Screening Ashes - How Much Do You Recover?

Just curious if anyone screens their ashes and how much usable coal you recover?

I have been thinking about doing this, but I don't think there is a lot of unburned coal in my ash.

None because the fuel is exhausted and so should yours especially if you're using a hand fired stove. Stokers are little more problematic to get a full burn especially if they have too few adjustments on them but overall when it hits the ash pan it should be spent.

Good question.

I have a Keystoker KAA-2 boiler burning rice and there is a fair amount of unburned coal in the ash. I'm new to a stoker, but I expected more efficiency than my handfired. Not really true, but far more convenient.

I hadn't considered if it was practical to attempt to recover any of it. Rather, I've been trying to minimize it. When the stoker runs flat-out, the ash is almost ceramic and fused, breaking into clumps as it falls into the pan. Otherwise it does drop a suspicious (to my inexperienced eye) amount of coal. I haven't figured out why. I've played with more air/less air, more stoker/less stoker, but I haven't nailed it.

The unit otherwise seems to work well. Much ado about nothing or a chance to squeeze out a few more BTU?

Stoker ash will always be "chunkier", as I've posted many times the very same coal burned in our stoker produces a chunky ash but when burned in a Franco Belge it was nothing but powder. When I say same I mean the coal was taken right out the same bin from the same delivery.

I screened mine a few time from a hand fired Russo and found it was not worth the effort unless it was early in the season and I let the stove go out durring the warmer days.

This time of year when the stove is going 24/7 the few pieces that fall through the grates are not worth the trouble to screen.

Gary

[quote="Kenbod"]Good question.

I have a Keystoker KAA-2 boiler burning rice and there is a fair amount of unburned coal in the ash. I'm new to a stoker, but I expected more efficiency than my handfired. Not really true, but far more convenient.

How large is your fire bed? I believe that Keystoker recommends about 3" in width, I started there and adjust as needed based on demand. I've not noticed coal but have had some with shale or other type of rock in it. Too bad we pay by the pound.

I ran into a person this week that claims they sifted and saved their unburned coal and tried to burn it. They said it will not sustain a fire. Mixed with new coal, it goes through and who knows how many BTU's come from it, but it will not burn on it's own. They stopped sifting and let it go out with the ashes.

This reminds me of a buddy of mine that was talking to me in my driveway and spotted a beer tab on the the ground. He bent over and picked it up and put it in his pocket. Then he said he was saving aluminum to take to the junk yard. Well its a good thing I did not have a mouthful of coffee or it would have come out when I started laughing.

Unless your stove is burning the wrong sized coal or you are not burning it properly, my belief is its hardly worth the effort and dust it must create. My time is more valuable that that.

I "lose" more coals if I burn pea (vs nut). Neither is worth the effort to to screen during normal stove operation. I'll screen if I have to shut the stove down. I'll just shake with longer strokes (lose the fire on purpose) , take the ashpan outside and dump on a screen. Very messy...

Kenbod wrote:I have a Keystoker KAA-2 boiler burning rice and there is a fair amount of unburned coal in the ash. I'm new to a stoker, but I expected more efficiency than my handfired.

a lot of it has to do with the quality of the coal. I suspect if you did sift out the unburned coal and tried to reburn it it would come out of your KAA-2 looking the same as it did when it went in. You could try it and see as it won't cost you anything.

I screen rocks and small stones out of the part of my garden where I grow root veggies. Given how time consuming and mindless that activity is, I can't imagine what it would be like to try and recover little pieces of 1/2 burnt coal when a 50 lb bag is what, $6? I don't know about you, but my time is way more valuable than that.

Years ago when I burned coal in a Vermont Castings combination wood/coal stove, I used to have problems burning nut coal but stove coal burned fine. The rotating grates of the Vermint Castings stoves let lots of unburnt or still-burning coal into the ash pan when shaken vigorously. When I emptied the pan into a 30 gallon galvanized trash-bucket outside I had a round woven wire basket that fit the top of the bucket exactly. I'd dump the ashes into the basket and recover 2-3 pounds or more from each load of ashes but would have some white stony stuff and melted crusty stuff that wouldn't burn mixed in with it. I'd pick those out with stove-gloves and return the rest to the stove.

I gave my coal burning stuff to my brother when I moved from that house and he gave it away when he sold his house. I've been looking for a screen basket like the round one I had for a long time. Anyone know where to get one that fits in the top of a 30 gallon ash bucket and can screen out unburnt pea coal?

You wrote: Anyone know where to get one that fits in the top of a 30 gallon ash bucket and can screen out unburnt pea coal

I would try a Kitchen supply store. I have seen something like you are describing at the IKEA Market place. In kitchens they are used to strain bigger items or for dunking things in hot water or oil. Or maybe you could use one of the metal vegetable baskets people hang in their kitchens. The ashes would fall through and leave the unburned pea coal.

Personally, I don't think it would be worth my time and effort to screen my ashes - not with 40lbs only costing $6. When I was a newbie and dumping my fire frequently I did but there'd have to be an awful lot of unburned coal for me to spend my time on it now. Good luck, Lisa