gravity dredge + modified sluice box = Need some help guys

Made a little vid for you .

Cheers Emilio


cheers bro --- didnt go dredging for sometimes now---
getting ready for the new adventures ---
summer is here8-)
 

The rule of thumb for sluice angle is only as much as you need to prevent load up. I never run my sluices at an inch per foot. I run as flat as the water and material will let me.

On thing i see is too many dips/low points in the hose.

For every foot you need to get good siphon your fighting your gains with those dips.

Try to get a bunch of boards set up to lay the hose along. It will help stop plug ups and keep the water moving. I know it is more stuff to move but it will help a lot.
Having the hose straight and even grade is key. That last dip before entering the sluice needs to go.

For priming have a splice about 1/3 from the intake that is slip fit. A cap at both ends. When your ready to run fill upper section with cap at bottom,when full cap it.
Go to bottom uncap and join to rest of the run. Go back to intake remove cap with it under water and you should be good to go.

Looks like you have some help so it should be pretty easy.
 

Plumbers stoppers come in 3" & 4". They have the big wingnut to tighten in the pipe.
Mostly used when changing toilet-to-floor seal, to keep gasses from coming into the house.

Put one into the exit end of your hose, then at the top... sip/gulp water into the pipe until all (most) the air is out.

We take from 5 to 15 minutes to prime 70' of 4" hose.
Well gold NH.jpg
 

Amen jack, mighty fine lookn' gold -Smooth inside hose works much better as corrugated slows down the water flow with the ribbing. 4" hose is my favorite size and sometimes a 2 1/2 " extension to get around to smaller cracks -John
 

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Ok, now have data time to view videos. :hello2: I watched the video in the OP and, at 10+ foot of drop and 100' of hose, I have to ask why your water isn't coming out with more force. Would be great if we could have seen toe other end of the 100' run, where the water comes into the pipe. One thing that would have helped that a lot would have been to have a length of larger pipe/hose, like 4", then for the last 25' or so, switch back down to 3". The weight of the water in the 4" will help push more water through your 3", which should increase both your volume and pressure.
 

Ok, now have data time to view videos. :hello2: I watched the video in the OP and, at 10+ foot of drop and 100' of hose, I have to ask why your water isn't coming out with more force. Would be great if we could have seen toe other end of the 100' run, where the water comes into the pipe. One thing that would have helped that a lot would have been to have a length of larger pipe/hose, like 4", then for the last 25' or so, switch back down to 3". The weight of the water in the 4" will help push more water through your 3", which should increase both your volume and pressure.

Hi, the hose is a 3'' all the way - I am planning a new setup with pvc pipes... Maybe it will be better
 

One more question...
Do the hose size need to be different in every section in order to have a high pressure?
 

Hi again guys.
will this setup work?
with a drop of over 6 feet.

correct me if i am wrong, especially for the hose size or the location of the connexion-
cheers
gravity dredge setup.jpg
 

Hi again guys.
will this setup work?
with a drop of over 6 feet.

correct me if i am wrong, especially for the hose size or the location of the connexion-
cheers
View attachment 1451452

NO - With 6' of drop you are only developing about 12 psi of pressure. You will need at least 40 psi of pressure, about 80 feet of drop, to start to get any form of usable suction from your nozzle. You really want to look to get at least 60 psi, about a 120' of drop. Also, loose loose the 4" pipe the way you have it configured, this is going to cause you several problems including suction and plug ups - even with a 3" nozzle. Use 3" hose for all of it with a 2.5" nozzle.

ratled
 

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NO - With 6' of drop you are only developing about 12 psi of pressure. You will need at least 40 psi of pressure, about 80 feet of drop, to start to get any form of usable suction from your nozzle. You really want to look to get at least 60 psi, about a 120' of drop. Also, loose loose the 4" pipe the way you have it configured, this is going to cause you several problems including suction and plug ups - even with a 3" nozzle. Use 3" hose for all of it with a 2.5" nozzle.

ratled

i may get like 10-12 ft drop --- and will use as suggested the full 3 inches pipe -
will make new video as soon as i do it.
cheers ratled
 

NO - With 6' of drop you are only developing about 12 psi of pressure. You will need at least 40 psi of pressure, about 80 feet of drop, to start to get any form of usable suction from your nozzle. You really want to look to get at least 60 psi, about a 120' of drop. Also, loose loose the 4" pipe the way you have it configured, this is going to cause you several problems including suction and plug ups - even with a 3" nozzle. Use 3" hose for all of it with a 2.5" nozzle.

ratled

hey ratled, iam trying to have a similar set up than this guy ( who actually go to the same river than i do) but we had never a chance to meet.
his set up seems to work very smoothly, however he use i think:
blue pipe = 4 inches = maybe 15-20 feet to suck the gravel
grey pipe = 3 inches = maybe 10-15 feet to add more pressure
i guess a 4 feet maximum of drop

here is his video on youtube:




how is it possible for him to have such flow and pressure?

cheers
 

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He has things different than your picture. The biggest is the blue pipe goes straight into the sluice and does not reduce into 3" like your picture - no chance for a plug up. Second he is using the blue pipe as siphon suction dredge not a a true gravity like you described. I would say he could loose the grey pipe and have no loss in pressure and he may actually be better off doing so as the grey hose is adding a volume of water, not pressure, and is causing a hindrance to the natural flow of the siphon of the blue hose - could cause plug ups.

I hope this makes sense, trying to paint a picture with words is hard

ratled
 

One more question...
Do the hose size need to be different in every section in order to have a high pressure?

Hose size doesn't cause pressure in this case, atmospheric pressure is "pushing" on the water causing the pressure you seek and is assited by gravity pull on the water which is why the the more "drop" you have the better the presure
 

Hose size doesn't cause pressure in this case, atmospheric pressure is "pushing" on the water causing the pressure you seek and is assited by gravity pull on the water which is why the the more "drop" you have the better the presure

so basically i should keep just the one 3 inche hose with nothing else ---
i was thinking by adding a second hose it will add more water so more pressure--- but obviously iam wrong-

i should receive my BGT prospector next week and try up the gravity dredge in 2 weeks time - will do more detailled videos too so u guys can give me more advices

any other hint will be highly appreciated.
cheers bro
 

Hi everyone -- now it is time to re-study the river design-
I have completed a google map with locations on where i have got my nuggets and smaller one, + specs
i uploaded some google view photos to give you an idea on how the terrain looks like, however, a couple of VERY important point to keep in mind:

1) on each side of the river there is some huge tall walls ( 8-10 meters) to control the river-
2) this is Taiwan --- we are hit by an average of 3 to 5 typhoons every year ( june to september maximum)
3) we do have earthquake in a daily basis ( less than 4.5 ---- it doesnt count for us)
4) all the gold from this part of the river comes from the mountain on the back ( which was mined 50 years ago)
5) during typhoon, and because of the walls, the level of the river rise by 6 -9 meters as it just filling up so basically gold will have a different path i guess
6) guys find nuggets in a weekly basis ( sniping, panning etc...)
7) configuration of this river change every time we have a heavy rain --- during typhoon season, you just cannot recognise the place anymore ( i mean boulders as big as rooms are moved without a pbm

so my question is: waz uppp!!! :laughing7:
nah, to be serious, how do you think gold travel in this kind of closed environment ( i means once flled with rain from typhoons)

PS= from A to B = around 500 meters ---- and B to C = 300 meters ===== 800 meters where there is gold all year long
Width of the river = 80 meters maximum from each side ( not wall to wall)

SMALL DESIGN
riviere - finale.png

A
A - B - C.PNG

FIRST CURVE
FIRST CURVE.PNG

INSIDE THE CURVE
INSIDE THE CURVE.PNG

END OF CURVE
END OF CURVE.PNG

B
B.PNG
 

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One easy way to fill the hose is to find a deep pool and start coiling the hose on the bottom of the pool starting with the bottom end of the hose. Once the hose is all submerged, then cap the bottom end (and the top end too if you will be moving it much) and then move the hose to where you want to suction. Once you have the hose in place, remove the caps, top first, making sure the top end is under the water. This only works if you have a water-tight seal on the bottom end though.
 

Is a dredge legal where your at ? If so , get the biggest one you can afford (you can always buy a bigger dredge with the gold you suck up:headbang:) and while your at it , hire a crew to run this for you! you ought to be able to afford it now!
 

Is a dredge legal where your at ? If so , get the biggest one you can afford (you can always buy a bigger dredge with the gold you suck up:headbang:) and while your at it , hire a crew to run this for you! you ought to be able to afford it now!

nahhh--- over here you need to keep low profile and can't use any motor/engine.

you can't imagine how i would love to dredge like guys in the states.
 

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