Sciencemadness Discussion Board - Preparation of Charcoal by the Slow Pyrolysis of Wood Scraps

Preparation of Charcoal by the Slow Pyrolysis of Wood Scraps

VSEPR_VOID - 19-4-2018 at 18:31

Charcoal is composed elemental carbon, in the amorphous form, with organic residue throughout. Its primary use application is in its use as a fuel. Charcoal is free of water, in stark contrast to wood, and burns at a great temperature (2700 degrees celsius). It also finds a place in fluid filtration, being able to remove asphyxiating and poisonous gases from air and pollutants from water when activated. It is manufactured by the heating of wood in a low oxygen environment. This is performed often on the industrial scale by charging large metallic retorts with sawdust. The advantage of this method being that the byproducts (spirits, tars, and organic acids) can also be collected and purified. The intention of this publication is to detail how the amatuer may prepare small amounts of charcoal for use in chemistry and pyrotechnics. The following procedure is meant to be general and not specific to the volume of charcoal wished to be produced or type of wood starting material.

The condition of the charcoal is dependent upon the temperature at which the vessel containing the wood is fired. Well the minute and specific properties of charcoal will change with the type of wood used they all are carbonized by the same methods. Sawdust, hardwood, and wood scraps may all be converted for general use. Wood becomes a brown hue at 220 degrees celsius, brown-black at 300, easy powdered at 310, and readily inflames at 380 degrees celsius. At temperatures any higher the product of pyrolysis is hard and brittle and will not fire until 700 degrees celsius.
J. Percy

A. Reagents
Wood scraps cut to fit in reaction vessel: may also be sawdust

B. Apparatus
Metal can with a matching lid. Said lid must contain a hole for venting purposes
Fire pit
Hot air gun (a hair dryer may be used but care must be taken to prevent it from melting)
Mortar and pestle

C. Optional Apparatus

250ml vacuum flask
Büchner funnel and stopper
Hand operated vacuum pump
Filter paper
Vacuum desiccator

D. Procedure

The wood material to be used is trimmed to fit in typical soup can, which when charged is to be no more than ¾ the way full. The metal can is placed within a suitable fire pit and wood stacked around it. Enough fuel must be placed on the fire to allow it to burn for one hour. The lid is placed over the head of the can and secured. The fire is started and as soon as mature is intensified by the air of a hot air gun set the maximum air flow and minimum temperature. This will act as a simple bellows. The air is best directed when a suitable pile of coals is maneuvered around the reaction vessel. The amount of time the can is left in the fire is not essential but one hour is advised to allow full pyrolysis. During heating the vent of the can may catch fire due to the emission wood glasses. Once the one hour has passed the reaction vessel is removed by means of tongs and allowed to cool. Once cool the charcoal is removed and pulverised by means of a mortar and pestle.

E. Optional Procedure to Reduce Organic Residues Present

Using vacuum filtration, the pulverised charcoal is washed with 500ml of water and 100 ml of alcohol per 100g of charcoal. The charcoal is placed into a vacuum desiccator until dry.

D. Discussion

The final product smelt slightly of gasoline (which was used to start the fire in the pit). Washing helped remove this.

I did not feel this was good enough to go in publications. It is a first attempt at writing and I under took this to practice my scientific writing.

[Edited on 20-4-2018 by VSEPR_VOID]

RogueRose - 19-4-2018 at 18:49

Are you sure you are drying the filtrate or are you drying the charcoal that remained in the filter? the filtrate would be the water and alcohol and any dust that came through in the filtering process I believe.

[Edited on 4-20-2018 by RogueRose]

VSEPR_VOID - 19-4-2018 at 19:20

My mistake, thank you for spotting the typo.

Ubya - 20-4-2018 at 01:17

ashes of charcoal contain soluble and insoluble compounds, just washing the powder won't get rid of silica and other stuff.
for really pure carbon i would treat table sugar as you did for wood.

aga - 20-4-2018 at 01:19

Pretty good write up, especially for a first attempt.

Critique:

The "J Percy" reference should be given in full so readers could find it easily - some authors have hundreds of papers.

Also good to put quotes around the sections copy-n-pasted from other publications.

Putting the section titles in Bold and adding more white space/paragraphing would make it look better and read more easily.

e.g.
https://www.sciencemadness.org/whisper/viewthread.php?tid=15...

j_sum1 - 20-4-2018 at 01:52

Concur with what others have said.
Nice work VSEPR.
I have never had occasion to make charcoal myself and I think I would get there if all I had to follow was this.

VSEPR_VOID - 20-4-2018 at 02:01

Quote: Originally posted by Ubya

ashes of charcoal contain soluble and insoluble compounds, just washing the powder won't get rid of silica and other stuff.
for really pure carbon i would treat table sugar as you did for wood.

You are right. Thus why I wrote that it was only reducing the amount of residues, not completely removing all impurities.

Ubya - 20-4-2018 at 02:27

Quote: Originally posted by VSEPR_VOID

Quote: Originally posted by Ubya

ashes of charcoal contain soluble and insoluble compounds, just washing the powder won't get rid of silica and other stuff.
for really pure carbon i would treat table sugar as you did for wood.

You are right. Thus why I wrote that it was only reducing the amount of residues, not completely removing all impurities.

charcoal made this way is more than enough for the majority of experiment, so it's a useful guide.

Sulaiman - 20-4-2018 at 03:40

Your article mentions the use of charcoal for burning and filtering,
so some measure of the success (or failure) of this experiment would be to indicate the burning and/or filtering performance of your product.
One other mentioned application is pyrotechnics - tested ?

My only chemistry use for charcoal so far has been decolourising/adsorbing,
It would be good if the product produced by your process has an expected iodine number range (mg/g) (or e.g. methylene blue, molasses etc.)
https://en.wikipedia.org/wiki/Activated_carbon

One of my biggest frustrations as a hobby chemist is not knowing if what I intended to make is what I actually made.

(could some kind person(s) send me a GC-MS machine, a spark spectrometer, and an electron microscope please

P.S. I doubt that any of us have difficulty accessing BBQ wood charcoal,
probably easier to find than wood chips or sawdust

Even so, I have previously made a little charcoal for chemistry use,
long-story-shortened ... tooth-whitening activated carbon powder from China via eBay is very effective, cheap, clean.
(it also works much better than commercial toothpaste for cleaning and protecting teeth ... with no added 'CHEMICALS

If you are young with good teeth, I suggest that you switch a.s.a.p.
I discovered this too late ... I've lost many teeth due to bad habits

VSEPR_VOID - 20-4-2018 at 05:52

The nice thing about this method comparted to buying charcoal is that its free as long as you have a soup can and wood. I will look into the tooth paste idea.

How should I test the charcoal? I have no sulfur for black powder.

Bert - 20-4-2018 at 06:00

8th grade.

The destructive distillation of wood was the FIRST junior high school chemistry lab I did, beginning of the '73 -'74 school year. Thank you, Mr. Chappell.

We had to finish the pyrolysis in a 1.5 hour lab class. The charge was one large test tube worth of wooden tongue depressors.

Next several labs were various analysis of the products.

[Edited on 4-20-2018 by Bert]

VSEPR_VOID - 20-4-2018 at 06:20

One of my first expirements at home was making wood gas by the destructive distillation of tooth picks. I was very disapointed to learn that it stained my favorite test tube.

aga - 20-4-2018 at 08:39

Quote: Originally posted by VSEPR_VOID

... How should I test the charcoal? ...

If you have iodine, potassium iodide, potassium iodate, sodium thiosulphate, sodium carbonate, hydrochloric acid and some starch, then you could test the charcoal's I.N. value, although that would be very much affected by how finely ground it was.

VSEPR_VOID - 20-4-2018 at 08:50

Almost no effect, sadly it is not in any way activated and so the surface area would be negligible. Maybe I could test it in a simple pyrotechnic mixture? Like I said I do not have any sulfur but I d have on hand ammonium perchlorate, potassium permanginate, and potassium nitrate. Would any of these warrant a reaction worthy of posting a video?

Bert - 20-4-2018 at 08:58

Of course, you will have done any lab yourself, before writing up as an instructional post? That really should be done, little technical details not apparent when thinking about a process and reading online descriptions quickly make themselves known.

In the OP, mention is made of using a HAIR DRYER to heat the can?! Might not want to do that, it would take a geological age.

Copy on the mention of dammage to your test tube from pyrolysis of wood.

When using a test tube back in 8th grade we ended up with only a few grams of products- Charcoal, liquids condensed from the gas (pre weigh and use a disposable piece of glass tube for an air condenser, some of the tars deposited in there won't be coming out either), finally, ash from burning of the charcoal and the soluble lye extracted from the ash.

A larger charge will give you enough product to do something with in further work. If teaching, the larger quantity helps reduce % of mechanical loss type errors and needs a less sensitive scale.

When using a "soup can", I suggest you pre burn the can to remove the plastic interior coating, label glue, etc.

If you use the usual type of can opener with drive teeth and a cutting wheel, reclosing the can to form a more or less airtight seal will present some difficulty. I have used various sizes of cooky tin when actually making charcoal for pyrotechnic testing and small scale use.

If you want to use a soup can for a retort, try using one opened by a can opener like THIS, the can end comes off nice and flat, with a smoothly turned up edge. You can just re-insert the end like a plug. If you are feeling fancy, add a smear of luting on the seam to seal the end.

[Edited on 4-20-2018 by Bert]

Bert - 20-4-2018 at 09:21

Potassium nitrate and charcoal will burn, a crude mixture smoulders and leaves a lot of slag.

Sulfurless black powder was used in late BP era militaries, it had a higher specific impulse than that made with Sulfur. However, they often used an incompletely cooked "Brown charcoal" for this. See "brown powder".

VSEPR_VOID - 20-4-2018 at 12:43

Here is me testing it:
1g charcoal
3g Ammonium Perchlorate

Wrapped in paper after being mixed and placed on a bed of napalm to ignite it (I love napalm)

https://www.youtube.com/watch?v=K9bMEJomLzI&feature=yout...

[Edited on 20-4-2018 by VSEPR_VOID]

VSEPR_VOID - 20-4-2018 at 12:50

Quote: Originally posted by Bert

Of course, you will have done any lab yourself, before writing up as an instructional post? That really should be done, little technical details not apparent when thinking about a process and reading online descriptions quickly make themselves known.

In the OP, mention is made of using a HAIR DRYER to heat the can?! Might not want to do that, it would take a geological age.

THIS, the can end comes off nice and flat, with a smoothly turned up edge. You can just re-insert the end like a plug. If you are feeling fancy, add a smear of luting on the seam to seal the end.

[Edited on 4-20-2018 by Bert]

The hair dryer is to act as a bellows not to heat the reaction vessel. Yes, I did the lab. I also posted a video of me testing the charcoal in a pyrotechnic mix.

[Edited on 20-4-2018 by VSEPR_VOID]

aga - 20-4-2018 at 13:16

Oh dear Bert - you're succumbing to agaism.

I've kinda come out of that phase, with a lot of Texan help, and thought i was gradually achieving a more Bertist view.

Reality remains the same, all around.

My daughters are despairing at ever finding a potential husband who can actually change a light bulb with no external help.

Small things like a light bulb high up means you need ladders (this defeats most of 'em).
Moths are attracted by the bulb and die up there, around the light fitting.
It's a natural reflex to open your mouth when you tip your head back so you can see up.
Unscrew the light bulb and the moth corpses obey gravity.

The rest is obvious.

This defeats all but the most ardent would-be suitor, which is in the high 90% range, as they have no direct experience of anything.

[Edited on 20-4-2018 by aga]

aga - 20-4-2018 at 13:22

Adding more air to a fire, even with a hairdryer makes it burn hotter.

My little charcoal furnace uses a hairdryer, albeit at the end of about a metre of steel fencing post pipe to prevent the plastic melting.

The furnace melts steel (unfortunately) when the hairdryer is turned up to max.

VSEPR_VOID - 20-4-2018 at 13:43

Quote: Originally posted by Bert

Of course, you will have done any lab yourself, before writing up as an instructional post? That really should be done, little technical details not apparent when thinking about a process and reading online descriptions quickly make themselves known.

If you want to use a soup can for a retort, try using one opened by a can opener like THIS, the can end comes off nice and flat, with a smoothly turned up edge. You can just re-insert the end like a plug. If you are feeling fancy, add a smear of luting on the seam to seal the end.

[Edited on 4-20-2018 by Bert]

That would be great if I wanted a seal. The procedure calls for the vessel to be able to went the highly flammable wood gas produced.

[Edited on 20-4-2018 by VSEPR_VOID]

aga - 20-4-2018 at 13:54

Quote: Originally posted by VSEPR_VOID

... The procedure calls for the vessel to be able to went the highly flammable wood gas produced. ...

Typing like Chekov from StarTrek is really odd. Funny though.

VSEPR_VOID - 20-4-2018 at 13:55

I would go back and edit that but now I must honor Checkov's dialect

Bert - 20-4-2018 at 15:30

There you went again. Yes, you want a went, not a great, gaping rent.If the went is too large, gas pressure from the pyrolysis will not sufficiently pressurize the wessel and conwection may allow Oxygen to enter. This results in a small charcoal brazier, rather than a charcoal retort. When using a sealed can over a fire, you may put a small hole in the BOTTOM of the can, then the wented gasses will be ignited by the fire and add even more heat to the wessel.

VSEPR_VOID - 20-4-2018 at 16:30

Yes that is true. My can employed a small hole for that very reason.

I am pleased with the quality of the final product. It is clear of debris, uniform in color and particle size, and burned well when combined with an oxidizer. In the future I would do it again on a larger scale. I also do not think the hot air gun was needed and that a regular fire would be enough to drive pyrolysis. I will be trying this again and taking better notes for a version 2.0. I hope it will be better received. Thank you for the advice.

[Edited on 21-4-2018 by VSEPR_VOID]

WangleSpong5000 - 20-4-2018 at 16:55

Quote: Originally posted by Bert

There you went again. Yes, you want a went, not a great, gaping rent.If the went is too large, gas pressure from the pyrolysis will not sufficiently pressurize the wessel and conwection may allow Oxygen to enter. This results in a small charcoal brazier, rather than a charcoal retort. When using a sealed can over a fire, you may put a small hole in the BOTTOM of the can, then the wented gasses will be ignited by the fire and add even more heat to the wessel.

Post sources please, preferably signed by no less than 7 scholars, 4 in the relevant field of discussion, 1 Dr of Logic, 1 Dr of Statistics, 1 Dr of supercalifragilistics... or it didn't happen...

AJKOER - 20-4-2018 at 17:00

Heat saw dust in a pipe in a hot fire (via air fed coal, for example).

Allows venting or burning of fumes.

Reduces oxygen exposure so less conversion of carbon to CO/CO2.

Bert - 20-4-2018 at 17:57

Look for Takeo Shimizu' description of traditional small batch charcoal production for shell lift BP from hemp stalks.

Many, many descriptions of traditional European batch production charcoal burning under heaps of earth. Up to half of the wood was wasted... Europe was largely deforested from the wood demand of such processes by the the 16th century. So some enterprising guys in the low countries substituted dug and dried PEAT- and got rich from cornering all the local heat intensive industrial processes.

Then came engineers and efficiency. The industrial age developed more economical practices, moving big sheet Iron retorts through a furnace horizontaly by rail in a continuous production.

Henry Ford had a waste disposal problem- All the oak wood scraps and sawdust from left over from production of the wooden bodywork on model T automobiles. His friend Mr. Kingsford gave him an idea about how to merchandise his waste material to Americans as leisure time cooking charcoal- and turned his trash into profit, after virtually everyone had ceased smelting Iron with.charcoal.

In the 3rd world even now, you will find VERTICAL furnaces built into hillsides where the movement of stacks of materials is from top to bottom, the waste gasses from calcining lower levels serving to preheat the newer stacks of materials coming down the chimney.

Enjoy your charcoal. You are at the tail end of a long tradition-

.

VSEPR_VOID - 20-4-2018 at 20:33

I made another attempt and out of about 100g of wood (fresh green wood) I got 10g of a fine black flowing powder.

hexahydrate - 21-4-2018 at 03:04

There is a simpler and more portable way to make charcoal, without a hair dryer or a fire pit and it's clean too (no visible smoke). It's called a TLUD (Top-lit Up Draft) woodgas stove. It was developed to help poor people in third world countries, but as charcoal is its byproduct, it quickly gained popularity among organic gardeners, who use it to produce "biochar" (biologically activated charcoal) to be added to the soil. It can be made from two tin cans of slightly different sizes. I made my own in like 20 minutes and after a few burns I have two cans of charcoal.

Here are a few links, that will let you understand and build your own TLUD:

https://en.wikipedia.org/wiki/Top-lit_updraft_gasifier
Manual how to build TLUD (pdf)
TLUD in action, with glass combustion chamber (YouTube)
How to build TLUD from tin cans (YouTube)

Attached images show my TLUD and some charcoal I made with it. First, inner can, where biomass is loaded. At the bottom, primary air inlets are visible. There should be only enough primary air to sustain pyrolisis (actually, I made too many holes). At the top, there are secondary air inlets. When a bigger can is put over this smaller can, secondary air is drawn from the bottom by a slit between the cans, as it goes upwards, it gets hot from the walls of the inner can, then as hot air enters via holes at the top it mixes with woodgas and burns quite clean. No visible smoke if biomass is dry and ratio of secondary to primary air is correct.

The charcoal that comes out of TLUD is completly dry. All tars etc. get vaporized and burnt as woodgas.

Second image shows complete assembly, with a third can as a chimney, to increase draft and to be able to put a pot on top, i.e. to boil water (I use my TLUD as a camping stove, too).

RogueRose - 21-4-2018 at 03:22

IDK if this has been said but there are 2 ways to make charcoal without a blower or complex burning container. First off there really is no reason to use a blower in this endeavour and will just end up causing the can to melt and the fuel to burn too fast. The heat produced from a normal wood fire is plenty to turn the wood into charcoal, just fill the canister (with a small hole in the top) and drop it in the fire.

Another method is to burn some wood and then take the hot coals and fill a container about 1/3 full of hot coals. Fill the rest with dry wood or sawdust and put the lid on it. place the container where you pulled the coals from (should still be pretty hot and probably some more coals). Allow to sit for 4-6 hours and then remove the charcoal that is above where the coals were.

I've done both a number of times and it works very well and is very easy.

XeonTheMGPony - 21-4-2018 at 07:19

May I recommend a old pressure cooker for the vessel, and a vacuum pump to pull a vacuum in said chamber and keep it for the whole time

hexahydrate - 21-4-2018 at 07:32

Quote: Originally posted by XeonTheMGPony

May I recommend a old pressure cooker for the vessel, and a vacuum pump to pull a vacuum in said chamber and keep it for the whole time

Why so much hassle with a vacuum pump? There is no need for vaccum to make charcoal. Simple, two can gasifier works very well, as I described in my post above.

unionised - 21-4-2018 at 08:44

Quote: Originally posted by XeonTheMGPony

May I recommend a old pressure cooker for the vessel, and a vacuum pump to pull a vacuum in said chamber and keep it for the whole time

I am going to have to report you to the society for the prevention of cruelty to vacuum pumps.

aga - 21-4-2018 at 09:46

Please don't call the RSPCVP.

I'll change the oil in mine immediately.

VSEPR_VOID - 21-4-2018 at 11:38

Too late PETVP has already started a protest and will be outside your place of work soon to harass you

aga - 21-4-2018 at 11:45

Phew !

If they think i have a place of work, i'm safe.

Edit:

Well, depends on if they can find me in 2,500 square kilometres,.

[Edited on 21-4-2018 by aga]