Clarkston riffle design questions PICS!!

[joebwhit]

So I got a wild hair and weled up some new riffles. I based everything off the clarkston research. I used 3/4"x3/4" angle iron and 1 1/2" flat bar. at 3/4" tall they should have been spaced 1 1/2" apart from down stream edge to up stream edge with a 15 degree pitch to them. I am running it with a 2" pump at about 120gpm. I know these riffles can handle more water but this should have been close to enough. the material piled up behind the riffles. when poking at with my finger you can tell there is a lot of force holing it down, but a full circle vortex was not forming. I think but am not sure, that due to the riffle being pushed down fairly hard into my moss that the actual height of the riffles was closer to 1/2" or 5/8" at best. that being said my spacing should have been closer 1" - 1 1/4". what do you think? thoughts, advice? dont' judge my welds. that was nearly my first time stick welding something this small.

 

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[Campngolf]

I'm no expert by any means, but it looks good to me. I wish I had any type of welding skills.

I think it may need a little more pink sidewalk chalk.

 

[joebwhit]

my daughter's special touch. I'll have her draw up the next set on the side walk before I start welding

 

[Timberdoodle]

My welds looked a lot like those until I bought a tig.
I would pull the miners moss out and try it to see if the vortex is forming properly without the moss. I have run into this problem before with the fine miners moss since it likes to reform around riffles and effects the vortex. There are thicker MM products out there but they are harder to clean since they are much stiffer. Each have their pro's and con's. It usually takes some time to dial in these riffles, but once you do they work very well. You could also cut a slightly shorter piece of angle to mount to a following welded in riffle with clamps and try it with the moss to allow you to change spacing dimensions easily and see if you can find the sweet spot.

 

[Goodyguy]

So I got a wild hair and weled up some new riffles. I based everything off the clarkston research. I used 3/4"x3/4" angle iron and 1 1/2" flat bar. at 3/4" tall they should have been spaced 1 1/2" apart from down stream edge to up stream edge with a 15 degree pitch to them. I am running it with a 2" pump at about 120gpm. I know these riffles can handle more water but this should have been close to enough. the material piled up behind the riffles. when poking at with my finger you can tell there is a lot of force holing it down, but a full circle vortex was not forming. I think but am not sure, that due to the riffle being pushed down fairly hard into my moss that the actual height of the riffles was closer to 1/2" or 5/8" at best. that being said my spacing should have been closer 1" - 1 1/4". what do you think? thoughts, advice? dont' judge my welds. that was nearly my first time stick welding something this small. View attachment 1008103 View attachment 1008105

You would have had better results using the "modified" Clarkson riffle. 3/4" X 3/8" the top leading edge being 3/8" (half the distance of the vertical height). The recommended spacing between riffles is twice the height. Measure from the top of the leading edge of the riffle down to the sluice and double that measurement as the spacing between riffles. That 2:1 ratio is the formula for creating the proper vortex between riffles. (provided the angle of the sluice and the flow are adjusted accordingly)

The 15 degree angle allows for the back of the riffle to be vertical when the sluice is set up at 3" to the foot of drop. The Clarkson study was performed to improve the gold recovery performance of sluices designed for use on high volume fast flow commercial washplants.

Those riffles will need more flow to work properly when used on a highbanker than typical highbanker riffles.
And yes you will have more cons to deal with using Clarkson riffles.



*Also on any sluice using riffles avoid stopping and starting the flow of water once feeding the sluice commences. If you stop the flow for any reason you might as well do a clean out right then because once the flow stops two things happen. #1 the material behind the front of each riffle will run out from under the low pressure area (where the heavies are protected) and #2. the material trapped in the miners moss will pack solid when the water runs out of it rendering it useless for further gold capture.

Below is an example of the modified Clarkson riffle.
Illustration shows a 1" X 1/2" riffle.



GG~

 

[Hoser John]

Clarkson was a sluicebox ,not a highbanker or dredge study so different riffles required for much higher velocity recoveries.Same as hungarian(sluice) vs modified hungarian(dredge).John

 

[WINTERBEAR]

Joeb, welds look fine to me. Hey I work in pullman we should visit sometime I have taken my daughters out panning a couple times and would like to do more. My issue is knowing where there is gold and where we could go with out claim jumping etc.
Chris

 

[Timberdoodle]

Joebwhit - Solid advise from GG as expected . Also lot's of good reading on Heckler Fabrications website. They build highbankers and use Clarkson riffles. A must read is "How to build a sluicebox part3". They do a great job explaining the importance of the leading edge of the following riffle.

 

[principedeleon]

So how you setup angle iron as riffles on a dredge ?.. Is there a different slope angle or lip size to make it work right?

 

[Timberdoodle]

Hi P.. The 15deg angle and lip size (I prefer modified Clarkson's also) can remain the same, but the whole dredge would need to be built to accommodate the flow rates which drive the operation of the riffle's so it takes some time to optimize a system built for Clarkson's and should probably not be viewed as a simple swap. My personal take on this style of riffle is that it is essentially a high energy drop riffle system when in operation. The slurry stratifies well and flows fairly smooth over the top and the vortex energy pulls material down and slams it into the matting for storage. If it's gold it is much harder to release from the matting and works down through. Smaller Clarkson's (1/4"- 3/8") require less velocity and work very well on 1/2" classified material based on testing I did 3 years ago. Don't know if this helps, I'm sure there are others who will chime in with some good info.
I believe the true key to improve recovery in dredges is classification so I haven't done much more testing on the larger Clarkson's for the use in a dredge. Just the smaller Clarkson's for possible use in an underflow. Of coarse this means I do not use punchplate since the flow rates are too slow to properly process the material in the underflow.

 

[principedeleon]

tim..what i want to do is create different kind of obstacles for different shape of gold on my upper current..

 

[joebwhit]

Clarkson was a sluicebox ,not a highbanker or dredge study so different riffles required for much higher velocity recoveries.Same as hungarian(sluice) vs modified hungarian(dredge).John

A highbanker is a sluice with a hopper. the only thing different is washing proccess and the caliber of the equipment. once the water and classified material hit the sluice it is the same physics no matter what you call it. but I do agree that water flow is vital. I was having to slow my feed rate and water flow to match my hungarian riffles. My thoughts are that I wanted to modify my equipment to meet what I could feed it. not modify my feed rate to match my equipment.

Thank you GG for the advice. I think it will just take more fiddling with. I wanted to use modified clarkstons but I was avoiding cutting that much 1/8" steel with my grinder. I talked to a couple of fabrication shops aroung about breaking some for me. The problem I came across was the rounded corner that would result. I wanted that sharp 90 deg corner to help create the vortex.

I think I am going to take the time to rip them down to 3/8"x3/4" and space them at 1 1/4" and increase the flow. I am going to split my 2" hose down to two 1 1/4" hoses. one feeding the hopper and the other feeding directly into the back of the sluice. that way I can increase to sluice flow without blowing material out of the back of my hopper. I somewhat limited myself with my hopper to begin with. that problem will eventually be addressed as well.

 

[joebwhit]

Joebwhit - Solid advise from GG as expected . Also lot's of good reading on Heckler Fabrications website. They build highbankers and use Clarkson riffles. A must read is "How to build a sluicebox part3". They do a great job explaining the importance of the leading edge of the following riffle.

I have spent some time on the phone with the guys at hedkler and read how to build a sluice box. I was going to just order riffles from them but after a couple of emails and phone calls I could never get a quote for the material so I made due with what I could get locally. great company and very friendly but they are very busy with international commercial wash plants. no hard feelings at all. If I could swing it financially I wound just order their 5-10 or 8-10 higbanker.

 

[Goodyguy]

Joe,
I use modified Clarksons on my trommel sluice and they work excellent! They are 1" x 1/2" at 2" apart. The sluice is 10" wide x 48" and I use vortex mat under them.
They would NOT be good for a dredge sluice however due to several factors, not the least of which would be the necessary 3" drop per foot of sluice.






GG~

 

[Timberdoodle]

tim..what i want to do is create different kind of obstacles for different shape of gold on my upper current..

Hi P.. I'm sure you can achieve this, but you may need to try a few different sizes of riffles and spacing to match the flow in your dredge. I like to build jig's and used clear plastic to monitor operation until I settle on a configuration so it can be time consuming. There are some video's on youtube from Greywolfminer and 3n1productions100 that are good to watch if you want to see some in action and give you an idea on what to look for when running them.

 

[Timberdoodle]

Joe,
I use modified Clarksons on my trommel sluice and they work excellent! They are 1" x 1/2" at 2" apart. The sluice is 10" wide x 48" and I use vortex mat under them.
They would NOT be good for a dredge sluice however due to several factors, not the least of which would be the necessary 3" drop per foot of sluice.
GG~

GG- what do you think about 1/2" x 1/4" at 1' apart in a dredge. You would need to decrease sluice width to approximately the same width as the flare width to increase velocity instead of needing 3" drop?
I'm glad to hear you are using vortex with clarksons and getting great results. I have been wanting to try this.

 

[Goodyguy]

GG- what do you think about 1/2" x 1/4" at 1' apart in a dredge. You would need to decrease sluice width to approximately the same width as the flare width to increase velocity instead of needing 3" drop?
I'm glad to hear you are using vortex with clarksons and getting great results. I have been wanting to try this.

You must have the drop in order for the 15 degree riffle angle to create the proper vortex between riffles. You don't want the gold launching from riffle to riffle and out the end of the sluice. Proper velocity is very important along with angle.

I like your clear plastic method but having a waterproof camera video the action in addition is a great way to watch the flow of gold over the riffles (in slow motion) to see where it actually drops out. You may be surprised at what actually happens vs what you expected to happen. And of course smaller gold will act differently than the larger sizes.

You may want to check out the "Gold Hog Study" http://www.goldhog.com/riffle_sluice_gold_study.htm Doc has come to some of the same conclusions as I have independently of one another.

As far as using vortex mat with Clarkson's goes, it's a great match up because the vortex mat also works best at the 3" to foot of drop angle. So it's a double whammy.

GG~

 

[Timberdoodle]

You must have the drop in order for the 15 degree riffle angle to create the proper vortex between riffles. You don't want the gold launching from riffle to riffle and out the end of the sluice. Proper velocity is very important along with angle.

I like your clear plastic method but having a waterproof camera video the action in addition is the best way to watch the flow of gold over the riffles and to see where it actually drops out. You may be surprised at what actually happens vs what you expected to happen. And of course smaller gold will act differently than the larger sizes.

You may want to check out the "Gold Hog Study" Riffle Study - Sluice Science Doc has come to some of the same conclusions as I have independently of one another.

GG~

I have done a lot of testing in submersibles and using pressure to control flow speed and found good operation of the vortex can be achieved by applying the right velocity, but I will have to look at this closer going forward. Thanks GG

 

[joebwhit]

GG,
What kind of gpm/gph are you running? I have a pretty good eye for plumb (carpenter for 11 years) so I welded the hardware for my front legs at 15 deg. When the legs are plumb my sluice is at 15. I like your trommel set up. I have toyed with the idea of building something like that. What kind of RPMs do you shoot for on a trommel like that?

 

[joebwhit]

better yet...more trommel drive pictures please?