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Designing a biochar grinder

 
Matthew McCoul
Posts: 72
Location: Southeast Michigan
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So I'm designing something that will grind biochar down into smaller bits. Aiming for 1/4 inch or less.
Now, I'd like to be able to do this on a pretty large scale, I'll be clearing out at least an acre of woods and i hope to char all of it.

My first thought was to turn a dryer into something like a large meat grinder.
http://www.tsmproducts.com/image/61232_stainless_steel_meat_grinder_300_2.jpg

I'd disconnect the motor from the dryer's drum and attach something like an auger to the motor shaft, so the auger turns but the drum stays.
Then replace the dryer door with a metal plate with holes, so the biochar would get pushed through and crumble.
I'd have a hole in the top of the dryer to feed the char into it.

Just like a big meat grinder


Am i reinventing the wheel? Is there a better way to do this? Any input on the above design?
Anything that will help make a lot of biochar smaller is appreciated.

Thankyou much,
Matt
 
John Elliott
pollinator
Posts: 2310
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Cough-cough-ack-cough! Warn me so I'm not downwind of you when you fire that contraption up.

Grind it wet. Put it in a 5 gallon bucket and cover it with water and use an immersion blender. Or scale up from there. I use a 44oz. plastic cup when I grind biochar, and after 30 seconds with the immersion blender it goes into the compost tea. As friable as biochar is, it doesn't take much time with the blender and it will easily pass a 1/4" screen.
 
Landon Sunrich
pollinator
Posts: 1703
Location: Western Washington
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I've mentioned this before but I just put it into a bin or a garbage can, wet it down, and smash/grind at it with a 4-6 inch wide wooden pole. It works pretty well and I can get 10 -15 gallons done at a time in well under 20 minutes.
 
Abe Connally
Posts: 1502
Location: Chihuahua Desert
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Here's the easy way: a ball grinder. Take a concrete mixer, or similar rotating drum. Take out any paddles in there. Then, drop several steel balls in the drum, drop in WET biochar (dry could explode). Turn it on for a while, and wait. It will come out as a very fine powder, adjust the time in the drum for larger/smaller chunks.
 
Steven Edholm
Posts: 15
Location: norcal
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Cool Idea on the immersion blender! I'd like to scale that up to a heavy duty drill with a custom bit. How to grind seems to be a common topic in biochar. Re: the dryer thing. I had an idea similar to Abe's idea using an old drier or similar perforated drum. Toss in some hard stones and tumble. When the char is done it will sift through the holes. Might clog with wet char and dry char is awfully prone to being airborne, so those issues would have to be addressed. I've use many techniques, most inconvenient. Garbage disposal worked well, but not long until it died. I have a hammermill type garden shredder that I'll probably hook up eventually, with a magnet somewhere in the drum to catch nails. In the mean time, it's boots on plywood. A recent discussion on my blog brought up the idea of using a fruit crusher of the double roller type.
 
William Bronson
Posts: 1140
Location: Cincinnati, Ohio,Price Hill 45205
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