Water volume & velocity questions...

[X4FRNT]

Just trying to figure out the right amount of water velocity needed to clear out the 1/4” rocks, leaving the gold and heavies behind the riffles. I’m using a simple Royal 24” backpack sluice, it works fine but I constantly find myself spending 20-30 minutes to process about 2.5 gallons of screened material. And yes, I’ve seen the gold hog videos of doc explaining proportional force and all that.

I’ve been experimenting using different matting in my sluice, the standard carpet with riffles, the carpet + expanded metal + riffles, and carpet with expanded metal + riffles and using miners moss at the tail end.

I may try using 2 sluices, one in front of the other with a slight drop to the second sluice, that way I can increase the water velocity and not worry too much about losing gold because the second sluice can grab it.

Anyone have a video of a stream sluice with the correct water flow and velocity they can share?

One another note, found a nice picker (nice for N.C. standards are least, at Uwharrie) View attachment 1788747

 

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[Koalajones]

From what I been told and seen the sluice should be at around 5 degrees. Also I watch flowergold wizard on YouTube

 

[X4FRNT]

Found this video- looks like that sluice is running with about the perfect volume and velocity, seems like I answered my own question. What do y’all think of it?

https://m.youtube.com/watch?v=gxe4N9fUhuU

 

[johnedoe]

Just trying to figure out the right amount of water velocity needed to clear out the 1/4” rocks, leaving the gold and heavies behind the riffles...............And yes, I’ve seen the gold hog videos of doc explaining proportional force and all that.

Then you weren't paying attention........................

 

[KevinInColorado]

The real answer is “it depends”. Set up your sluice and see how it behaves in he river conditions that day. Simply adjust until it is shedding the blonde sands and small rocks within about 5-10 seconds. If you can’t get it to shed the small rocks, either
- get it steeper
- move into an area of faster current
- classify the paydirt down so only smaller stuff is going in the sluice

 

[PickAxeCA]

If it's taking you 20-30 minutes to process 2.5 gallons (half a bucket) then you would be way better off using a different concentration method than a sluice in poor flow.

If flow is seldom strong in your area you might want to look into a production panning system like the Pyramid Pro Pan.

With my PPP I can get a half bucket done unclassified in 1-2 minutes - much faster than a sluice in poor flow.

Even a Garret Super Sluice could get it done in 5-6 minutes unclassified if you: 1. Stratify fast and then 2. Skim material off the front of the pan with your hand (but not the back as gold can creep upwards to the surface there). Rinse and repeat until you're down to black sands, and then keep going with the concentrates still in the bottom of your pan.

It shouldn't take you 20-30 minutes to process 2.5 gallons of material.

 

[johnedoe]

For production panning I still like this one....
As you get used to the pan you can cut the time he shows in the vid easily in half.....

 

[arizau]

If it's taking you 20-30 minutes to process 2.5 gallons (half a bucket) then you would be way better off using a different concentration method than a sluice in poor flow.

If flow is seldom strong in your area you might want to look into a production panning system like the Pyramid Pro Pan.

With my PPP I can get a half bucket done unclassified in 1-2 minutes - much faster than a sluice in poor flow.

Even a Garret Super Sluice could get it done in 5-6 minutes unclassified if you: 1. Stratify fast and then 2. Skim material off the front of the pan with your hand (but not the back as gold can creep upwards to the surface there). Rinse and repeat until you're down to black sands, and then keep going with the concentrates still in the bottom of your pan.

It shouldn't take you 20-30 minutes to process 2.5 gallons of material.

See how easy it is to overlook an obvious solution.

 

[Johnnybravo300]

I run my sluices on the fast side if anything. Then again I run Angus sluices and they are gold catching BEASTS!
Dont be afraid to lose gold. Its heavy enough that it will fall out.
If your catching black sands then you'll catch gold. Run that sluice hard.

 

[X4FRNT]

I just picked up a Robinson backpack sluice this week, it’s a drop style sluice and it’s been catching a lot more than my Royal sluice. It has been clearing the 1/4” rocks with no problem and leaving the heavies in the riffles just like it should, thanks for the help!

 

[Goldwasher]

I just picked up a Robinson backpack sluice this week, it’s a drop style sluice and it’s been catching a lot more than my Royal sluice. It has been clearing the 1/4” rocks with no problem and leaving the heavies in the riffles just like it should, thanks for the help! View attachment 1791043View attachment 1791043

With a drop riffle and good flow you barely need to bother classifying a one inch screen will work or milk crate

 

[Johnnybravo300]

That looks like a nice lil prospecting sluice. I have the Angus Grub Stake about that size. Practically weighs nothing and with the nice drop riffles theres no expanded metal or mats or wing nuts to lose. Run that baby hard then rinse out right in the gold pan in seconds flat.
When im hiking in a distance and I take that sluice I will take a couple extra gold pans instead of buckets. Way easier to pack and lighter than buckets. They dont hold as much but it dont matter, just keep working and it evens out in the end.
By the time you pack food and water, the basic tools, it adds up dang fast to carry for a distance.

I've done the milk crate classified onto a sled thing before and it worked fine. Once the riffles fill with black sands the bigger rocks roll right down.

 

[X4FRNT]

Yeah I was out this morning doing some sluicing and within 2 hours I ran 3x 5gallon buckets full of 1/4” material (majority of the time was classifying... cleanup was done in less than 1 minute, and I just put my cons into a large ziplock to pan out later on. Did 2 cleanups, black sand in this area is prevalent, ended up with about half a large ziplock bag of concentrated left to pan.

This sluice is 33” long, flared to a 10” wide drop riffle sluice, I think I paid $38 for it! It weighs absolutely nothing, drilled a couple holes and with a couple carabiners I can attach it to my backpack and good to go. It’s perfect for what I’m doing.

What do you think is better though, the fluid bed sluices or the drop ruffle design sluices? Just curious...

I can see how some of the very fine gold can escape, based on Doc’s vid on proportional force and depending on the water level within the sluice, very fine gold could escape because not enough turbulence within the sluice to let it drop out. With a fluid bed sluice this is not ever an issue. Just wondering if any has contemplated the idea of adding a fluid bed to the end of a drop riffle, powered by a hose upstream to fluidize the material that ends up there. It’s a theory in development for me obviously.

I have a flap that I have contemplated experimenting with in my drop riffle sluice, just to push the fine gold down from the top column of water moving through the slurry allowing it to drop into the riffles.

Any thoughts?

 

[Johnnybravo300]

Fluid bed sluices are nice but they take heavy water flow and theres more that can wrong with tubes that can clog then you lose all the gold.
Molded drop riffles are super easy and can work in much less water and in shallower water.
I've had two different size bazookas but only use drop riffles anymore. My own personal preference to save weight and bulkiness.

They both catch gold just fine so run what you like.

 

[KevinInColorado]

I have both and use both depending on circumstances.

 

[Lemarquez]

Just trying to figure out the right amount of water velocity needed to clear out the 1/4” rocks, leaving the gold and heavies behind the riffles. I’m using a simple Royal 24” backpack sluice, it works fine but I constantly find myself spending 20-30 minutes to process about 2.5 gallons of screened material. And yes, I’ve seen the gold hog videos of doc explaining proportional force and all that.

I’ve been experimenting using different matting in my sluice, the standard carpet with riffles, the carpet + expanded metal + riffles, and carpet with expanded metal + riffles and using miners moss at the tail end.

I may try using 2 sluices, one in front of the other with a slight drop to the second sluice, that way I can increase the water velocity and not worry too much about losing gold because the second sluice can grab it.

Anyone have a video of a stream sluice with the correct water flow and velocity they can share?

One another note, found a nice picker (nice for N.C. standards are least, at Uwharrie) View attachment 1788747

To answer your question, I advise you to read this web page that I found on a French site. There is a translator at the top of the site to have it in English.
https://www.goldlineorpaillage.fr/formule-mathematique-orpaillage/

 

[Placermaster]

Gold drops from a water stream below 8feet per second so speed of water must be kept same. Fluid beds have a lot of velocity issues that can blow out placers. I like drop unless a lot of heavies like garnets then you need hydraulic riffles. Big boxes for hydro lock systems. Stick with clarkson study that recovered 100percent recovery with 1inch hungarian riffles on 3m moss for 40 feet... 100 percent gold caught. Flow math was about 1 inch lift for every foot of sluice. For shorter box use combo mats.