Combustion of Coal

[Hal.]

Recently , I put some coal on the fire and noticed an unusually high frequency of popping sounds and sparking with the expulsion of small pieces of material . I examined some unburnt coal and saw what appeared to be thin metallic layers , of the colour of copper and zinc , on the surface of some pieces . I also snapped some pieces and there are layers of these metals , assuming they are metals , in thin layers like pages in a book . The momentum of a typically ejected piece seems quite high compared to usual and I was wondering how the metals and the coal were interacting with the air to give these results . Any thoughts ?

[Fuzzwood]

Thin layers of graphite have a metallic luster due to their conductive properties. And that is going to be right on the surface of those pieces of coal.

[Hal.]

If there is graphite there , it may or may not be what I am describing and observing . I would have thought that graphite has a greyish shine like a pencil , though a shine will be affected by the colour of light that has been bounced to your eye and some pencils are also made of materials that have all the look and none of the content of graphite . What I am observing are possibly metals of the colour of copper and zinc , whether they be copper or zinc or none of them . On the assumption there is graphite , could the extra motion energy be attributed to it's combustion as compared to normal coal ?

 

 

[Essay]

I've been trying to learn as much as possible about coalification (from a soil-science perspective) over the past year....

 

It sounds as if you have a very hard coal, and so it's not just graphite but graphene, which is even more lustrous. And even the hardest coals still contain at least 40% to 50% humic substances in addition to the more transformed, coalified, organic matter called macerals.

They describe the macerals (most fully mineralized, or petrified carbon), which form the foundation of the bulk mineral forms called anthracites (& the other coals such as bitumins), in terms of transmittance/ reflectance/ fluorescence, and that shiney lustrousness is probably what you're seeing.... Especially if the pieces were heated, which would release fresh humics into/onto the macerals; but I'm just speculating on that heating scenario....

But as for metals, they should be dispersed as single, fairly reduced, atoms throughout the matrix (imho), so I don't think you're seeing metallic layers.

 

Seriously though, I've been experimenting with making charcoal (via pyrolysis) and have been amazed by the brilliantly coloured reflectances from within the finished product. It's like those sparkling little prismatic points you can see on cold dry fresh snow, on a sunny day. In the plane of the graphenic layers of true (highly-compressed) coal , which usually has its sedimentary structure intact {as opposed to charcoals which retain the biological structures}, you get what looks like the sheen of oil on water. ... Probably the color of the Gulf oil spill...? ...and maybe also with some copper and ruby highlights, with hints of green...?

 

Different source materials for the coal leave their fingerprints in the macerals and the intercalated humic substances. In Earth's past, pollens (from bamboos? and other dominant species) covered vast regions in banks of yellow. Coals (well, the macerals of the coal) that were formed from these deposits are termed sporinites. There are also cutinites, alginites, resinites... and even more interesting sources... all of which impart unique spectral properties to the macerals--and the bulk coal pieces.

 

As a biochemist, I was amazed at the familiarity of these petrochemical processes (there's basically no difference!) and also at the "biodiversity" of coals and kerogens and oils. There are even pockets of less degraded organic matter (more humic substances) within younger coals, and maybe that's what you have... so sort of like the popping sound from wood with beetle grubs in it, or other uncured woods that pop.

 

~

[Hal.]

It is difficult to make a photograph of these pieces and have them looking like the view from the human eye . I could put more detail in a higher pixel density image , but they are a good approximation of how they then would be , already . In sunlight they look very shiny , whereas in the shade they look comparitively dull .

Edited May 22, 2011 by Hal.

[Essay]

I'm gonna try to post some pics too. I made charcoal and got some pics of the multicolored, prismatic, glints of light coming from within that blackhole-like matrix.

 

This is some pieces of charcoal sitting on damp dry ground [damp ground below, note tread of shoeprint].

 

Crushing those pieces. Note the brightly colored sparkles. I wish the rainbow of glints were in focus.

 

More attempts to get the amazing colors and reflectances. If you can magnify....

 

Here is the batch after it cooled. Still see the knots in the woodchips used; the porous wood structure is retained in the char.

 

...and here is the pyrolyser used to make that charcoal. Here: Pyrolysis of wood pellets, which can be seen below the flame front. It's a carbon negative way of making energy.

 

~

 

p.s. Thanks for the tip on memory. BTW...

The chemistry of charcoal and coal is about the same, so that's why I think these pictures are relevant. It's the formation of chromophoric carbon compounds and the parallel sheets of graphene (lots of conjugated double bonds) that is the key... to the colors ...and the high energy stored within.

Edited May 22, 2011 by Essay

[Hal.]

Just a short note Essay , if you post images try to keep the memory small because otherwise they will fill up your personal memory allocation pretty soon , meaning you might have to soon delete some of these images from your posts . You could probably request more from an administrator but I don't know if they will allow it .