Pelletizing sawdust?

[Fether Hardwoods]

Anyone done any experimenting on using your sawdust for pellets?
I have way to much dust and it keeps getting worse.
Thank You Nathan

[JimBuis]

I know there have been a couple of threads on this and similar topics over the last several years. You can probably do some searches and find them.

I would tell you all about it myself, but I'd be making it all up since I don't know anything about it.

Good Luck,

[Magicman]

Commercial pellet mills here do not use sawdust.  They use wood chips the same as papermills and they contain less than 6% impurities such as bark.  The chips go through a hammermill and then they are dried to a certain moisture content so that the pellets will form in the presses.

[Don_Papenburg]

I have read a little bit on pellet mills , planer shavings would work better than saw dust .  The saw dust is just too small in size to compact and bond . the larger shavings from planer shaper and maybe a circle mill would work best . This is from what i have read not real life experiance  :P

[pyrocasto]

I've done a lot of research on the subject and I still cant get myself to spend $5k on a machine to try it out. I'ver heard they work great for everything but straight wood dust, as it's the hardest to pelletize. Most people suggest a binder mixed in with the dust, which I'm sure would work, but would just be annoying to have to do.

If I could spend $5k-$10k and just pour sawdust in and get pellets out guaranteed, I'd be sold on the spot.

Larger machines would work but cost is prohibitive unless you plan on starting a pellet business.

[thecfarm]

I use to buy sawdust from a sawmill,$7 for a pickup load,for horse bedding. We got rid of the horses.  Last year needed some sawdust for the raspberries,$20 now. Just an idea for you. This was hemlock,pine and some hardwood mixed in. Cedar they would keep separate and charge more for it.

[Josef]

Finally a topic I might be able to contribute intelligently to. Sawdust makes decent pellets but require binder additives and lubricants to efficiently pelletize. The binder adds to the effect of lignin in the wood fiber which is necessary to bind the wood particles together. Lignin binds under the extreme pressure and temperature created in the plate die of the pellet machine.

There are many pellet machines on the market but unfortunately the Chinese imports seem designed more for feed product processing which is less demanding on the dies than wood or other cellulose fibers. Many of them haven't proven themselves able to take even the demands of the homeowner user looking to make furnace pellets for their own use in long term service.

The machine I've used was made by Buskirk Engineering, had a 12 inch die plate that was 1.5 inch thick, with two rollers and was PTO driven. Not a cheap machine, most definitely many times the cost of the lowest end Chinese import, but a much heavier construction. This machine took about all my 60 horse tractor wanted to handle at the PTO under max production.

Buskirk engineered and produced the switch grass pelletizer that was on display across the country last year, a well engineered vehicle mounted product but the aspect of it that intrigued me the most was the fact that it could form the pellets without additional binder. It seems grass fibers have a higher lignin content than wood fibers. In my own application that's very advantageous as I'm looking to pelletize horse manure (which is combined with the sawdust bedding it's collected from). This comprises mostly soiled hay, sawdust bedding and "equine processed" feed products. I have to tell you when the first load of horse manure pellets came out of the machine I grinned for a week, finally a use for the byproduct of all that expensive feed I'd been putting into my horses.

The grass fiber based pellets actually seem to have a higher btu content per ton than the wood fiber based pellets and as such require a biomass designed pellet stove to burn them without damaging the stove. These stoves have a shaker grate to discharge the clinkers formed when burning biomass. Since my pellets are more grass fiber than wood fiber I leaned quickly that a biomass stove was necessary.

One important fact about pellet machines that is seldom discussed is the importance of regulating the moisture content of the wood or grass fiber material. The machine produces a great amount of heat and that creates steam in the pellet, too much moisture and the pellet disintegrates upon exit from the die, too little and it plugs the die. Experiment on your own materials, but I've found that any more than 17% moisture and I have to run it thru the machine a second or third time to form a stable pellet.

Another important fact is that a hammer mill is almost essential in preparing the fiber materials, the particulate size needs to be (in our application) about 1/4 to 1/2 inch max in size, larger and it builds up in front of the roller and doesn't compress thru the die.

Hope some of this information was useful.

[Buck]

Can you describe more on the manipulation of the moisture content in your application?

[Josef]

It's pretty low tech, I have a 24 x 48 building with a concrete floor that I back the manure spreader into and just "spread" the manure on the floor to about 4 inches deep. Obviously I can only do this during the summer, but it takes about 2 days to air dry to below 17% (it starts out at about 35%). Then put it thru the hammer mill to reduce particulate size and it's ready to go thru the pellet mill. Someone asked once the ratio of sawdust to grass fiber/manure in my spreader, a rough guestimate would be 3 to 1, since I take out 3 wheelbarrows of manure to one wheelbarrow of sawdust I put back in a stall. If I were trying to put straight sawdust thru the pellet mill I'd probably spread and air dry it as well since I'm only producing pellets for my own use (about 8 tons a year for various stoves and boilers)

[711ac]

I read a post on another forum, (hearth.com) A guy had some type of wood working shop and was making his own pellets. You might be able to find it with a search there. I can't remember what section of the forum it was in but brolly the "boiler room"

[red oaks lumber]

finally hay burners have a productive use ;D
if you didn't want to pelatize, couldnt you use a slow converoy system to use loose sawdust or horse dung?

[RickF]

What type of binder agents does one use? Could one use used vegetable oil or other used oils to make a kind-of hybrid wood/oil pellet? I also wonder if there is any old techniques of using hand presses or weights and metal molds to create bricks or pellets?

[Dale Hatfield]

Bricks now were talking. If I could brick Horse POO . They would be giving back.

[Ironwood]

Good input Josef and thanks for giving some realistic perspective.

I have a buddy who runs all his vehicals only on WVO, and wants to take his soaking wet Woodmizer dust and design a "pellitizer" to use it for heat. I told him he is nuts, work a few side jobs and buy what you need.

I say sell the shavings too horse people and take the cash and buy NG or cordwood. Just me and my situation, others have resources and grass, manure to burn, but at some poiint the RIO (return on investment) zeros out. Include your time, capital equipment, opportunity cost, and all, it seems unless it is a hobby it would not add up.

I like to be "green" but for me anyway, turning up the NG fired boiler at the thermostat seems to make sense. I optimize/maximize other things in other areas. I suppose if I were heating a big ineffiecent home or outbuilding it would make sense, but my 1300 sq. ft. super insulated "rebuilt house" heats for about $120 a month on the coldest month of the year.

About the only good math I see for me is a OWB once I have more buildings to heat (greenhouse, bigger shop etc...)

Ironwood
Ironwood

[Ford_man]

I truck wood pellets from a commercial Pellet mill. I have ask a lot of questions and what I've learned from those people is they use sawdust, they dry it to 12% going into the mill they do not use any binder, they use about 1 quart of veggy oil per ton to lub the die. the pellets come out hot and are cooled , after cooling they are about 8%. The sawdust they use is from debarked logs, they also grind their slab wood. The material I saw going into the mill is fine dust. They also screen the fines out and run the fines back thru.
You can google small wood pellet mills, it will show you small setups and driers.

[shelbycharger400]

i talked to a seller of the "china" made pellet mill, they told me that i couldnt run straight saw dust through their mill, and i needed a 2 stage mill.   Its too bad my stepdad dosnt work at the machine shop anymore, they had a machine that made "honeycomb" (not the cereal)  It was a really neat electric discharge machine for making aircraft parts. I have no idea what they would charge if you came up with a design nor if they could do it.

[bushhog920]

https://www.sawmillmag.com/app/home/index did an article this past year about a man that with his trim shop. used the pellets to heat his shop, wife's resaunt and would sell the rest. you could contact them and buy that one issue.

[Kansas]

There is a guy here in Kansas with a smaller pelleter, I believe out in south central Kansas. His business is making pellets for smoking or bbq-ing. I met him back in the day when we used to have shows and such. He called the other day wondering if we had any hard maple that he could use. I will be talking with him soon and find out what his capacity is, if different species matter, and what he uses if any for a binder. My experience with pelleters were at a feed mill and an alfalfa mill. I saw a guy spend a week and untold drill bits to clear out a die that had been plugged. Then there was the issue of the boiler, having to be inspected. Hopefully a small scale pelleter would get around some problems.

[Ford_man]

Go to http//www.smallpelletmill.com
It looks like a machine that will work.

[Dave VH]

i burn straight sawdust in my shop, from the bandmill, and the planer, whatever.  I get a good hot coal base going first, then I use more sawdust than wood, makes my firewood last a lot longer.  Just a woodburner stove

[bandmiller2]

Back in the eighties I was looking for something to do with copius amounts of circular mill sawdust.There was a pilot project in wester Ma. in the hills near Conway Ma.I know they were just burning up gov. grant money.What they had were what looked like commercial air compressors with big flywheels.they had probibly a 3/8" piston that had a long stroke and would take in sawdust from a hopper on the back stroke and compress it like a hay baler.I could not see in the machine but it looked like the compressed dust provided the resistance.pellets came out and broke into random legnths.I remember thinking this is too slow and really  not practical.I do believe sawdust can be burned efficiently if fed or blown into a hot masonry lined firebox. Frank C.

[Ron Wenrich]

Fluidized bed boiler.  Sawdust is burnt while in suspension.