[Terrapreta] pulverizing charcoal

[Kevin Chisholm]

Dear Ray

A gram of charcoal typically has an internal surface area of about 400 
square meters. A cube of charcoal weighing 1 Gram  would have a 
dimension of about 1.44 cm on a side. The total apparent area of the 
external surface would be about 12 cm^2. If you cut it into 8 cubes, 
each of 1/2 the size, the apparent surface area would double to 24 cm^2. 
To get an apparent surface area equal to the internal surface area of 
the charcoal, you would have to reduce the size of the cube to 0.012/400 
of the original 1.44 edge dimension, or about .0000432 cm, or say 
.000432 mm, or say .432 microns. 200 Mesh Screen Size is about 72 
micron... about the size of normal flour. Crushing or breaking up 
charcoal will not make an appreciable or significant difference to 
active surface area.

On the other hand, even moderate grinding will permit much more uniform 
distribution of the char.

Best wishes,

Kevin


Roy Lent wrote:
> May,
> The functions of the charcoal, especially in holding elements like 
> phosphorous, seem to involve its surface area. That automatically 
> suggests grinding it fine in order for it to start acting at full 
> force right from the beginning. This is obviously something to 
> research though.
>
> Roy
>
> On Tue, May 20, 2008 at 2:17 AM, folke Günther <folkeg at gmail.com 
> <mailto:folkeg at gmail.com>> wrote:
>
>     * Why do you want to crush he char? I don't understand why it is
>     necessary.
>     Unless the pieces are so large that they cause an unbalance in the
>     distribution of the  precious material, I just put them on/in the
>     ground/compost. The worms and the plant roots  will do the job.
>     After a year, all pieces are conveniently small.
>     FG*
>
>     2008/5/20 May Waddington <may.waddington at gmail.com
>     <mailto:may.waddington at gmail.com>>:
>
>         Ideas you do have! I think the party idea is the most
>         sustainable, though. Thank you!
>
>         2008/5/19 Roy Lent <rwlent at gmail.com <mailto:rwlent at gmail.com>>:
>
>             I have to try as I'm supposed to be an idea type person. 
>             Get a good sized piece of the heavy plasic sheeting used
>             to line land fills and such. Decide where to hold a
>             pulverizing party. Lay out the sheeting on the floor and
>             cover it with the lumpy charcoal. Fold the rest of the
>             sheeting on top and clamp the edges, This will have the
>             same sort of attraction as do the plastic bubbles in that
>             wrapping sheeting. Everyone loves to pop them! Everyone
>             one will love to search out and crunch the charcoal lumps.
>             Hold regular charcoal crunching parties or dances. The
>             kids will love it!
>
>             Roy
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