Biochar crushing techniques

This is my summary of Kelpie Wilson's description of biochar crushing techniques.  If you don't particularly like my descriptions or you want ALL of the information, buy it from her, you cheapskate! It only costs $2.50, or so.  

Obviously, just driving over it is the cheapest, because you don't have to buy anything new.  I bought burlap bags off of Facebook marketplace, but they were only $1 each and I've worn out none of them over the last couple of years.  The other options can definitely scale up in price, but if you have a biochar business or large acreage, it might be worth it.

John S
PDX OR

Biochar crushing techniques

Crushing Char by Driving Over It cheap and easy

Crushing with DR Leaf Vacuum
More consistent char size. Doesn’t work well wet.

Hand-held Leaf Vacuum: underpowered, rocks destroy it, won’t work wet


Hammermill: too dry-cloud of dust. Too wet-plugs up

Pelletmasters Hammermill-The one she uses. Dry char out on a tarp beforehand $1695.00

Honda hammermill in garden chipper/shredder-same price-doesn’t work as well $1695.00

Best option for very large scale: Clinker Grinder?
ECON Clinker Grinder SPD 1600420 7-9-ECON Rebuilt Condition: Used
Price: US $4,850.00
www.ebay.com/itm/ECON-Clinker-Grinder
This would be great for high volume producing

I have just acquired my forever homestead yesterday (Yay!) but having unlimited kiln dried wood at my disposal means I'm getting ready to turn biochar production up to ten. I've been mulling over better ways to do this, and I think what I am going to try is the following:

Large drum probably 55 gallon, the kind with the whole lid that comes off of one end. Build a frame for the drum to lay on that has casters or wheels, allowing the drum to spin freely while laying down. Attach a v groove pulley to the top of the drum and spin it with a gearbox and motor combination at a slow enough pace to allow things to tumble inside. I'll put a few lead  balls (baseball size or so) inside the drum to roll around with it, helping crush and pulverize. Fineness of powder can be controlled by duration of tumbling. Wet biochar would be much better than dry. This unit would not be a quiet one.  

I think one could build this with salvaged materials totaling less than $250 dollars and perhaps much cheaper if you are thrifty.

I tried this with a mortar mixer, Rusty. I had high hopes, but the biochar acted like a cushion and the steel balls (from an ore crusher, as it happens) just rolled around on top.

Lead? Really? Do you want to put lead into your soil or your body?
John S
PDX OR

Sorry,  it's a carry over from making gun powder. It's made in the same way,  but lead will never spark out build static. You could use steel or brass or dense wood chunks if you wanted.

My current biochar crushers.  They do a remarkably good job!  And they taste great!

Rusty Ford wrote:I have just acquired my forever homestead yesterday (Yay!)  

Congratulations Rusty!

Make it out of junk hay instead of wood so it is already in small particles?

This might be a contender
for less than $200

I tried an older meat grinder. It was really hard to use, then it got stuck. Then I had to buy another meat grinder and find a different way to crush biochar.

John S
PDX OR

Gray Henon wrote:My current biochar crushers.  They do a remarkably good job!  And they taste great!

Do I see some Wiltshires in that mob? How are the sheep liking your biochar? Do you mix it with anything to feed to them, and what sort of size do they prefer?

Mine weren't interested until I added some salt (mineral block) but now they'll eat small amounts plain. They seem to like smallish chunks but not too fine, because that makes them sneeze.

Phil Stevens wrote:

Gray Henon wrote:My current biochar crushers.  They do a remarkably good job!  And they taste great!

Do I see some Wiltshires in that mob? How are the sheep liking your biochar? Do you mix it with anything to feed to them, and what sort of size do they prefer?

Mine weren't interested until I added some salt (mineral block) but now they'll eat small amounts plain. They seem to like smallish chunks but not too fine, because that makes them sneeze.

Katahdins.  Not sure how much they eat, but their hooves do most of the crushing.  I spread the char in my food savanna and after a month or so, it is hard to find a piece that has not been crushed.

I'm curious what the target (approx) screen size is for your applications, or in general. I'm happy with around 1/2-3/4" minus, and get this pretty much by default due to mostly burning brush and branches of 2" diameter or less. Is there much advantage to a really pulverized output?

In general, the smaller the particle size the better for most applications. The main thing is increasing the surface area and ability to mix. But there are exceptions, such as having slightly larger pieces to provide structure in fine-grained soils subject to compaction, or in a building material where it's acting as an aggregate.

I'm a fan of doing as little work as possible, so I use Gray's technique of crushing with animal hooves on the grazed areas. I also make use of teeth and gizzards to grind and prep for distribution.

Phil Stevens wrote:

Gray Henon wrote:My current biochar crushers.  They do a remarkably good job!  And they taste great!

Do I see some Wiltshires in that mob? How are the sheep liking your biochar? Do you mix it with anything to feed to them, and what sort of size do they prefer?

Mine weren't interested until I added some salt (mineral block) but now they'll eat small amounts plain. They seem to like smallish chunks but not too fine, because that makes them sneeze.

Rowdy from High Plains Biochar has a cool tutorial on how to make your own mineral lick with biochar. Chickens also seem to like biochar and it mitigates odors in the run.

Phil Stevens wrote:In general, the smaller the particle size the better for most applications. The main thing is increasing the surface area and ability to mix. But there are exceptions, such as having slightly larger pieces to provide structure in fine-grained soils subject to compaction, or in a building material where it's acting as an aggregate.

Okay, makes sense for a more careful field amendment type application in loose soil. I do appreciate the chunkiness for most of my uses.

I would be curious to see - or maybe someone here can point to good online microscopy pics - what the smaller size post-crush 'fines' look like up close. Just scaled down versions of the typical larger chunks, or do they have a more faceted, complex shape?

There is some data on larger chunks for desert-like systems that are extremely arid.  I won't say that the question is settled.  If you take a 2 cm chunk of biochar that has been in the ground, and crush it, water will come out.  There are people who fervently believe that larger chunks will be better in a desert, and there are those who disagree.  I don't think that they have really good studies on it yet.

John S
PDX OR

I think there's a lot of merit in using larger chunks for arid environments, so that they act as reservoirs of moisture that plant roots can tap into and draw from.

My guess is that once the scientists are doing sciencing, the detractors are done detracting, and the disagreers are done disagreeing, we'll find that a mix of sizes is good for most all applications.

Anybody use a dedicated garbage disposal?

I got a free, used garbage disposal and old sink that is working quite well.  You need to feed in a fair amount of water.  You can immediately apply the resulting slurry or put in a drum to settle.