×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Spontaneous Combustion of Aluminum

Spontaneous Combustion of Aluminum

Spontaneous Combustion of Aluminum

(OP)
Had a liitle fire that I think may have been caused by spontaneous combustion.

Scenario:

Aluminum "sawdust", chips and small pieces deposited in a plastic bag in a plastic trash container.  Could easily have been 50 lbs. or more.  It was probably contaminated with oils, water and maybe even cement dust and/or drywall mud dust.

Nobody was nearby when it happened (at night).

My Web search says that this may be possible.  Can any of you chemicals help this structural and verify that this is indeed a very real possibility.

Thanks for any help

RE: Spontaneous Combustion of Aluminum

Google for "spontaneous combustion of aluminum"....you'll find a variety of information that may fit your situation.

Orenda

RE: Spontaneous Combustion of Aluminum

(OP)
Thanks Orenda1168

I did that and got the "maybe"

Kind of hoping for a more definitive answer... or "maybe" is all I will get....

RE: Spontaneous Combustion of Aluminum

Insufficient information. Quantity of aluminum powder, powder size, age of the powder (aluminum self-passivates, with an oxide film slowly thickening in air), how well it was mixed with a) oxidizer & b) solid pieces acting as heat sinks, ambient temperature, etc. all may influence. If an aqueous cutting fluid was used in machining, probably the aluminum chip surfaces were pre-oxidized by combination of cutting heat & water, so less reactive.

Can only say maybe. Possibly, very sharp thin edges catalyzed the oxidation of oil, picked up some heat & then ignited.  But, note that in the thermite reaction, a magnesium ribbon is used to ignite the reaction (between aluminum powder & iron oxide).

Generally, aluminum powder is considered hazardous for particle diameters < 420 microns (0.0168").  See
Recommendations for storage and handling of aluminum powders and paste, 4th Edn., The Aluminum Association (2006). Free.
http://www.aluminum.org/Content/NavigationMenu/The_Industry/Powder_and_Paste/TR2_2006.pdf

National Fire Protection Association (NFPA) standards:
NFPA 651, Standard for the Machining and Finishing of Aluminum and the Production and Handling of Aluminum Powders [651 seems to have been withdrawn & incorporated into 484 below]
NFPA 484, Standard for Combustible Metals, Metal Powders, and Metal Dusts. $42.50 non-member price.
http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=484

RE: Spontaneous Combustion of Aluminum

(OP)
Kenvlach -

Thanks for your help...  Since this was a "trash" or "scrap" type fire that burned up - no one will ever know exactly what was in the container.  

So "MAYBE" is probably as good an answer as there is.  

What now needs to be done - is to establish guidelines to prevent any repeat.

Thansk again.

RE: Spontaneous Combustion of Aluminum

Since most machinists use a feed rate around .001" per tooth so their tools, and the job, will last longer, most of the chips in the bucket were probably well under the 420 micron threshold in at least one dimension.

You could:

** Use metal waste containers for chips (this may be a legal requirement in your area anyway).

** Encourage your machinists to use higher feed rates.  At ~.005" per tooth, you start getting frangible thick curled chips that fly away from the tool and don't wrap around it in "birds nests", at least in 20xx aluminum.  And you get your parts sooner.



Mike Halloran
Pembroke Pines, FL, USA

RE: Spontaneous Combustion of Aluminum

If you believe the work done by DMIC in '66, then no way.  Ignition temp for Al fines in air is over 1,200F.
There is a greater chance that the oil and solvents along with some rags was the ignition source.  Many light oils and solvents have ignition temps plenty low for this.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm

RE: Spontaneous Combustion of Aluminum

From the Aluminium Federation (UK):
'does aluminium burn?'.
The answer is, of course, "No".  
http://www.alfed.org.uk/templates/alfed/content.asp?PageId=111

Interesting paper, especially if you've heard (the common misconception) that the British destroyer Sheffield sunk by Argentina in 1982 was due to a burning aluminum superstructure: The Ministry of Defence says it was steel.

Anyway, solid-fueled rockets commonly use fine aluminum powder or flake for fuel, but the Al particles must be small enough that the ignition heat isn't carried away from the surface.  As EdStainless says, ignition is pretty difficult.

I've even intentionally oxidized molten aluminum alloys up to 1400 oC. Due to the protective oxide film that forms on both solid & liquid Al, alloying with Mg or Zn is necessary for a reasonable reaction rate [but nowhere near 'burning'].

RE: Spontaneous Combustion of Aluminum

(OP)
Thank you everyone for your input...

At the least we have made a few "house keeping" changes to insure that this remote possibility cannot happen.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources

Overcoming Cutting Tool Challenges in Aerospace Machining
Aerospace manufacturing has always been on the cutting edge, from materials to production techniques. However, these two aspects of aerospace machining can conflict, as manufacturers strive to maintain machining efficiency with new materials by using new methods and cutting tools. Download Now
3D Scanning in the Automotive Industry
With over 100 years of production history, the automotive industry has been at the forefront of manufacturing technology since its inception. Whether the transformative technology of the day was the assembly line, the integration of robotics into the manufacturing process, or the switch from steel to aluminum frame chasses, the automotive industry has consistently implemented advanced technology into its manufacturing and production workflow to improve manufacturing and product performance. Today, the same is true. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close