a bit of a bugger to put out.

Steve
6 July 2011 at 07:16 #71377
Keith
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@keith
When I taught science one of my party tricks was to explode custard powder.

Keith
6 July 2011 at 07:43 #71378
Clive Hartland
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@clivehartland94829
I was told by an engineering friend of a fire in the swarf of a CNC lathe, it was cutting dry and the mass of fine turnings ignited.

I did later see the machine and all the paint around the housing was scorched!

Clive
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