Advice on Crushing Biochar

I am planning to in a few months to make my own Biochar (a type of Charcoal if you don't know), and I am looking for a simple way to grind it up. I was hoping someone here might have an idea, something I could hopefully build for not a lot. The size I would want it to be crushed etc into is roughly 2 Millimeters. One thought I had was some sort of hand operated rock jaw crusher. Something like they have in this video or something else that would work, but not be 500 dollars. A cheap motorized crusher would work as well.

At any rate I hope someone here might be able to point me in the right direction.

How much volume are we talking about, Tim?

If you want to crush a small amount, say a couple of cupfuls at a time (which is enough for a wheelbarrow full of soil), then put it in a large metal can like a gallon paint can and use a 2x4 for a pestle to pound it into a powder.

Another way to do this, which also takes care of the dust problem, is to use an immersion blender to grind it. Put it in a bucketful of water and work the immersion blender up and down. The largest pieces left over after this method may be about 5mm on a side, but the longer you blend, the fewer large piece are left. I like this method, because I can add the biochar to compost tea right before I apply it.

About a wheel barrow full at a time would be an accurate amount, of how much Biochar would be made. I'll look into the immersion blender, I am also thinking about adding some biochar to my Vermiculture bin.

Then a 30 gallon metal drum and a good size sledge hammer should work. Keep dropping the sledge into the drum and that will crush the biochar small in no time. It does tend to raise a cloud of particulate though. After you've done it a couple of times, I think you will prefer the 5 gallon bucket of water and the immersion blender method.

Biochar is so much easier to apply when it is in the form of a liquid slurry.

You mean an old Kitchen Immersion Blender right?

Yes, like this



Sometimes you can find them on sale for $10. Oh, and by the way, you don't want to be taking this back into the kitchen and trying to clean it. It becomes a tool dedicated to the biochar operation.

What if i like the taste of Charcoal?

Tim Ries wrote:What if i like the taste of Charcoal?

Now you make me nostalgic for my uncle's barbecues when I was a kid. Oh, could put a black crust on a piece of meat!

For large quantities, a lawn roller could crush the biochar against a smooth concrete slab. It will color the slab.

A cement mixer containing rounded rocks could work as a ball mill.

I would soak the biochar in water for 4 months to soften it. Then I would try putting it between two pieces of plywood and set that in the middle of the driveway so every day it gets driven over. If I had cows that ever stood on cement I would put the softened char where they stand. Can the object the char is made out of be ground before being made into char? Can the char be used for something like filtering water or capturing the nutrient in urine before being crushed for char? Filtering water for people to drink or for a tank of fish?

Please do not breath biochar dust.

The biochar needs to have a living biofilm added to it so one might as well get that by using it for something useful other than the garden first.

Nancy Sinclaire wrote:I would soak the biochar in water for 4 months to soften it. Then I would try putting it between two pieces of plywood and set that in the middle of the driveway so every day it gets driven over. If I had cows that ever stood on cement I would put the softened char where they stand. Can the object the char is made out of be ground before being made into char? Can the char be used for something like filtering water or capturing the nutrient in urine before being crushed for char? Filtering water for people to drink or for a tank of fish?

Please do not breath biochar dust.

The biochar needs to have a living biofilm added to it so one might as well get that by using it for something useful other than the garden first.

Why four months? Sawdust is a pre ground feedstock that could be used. Ground biochar would blow away very quickly if driven over daily. When charcoal is ground in a ball mill to make gun powder, it is processed until it reaches a fineness called "air float". I think we want to stop long before that point. Large quantities could go into pond filters. I doubt that this would improve the char, but it would clean the pond. Now, imagine that a million little water creatures live and die in the char. It may stink of dead fish. I don't much care for the smell, which is part of why I have never ground a dead fish.

I betcha this would work

Dale you may have answered your own question there. If you were to soak the charcoal in a pond for a good long while, it would act as a filter for the water and a home for tons of microorganisms. Four months is about right for setting up these colonies in the biochar structure. I'm not sure if it would soften it up but I know it would be loaded with all kinds of nutrients that would be great in garden or forest soils. Aquarium filters use charcoal for the chemical absorption power of carbon AND also because it has a really porous structure for lots of bacteria and other micro-critters to live in. If the goal of the biochar is to help hold nutrients in the soil, then soaking up nutrients from a pond and then "transplanting" them via biochar to the garden would seem to be a solid idea to me.
You probably can't add a lot of biochar to an established pond because it might throw it all out of whack. maybe

Ken Peavey wrote:I betcha this would work

Thanks Ken, It took me to their Projects Site!

I'd like to reopen this subject ..... Has anyone found a GOOD way to grind/crush Bio Char ?

Nothing beyond hitting the occassional bigger bit with the fork while spreading it or turning it in. Personally I don't worry too much about it - plant roots force their way through chunks of biochar and it doesn't seem to take too long before the bigger chunks get broken down smaller. I wouldn't attempt to fine grind it unless I had some specific purpose. But then my garden and veggie beds are rather on the messy side anyway.

I've been using a plastic tote type container and a 4 inch wide alder poll as a mortar/pedestal sort of deal. It works pretty well. I wet it down first. I also use WAY more than a couple cups per wheelbarrow full. Hope I'm not over doing it. MY potting soil w/ biochar is producing some amazing results.

Edit: Its a smash/twist/grind... smash/twist/grind... rhythmic sort of crush job, if that makes sense.

George Bowman wrote:I'd like to reopen this subject ..... Has anyone found a GOOD way to grind/crush Bio Char ?

There is a real need for a definition of "good" in your question I think that the suggestion of the stick blender made by John Elliott early in the thread would qualify as a good way of doing it, but the fact that you are asking suggests it does not meet your criteria.

So, what do you mean by "GOOD" ?

I bet a garbage disposal would make a good rough slurry on a wheelbarrow at a time scale.

R Scott, I bet you're right!

I've wondered about a garbage disposal to grind up the stuff that goes to the compost pile, but really, all you gotta do is wait......

I've used a garbage disposal, but but on dry char. It worked well with a cloth bag over the outlet to keep dust in. It stopped working though, as my friend put it, "because you were grinding charcoal in it!" :-/

It worked pretty good though, fast, about the grind I wanted, 1/4 inch and down with lots of powder too. This was a heavy duty kitchenaid unit of 1 hp I had modified as an apple grinder (mixed results on apples).

Designed for the job:
http://www.appropedia.org/Corn_Cob_Charcoal_Crusher

that corn cob crusher looks pretty good. It's a lot like an apple scratter. The grape crushers are made with two ridged cylinders like that and both turn at once. Scratters are usually a larger cylinder with metal teeth, but they turn against a "wall" like the cob charcoal crusher. So it's kind of a hybrid between the two. Single cylinder is esier, because they don't need gearing to turn two cylinders at once. I'm inclined to think that the fruit crusher's two cylinders might work a little faster, but there is a lot to be said for accessibilty and i think making one from scratch could be difficult. After all, accessibility is the main problem with charcoal crushing. I mean, we could all go out and buy something awesome if we could spend the money. I might try to make something like this. Thanks for the link.

This is a few years late as I've only recently started making biochar, so I apologise!

I second John Elliott's solution. I use a powerful stainless steel Electrolux stick blender with a longish shaft. I dump my 12 litres of char out of the retort straight into a 20L bucket half filled with urine, and then pound it for a couple of minutes with a piece of 2x4 to initially break it up into smaller chunks. Then, using the stick blender at an angle, and set to turbo, it soon creates a vortex and the char becomes a very fine slurry which is then poured onto the garden or around plants. The particle size would be around 1 mm and it takes just a minute or two to complete. I use the Back to Eden garden method so the char gets itself to the root zone naturally, with rain, planting activity and worms. Where the bed is empty, I rake it in to a depth of about 100 to 200mm.

The beauty of this method is that there is no dust and the newly made biochar is at its most adsorbant (is this the right word?!). It fairly hisses while it sucks up the liquid. It also ensures that the biochar is fully charged with nitrogen and moisture to kick things off with a bang in the soil. The reason I like to micronise it is because I'm only making biochar on a small scale (12 litre batches), so micronising it gives me the biggest surface area and therefore the most bang for the small volumes I'm producing.

For use in the soil I don't bother crushing mine at all.  It gets mixed with my food scraps to eliminate smell in the bucket under my sink and then it goes through composting with those scraps which causes composting to go faster/hotter.  The Biochar holds onto a lot of nutrients that would have leached out of the pile and holds them for the soil.  Then when I incorporate the compost my soil gets the nutrient loaded Biochar.  Crushing seems unimportant for this and some publications show no difference with crushed or non-crushed.  I mostly use softwood and it breaks down with freeze/thaw cycles pretty well over the years.  If you want to crush a lot fast then finish your char making by water quenching, let it drain so that the Biochar has water in the pores and then send it through a chipper shredder.  The water in the Biochar pores will help keep dust down, which would otherwise be dreadful.  I do like a lot of the suggestions here, but I don't plan to ever crush mine....don't see a reason to do the extra work.  I make quite a few yards every year and the extra work would add up.

William Bronson wrote:Designed for the job:
http://www.appropedia.org/Corn_Cob_Charcoal_Crusher

For the roller I wonder if you could get away with an oak roller/log with the expanded steel screwed on....seems like it would be much easier/cheaper to make.

We sift the ashes from the wood burner several times during the heating season. In the spring I make a fresh compost pile and incorporate the char I've collected. I don't usually worry about the size of the char going in the pile. If I do find large chunks. I will just throw them all into a metal bucket, then drop a sledge hammer vertically into the bucket a few times. After that just throw them in the compost with everything else.

Big biochar movement where I live.  We have way too much "biomass in a vertical orientation" for fire safety, so lots of remediation going on.  I'm talking three or four or five foot diameter char kilns--lots and lots of them!  It works pretty well to put char on a tarp, fold the tarp over it and drive a tractor or truck over the whole thing to break it up.  I suppose you could do the same tarp thing and run the cattle or whatever over it too, as you can when mixing cob.

I don't think I'll ever have a need for this, but it's pretty cool!

I pulverize a variety of things with my cement mixer. I would think just putting in the biochar, throwing in some rocks or bricks, then letting it churn for awhile would work. Your degree of pulverization would depend on how long you let it churn.

Used cement mixers can be had pretty cheap, or you can buy small inexpensive ones at Harbor Freight or Home Depot.

They are a worthwhile investment. We use ours all the time for mixing garden starter soil, potting soils, white-wash, compost...and sometimes even for making concrete. A very versatile machine to have!

Greg Martin wrote:I don't think I'll ever have a need for this, but it's pretty cool!
https://www.youtube.com/watch?v=IMjLPjUUedg

That thing works great.  

Bruce Taylor wrote:This is a few years late as I've only recently started making biochar...
I use the Back to Eden garden method so the char gets itself to the root zone naturally, with rain, planting activity and worms. Where the bed is empty, I rake it in to a depth of about 100 to 200mm.

I'm even newer to biochar, so I guess I'm a few years plus a few months late to this post

Bruce Taylor, I'm very interested to know your method of incorporating the BTE method with biochar. I'm a BTE gardener, and I attended a talk this weekend in which the speaker discussed tilling in the biochar, and then returning to no-till methods, but which I'm definitely not going to do. The "compromise" I reached with him in Q&A was to scratch some into the surface of the soil, below the covering. Can you talk about what you do? Are you layering it on top? Are you moving aside the chip/covering layer, layering on top (or scratching into top inch or 2?), and then putting back the covering? Just doing it when you move chips and expose soil at planting?

Thanks in advance for your help,
Deborah

Deborah Epstein wrote:

Bruce Taylor wrote:This is a few years late as I've only recently started making biochar...
I use the Back to Eden garden method so the char gets itself to the root zone naturally, with rain, planting activity and worms. Where the bed is empty, I rake it in to a depth of about 100 to 200mm.

I'm even newer to biochar, so I guess I'm a few years plus a few months late to this post

Bruce Taylor, I'm very interested to know your method of incorporating the BTE method with biochar. I'm a BTE gardener, and I attended a talk this weekend in which the speaker discussed tilling in the biochar, and then returning to no-till methods, but which I'm definitely not going to do. The "compromise" I reached with him in Q&A was to scratch some into the surface of the soil, below the covering. Can you talk about what you do? Are you layering it on top? Are you moving aside the chip/covering layer, layering on top (or scratching into top inch or 2?), and then putting back the covering? Just doing it when you move chips and expose soil at planting?

Thanks in advance for your help,
Deborah

I incorporate it by mixing the charcoal into my compost when I turn it.  If I had enough at one time, I would layer it in throughout the compost, but I normally don't make enough to do that, so I try to make a batch every week and when I turn my compost once a week, I mix in what charcoal I have.  When the compost is ready, I just put it on top of my gardens.  Every time I had a layer of wood chips or compost or leaves or whatever, that first layer with the biochar gets farther down into my soil.  It is also being moved down by rain, by worms, by chickens scratching in the garden.

If I was making a new bed, I would have no problem tilling the biochar or biochar/compost mix into the area the first time, although I haven't done it that way.  I have just spread crushed charcoal on the ground and piled the wood chips on top of it.  

Now that I have been making charcoal for a while, the best method I have found for crushing it is to take an empty chicken food bag, fill it about halfway or a little more with charcoal, and then pull another bag down over the first one.  then I lay it on my driveway and kind of even out the charcoal in the bags and run over it a few times with my pickup.  I don't run back and forth over it at one time, I just leave it lying there for a day or two and run over it during my normal trips.  Most of it crushes down nicely to sizes from chunk an inch or so across all the way down to powder.  I use it as-is.  The stuff that isn't too small with just help with drainage and I think the freeze cycles through the winter will crush it up smaller.  If not, I don't mind.  I figure it's all useful and what do I care if the microbes live in a single family home or an apartment complex?

I just found my old meat grinder I used for grinding really big tough clams like gapers into great clam chowder.  I'm going to try to put chunks of biochar into the meat grinder to see if it will make it pretty small.  The method I was using was about a 3 foot tall 2x10 with another 1 foot 2x10 screwed onto the bottom of it, to lean on it and crush it. It was a tremendous amount of work.  I think this will work better.
John S
PDX OR

I've heard of folks putting the biochar between two sheets of plywood and then running it over with their car or truck a few times.  If you put it in the driveway, you can probably just leave it there for a few weeks and crush it as you go to and from your house.  Seems like a good idea unless the wood you are using has nails in it.  

If you have access to heavy equipment like I do, and a paved road; you could use a smooth drum packer to crush it down.

Then just sweep and shovel it up into a container.

For a large amount of biochar, it may be worth it and would take no time at all to crush it.

I'll try it one of these days, when I make myself some biochar.

I like the private road and drum crusher idea. A scaled-down method I like resembles the earlier chicken feed bag and driveway approach, except I fill my feed bags about a third of the way, lie them out, and then roll over them with a lawn roller. The one I used was a 55 gallon drum on its side filled with brine water.

Dust guards or soaked charcoal would be required, but I think a hammer mill, like what is used for preparing biomass for pelletisation, would be ideal. I mean, what better than a conical grinding wheel armature with a textured stator around it, such that you could adjust the fineness of the grind, much as with a burr grinder?

I have also used a homemade cage insert for a homemade 55 gallon drum mixer, wherein the insert, made of welded wire, held a metal filter screen. I don't recall the size of the particulate screen, but it was something like a sixteenth of an inch or smaller. The mixer just spun, and I just kept heaving (and later shovelling) charcoal into the centre area, where some rounded river rocks crushed it against themselves and the screen, and particles of the right size to fall collected in the outer void space within the spinning drum.

I like crushed charcoal for composters and collection bins. I also like brewing oxygenated compost extracts with it. I like the idea of applying biochar as part of an oxygenated compost extract because not only does being incorporated into the extract brewing process inoculate the charcoal, making it biochar, as mentioned above, it is most easily applied to the soil as part of a liquid suspension.

I think there are many situations where forking in, or even tilling, biochar into the top six to eight inches of the soil would be better than just watering it in and hoping it does something. What, for instance, is the point of applying a biochar slurry to the soil surface if the soil particles are too close to let the biochar down? If the biochar sits in the sun for too long, those colonies of microbes will die.

I think, in general, that the specific causes of harm with regards to tillage, that being the inversion of soil structure and the rendering into dust the soil particle structure, must be stressed. If the soil has little to no life, and the forking or tilling in of inoculated biochar represents a seeding of life that the soil couldn't possibly otherwise achieve, and so quickly, then the harms of soil disturbance are moot. Likewise, if the soil is too compacted to allow water to move the biochar particles and their populations down, not forking or tilling could result in no real gains.

-CK

I install biochar anytime I am doing a disturbance that gets the char down into the soil where it can do some good quickly.
Char is a lot like using wood chips except that since you have spent the time to inoculate the char, waiting for it to migrate down also means death to many of the beneficial organisms you inoculated it with.
That seems a huge waste of biology which is one of the main factors of biochar and terra preta, so why not get it under the soil right away instead of waiting for nature.
The first people to use it obviously dug it into the soil after spreading it because that would be the only way to have a 2 foot thick layer over a foot under the surface, which is how it was found back in the late 1800's.

For crushing I use my chipper then it goes into a compost heap for inoculation.

These are great ideas for different scales of biochar.  I have been using the meat grinder. It is an effective method of grinding it to a kind of coarse sand texture, which is much better than the gravel that I was getting with the giant mortar and pestal version I was using earlier.  I am intrigued by the plywood boards in the driveway to see how that will work, but I'm going to have to talk to the boss first.
JOhn S
PDX OR

I went ahead and put it between two panels of plywood, stepped on it, and then drove over it.  It was amazingly easier!  I went in with a dustpan, especially to the areas that looked like they had been very crushed.  I took the big chunks out of the dustpan, threw them back in between the layers, removed a lot of the crushed and gravel sized stuff and put it in a pot.  Then I releveled the biochar, put the panels back and redrove over them.  I think I'm going to keep doing this at my scale.  Check on it after a few drive overs, and repeat.
John S
PDX OR