[Stoves] Fwd: briqetting charcoal dust and fines with fibers as binders as alternative to starch.

Sat Jun 21 19:18:27 CDT 2014

Dear Jeff and Rolf and  AD, 

For  all who are considering the use of starch as the main binding agent for char and charcoal based briquette blends,  I would offer an alternative: The use of  natural plant fibers as naturally occurring agricultural residues. These grasses straws fronds stringy stem materials can make great binders If you know how to soften them such that they deform plastically while still retuning fiber tensile strength. We cover this ad nauseam in our User Producer Manual available thru our website but its not all that complicated  in its basic form. 
We do this because a) starch in itself f does not burn well and b) Starch requires boiling at least heating water to make the paste. The waste plant material is combustible, and it only requires chopping and semi decomposition in natural sunny conditions, but thats about it.   
I just sent this out to a more recent briquetter, Eric Theiss. Thought it might assist you all in what we are learning about how to densify and rigidify  briquettes without need for more force or starch binder. 

(At least when it comes to infilling granular materials in the blend, size matters ! 

Richard Stanley
www.legacyfound.org, 
Ashland Oregon,  

=========

Begin forwarded message:

From: Richard Stanley <rstanley at legacyfound.org>
Date: June 10, 2014 1:57:54 PM PDT
To: Eric T <2etpdq at gmail.com>
Subject: Fwd: briq. sample comments 

HI Eric, 
Well I did a few tests on your samples and discovered that while your mix is very fibrous the fibers are far too plentiful to really benefit from just compaction in and do of themselves What you had been adding was too coarse to fill int the gaps that existed too. i added fine sawdust then crumbles charcoal in varying quantities and found that if I selected the finer stuff (falls thru a door screen) it does a great job of densifying the material…(I used our standard compound lever press which was generating at max 1000 kgs over a 10 cm dia. cylinder face. Minus the 1 1/8th's inch dia. hole in the center. That= a net surface cross sectional area of ~75 cm ^2 or a pressure per unit area of 1000/75=13 kgs per cm ^ or roughly about 190 psi.  

Adding more force does not increase the density. In-filling with the right size of material does. (By the way I am using soupy slurry of probably 50% water or more--to assure full dissociation and distribution of the fines and fibers within the feedstock)..(I am also measuring on basis of unit weight per dry volume of samples)

the compressed donuts (bottommost photos) are drying as well speak but even a day old the difference between them in terms of felt density is remarkable. the charcoal fines sample below easily doubles the density of the raw sample and is about 1.5x the fine sawdust additive blend.

Some other observations: 
I pushed the charcoal additive to the point of fiber binding failure  per below. ( you sample on left for control, 25% sawdust added, then 50% (Next, --no sample shown here--  adding more sawdust than that failed the test; ie., not enough fibers to hold the mass together. 

Next with charcoal fines first ( sample not shown here) I tested crude crumbled charcoal that would fall only through ¼" square wire mesh it was not densifying much at all despite about 50% added force in the press-- Then ( shown below second from right) I added further pulverised charcoal that would fall through a door screen ≈ ⅛" mesh size. Per sample --second from right-- I added 40% then pushed it on up to 60% ( that sample not shown here but represented in the donut briquette below) with good binding  and excellent  infilling. When I pushed it on up to ≈75% fine charcoal I saw the failure as shown on the right sample below. 

close ups show gradations of infilling ;

below:
(your raw sample unaltered composition, reformed and squeezed in my hand) 

Below: same raw sample blended with 25% added blend of medium to fine sawdust equal mix of residues off chop saw and belt sander..

Below: pushed sawdust to 50% but while it was still binding up well it was still not densifying as much as it could. 

below; charcoal fines as infiller ≤40%

Below; charcoal fines ≥70% = insufficient fiber binder and structural failure 

compressed briquettes below 

1) ( on left);  your original material reformatted into the donut shape per description above: 
2) (center) your raw sample blended with 40% charcoal fines (⅛" dia minus --down to powder-- sieve size) 
3) (right) 60% charcoal fInes same sieve size )

Other characteristics as additional indicators: 
• The rate of compaction (amount of movement of piston to buildup of resistance / pressure) decreases to right. 
• There is a  noted reduction in the rate of expansion just after molding  to the right. 
• The amount of slurried feedstock added to the cylinder pre-compression, was about equal in the samples below. 

In short:
Your feedstock is too fibrous (you are going to too much work processing using these precious fibers, when you could instead be using far less of them with far more really fine additives. Note course "sawdust or charcoal crumbs larger than the ⅛" minus size will not add much at all. ). For the   biggest bang for your buck,  get ahold of really fine 1/8" minus sieve size combustible material. The best for heat output is charcoal but any wood or oily based combustible husk material would come in a close second creating moor of a wood fire.... 

These same samples were then dried over four days in ambient conditions and measured. the starting sample of  ≈sg 0.23,  to  40% charcoal fines at sg 0.30,  to 60% charcoal fines (amour maximum before structural failure (due to an insufficient fiber binding content), with an sg of 0.42

hasta,
Richard Stanley

Sent from my iPhone

Sent from my iPhone

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