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2 Stage Sluice Gravity drop w/ Powerhead

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After looking at alot of sluice designs, I tried to make one that incorportated a few different aspects of some I liked the look of. I like the gravity drop idea, like a le trap so that is where my thinking started off with. I was working with metal, scrap metal, in fact the majority of this sluice was a scrap washing machine only a week ago... Last time I was buying some steel for another work related project, I saw some 4' long prebent metal scraps that were various sizes which I got for less than $5, These are what I used for my riffles, they are each different widths and heights which vary each slope to change up flows and hopefully retain the gold. My sheet metal brake is only 30" long so it limited what I can bend, but I wanted to play around with the 2 stage idea anyway, so I bent two boxes, one with 1" taller sides, and when I joined them up, I raised the slope of the top half 3/4" so it has some extra slope. Midway down the riffles, there is one that is a punchplate for the fine heavies to drop into the lower box. The extra slope in the top box, is actually intended to make this lower portion be flatter sloped for the fines, the upper slope almost continues on down the box on the upper set of riffles, there is a slight change in angle there too though. The powerhead is pretty much my version of a straight copy of many I have seen, Mostly a Keene with expanded metal instead of slats but mine has sprayers on 3 sides. I also added a section of rubber mat glued to the flat portion of the bottom of the head, I am wondering if that is a mistake and this should be smooth to get the material moving?? These pics are first mock up complete in the stand, still needs a little finishing touches. This is 10" wide and 4' long before adding the head, My initial concern pre-testing, is that my drops are too big or this is just not going to work as planned, but I will find out soon.

NOTE: If anybody is looking for something built to save money over buying equipment, let me know... My 25 year drafting career disappeared two and a half years ago and I dont expect it back anytime soon... without leaving the state. Since then, I have been helping my nephew with maintaining foreclosed homes, doing Yardwork, Tree Trimming, Hauling and any repairs we can get bid approvals on, but he hired some lazy guys that messed things up and he has lost alot of work recently... so I have had some free time. I am tired of working for these property management crooks and helping the banks HIDE stuff from future buyers instead of fixing it right anyway and would much prefer to be building prospecting equipment and/or doing metal fabrication work anyway. Besides this stuff, I have built a puffer type drywasher, and a small sampling drywasher (great learning tool/time occupier for your kids or grandkids to learn on while helping you), a gas powered vacuum, a cool classifier, a small hand suction pump and many small crevicing tools and mining spoons, I can do just about anything you have a design for and possibly more with just a picture to get started....

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Again, nice job!

Can I make a suggestion? Replace that expanded metal on the bottom section... with some smaller stuff. 3/16" is perfect!!

these drop riffles will catch most of your gold, so the main use of that lower section, will be the retention of fines and tiny flakes that flip up out of the top box.

Thanks for sharing and good luck

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THANKS! I appreciate all the input I can get... I assume you mean 3/16" opening right not tall? The stuff I used as a classifier in the power head is called 1/2" flat, those openings measure 1/4" across the short way. Actually I was thinking the same thing last night, after I saw my pictures, something clicked and thought about the keene 8" box only having 3/8" or possibly 1/2" raised expaned metal, all the way down, So, I changed it up this morning, but did not go that small, This stuff was huge really, it is raised and the opening measures 1 1/8" and at the deep portion that makes the riffle where two are stacked up, it measures 7/16" tall... I ended up modifying that lower section and using it for standard riffles above the gravity drops... For the bottom, I used 3/4" raised which has a 3/4" opening and is just a hair under a 1/4" tall where two stack. I was getting ready to test it out and I remembered something from last time, it was a hassle to drain this, Dont know that it's needed, but I try to fill/drain equally so I dont put to extreme pressure on the dividers I glued in... so and added a valve to each of the compartments on my recirc. tub so I can drain the water out easier. I grabbed the wrong glue and it needs to dry for 24 hours so going to test it out tomorrow...

Again, nice job!

Can I make a suggestion? Replace that expanded metal on the bottom section... with some smaller stuff. 3/16" is perfect!!

these drop riffles will catch most of your gold, so the main use of that lower section, will be the retention of fines and tiny flakes that flip up out of the top box.

Thanks for sharing and good luck

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O.S.F. This is the stuff i was talking about: 3/16" measured the short way. Becoming popular up here for recovering super-fine beach gold.

102_4189.jpg

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Have you heard of the popandson sluice? If not, google it when you get a few minutes. I've heard it works better over reg. carpet vs. nomad(i've only used carpet and recovery was awesome :brows: )

My personal line of thought is a primary recovery by drop riffles, followed by (a'la' popandson) expanded metal over carpet(that low nap stuff keene puts in their sluices) would catch anything worth catching. Of course, you'd have to build a frame for holdin down the expanded section, if you used the 3/16".

:twocents:

I do like how wide it is, should be able to process a fair amout of material in short order. :grin:

Again, good luck

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I like all the features you incorporated in your sluice.

Any progress report on how it is performing? :thumbsupanim

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Well here is a long report from first test and a couple mods. I am a little long winded, but wrote it out for future reference... Just a FYI besides the ribbed v matting glued down (I got from an upolstry shop) I am using a nice ribbed carpet that you get at home depot for about $12 for a 6'x9' precut piece. I have had great luck with this in my previous sluices getting super fine flour gold and stayed with it. The other one, I have also used is a different rubber backed ridged welcome mat under one section, I will probably use that in this one too if I can find another one like it better. BTW, I really like that raised 3/16" stuff, that is nice! will keep an eye out for it.

Well it was a fail as far as initial setup... Took alot of playing around to get it to flow right because of the difference in slope within the box and also the punch plate that let water and fines go to the bottom box... but, it was a resounding PASS overall. I took 10 split shots, the couple I weighed were 1.6 & 1.8 grams, I cut half of them in half, and hit all with a hammer, I had 10 little .6 to .9 gram nugs and 5 more that were full sized. Then I took a bunch of tiny shot from a shotgun shell. These weighed in at less than a 10th of a gram each... took 12 for a gram. I hit 10 lightly to deform a little, then hit 10 more really hard and flattened to a flake, lastly I smashed another 10 and cut 5 in half to make 10 more half that size and I quartered 3 more and used another 10 of those... started out with 55 pieces of lead that I put into 2 buckets of my tailings... I added in some bigger rocks to my classified tailings to work the classifier too...

I set it up initially where I thought it should be, about 7" of total slope over the 4' (measured on the top of the box only)... I turned it on and it looked like it was going to go alright with it almost full on, had to cut it back a little because water was splashing out of the head. I played around a little and it I cut it way back, it appeared it was flowing enough to work in the top, but there was no water at all coming out the bottom of the top tray, it all went to the lower tray through the punch plate. I started thinking... this might pose a problem... I cranked it back up and shoveled my first shovel full in. The material went across the top fine, but it stopped when it got past the punch plate, the dam it created, forced more water though the punchplate. I was running all the water I had, and thinking I may need to add some holes to the spray bar, it seemed like it was not well dispersed down the sluice and I was not sure if I was restricting the pump with the amount of holes I had in it or if it had more to give.

Well for now, this is all I had, so I tried to take care of it with some adjustments. I added some slope to it and tried again, this time the material moved a little better, but now the power head was sloping too much and the material was not exiting without help and it was still not enough slope. I shut it off again and adjusted it as steep as I could on this base, I had 13 1/2" of total slope over 4', that seemed way too steep to me, but I fired it up and shoveled another shovel in. This time the material went right on down through the box, looked like it was working great, but still just seemed to steep to me. I put in 6 or 8 shovels and it seemed like it was working alright, but the exit angle out of the power head was such that I had to help the material with my hands... I shut it back off to see if I could adjust it easily...

When I shut it off, I saw one of my smaller big nuggets fall down from being sucked up against the gravity riffle and it was laying on the third short flat spot after sticking in the second gravity drop. If it were gold, I would pick it out when I saw it, but I wanted to see if it would stay in the box so I left it alone. Well the head was as flat as it would sit without drilling an additional hole and I did not think it should be running this steep so I did not want to do that. I figured lets finish the test and see where I am at... So turned it back on and started shoveling... that lead just sat there on the flat part even with rocks coming off and hitting it... As I keep going, I start seeing these large nuggets dropping out of the box and getting caught up in the very top of the box, barely out of the head... Looked like it was working great. The main problem was in the power head, I had to manually help the material and was hoping to not have to do that. A couple times, my shovel was too much and some material that should have been in the box, ran out the end in a slurry. After about the 3rd time, I figured no way was I getting all my lead back.

Finished up the buckets started cleanup, first pulled the carpet at the bottom upper tray, I could see a couple of my small "flakes" down there. I panned it out and there was 3 of them. Then I pulled the carpet from the top and rinsed it out and then rinsed the rest of the sluice including the lower bottom tray, there was not much chance my lead made it in there, a few of the quarter pieces would fit through but had to hit the hole just perfect. I panned that out and found one of the small flakes that must have been in the material in one of the gravity drops, I thought man this does not look good, I know most of the big nugs were in the upper portion but figured some of the smaller pieces had to go through with that much slope... Then I panned the upper material and when it was all said and done, I lost one of the tiny ones that I barely hit with a hammer and one of the hard hit flakes that had been cut in half... I caught every other piece up in the top besides (4) 1/10 of a gram flakes that got caught below and another 10th plus a half of a 10th that may have never made it into the box.

Today, since this was not running like I thought it should, I ended up adding a second spray bar right over that punch plate, but had to run the pump full out to get enough water flowing to lower the slope some. I was able to run material and get it all the way through with the first set of riffles past the punch plate clearing in about 10-15 seconds. I had it down to just below 9” total slope and I took some measurements with a cool level I have that measures slopes. With it sitting on the top rail of the box, I got an 18degree reading, At that angle, the upper riffles right out of the head are sitting at 20degrees slope and the lower riffle section is 17.5 degrees on the top tray and 17 degrees on the bottom tray. Still felt like I would be better off if I had some extra flow to play with and started looking into a larger pump, mine is only 1/2 HP and I can get the same 1 HP pump new for $60 that is rated at double the flow (3400gph).

After reading some specs and it mentioning you got more flow with the largest pipe (yeah I know, a DUH! Moment) I re-plumbed the whole system to try to get some more flow out of my pump. I always have had a 1” tube coming off the pump that slipped over a 3/4" pvc pipe going to the sprayers, so I necked it on down to 3/4" only a foot out of the pump. Well the pump has a 1 1/2" outlet immediately necking down to a 1” with a tapered adapter, so I unscrewed the adapter tube and screwed on a 1 1/2" piece of PVC then plumbed it with 1 1/2" all the way up to the valves to give it some more volume to hopefully create more pressure off the sprayers. Seems like it did the trick, now flowing so well it is overflowing my tub, I had to cut that divider down a couple inches… which works out better anyway, this setup took 40 gallons of water to fill before and I was hoping for something closer to 30, so I can get two fill ups with a 55 gallon barrel plus one that is 15 gallons. The main weak point now is my bucket at the bottom, I still lose some water there and had to add 5 gallons about every 20 minutes last night.

I like all the features you incorporated in your sluice.

Any progress report on how it is performing? :thumbsupanim

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Could you post a couple of picks on how you built your recovery Tub ?

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O.S.F. This is the stuff i was talking about: 3/16" measured the short way. Becoming popular up here for recovering super-fine beach gold.

102_4189.jpg

102_4190.jpg

Have you heard of the popandson sluice? If not, google it when you get a few minutes. I've heard it works better over reg. carpet vs. nomad(i've only used carpet and recovery was awesome :brows: )

My personal line of thought is a primary recovery by drop riffles, followed by (a'la' popandson) expanded metal over carpet(that low nap stuff keene puts in their sluices) would catch anything worth catching. Of course, you'd have to build a frame for holdin down the expanded section, if you used the 3/16".

twocents%5B1%5D.gif

I do like how wide it is, should be able to process a fair amout of material in short order. Grin_anim%5B1%5D.gif

Again, good luck

Yes, I agree (Popandson) fine gold sluice is very efficient at catching fine gold. Run properly it will catch almost all of the gold -albeit - some loss.But it is proven to catch near 98% of the gold, when setup and run according to guidelines . And yes, one should use some hold down method for the small expanded metal mesh or it will raise or bend easily and not function very well.

Thanks Dave for the feed back on this type of sluices.

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