Get a cannon, load in black powder, wad material (maybe not necessary)
manure and rocks, touch off the powder. The rocks will be at the longest
range an the 'sifted' manure will be close to the cannon. With a few
practice shots, a few well placed blue tarps will collect the sifted manure
and the rocks will land on your road.

Get the neighbors involved and let'em touch off the cannon for a few buck.



--
J Miller
"R. Zimmerman" wrote in message
news:nLJUf.176416$H%4.88867@pd7tw2no...
Your rotary drum is called a trummel. They very common in placer mining
for gold. I have seen huge plate steel trummels with three inch holes in
them. Obviously they were for big operations.
I would expect that unless the manure is very fine and dry it will plug
up the holes.
The other alternative is a screen deck. It is a large steel box with
one
or more layers of woven steel mesh or perforated sheet steel. The box is
slanted slightly and hung on springs. A shaft with counterweights is
rotated by a small gas engine via a long flexible Vee belt. The whole box
vibrates working the material down the slope. You might look up gravel
screening equipment websites for ideas.
I worked for a guy who built these units regularly... Any size and
screen spacing the customer wanted. Part of gold fever is the need to
have
bigger and better screen decks and bigger, longer and better sluice boxes.
Randy




"Tim Wescott" wrote in message
...
We have this big ol' pile of horse manure out back, which we can't
spread out in the pasture because it is full of rocks that are just
about exactly the right size for causing problems with horses feet
(according to SWMBO, at least). The sizes range from sand to 3-4 inches.

Since clean, rock-free horse manure is pretty easy to get around here,
I'm assuming I cannot give it away. So I'd like to build a sifter for
the stuff, to separate the good rocks from the good fertilizer.

I'm considering making a big drum with a 1/4" screen, rotating it with
either an electric motor or a Vibration & Stratton engine. I'll load in
dirty manure in one end with my loader, get clean manure out the bottom,
and occasionally dump slightly odiferous rocks out of the drum.

What I need to know is:

1. Is this a good approach?
1a. How do quarries sift their rock?
1b. Is there something out there that I can get my hands on that does
this task? It doesn't have to look like what I think will work, it just
needs to separate the rock from the crap.
2. Anyone have any suggestions for screen? I'm considering expanded
metal, but it looks like I can't get really thick expanded metal with
1/4" holes. I'm afraid that the 18 gauge that it seems I can get will
wear too quickly, particularly if I get a big rock bonking around in
there.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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